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Exam 2 Chapters 13-15,18
URI Anatomy with Mazurkie
87
Anatomy
Undergraduate 1
02/26/2010

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Term
What is the overall function of both the nervous and endocrine systems? (Ch. 13 pg. 341)
Definition
To control and adjust the activities of other systems.
Term
Compare and contrast the nervous and endrocrine systems. (Ch. 13 pg. 341)
Definition
Both rely on chemical communication to control targeted tissues and organs, but the nervous system is faster and more focused, but also breif, whereas the endocrine system responds slowly but can continue a response longer (up to years).
Term
What are the 2 subdivisions of the nervous system, what do they contain, and what are their most general functions? (Ch. 13 pg. 341)
Definition
  1. Central Nervous System (CNS) - brain and spinal cord, which integrate, process, and coordinate sensory input/motor output, and control higher functions such as intelligence, memory, learning, and emotion
  2. Peripheral Nervous System (PNS) - all neural tissue outside the CNS,which provide sensory information to the CNS and carry motor commands from CNS to peripheral tissues & systems
Term
What are the 2 subdivisions of the PNS and what does each do? (Ch. 13 pg. 341)
Definition
  1. Afferent division - brings sensory information to the CNS
  2. Efferent division - carries motor commands to muscles & glands
Term
How are both the afferent and efferent divisions of the PNS divided? (Ch. 13 pg. 342)
Definition
Both have somatic & visceral components.  For the afferent division, the somatic portion brings sensory info from skeletal muscles, joints, and skin, and the visceral portion monitors other internal tissues such as smooth muscle, cardiac muscle, and glands.  In the efferent division, the somatic nervous system (SNS) controls skeletal muscle contractios and the autonomic nervous systems (ANS) controls smooth muscle, cardiac muscle, and glandular activity
Term
What are the two distinct cell type in neural tissue? (Ch. 13 pg. 342)
Definition
Neurons (nerve cells) and Neuroglia (supporting cells)
Term
What are the general functions of neuroglia? What is the ratio of neuroglia to neurons? (Ch. 13 pg. 344)
Definition
  • Isolate the neurons
  • provide a supporting framework for neural tissue
  • help maintain the intercellular environment because neural tissue canot withstand changes that the rest of the body can
  • act as phagocytes
  • 100 billion neuroglia, which is 5x the number of neurons
Term
What are the 4 types of glial cells found in the CNS, and the 2 types found in the PNS? Whose functions are similar? (Ch. 13 pg. 344-5)
Definition
  • CNS - astrocytes, oligodendrocytes, microglia, and ependymal cells
  • PNS -  satellite cells, schwann cells
  • Oligodendrocytes & schwann cells have similar function
  • Astrocytes/ependymal cells have function similar to satellite cells
Term
What are the functions of the astrocyte glial cells in the CNS? (Ch. 13 pg. 344)
Definition
  • Control the interstitial environment (facilitate exchange of ions/molecules and feet of processes cover most of the neuron surface)
  • Maintain blood-brain barrier (feet also cover capillaries so that general circulation concentrations do not upset the delicate balance in the brain)
  • Provide 3D framework (reinforcement & support of neurons with microfilaments)
  • Repair of damaged neural tissue (structural repairs/scar tissue limit additional damage)
  • Guiding neuron development in embryonic brain
Term
What is the structure of a representative neuron? (Ch. 13 pg. 344 fig. 13.3)
Definition
Dendrites at end (branching where impulse is received), cell body with nucleus & other organelles, axon (tail which conducts the nerve impulse), and  synaptic terminal (passes impulse to another cell through terminal boutons)
Term
What is the function of an oligodendrocyte of the CNS and how does this help the goals of the nervous system? (Ch. 13 pg. 345)
Definition
Oligodendrocytes sheath axons of neurons, called myelination.  Myelin improves the speed at which an action potential (nerve impulse) is conducted along an axon, making a sensory/motor complex much faster.
Term
What are the functions of microglia and ependymal cells of the CNS? (Ch. 13 pg. 345)
Definition
  • Microglia - remove cell debris, waste, & pathogens by phagocytosis
  • Ependymal cells - line brain ventricles and central canal of spinal cord, assist in producing, circulating, and monitoring cerebrospinal fluid
Term
What are the functions of satellite cells and schwann cells, the microglia of the PNS? (Ch. 13 pg. 345-8)
Definition
  • Satellite cells - surround neron cell bodies in peripheral ganglia, regulate exchange of nutrients & waste products between the cell bodies and extracellular fluid, isolate neurons from stimuli other than those provided at synapses
  • Schwann cells - Sheath peripheral axons, responsible for myelination of said axons although all are wrapped in schwann cells whether they are myelinated or unmyelinated 
Term
Describe the 4 types of neurons based on structure. (Ch. 13 pg. 350 incuding fig. 13.10)
Definition
  1. Anaxonic neuron - no anatomical difference between axon and dendrites, found only in CNS
  2. Bipolar neuron - dendritic branches fuse into a single dendrite string, which attaches to cell body, axon, and synaptic terminal, rare, with unmyelinated axons                     >--O--<
  3. Pseudounipolar neuron - Looks like bipolar, except cell body is off to one side, and both single strings are axons, most sensory neurons of PNS are pseudounipolar
  4. Multipolar neuron - Dendrite branches attached to cell body, axon length off back attached to synaptic terminal, most common

