1. What evidence is there that some behavior is genetic, and that some behavior is learned?

1.  
   1. Evidence for genetic behaviors – instinctual behaviors.  Inbreeding creates lineages with specific behaviors. Cross breeding dilutes these behaviors, sometimes along Mendelian ratios if relatively few genes are involved. Specific genes are associated with behavior
   2. Evidence for learned behaviors – learning where to forage, where, where to find water, or shelter at specific times of year.  Animals that spend a long childhood with a parent tend to learn more

1.  
   1. active conditioning. This is when an animal must perform and act in response to a stimulus to get the reward. The reward follows the behavior (not the stimulus). Animal training involves operant conditioning. A dog that shakes your hand or sits before receiving a biscuit is operant conditioning. 

1.  
   1. occurs when an animal responds to a specific stimuli:  a dog conditioned to salivate to a specific color of light.

1.  
   1. learning that occurs in the absence of an immediate reward. Latent learning includes an animal learning the lay of its home range which helps it to know where to run for safety and such.

1.  
   1. Insight learning 

1.  
   1. Imprinting – 

1.  
   1. Retrieval – 

1.  
   1. Long-term memory – 

1.  
   1. Short-term memory – 

1.  
   1. does not leave an engram. Thought to be created by reverberating circuits of neurons. These circuits include positive feedback loops that increase the activity of certain stimuli. These loops will break down without repeated outside stimuli.

                                                              i.      certain events, especially those that emotionally stimulating, are much more likely to be retained in short-term memory and consolidated into long-term memory

1.  
   1. Coloration – 

1.  
   1. Tags – 

1.  
   1. Posture – 

1.  
   1. Sound – 

1.  
   1. Pheromones – 

1.  
   1. Chemicals – 

1. How is behavior related to the genetic isolation that forms a species? 

1. Describe the role of aggression between and among species. 

1. Aggression appears to be highly instinctual and is influenced by a number of triggers such as development, hormones, seasonality, pheromones, and visual and auditory stimuli.
   1. 
      

1. Intraspecific aggression – 

1. combat between males is a ritualistic but can become very violent and dangerous. Most intraspecific fighting adaptations such as antlers are designed to prevent injury to self and opponent. Tines of the deer antlers lock together rather than puncture.   Most vertebrates seem to possess some sense of self-awareness. Intraspecific triggers of aggression relate to territorial defense of food and/or mating resources

1. 
   
2. Interspecific 

1. Social behaviors are those that permit animals to coexist in groups, forming discrete functional entities.
   1. Cooperative behaviors help both parties.

                                                              i.      Intraspecific cooperation is widespread and generally revolves around one of the following:  helping one another obtain food, obtaining mates, protection, maintaining health (grooming)

                                                            ii.      Interspecific cooperation also occurs but is not important in social behavior

1.  
   1. Altruism – is a behavior that benefits another at cost to self. Altruism is an effective evolutionary strategy in species with social hierarchy.

1. What evidence is there that animals possess emotions and culture? 

1. Describe the parts of a neuron and how they function in impulse conduction. 

1. Neurons and muscle fibers are excitable cells that conduct impulses.  Parts of a neuron include:
   1. Dendrites  - are a process of the cell thatreceives impulses. There may be numerous dendrites
   2. Soma – is the cell body that contains the nucleus and the bulk of the cytoplasm
   3. Axon – a process of the cell that carries impulses away from the soma. Typically there’s a single axon, although it may have many branches called collaterals.   The end of the axon is call the axon terminals.

1. What are the excitable tissues and what makes them excitable tissues? 

1. Describe how a resting potential is established in an excitable tissue by the sodium-potassium pump and is this an active or passive process? 

1. Before an impulse can be generated, a resting potential across the cell membrane must be established.
   1. Excitable membranes contain active transport systems known as Na+ / K+ pumps
   2. Sodium is pumped across the cell membrane from the inside of the cell to the outside, and Potassium from the outside to inside in an unequal ratio  3 Na+  to 2 K+
   3. The Na/K pump establishes a concentration gradient and a charge gradient of the two ions across the membrane. There are more Na ion on the outside than there are K ions on the inside. This makes the inside negative compared to the outside.  This charge gradient is know as theresting potential of the cell, and measured at 65 mV, meaning the cell cytoplasm is 65mV more negative than the extracellular solution.
   4. The gradient stabilizes at -65mV because at this point the pumping of ions is offset by their diffusion through ungated channels

1. Na+ ions are concentrated in the extracellular solution.  K+ is concentrated within the cytoplasm of the cell.

1. Events of an action potential:
   1. A chemical or physical stimuli will alter Na ion gated channel proteins making them permeable to Na
   2. Na leaks across the membrane into the cell effecting the resting potential making the cytoplasm more +
   3. At -55mV a threshold potential is reached. The local voltage gated Na channel proteins open allowing Na to flood into the cell at that spot. 
   4. This is the beginning of an action potential. Now an impulse will be generated
   5. As Na rushes into the cell the charge of the cell changes from -55mV  to  +40mV in a millisecond
   6. The Na voltage gated channel proteins close immediately.  The influx of Na ions is know as depolarization
   7. K voltage gated channels opens allowing K ions to flood out of the cell.
   8. The out flux of K ions makes the cytoplasm negative again and drops from +40mV  to -70mV
   9. The K voltage gated channel proteins close immediately.  This is know as repolarization of membrane
   10. The Na/K pump will reestablish the resting potential of -65mV.  This ends the action potential

                                                              i.      Resting potential                           -65mV

                                                            ii.      Threshold potential                       -55mV

                                                          iii.      Action potential depolarization     +40 mV

                                                          iv.      Repolarization                                -70mV

1. Describe how an impulse is propagated along a membrane.

1. Why is an action potential considered an “all-or-none” event? 

1. Why is an impulse considered an “all-or-none” event?

1. Describe saltatory conduction in a peripheral nerve fiber using the following terms: Schwann cell, node of Ranvier, axon, and myelin sheath. 

1. A salutatory conduction is a more rapid impulse conduction than the “normal” impulse
   1. Some neurons that form the peripheral nervous sys (PNS) have myelinated axons or dendrites
   2. Myelinated peripheral nerves have specialized glial cells called Schwann cells associated with axons or dendrite as it grows
   3. Schwann cells attach and wrap around the dendrite or axon. Schwann cell membranes have white fatty substance called myelin
   4. Myelin prevents Na and K ion channels from functioning
   5. Gaps between the Schwann cells called Nodes of Ranvier expose the neurilemma (neuron cell membrane), these gaps have a high concentrations of Na and K voltage gated channel proteins.

1. Why do myelinated fibers conduct impulses faster than unmyelinated ones? 
   1. 
      

1. As Na ions flood into the cytoplasm in depolarization, they repel other positively charged ions creating a magnetic flux
2. The flux passes from one node of Ranvier to the next
3. The flux opens all the highly concentrated Na voltage gated channel proteins of the next node of Ranvier
4. An action potential is generated at the node, creating another magnetic flux which jumps to the next node
5. It jumps from node to node because the myelin prevents impulse conduction along the membrane. Axon potentials can only occur at exposed neurilemma sites (nodes of Ranvier). The highly concentrated voltage channels create a stronger flux than normal neurilemma. As a result myelinated fibers are faster

1. Describe the events that occur at a synapse using the following terms: synapse, presynaptic cell, postsynaptic cell, axon, dendrite, neuronal synapse, neuromuscular synapse, synaptic vesicles, neurotransmitter, and receptor proteins.

1.  
   1. Impulses are conducted in all direction from the site of action potential initiation. However, functionally and impulse works from dendrite to axon.
   2. When the impulse reaches the end of the axon there is a space between the neuron (presynaptic cell), and the next cell (postsynaptic cell) called a synapse.
   3. The next cell (postsynaptic cell), the dendrite of another neuron, forms a neuronal synapse (junction)
   4. Or, the next cell (postsynaptic cell), a muscle fiber cell, forms a neuromuscular synapse (junction)
   5. The axon contains numerous synaptic vesicles that contain chemicals called neurotransmitters
   6. An impulse causes the vesicles to fuse with the neurilemma, spewing the contents into the synapse
   7. Neurotransmitters diffuse across the synapse and bind to receptor proteins in the postsynaptic membrane, producing one of two effects (if postsynaptic cell is excitable)

                                                              i.      Excitation – increases Na ion permeability leading to the threshold potential

                                                            ii.      Inhibition – decreases Na ion permeability preventing action potential generation

1.  
   1. Postsynaptic cell enzymes degrade the neurotransmitters and reabsorbed by presynaptic cell

1. How are excitatory neurotransmitters different from inhibitory neurotransmitters, and what determines whether a neurotransmitter will be excitatory or inhibitory?

                                                              i.      Excitation – increases Na ion permeability leading to the threshold potential

                                                            ii.      Inhibition – decreases Na ion permeability preventing action potential generation

Excitation or inhibition of the postsynaptic cell depends on the combination of neurotransmitter secreted by the presynaptic cell, and the receptor protein of the postsynaptic cell. The postsynaptic cell may not be excitable, in which case the neurotransmitter may produce some other effect.

1. Why are synapses necessary?

1. Describe the events that occur at a neuromuscular junction using the following terms: acetylcholine, Ach receptors, adenyl cyclase, cyclic AMP, kinase, ion gated Na channel proteins, threshold potential, action potential.

1.  
   1. Neurons that innervate skeletal muscles have synaptic vesicles that contain the neurotransmitter acetylcholine (Ach)
   2. In response to an impulse the synaptic vesicles spew Ach into the synapse
   3. Ach binds to the membrane receptor protein of the postsynaptic sarcolemma (cell membrane of muscle cell)
   4. In response to binding Ache, the membrane protein binds and activates the cytoplasmic enzyme, adenyl cyclase
   5. Activated adenyl cyclase converts ATP into cAMP (cyclic AMP)
   6. cAMP binds to and activates the enzyme kinase
   7. activated kinase enzymes phosphorylates an ion gated Na ion channel protein
   8. phosphorylating the ion gated Na channel protein opens its gate, increasing the membrane’s permeability to Na ions
   9. enough Ach will cause the membrane to reach threshold potential, generating an action potential.

1.  
   1. muscle cells

                                                              i.      Sarcolemma – muscle cell membrane and has deep invaginations called transverse tubules (t-tubules)

1.  
   1. Endomysium – a thin layer of dense irregular tissue in which each muscle fiber is incased

1.  
   1. Perimysium –

1.  
   1. Epimysium – 

1.  
   1. Myofibrils –

1.  
   1. Myofilaments – 

1.  
   1. Thin myofilaments – 

1.  
   1. composed of the globular subunits of the protein actin, which form a double helix, troponin-tropomyosin complex is also helical and overlays the myosin binding sites of the actin subunits

                                                              i.      actin proteins have myosin binding sites where myosin heads will bind

                                                            ii.      the troponin-tropomyosin complex normally cover the myosin binding sites

                                                          iii.      when troponin-tropomyosin complex binds Ca ions, the shape changes exposing myosin-binding sites 

1.  
   1. thick myofilaments – 

1.  
   1. are composed of the protein myosin

                                                              i.      the myosin protein has a myosin head

                                                            ii.      the myosin head will bind to actin and has two pivot points

                                                          iii.      when bound to ATP, it will be in a power position

                                                          iv.      when ATP is released, the heads spring forward

1.  
   1. sarcomere – 

1. Using the terms above as well as the terms sarcoplasmic reticulum and transverse tubules, describe the sliding filament mechanism of muscle contraction.

1.  
   1. A neuron innervating a muscle, conducts an impulse, initiating an action potential in the sarcolemma
   2. The impulse is conducted throughout the sarcolemma including the t-tubes down into the interior of the fiber to the membrane of the sarcoplasmic reticulum (SR)   -(smooth endoplasmic reticulum)
   3. When the impulse reaches the SR, voltage gated Ca ion channel proteins open and Ca floods out of SR
   4. The Ca binds to the troponin-tropomyosin complex which changes the shape of the helix exposing myosin-binding sites
   5. Myosin heads having already bound ATP, and in a power position, bind to actin causing myosin heads to release ADP and phosphate
   6. This causes a change in shape of the myosin head - - it pivots forward in two positions, pulling the actin (thin filaments) over the myosin myofilaments
   7. The sliding of thin myofilaments past thick myofilaments shortens the muscle
   8. The Ca pump in the SR will actively transport Ca ions back into the SR
   9. When the Ca back in the SR, the troponin-tropomyosin complex recovers the myosin binding sites on the actin protein, ending the contraction.
   10. Muscle contraction is an all or nothing event

1. Is contraction of a muscle (organ) an all-or-none event?  Explain. 

1. No
   1. Each muscle fiber contraction is all or nothing, but each fiber is separated from the others by the endomysium
   2. The endomysium will conduct impulses (dense irregular tissue), and acts as insulation between muscle fibers
   3. Strength of contraction of a muscle is dependent on how many muscle fibers are contracted
   4. A motor unit consists of a neuron and the muscle fibers in innervates
   5. Motor units are recruited, the greater the strength of the contraction

1. Describe the relationship of the following: CNS, PNS, ANS, and Somatic SNS.
   1. 
      

1.  
   1. CNS – central nervous system, composed of the brain and spinal chord
   2. PNS – peripheral nervous system. Composed of nerves that radiate to and from the CNS. Important structures associated with PNS are: sensory receptors such as, mechanoreceptors, chemoreceptors, photoreceptors, thermoreceptors.Ganglia are masses of cell bodies outside the CNS. There are 12 pairs of cranial nerves that arise from different parts of the brain.  There are 31 pairs of spinal nerves named for where they attach to the spinal cord

                                                              i.      SNS – somatic nervous system, composed of nerves that innervate skeletal muscle, i.e. motor nerves and the sense organs

                                                            ii.      ANS – autonomic nervous system, composed of nerves that sense and regulate the viscera (body organs) and related unconscious activities.  ANS is further subdivided into the Sympatheticdivision and parasympathetic division

1.  
   1. Frontal lobes – 

1.  
   1. Parietal lobes – 

1.  
   1. Temporal lobes – 

1.  
   1. Occipital lobes – 

1. How do the right and left sides of the brain differ? 

1. The right and left lobes are not mirrors of each other. About 2/3 of nerve tracts decussate (cross over) from one side of body to other side of brain in brainstem
   1. Left side – logical, temporal, language oriented
   2. Right side – artistic side, “gestalt” conclusion, spatial relations, abstract reasoning.

1.  
   1. Gray matter –

1.  
   1. White matter – 

1.  
   1. Fissure –

1.  
   1. Sulcus – 

1.  
   1. Gyrus – 

1.  
   1. Prosencephalon – 

                                                              i.      Cerebral hemispheres – 

1.      Corpus callosum – 

1.      Commissures – 

1.      Basal nuclei – 

                                                              i.      Diencephalon – 

deep to the cerebral hemispheres and surrounds the third ventricle.Composed of:

1.      epithalamus – forms roof of third ventricle

a.       pineal gland – secretes the hormone melatonin, which triggers sleep cycles

1.      thalamus –

1.      hypothalamus –

 inferior to thalamus, forms floor of third ventricle, and duperior to brain stem. Connects directly to pituitary gland. Has both neural and vascular connections to the hypophysis and has control over it. Includes mamillary bodies that are relay points in olfactory pathway.  Contains nuclei related to these functions:

a.       autonomic control center

b.      physiological response center related to emotions

c.       body temperature regulation

d.      satiety and thirst centers (hungry, full)

e.       circadian rhythms

f.       endocrine regulation via pituitary gland

1.  
   1. Mesencephalon –

                                                              i.      Midbrain – includes the following structures:

1.      cerebral peduncles – large t5racts of white matter that connect to thecerebral hemispheres

2.      corpora quadrigemina – four masses of tissue posterior and inferior to the pineal body composed of the following:

a.       superior colliculi – visual reflex centers such as tracking moving objects

b.      inferior colliculi – auditory reflex centers such as tracking sound and startle reflex

3.      substantia nigra – deep to cerebral peduncles, nucleus linked to basal ganglia, secretes dopamine (neurotransmitter). Motor activities.  If  it degrades, leads to Parkinson’s disease

1.  
   1. Rhombencephalon – 

                                                              i.      Metencephalon – the more superior portion of rhombencephalon, gives rise to:

1.      Pons – inferior to the midbrain, conduction pathway between higher and lower brain centers, respiratory center located in Pons, middle cerebellar peduncles communicate with cerebellum

2.      Cerebellum – athletic brain, dorsal to pons and medulla oblongata, integrates sensory and motor information to carry out learned motor activities. Develops an athletic memory so activities don’t have to be relearned.