 

Term
What are receptors in general and what are the 3 specific kinds? (Ch. 13 pg. 351)
Definition

Receptors may be either the processes of specialized sensory neurons or cells monitored by sensory neurons The three catagories are:

  1. Exteroceptors - provide info about the external environment from touch, temp, pressure, and more complex special senses (sight, smell, hearing) (carried by somatic sensory nerves)
  2. Proprioceptors - monitor the position and movement of skeletal muscles and joints (info on internal environment, carried in somatic sensory nerves)
  3. Interoceptors - monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems and provide sensations of deep pressure and pain, as well as taste (info carried by visceral sensory neurons)
Term
Define motor neurons. (Ch. 13 pg. 351)
Definition
Multipolar neurons that form the efferent division of the nervous system
Term
What are the 3 types of beurons based on funtion? (Ch. 13 pg. 351)
Definition

1. Sensory neurons (including receptors)

2. Motor neurons (efferent division)

3. Interneurons (situated between sensory & motor neurons)

Term
When will neural regeneration occur? (Ch. 13 pg. 352)
Definition
Neurons have limited ability to regenerate (no centromeres for mitosis), but if the axon is not completely severed, Wallerian degeneration  by schwann cells may occur
Term
What is excitability? (Ch. 13 pg. 353)
Definition
Ability of plasmalemma (cell membrane) to conduct electrical impulses.
Term
How does an action potential develop, and what is this potential termed when it travels along an axon? (Ch. 13 pg. 353)
Definition
An electrical impulse, or action potential, develops after the plasmalemma is stiumalted to the level known as the threshold.  Action potentials traveling along axons are known as nerve impulses.
Term
Once initiated, what does the rate of impulse conduction depend on? (Ch. 13 pg. 353)
Definition
  • The presence of absense of a myelin sheath (myelinated axons conduct impules 5-7 times faes than unmyelinated)
  • The diameter of the axon (the larger the diameter, the faster the impulse is conducted)
Term
Explain the process of a vesicular synapse (Ch. 13 pg. 354)
Definition
  • Arrival of action potential at terminal boutons trigger release of neurotransmitter from vesicles at the presynaptic membrane
  • The neurotransmitter diffuses across the synaptic cleft and binds to receptors on the postsynaptic membrane
  • Receptor binding results in a change in the permeability of the postsynaptic cell membrane, and will create either an excitatory (which promotes the generaton of action potentials) or inhibitory (which reduce the ability to generate an action potential) effect
  • If the degree of excitation is sufficient, receptor binding may lead to the generation of an action potential in the axon (or sarcolemma if the postsynaptic cell is a skeletal muscle fiber)
  • Action potentials are short lived, so inorder to prolong or enhance the effects, additional action potentials must arrive at the synaptic terminal to complete this process
Term
What are the 5 catagories of organization in neronal circuits? (Ch. 13 pg. 355)
Definition
  1. Divergence (One cell synapses on two cells, and each of those two cells synapses on another few cells, etc to spread information)
  2. Covergence (2 or more cells synapse onto one cell to permit variable control of motor options)
  3. Serial processing (One synapses one another single one which synapses on another single one - straight line)
  4. Parallel processing (One synapses on 2 or more, which then continue in series)
  5. Reverberation (One cell synapses on another cell. This 2nd cell synapses on the first cell & a 3rd cell)
Term
How is the spinal cord more than "just a highway for information"? (Ch. 14 pg. 362)
Definition