                                                              i.      Myelencephalon – more inferior portion of rhombencephalon, gives rise to:

1.  
   1. Afferent neuron – 

1.  
   1. Efferent neuron – 

1.  
   1. Associative neuron – 

1.  
   1. Dorsal horn – 

1.  
   1. Ventral horn – 

1.  
   1. Gray matter – 

1.  
   1. White matter –

1.  
   1. Conus Medullaris – 

1.  
   1. Cauda equina – 

1.  
   1. Lumbar enlargement – 

1. What is cerebrospinal fluid and what is its function?   

Cerebrospinal fluid (CSF) has the following characteristics and functions.

a) It is derived from blood plasma but contains more Sodium and Hydrogen ions and less protein, Calcium, and Potassium.

b) The CSF in and around the brain forms a liquid cushion that gives buoyancy to the brain tissue.

   (1) Brain tissue is notoriously lacking in connective tissue and is highly fatty.

   (2) The CSF provides a medium within which this fatty organ can “float” offsetting its tremendous     mass, and minimizing the need for internal skeletal support, whose rigid structure or sharp edges could rupture brain tissue if a blow to the head occurred.

Choroid Plexus - 

Lateral Ventricles - 

Foramen of Monro - 

CSF flows from each lateral ventricle through a small canal, called the foramen

of Monro into a narrow, centrally located chamber called the third ventricle.

Third Ventricle - 

CSF flows from each lateral ventricle through a small canal, called the foramen of Monro into a narrow, centrally located chamber called the third ventricle.

(1) The epithalamus forms the roof of the third ventricle.

(2) The thalamus forms the walls of the third ventricle.

(3) The hypothalamus forms the floor of the third ventricle.

(4) It is in the midline of the brain, slightly inferior to the lateral ventricles.

(5) The third ventricle also has a choroid plexus that also produces CSF.

Aqueduct of Sylvius -

 CSF flows through the cerebral aqueduct (Canal of Sylvius) to a still smaller

Fourth Ventricle - 

(1) The fourth ventricle is dorsal to the pons and medulla oblongata and ventral to the cerebellum.

(2) The fourth ventricle also has a choroid plexus that produced CSF.

(3) Lateral apertures in the fourth ventricle connect to the subarachnoid space of the cranium.

Central Canal -

Subarachnoid Space - 

Lateral Apertures - 

Superior Sagittal Sinus -

Mechanoreceptors - 

Chemoreceptors - 

Photoreceptors -

Thermoreceptors -

1. How are cranial nerves different from spinal nerves and how many pairs are there of each?

There are twelve pairs of cranial nerves that arise from different parts of the brain.

There are 31 pairs of spinal nerves named for where they attach to the spinal cord. There are 8 cervical spinal nerves, 12 thoracic, 5 lumbar, 5 sacral, and one coccygeal.

1. What are the subdivisions of the PNS?

The PNS may be subdivided according to nerve function.

1. The Sensory Nervous System is composed of sensory or afferent neurons leading to the CNS.

2. The Motor Nervous System is composed of efferent neurons taking impulses away from the CNS—the Motor Nervous System is further subdivided.

a) The Somatic Nervous System (SNS) is composed of nerves that innervate skeletal muscle, i.e. motor nerves, and the sense organs (discussed later).

b) The autonomic nervous system (ANS) is composed of nerves that sense and regulate the viscera (body organs) and related unconscious activities (including visceral motor responses such as vasodilatation and constriction, etc.)

1. How are the sympathetic and parasympathetic systems similar?

The ANS is further subdivided into two subsystems the Sympathetic division and the Parasympathetic division.

Their efferent pathways (impulses going away from the CNS) consist of two neurons, a preganglionic neuron that exits the CNS and a postganglionic neuron that innervates the target organ or tissue.

The preganglionic neuron and the postganglionic neuron synapse at a ganglion outside the CNS.

1. How are the sympathetic and parasympathetic systems different?

It is difficult to make broad generalizations about the two systems, as to whether one is stimulatory and the other inhibitory, etc.

1. What can be said about the sympathetic and parasympathetic systems when they innervate the same organ?

What can be said about the two is that they are antagonistic-- if they innervate the same organ they have opposite effects, i.e. if one vasodilates, the other will vasoconstrict, etc.

1. What are the five types of taste receptors; to which class of receptor (mechanoreceptor, chemoreceptor, etc.) do they belong, and where in the brain is taste processed?

The tongue is the organ of taste.

1. On the tongue are papillae that have taste buds composed of clusters of gustatory cells

with hairs (microvilli) that protrude from their ends.

2. The gustatory hairs have receptors that will bind food chemicals dissolved in the saliva, triggering a chemical cascade leading to an action potential and impulse.

3. The impulse goes to the parietal lobe cortex and is interpreted by the brain.

4. There are five types of gustatory cells that account for the five major tastes-- sweet, sour, salt, bitter, and umami (also called glutamate for the distinctive taste of monosodium glutamate (msg)).

5. The sense of taste is intimately tied to that of smell, and the texture of food.

1. To which major class of receptor do olfactory receptors belong, and where in the brain is smell processed?

The mucous membrane of the nasal cavity is the organ of smell.

1. Olfactory cells are chemoreceptors that line the mucous membrane of the nasal cavity.

2. Olfactory receptor proteins in the olfactory cells trigger a chemical cascade leading to an action potential and impulse.

3. Smell is interpreted in the frontal lobe cortex.

4. The olfactory lobes are in the frontal lobes of the brain, and are where the olfactory neurons enter the brain.

5. Olfaction is not well understood-- it is thought that there are hundreds of different olfactory receptor cells, in stark contrast to the five identified in taste.

1. How many types of olfactory receptors are there?

Olfaction is not well understood-- it is thought that there are hundreds of different olfactory receptor cells, in stark contrast to the five identified in taste.

1. What is the relationship between taste and smell?

The sense of taste is intimately tied to that of smell, and the texture of food. Chemoreceptors. 

1. Describe the tunics of the eye.

The wall of the eye is composed of three tunics.

a) The fibrous tunic protects the eye.

(1) The cornea forms the fibrous tunic anteriorly.

(2) The sclera forms the fibrous tunic posterior to the cornea and is the “white” of the eye.

(3) The sclera is particularly tough.

b) The vascular tunic is highly vascular and is composed of the following structures moving from anterior to posterior-- iris, ciliary body (composed of ciliary muscle, ciliary processes, and suspensory ligaments), and choroid.

c) The retina forms the nervous tunic-- it is where light is converted to impulses.

1. Describe the visual receptors and their distribution and density on the retina.

There are two types of photoreceptors in the retina.

(1) Cones.

(a) Cones require high intensity light, and are responsible for our day vision, visual acuity, and color vision.

(b) There are three types of cones-- red cones, blue cones, and green cones.

(2) Rods are sensitive to even low levels of light and responsible for our night vision.

1. Describe the mechanism of lens accommodation when looking at something near and far away.

Accommodation of the lens.

a) Images are focused at the fovea centralis of the macula lutea via light refraction by the cornea and the lens.

(1) The cornea’s shape is fixed, as is its position, so it acts as a fixed convex lens.

(2) The lens has a fixed position, but it can change shape in a process called accommodation of the lens-- it therefore acts as a variable convex lens, allowing one to focus objects both near and far.

b) Lens accommodation is controlled by the ciliary body and lens elasticity.

(1) The ciliary body is composed of the suspensory ligaments, which attach the lens to ciliary processes of the ciliary muscle.

(2) Like the lens, the ciliary muscle is highly elastic.

(3) The ciliary body attaches to the lens around its periphery.

c) Accommodation for near vision.

(1) Light waves from objects near the eye are strongly refracted and focused on the fovea centralis of the retina-- this requires a strong (thick) convex lens.

(2) When the muscle fibers of the ciliary processes contract they bunch up, and the diameter between the ciliary processes decreases, putting “slack” in the suspensory ligaments.

(3) This allows the elastic lens to assume its natural thickened (almost circular), convex shape.

(4) A thick (more convex) lens refracts light more strongly allowing objects close to the eye to be focused at the fovea centralis.

(1) Light waves from objects distant from the eye require only minimal refraction by the lens to be focused on the fovea centralis of the retina--this requires a weak (thin) convex lens.

(2) When the muscle fibers of the ciliary processes relax, the highly elastic ciliary process assume their normal shape, which is to lie flat against the inner wall of the eye-- this increases the diameter between the ciliary processes, putting tension in the suspensory ligaments that stretches (and flattens) the lens.

(3) With the suspensory ligaments stretching the lens around the periphery, the lens flattens into a thinner, less convex shape.

(4) A thin (less convex) lens refracts light less strongly allowing objects distant from the eye to be focused at the fovea centralis.

e) At first glance accommodation seems counterintuitive, but it makes sense when you consider real life experiences.

(1) The eye fatigues when reading or looking at objects close to the eye—this is because the ciliary muscle is contracting to thicken the lens, and it tires.

(2) Looking at distant objects (more than twenty feet) is easy on the eye because stretching of the lens is caused by relaxation of the ciliary muscle.

Myopia-- 

nearsightedness.

(1) Caused by elongated cornea or elongated eyeball.

Hyperopia (hypermetropia)-- 

farsightedness.

(1) Caused by shortened cornea or shortened eyeball.

(2) Corrected by convex lens.

Presbyopia-- 

loss of accommodation due to aging.

(1) Cause traditionally attributed to a loss of lens elasticity due to aging.

(2) Recent evidence shows that as we age, the suspensory ligament attachment sites move progressively anterior on the lens, which may affect accommodative capacity.

(3) The cause of the suspensory ligament changes is unknown.

(4) Typical onset around 42 years of age.

(5) Corrected by a convex lens.

Astigmatism-- 

From light to impulse to vision.

a) There are two types of photoreceptors in the retina.

(1) Cones.

(a) Cones require high intensity light, and are responsible for our day vision, visual acuity, and color vision.

(b) There are three types of cones-- red cones, blue cones, and green cones.

(2) Rods are sensitive to even low levels of light and responsible for our night vision.

b) The lens accommodates to focus light at a specific region of the retina—the fovea centralis of the macula lutea.

(1) The macula lutea is an area of the retina that has an extremely high concentration of cones, and no rods.

(2) Within the macula lutea is a small (0.4mm) depression where cone concentration is at its greatest.

c) As one radiates away from the macula lutea towards the periphery of the retina, cone concentration decreases, and rod concentration increases.

d) The cones and rods work with other neurons called bipolar cells to trigger action potentials in ganglion cells to trigger impulses.

(1) Cones, rods, and bipolar cells do not generate impulses, but work together to inhibit ganglion cells in the absence of light.

(2) Photopigments within rods and cones change shape in response to absorption of specific wavelengths and intensity of light.

(3) These shape changes lead to a cascade of events that eventually remove inhibition of ganglion cells causing them to depolarize and conduct impulses.

e) Impulses are conducted through the optic nerve to the occipital lobe cortex and interpreted as vision.

(1) Impulses from the medial retina cross over to the other side of the brain through the optic chiasma.

(2) Impulses from the lateral retina are conducted to the occipital lobe on the same side of the brain.

(3) The right occipital lobe, for example, receives impulses from the lateral retina of the right eye, and the medial retina of the left eye.

1. What is the optic disc and why is it called the blind spot?

This visual pathway is unique to Primates and possibly the Megachiroptera.

Where the optic nerve attaches to the retina there are no rods nor cones, hence no vision.

The blind spots are not noticeable for the following reasons.

(a) Our overlapping (stereoscopic) vision covers the gap in the field of vision of the other eye.

(b) We keep our eyes moving so we constantly see our surroundings from slightly different visual fields.

(c) Even if one eye is closed and stationary, it is not noticeable because the brain will “fill in” the blind spot for us, with memory from a previous visual field.

1. What is the function of tears?

a) Are lubricating and antiseptic.

b) Produced by lacrimal glands superolateral to eyeball within orbit of eye.

c) Tears wash across eye into lacrimal canals, drain into lacrimal (or nasolacrimal) duct into nasal cavities.

1. Describe the pathway of sound and how vibrations are converted to impulses.

a) Sound waves are captured by the auricle or pinna and enter the external auditory meatus of the temporal bone.

(1) The external auditory meatus contains hairs to keep things out of the ear.

(2) The external auditory meatus is lined by specialized apocrine sweat glands that secrete a waxy material, cerumen (ear wax) to protect the middle ear.

b) Sound waves vibrate the tympanic membrane (tympanum).

(1) From pinna to tympanum forms the outer ear.

(2) The tympanum is a composed of elastic connective tissue lined by skin externally and mucosa internally.

c) The tympanum vibrates the ossicles of the middle ear--they are, in order, the malleus, incus, and stapes.

(1) The malleus incus and stapes are the smallest bones in the body.

(2) They are connected to one another and the tympanum by connective tissue.

(3) The middle ear is an air filled chamber within the temporal bone.

(4) The Eustachian tube is an opening that leads to the nasopharynx.

(a) The Eustachian tube allows air to move freely in and out of the middle ear in response to changes in atmospheric pressure.

(b) If the middle ear lacked an opening to the outside, air would expand within the middle ear when one went up in altitude and would break the tympanum.

(c) The Eustachian tube is easily plugged by mucous and can cause pain or muffled sound as the air within the middle ear expands, stretching the tympanum.

(d) When pressure builds sufficiently the mucous plug is forced open stabilizing pressure within the middle ear, causing the ears to “pop.”

d) The stapes connects to a thin layer of connective tissue called the oval window.

d) The stapes connects to a thin layer of connective tissue called the oval window.

(1) The oval window is an interface between the middle ear and inner ear.

(2) The inner ear is a bony, fluid filled labyrinth within the temporal bone.

(a) This bony labyrinth forms a spiral tube within the bone.

(b) The fluid is called perilymph.

(c) Suspended within the perilymph is an organ called the cochlea, forming part of a “membranous labyrinth” within the “bony labyrinth”-- the cochlea mimics the pathway of the bony labyrinth.

3) The cochlea is filled with fluid called endolymph, and contains a structure called the Organ of Corti.

(a) The Organ of Corti runs the length of the cochlea.

(b) It is the organ responsible for converting vibrations to impulses.

(c) The Organ of Corti contains mechanoreceptors called hair cells.

(d) Hair cells run between the tectorial and basilar membranes of the

Organ of Corti.

e) The oval window vibrates perilymph (pressure generated is offset by another connective tissue interface between the bony labyrinth and the middle ear called the round window).

f) Perilymph vibrates endolymph within the Organ of Corti.

g) The vibrating endolymph causes a shearing action between the basilar and tectorial membranes, bending microvilli on the hair cells that run between the two membranes.

h) The shearing action on the hair cells triggers an action potential and impulse.

i) The impulse is carried by the cochlear nerve to the temporal cortex where impulses are interpreted as sound.

Bony Labyrinth -

Membranous Labyrinth -

 Suspended within the perilymph is an organ called the cochlea,

forming part of a “membranous labyrinth” within the “bony labyrinth”-- the cochlea mimics the pathway of the bony labyrinth.

Perilymph - 

Endolymph -

Cochlea - 

Utricle - 

Semicircular Canals - 

Hair cells -

Organ of Corti - 

Tectorial Membrane - 

Stereocilia -

Cupula – 

Maculae –

Otolithic Membrane - 

Otoliths - 

1. How is an open vascular system different from a closed one?

The Lymphatic (Lymph) System is an open vascular system that recovers fluid lost from the cardiovascular system, filters it for pathogens, and returns it to veins near the heart. It is an OPEN system, and the vessels have valves to prevent back up of lymph fluid.

Cerebrospinal Fluid - 

It is derived from blood plasma but contains more Sodium and Hydrogen ions

and less protein, Calcium, and Potassium.

Interstitial Fluid - 

Plasma lost from the capillaries of the cardiovascular system becomes interstitial fluid,

which percolates through tissues, and eventually enters lymph vessels as lymph.

Lymph -

Filtrate - 

Sino-atrial Node - 

Atrioventricular Node – 

Bundle of His - 

1. Explain how cardiac tissue is autorhythmic.

The conducting system of heart is composed of “autorhythmic” cardiac muscle that is "leakier" to Na ions, than typical cardiac tissue.

1. The sino-atrial node (SA node) or pacemaker of heart is located in upper, lateral corner of right atrium.

2. The sarcolemma of the SA node is “leaky” to Na ions

a) The membrane gated Na ion channels are not completely closed.

b) As Na ion trickle in, the threshold potential reached, and an action potential and impulse is generated.

3. The impulse is transmitted throughout the atria for the following reasons.

a) Cardiac cell membranes are directly connected, unlike skeletal fibers that are separated by a layer of connective tissue (endomysium).

b) Intercalated discs are concentrations of gap junctions, and are found where cardiac fibers connect to one another.

c) The intercalated discs of cardiac muscle facilitate impulse conduction, as contain gap junctions allow movement of ions across the membranes.

d) Cardiac muscle is referred to as "functional syncytium", in that it conducts an impulse, as would a single cell.

4. The two atria contract in unison.

5. The tricuspid and mitral valve tissue creates a septum of connective tissue that prevents transmission of the impulse into ventricles (connective tissue is not excitable tissue).

6. The impulse does, however, stimulate another mass of conducting tissue, the Atrioventricular node (AV node), located in the lower, medial portion of right atrium.

7. A band of conducting tissue that is an extension of the AV node, called the Bundle of His, conducts this impulse across the connective tissue barrier to ventricular cardiac tissue.

8. The Bundle of His branches into Purkinje fibers that extend throughout the ventricular myocardium.

a) The conducting tissue conducts impulses more rapidly than “ordinary” cardiac tissue.

b) As a result the Purkinje fibers deliver the impulse to the apex (inferior point) of the heart and the impulse quickly flows up towards the atria, only to be blocked by connective tissue separating the atria and ventricles.

9. The resulting ventricular contraction (systole) goes from the bottom-up, forcing blood through the aorta and pulmonary artery, which attach to the superior portion of the ventricles.

10. As with the atria, the ventricles contract simultaneously.

1. What causes the lub-dub of the heart sounds?

Even though there are four chambers, the heartbeat has a two beat cadence-- the heart sounds are described as a “lub-dub.”

1. The "lub" is the sound created by the simultaneous closing of tricuspid and bicuspid valves, caused by ventricular systole.

2. The "dub" is the sound created by the simultaneous closing of aortic and pulmonary semilunar valves, caused by ventricular diastole, and the elasticity of the arteries.

3. The heart sounds are not due to movement of blood, but the slamming of heart valves in response to that movement.

1. What is “normal” blood pressure and how is it related to ventricular systole and diastole?

“Normal” blood pressure is “120/80.” “Systolic pressure” is a measure of arterial pressure generated during ventricular systole (contraction)-- normal systolic pressure for an adult male is 120 mm Hg. Diastolic pressure is a measure of the arterial pressure generated during a ventricular diastole (relaxation)-- normal diastolic pressure for adult male is 80 mm Hg.

1. Describe the mechanism of blood clot formation.

1. Many factors important to homeostasis are dependent on blood volume and pressure including thermoregulation, excretion, gas exchange, and others.

2. When blood vessels and the surrounding tissue are damaged, the tissues release numerous clotting factors including prostaglandins, and thromboplastin into blood (these are considered extrinsic clotting factors since they were not produced by blood cells).

3. The extrinsic clotting factors cause platelets to also release thromboplastin and other clotting factors into the blood plasma (these are considered intrinsic clotting factors because they were produced by blood cells).

4. Prostaglandins make the platelets "sticky" causing them to stick to one another forming a platelet plug, which may partly or completely occlude a vessel opening.

5. Thromboplastin acts as an enzyme, converting a plasma-clotting factor called prothrombin, into a different clotting factor called thrombin.

6. Thrombin is an enzyme that converts the clotting factor fibrinogen into a tough fibrous protein called fibrin.

7. Fibrin fibers attach to one another creating a dense network that is the clot (a dried clot is a scab).

8. The clot seals the damaged area, stopping the loss of blood maintaining homeostasis.

9. Other comments about clotting.

10. Fatty diets high in cholesterol, and circulating triglycerides, can lead to fatty deposits on vessel walls called atherosclerosis.

11. These fatty plaques can lead to platelet plug formation and fibrin clots, which in turn, may calcify the plaque and vessel wall making it inelastic-- this is arteriosclerosis.

12. Both types of vascular disease increase blood pressure by decreasing vessel diameter.

13. Plaques can lead to vessel swellings called aneurysms, which may burst—typically these cause myocardial infarction (heart attack) or stoke.

14. A plaque may dislodge, now forming a moving thrombus, which will eventually lodge in a smaller vessel causing a blockage called an embolism.

Arteriosclerosis -

Atherosclerosis -

Aneurysm - 

Thrombus - 

Right Lymphatic Duct - 

The Right Lymphatic Duct drains lymph from the upper right quadrant of the body,

and empties into the junction of the Right Subclavian and Right Jugular veins converge to form the Right Brachiocephalic vein.

Thoracic Duct - 

Afferent Lymph Vessels -

Efferent Lymph Vessels - 

Lymph Nodes - 

1. Internally the lymph node is sectioned into several large spaces (or sinuses), traversed by a lattice of thin collagenous fibers called reticular tissue.

2. Lymphocytes, and antigen presenting cells like dendrocytes and macrophages cling to the reticular fibers.

3. As lymph percolates through the node, antigens and cellular debris will be phagocytized and may initiate immune responses.

4. Lymph nodes are also sites of lymphocyte reproduction and maturation.

5. Afferent vessels empty lymph into the nodes; efferent vessels drain lymph from the nodes.

6. The tonsils and adenoids are examples of lymph nodes.

Lymphocytes - 

APC’s Macrophages -

Dendrocytes - 

MHC 1 Protein - 

MHC 2 Protein - 

APC’s - 

Dendrocytes - 

Macrophages - 

B Cells - 

Antibodies - 

Antigens -

Gamma Globulins - 

T Cells - 

Helper T’s - 

Cytotoxic T’s - 

Natural Killer T’s - 

Suppressor T’s -

Memory Cells - 

Interleukin - 

Interleukins are chemicals that trigger immune cells to become active and divide.

a) Interleukin 1 is secreted by APC’s-- it activates Helper T’s to secrete interleukin 2 and to divide to produce a clonal population.

b) Interleukin 2 is secreted by activated Helper T cells-- it stimulates B cells to divide and convert to plasma cells (creating a clonal population of plasma cells), and Cytotoxic T’s to divide (creating a clonal population of Cytotoxic T’s) and “seek and destroy” infected cells.

1. Describe the events in specific humoral clonal responses, and why one is protected from future exposures to the antigen.

Specific humoral clonal response to an antigen is described below and confers “lifelong” immunity.

1. An antigen is consumed and displayed by an APC in its MHC 2.

2. The APC will encounter and briefly bind with Helper T cells.

3. When the APC encounters a Helper T with a CD-4 receptor protein that is complementary to its MHC 2/antigen complex, the APC secretes interleukin 1.

a) Interleukin 1 stimulates the Helper T to divide creating a clonal population of Helper T’s all sensitive to the specific antigen.

b) Interleukin 1 also activates the Helper T’s to seek out and interact with B cells and Cytotoxic T cells.

4. Helper T cells encounter B cells displaying the same antigen causing the Helper T’s to secrete interleukin 2.

a) Interleukin 2 causes the B cell to divide to create a clonal population sensitive to the same antigen.

b) Interleukin 2 causes the B cell to convert to a plasma cell to begin production of antibodies specific to the antigen.

c) The clonal population of plasma cells produces massive quantities of antibody.

d) The antibodies carry out a very effective “chemical” warfare against the antigen.

e) Antibody production is crucial to effective resistance to and recovery from disease causing organisms-- we would not survive with only cell-to-cell combat.

5. Helper T cells encounter Cytotoxic T cells displaying the same antigen causing the Helper T’s to secrete interleukin 2.

a) Interleukin 2 causes the Cytotoxic T cell to divide to create a clonal population sensitive to the same antigen.

b) Interleukin 2 causes the Cytotoxic T cell to aggressively “seek and destroy” infected cells in a “cell to cell” combat.

c) This prevents pathogens from increasing numbers by destroying their host cell.

6. At some point, as the infection is controlled and some Helper T cells are thought to convert to Suppressor T cells.

7. Suppressor T cells trigger apoptosis of Helper T cell, plasma cell and Cytotoxic T cell clones.

8. Some Helper T cell, plasma cell and Cytotoxic T cell clones survive and become Memory cells in the lymph tissue.

9. This ends what is considered the primary response to an antigen.

10. The memory cells will respond much more rapidly to a repeated exposure to the antigen in what is called a secondary response.

11. There is mutagenic mechanism at work in the Helper T cells, B cells, and Cytotoxic T cells affecting antigenic receptor proteins that generates new types of cells, sensitive to “new” antigens.

12. The key to resisting infection is having Helper T cells, B cells and Cytotoxic T cells that are sensitive to a specific antigen, and they being able to respond to the pathogen before it has done irreparable harm.

1. What organ plays a role in helping the immune cells determine self vs. nonself, and culls cells that are hyposensitive or hypersensitive?

The MHC’s play a role in allowing immune cells to determine whether cells are “self” vs. “non-self” and whether to launch an immune response.

1. Contrast passive and active immunity and how are they related to the processes above?

Passive immunity involves a vaccine that contains only antibodies

a) Since the vaccine contains no antigenic agent, an immune response is not launched.

b) Passive immunity is temporary, lasting only as long as the antibodies exist in the body, and it lends no secondary protection.

Active immunity is an artificially induced primary infection, which lends secondary protection--the host is making its own antibodies.

a) Live attenuated vaccines use a live organism that will trigger an immune response without causing disease-- the organism may be genetically modified or a close relative of the pathogen.

b) Some vaccines contain killed pathogens-- the organisms cannot reproduce, but the antigens are present to initiate an immune response.

c) Epitopic vaccines are highly purified solutions that contain the antigenic agent.

d) Nucleic Acid Vaccines—as the name implies, genes from viruses or other pathogens introduced into the bloodstream in plasmids; how they work is not entirely known, thought that immune transformed and produce proteins intracellularly; HIV, malaria, influenza vaccines being developed this way.

1. What are some types of vaccines used to protect public health, and what are epitopes and adjuvants?

Many vaccines are more effective when the epitope is combined with an adjuvant of ground up foreign tissue.

The epitope is the specific part of the antigen that causes the response.

1. Describe the events of inflammation.

1. Damaged tissue secretes several chemicals including histamine and prostaglandins.

2. They cause vasodilatation and increased capillary permeability.

3. This leads to plasma loss from capillaries causing edema of the tissue.

4. The edema contains clotting factors, which isolates fluid in the area, dilutes pathogens, and creates scaffolding for tissue repair.

5. Macrophages and other immune cells are attracted to the area possibly launching an immune response.

6. The swelling and prostaglandins also irritate nociceptors.

7. The hallmarks of inflammation are redness, swelling, heat, and pain.

1. Describe the male sexual organs and trace the pathway of sperm from seminiferous tubules to the outside world.

The scrotum is a sac of skin that houses the testes.

a) Cremaster muscles in the scrotum raise and lower the testes according to temperature differences.

b) Ideal sperm production occurs at about 40F below body temperature, so the scrotum works to maintain that ideal temperature by adjusting the position of the testes.

c) The scrotum has intense concentrations of sudoriferous glands for evaporative cooling of the testes.

d) The term testicles is inclusive for scrotum and testes.

2. Testes are the male reproductive organs housed by the scrotum.

a) They develop within abdominal cavity, and descend through the inguinal canal into the scrotum before birth.

b) The testes are the organs of sperm production as well as the site of important reproductive and developmental hormones.

c) The seminiferous tubules are found inside testes and are the site of spermatogenesis (spermiogenesis).

(1) Within the walls of the seminiferous tubules diploid spermatogonia undergo meiosis, with the aide and stimulation of sustenacular cells.

(2) With chromosomal replication the spermatogonium becomes a primary spermatocyte.

(3) The first meiotic division yields two secondary spermatocytes.

(4) The secondary spermatocytes complete meiosis II to yield four haploid spermatids (from each spermatogonium).

(5) The spermatids develop within the seminiferous tubules and epididymis to mature into spermatozoa.

. The epididymis is continuous with the seminiferous tubules and is a coiled tubule lying posterior to each testis within the scrotum-- 

5. The seminal vesicles are paired glands posterior to the prostate gland that secrete a yellowish, alkaline (to  counteract vaginal acidity) fluid that accounts for approximately 60% of the volume of the semen.

a) Seminal fluid contains fructose (sperm food), a coagulating enzymes (protection from vaginal acidity), and prostaglandins (stimulates vaginal and uterine contractions).

b) The union of the ducts of the seminal vesicles and vas deferens forms the ejaculatory ducts.

6. The ejaculatory ducts extend into the prostate gland, meeting the prostatic urethra.

7. Numerous ducts of the prostate gland (located inferior to the urinary bladder, surrounding the urethra) empty into the prostatic urethra as well.

a) Prostatic secretions account for approximately 1/3 of the volume of the semen.

b) Prostatic secretions are milky white, slightly acidic, and contain citrate (more sperm food), and several enzymes some of which activate the sperm.

c) Prostate specific antigen (PSA) is also produced here and is also secreted into the bloodstream-- is used as a marker for prostate cancer.

d) Prostatic hypertrophy and cancer very common as men get older.

8. The urethra exits the prostate gland is called the membranous urethra, 

9. The bulbourethral glandular secretions produce a clear alkaline mucous that drain into the spongy urethra of the penis before ejaculation.

10. The spongy urethra carries semen (sperm and accessory gland secretions) out of the body.

11. The penis is the copulatory organ that deposits sperm within the female reproductive tract.

a) The penis is divided into the bulb, shaft, and glans penis.

b) The skin covering the penis is loose, and slides distally to form a cuff of skin called the prepuce (foreskin), which is removed during circumcision—though circumcision is widely practiced, there is no compelling medical reason to circumcise.

c) The penis contains three masses of erectile tissue.

(1) Two corpora cavernosa and one corpus spongiosum.

(2) The corpus spongiosum extends from the bulb, surrounds the urethra (hence the term spongy urethra), and forms the glans penis.

(3) Erectile tissue is “spongy” filled with sinuses and is highly elastic.

(4) Sexual excitement causes dilation of the arteries leading to the penis and constriction of the veins from the penis as the arteries swell.

(5) Blood is pumped under increasing pressure into the spaces in the erectile tissue, causing the penis to become hard and erect.

(6) Vasoconstriction of arteries decreases blood flow allowing blood to drain from the sinuses, ending the erection.

d) The penis of some members of the Order Carnivora such as bears and cetaceans contain a bone called a bacculum--the bacculum "hooks" over the lip of the female's cervix while the penis enlarges, holding the penis in place until fertilization is accomplished.

a) With sufficient stimulation by friction, reflexes involving the sympathetic nervous system cause male orgasm-- waves of contraction in the smooth muscles of the walls of the epididymis, vas deferens, accessory glands, and urethra.

b) Semen is moved quickly (200 inches per second) through the system and ejaculated involuntarily into the vagina of the female.

c) Ejaculate volume is between 2.5-5 ml, with 50-150 million sperm per ml.

d) If sperm concentration falls below 20,000,000 sperm/ml, a male can be considered sterile—sperm motility and shape are as important to fertility a number.

e) Frequency of ejaculation may decrease with age; men can remain fertile (with proper testosterone levels) well into old age.

1. Describe the organs that produce seminal fluids and the approximate volume of ejaculate they produce.

The seminal vesicles are paired glands posterior to the prostate gland that secrete a yellowish, alkaline (to counteract vaginal acidity) fluid that accounts for approximately 60% of the volume of the semen.

a) Seminal fluid contains fructose (sperm food), a coagulating enzymes (protection from vaginal acidity), and prostaglandins (stimulates vaginal and uterine contractions).

b) The union of the ducts of the seminal vesicles and vas deferens forms the ejaculatory ducts.

1. Describe the erectile issues of the penis, and how they function to produce an erect and flaccid penis.

Male reproductive problems.

1. Impotence is the inability to ejaculate.

2. Erectile dysfunction the chief cause of impotence-- pelvic nerve and blood vessel damage primary causes of erectile dysfunction.

3. Viagra is a vasodilator.

1. What is a bacculum and do humans possess one?

Humans do not possess one. The penis of some members of the Order Carnivora such as bears and cetaceans contain a bone called a bacculum--the bacculum "hooks" over the lip of the female's cervix while the penis enlarges, holding the penis in place until fertilization is accomplished.

1. Describe the hormonal control of spermatogenesis and secondary sexual characteristics

1. Puberty triggers the hypothalamus to secrete Gonadotropin Releasing Hormone (GnRH), which flows via a portal system (capillary to vein to capillary) into the adenohypophysis (anterior pituitary).

2. GnRH causes the pituitary gland to release the following hormones (gonadotropins) into the bloodstream (target site: testes).

a) Follicle stimulating hormone [FSH].

(1) Stimulates sustenacular cells of seminiferous tubules to produce androgenbinding protein (ABP).

(2) ABP binds testosterone-triggering spermatogenesis.

b) Luteinizing hormone (LH), in males usually called Interstitial Cell Stimulating Hormone (ICSH) -

(1) Stimulates interstitial cells of Leydig, located between the seminiferous tubules of testes, to begin secreting Testosterone.

(2) Testosterone causes maturation of primary sex organs, and the development of secondary sexual characteristics.

3. Testosterone levels will reach threshold concentrations in the blood inhibiting hypothalamic release of GnRH, which inhibits production of FSH, and ICSH production.

4. When testosterone levels drop, the hypothalamus secretes GnRH again-- this keeps testosterone levels and spermatogenesis fairly constant.

5. The challenge in developing a male hormonal contraceptive pill is inhibiting FSH, while maintaining high levels of testosterone..

1. The ovaries

2. The oviducts (fallopian tubes) 

3. The ovum is carried to the uterus, a muscular, hollow, pear-shaped organ that is the site of blastocyst implantation and embryonic and fetal development.

a) The innermost lining is the endometrium, a vascular layer, which grows and is sloughed off with each menstrual cycle.

b) The myometrium is the very thick smooth muscle layer.

c) The perimetrium is the serous membrane covering the organ.

d) The cervix is the inferior portion of the uterus with an opening from the uterus to the vagina-- strong circular muscles prevent the fetus from falling out of the uterus during development.

4. The vagina 

5. External Genitalia (collectively known as the vulva), includes the following.

5. External Genitalia (collectively known as the vulva), includes the following.

a) The clitoris is a small mass of erectile tissue lying superior to the vaginal opening-- it is homologous to the male penis, engorges with blood, and is involved in female orgasm.

b) The labia are folds of skin around the vaginal opening-- the labia major are lateral to the labia minora.

                                    (1) The labia protect the delicate inner organs, and play a role in sexual stimulation.

(2) The labia majora are homologous to the male scrotum.

. Oogenesis takes place in the ovaries.

1. In approximately the sixth month of fetal development the following events take place.

a) Diploid oogonia within primordial follicles undergo chromosomal replication becoming primary oocytes.

b) Within the primordial follicle the primary oocyte advances to crossing over of prophase I of the first meiotic division.

c) All follicles of a female are produced by the 6th month of fetal development.

d) They stay at Prophase I of meiosis until the follicle containing them matures just before ovulation.

2. During childhood of the 2,000,000 original primordial follicles, 300-400 will mature into primary follicles, still containing a primary oocyte stuck at prophase I.

3. At puberty a small group of primary follicles are stimulated in one ovary each month, to develop into secondary follicles.

            4. Only one from this group of secondary follicles will develop into a Graafian follicle.

a) The Graafian follicle is a fully developed fluid filled follicle.

b) How the secondary follicles determine which will become Graafian is unknown.

c) Within the Graafian follicle the primary oocyte completes meiosis I to yield a secondary oocyte (which proceeds to metaphase II and stops) and a small cell called a polar body.

(1) The cell division has an unequal division of cytoplasm.

(2) The secondary oocyte is very large and will divide to form an ovum; the polar body cannot produce ova.

5. When properly stimulated the Graafian follicle ruptures spewing the secondary oocyte into the abdominal cavity-- this is called ovulation even though there is not yet an ovum.

a) The remaining cells of the ruptured follicle give rise to the corpus luteum.

b) The corpus luteum will secrete the hormones estrogen and progesterone (which keep the endometrial lining from being shed during pregnancy).

6. The oviduct is lined by ciliated epithelium and sucks the secondary oocyte from the abdominal cavity and propels it tube towards the uterus.

7. For completion of Oogenesis fertilization is required, so sperm must be delivered into the vagina, swim through the cervical os, through the uterus, and up the fallopian tube until they encounter an ovum.

8. Upon fertilization the zona pellucida will form a fertilization membrane and the secondary oocyte will finally complete Meiosis II to yield another polar body and an ovum.

9. The ovum nucleus and sperm nucleus then fuse to form a zygote.

10. A fertilized egg will take 3 days to reach the uterus and another 4 days to implant in the endometrium as a blastocyst.

The ovum is carried to the uterus, a muscular, hollow, pear-shaped organ that is the site of blastocyst implantation and embryonic and fetal development.

a) The innermost lining is the endometrium, a vascular layer, which grows and is sloughed off with each menstrual cycle.

b) The myometrium is the very thick smooth muscle layer.

c) The perimetrium is the serous membrane covering the organ.

d) The cervix is the inferior portion of the uterus with an opening from the uterus to the vagina-- strong circular muscles prevent the fetus from falling out of the uterus during development.

1. Describe oogenesis as it relates to follicle development.

During childhood of the 2,000,000 original primordial follicles, 300-400 will mature into primary follicles, still containing a primary oocyte stuck at prophase I. At puberty a small group of primary follicles are stimulated in one ovary each month, to develop into secondary follicles. Only one from this group of secondary follicles will develop into a Graafian follicle.

a) The Graafian follicle is a fully developed fluid filled follicle.

b) How the secondary follicles determine which will become Graafian is unknown.

c) Within the Graafian follicle the primary oocyte completes meiosis I to yield a secondary oocyte (which proceeds to metaphase II and stops) and a small cell called a polar body.

(1) The cell division has an unequal division of cytoplasm.

(2) The secondary oocyte is very large and will divide to form an ovum; the polar body cannot produce ova.

1. Approximately how many days after ovulation does implantation occur and what stage of embryogenesis implants in the endometrium?

You may recall that the secondary oocyte is fertilized in the fallopian tube, and implants after seven days or so as it develops into a blastocyst.

1. How does female orgasm contribute to the chance of fertilization?

1. Upon sexual excitement, the clitoris, labia, and other tissues in the pelvic region become engorged with blood.

2. The vagina secretes a lubricating fluid.

3. Orgasm brings a series of rhythmic muscular vaginal contractions, which propel and hold the semen towards the cervix, and the mouth of the cervix drops and dilates to facilitate sperm entrance into the uterus.

4. Orgasm is not necessary for fertilization, but it does increase the chances.

1. Describe hormonal control of the menstrual cycle.

The estrogen-progesterone is a powerful combination with the following effects.

a) It stimulates dramatic growth of the endometrium.

b) It negatively feeds back on the hypothalamus inhibiting secretion of GnRH.

c) This has a series of effects.

(1) GnRH inhibition means that the anterior pituitary will stop secreting FSH and more importantly LH.

(2) Without stimulation from LH the corpus luteum dies, and becomes a scar on the ovary called the corpus albicans.

(3) Death of the corpus luteum stops estrogen and progesterone secretion.

(4) Without estrogen, and more importantly progesterone in the blood, the endometrium not only stops growing, but also begins to die (endometrial cells require progesterone bind to membrane receptors to stay alive).

(5) Theses events unfold over a period of fourteen days (a 28 day cycle).

(6) Endometrial death leads to menstruation, and back to day 1 of the cycle.

1. Describe how the birth control pill prevents pregnancy.

1. The pill contains low concentrations of estrogen and higher concentrations of progesterone.

2. These inhibit GnRH secretion by the hypothalamus.

3. Without GnRH, there will be no secretion of LH, so follicles do not develop, and without a peak of LH in the blood, no ovulation.

4. Endometrial growth is stimulated and grows however, so you must go “off cycle” to permit menstruation.

1. How does the blastocyst (trophoblast) prevent menstruation, thereby saving itself?

1. You may recall that the secondary oocyte is fertilized in the fallopian tube, and implants after seven days or so as it develops into a blastocyst.

2. As the embryo is developing LH levels are dropping, so the corpus luteum is going to die, progesterone levels will drop, and the endometrium will menstruate taking the embryo with it, unless something is done.

3. The embryo saves itself by producing a hormone called Human Chorionic Gonadotropin (HCG).

a) HCG is the fetal equivalent of LH.

b) It is absorbed by the maternal blood vessels and carried to the ovary.

c) HCG stimulates the LH to stay alive and continue estrogen and progesterone secretion.

d) The endometrium stays alive and continues to grow.

4. HCG keeps the endometrium alive until the placenta develops to the point where it secretes its own estrogen and progesterone, negating the need for the corpus luteum.

1. What organ eventually secretes progesterone and maintains and controls the pregnancy?

HCG keeps the endometrium alive until the placenta develops to the point where it secretes its own estrogen and progesterone, negating the need for the corpus luteum.

1. Describe the first, second, and third trimesters of pregnancy.

1. Mature eggs are only viable for up to 72 hrs.

2. A sperm must travel high up into the oviduct within this period to reach and fertilize the egg.

3. Blastocyst penetrates wall of endometrium after about the 7th day.

4. The trophoblast of the blastocyst forms the placenta, and the inner cell mass develops into the embryo.

5. A placenta ultimately forms.

a) Maternal capillaries intrude into sinuses and are bathed in fetal blood for gas, nutrient, and waste exchange.

b) Maternal and fetal blood do not mix.

6. First Trimester (embryo state).

a) Formation of major organ systems, sensory organs, appendages.

b) Drugs or other environmental factors (teratogens) may cause the worst damage during this period.

7. Second Trimester (fetus stage).

a) Bony skeleton forms, growth continues, fetus becomes covered with a protective cheesy coating (vernix).

b) Mother can feel fetal movements by the 5th month.

8. Final Trimester--Fetus increases in size and weight (protein intake by the mother at this time is particularly important), placenta becomes tough and fibrous.

9. Childbirth.

a) Usually 266 days after conception.

b) Stages of Birth

1) First stage labor-- dilation.

(a) Opening of the cervix increases to 10cm

(b) Rhythmical contractions (labor pains) of the uterine walls increase from one every 15-20 minutes to one every 1-2 minutes (i.e. contractions get longer, stronger, and closer together).

(c) Amniotic sack is broken; fluid is released.

(2) Transition--labor contractions almost continuous, most difficult time for mother.

c) Second stage labor-- childbirth (pushing).

(1) Head of the baby appears at the mouth of the cervix (crowning).

(2) Contractions push the baby down the birth canal and out the mother's body.

(3) Mother must actively compress abdomen to help process (pushing).

d) Third stage labor-- (afterbirth (placental expulsion).

(1) About 5 minutes after childbirth, especially strong contractions break the placenta free from the uterine wall.

(2) The placenta, umbilical chord, blood, and other fluids are expelled as "afterbirth.”

(3) Severe infections and/or death of the mother can occur if all afterbirth is not expelled.

(4) Drugs to stimulate contractions may be given if the afterbirth is not expelled naturally (pitocin).

(5) The uterus is massaged to stimulate contraction of the uterus and vasoconstriction of vessels to stop bleeding and reduce size of uterus.

1.      Describe the pathway of air from oral cavity to alveoli.

A. Air is inspired through the nasal cavity or buccal cavity.

B. It then passes through the nasopharynx or oropharynx (lined with ciliated columnar epithelium).

C. Past the epiglottis through the glottis.

1. The epiglottis is a flap of connective tissue that folds over the glottis when eating or drinking.

2. The glottis is the opening to air passages, and is anterior to the esophagus, which is the tube that leads to the stomach.

D. Through the larynx (contains vocal chords) protected by the thyroid and cricoid cartilage.

E. Into the trachea (protected by cartilagenous rings to prevent collapse).

F. Air then goes into either the right or left primary bronchi (main tubes leading to the lungs).

1. The right lung has three lobes, and the left lung has two.

2. The right lung has a greater vital capacity.

3. The right primary bronchus is larger in diameter as a result, than the left primary bronchus-- inhaled objects more likely to lodge in bronchioles of right lung than left.

4. The primary bronchi branch into secondary bronchi--which lead to lung lobes (three on the right, two on the left).

5. Secondary bronchi branch into tertiary bronchi, which lead to lobules, which are internal divisions of lungs.

6. If part of a lung must be removed, lobules are the first level of removal, then lobes, then and lungs.

7. The tertiary bronchi branch into still smaller bronchi.

G. The bronchi continue to branch into smooth muscle lined tubules less than one millimeter in diameter-- these tubules are called bronchioles.

1. The cartilagenous rings become fewer as the bronchioles branch into still smaller bronchioles.

2. This branching network of bronchioles is called the bronchiole tree.

3. Bronchioles are surrounded by smooth muscle, which contracts in asthma attacks.

H. Finally air enters the alveoli.

1. The alveoli are air sacs surrounded by a dense capillary network at the end of respiratory bronchioles.

2. Gas exchange occurs in the alveoli.

3. A chemical called surfactant has detergent qualities to keep the alveoli open, preventing the cohesive quality of water from collapsing the alveoli.

1.      Describe the location and function of the epiglottis.

The epiglottis folds over glottis to prevent food from going down trachea-- diverting food to

the esophagus, which is dorsal to the trachea.

1.      How are the right and left lung different form one another?

1. The right lung has three lobes, and the left lung has two.

2. The right lung has a greater vital capacity.

Lobules - 

Lobes -

Lungs - 

1.      What is surfactant and why is it important to lung function?

Into the trachea (protected by cartilagenous rings to prevent collapse).

1.      Describe the anatomy and physiology of tidal and forced ventilation.

Tidal (unforced) inspiration.

a) The diaphragm contracts, dropping down, increasing thoracic volume.

b) The pressure within the pleural space decreases, creating a partial vacuum.

c) Atmospheric pressure within the air spaces now exceeds the intrathoracic pressure so air rushes in to the alveoli.

            Expiration.