The spinal cord has a significant degree of independence, with the ability to integrate and process some information instead of passing it to the brain.
Term
Where does the spinal cord end, and what continues from there? (Ch. 14 pg. 362)
Definition
Spinal cord ends at L1, the first lumbar vertebra, but nerves continue down the rest of the spine (see fig. 14.1)
Term
What and where are enlargements of the spinal cord? (Ch. 14 pg. 362)
Definition
Enlargements are portions of the spinal cord which are expanded with extra nerves to innervate the limbs.  The cervical enlargement supplies nerves to the pectoral girdle and upper limbs, while the lumbosacral enlargement supplies nerves to the structures of the pelvis and lower limbs
Term
What is the cauda equina? (Ch. 14 pg. 362)
Definition
The "horse's tail" - nerves leading off the end of the spinal cord, with many branching nerves
Term
What do the spinal meninges do? Describe them. (Ch. 14 pg. 362-5)
Definition
The spinal meninges provide protecton, physical stability, and shock absorption to the delicate spinal cord.  The outermost is the dura mater, which is tough and fibrous. The middle layer is the arachnoid mater, which is separated by the innermost layer by the cerebrospinal fluid-filled subarachnoid space.  This innermost layer, the pia mater, conforms to every bulge and fissure of the cord, while the other 2 are merely circular wrappings.
Term
What surrounds th central canal of the spinal cord? (Ch. 14 pg. 367)
Definition
Gray matter
Term
How are the cell bodies of neurons in gray matter of the spinal cord organized? Where are they located? (Ch. 14 pg. 367)
Definition
  • They are organized into groups, called nuclei, with specific functions.  (Sensory nuclei receive and relay sensory information from peripheral receptors; motor nuclei issue motor commands to peripheral effectors)
  • The posterior (dorsal) gray horns contain somatic and visceral sensory nuclei, whereas the anterior (ventral) gray horns contain neurons concerned with somatic motor control, and visceral motor nuclei are located in the lateral gray horns
  • (The gray commissures, which connect the each side of horns, contain interneuron axons crossing from one side of the cord to the other)
Term
How is the white matter of the spinal cord organized? (Ch. 14 pg. 367)
Definition
The white matter is divided into 6 columns.  Each column contains tracts, whose axons share functional/structural characteristics. All axons within a tract (and therefore each single tract) relays info in one direction (ascending tracts carry sensory info toward the brain, descending tracts convey motor commands into the spinal cord
Term
What are the 3 layers of connective tissue in each peripheral nerve? (Ch. 14 pg. 369, including fig. 14.6a)
Definition
  1. Epineurium (outermost layer)
  2. Perineurium - wraps fasicles (bundles of axons within nerve)
  3. Endoneurium (innermost wrapping - surround individual axons)
Term
How does a spinal nerve form? (Ch. 14 pg. 369-70, fig 14.7)
Definition
Each spinal nerve forms through the fusion of dorsal and ventral nerve roots
Term
What is a dermatome? (Ch. 14 pg. 370)
Definition
Each pair of spinal nerves monitors a specific region of the body surface. This region is known as the dermatome.
Term
What are the four major plexuses of the body? (Ch. 14 pg. 370)
Definition
Cervical, brachial, lumbar, sacral (Review tables; know major nerves in each plexus)
Term
What is a reflex and what is a reflex arc? Explain the steps in a reflex response. (Ch. 14 pg. 380, including fig. 14.15)
Definition

A reflex is an immediate involuntary motor response to a specific stimulus.  A reflex arc is the neural "wiring" of a single reflex, which begins at a receptor and ends at an effector.

The steps involved are as follows:

  1. Arrival of stimulus and activation of receptor
  2. Activation of a sensory neuron
  3. Information processing in CNS
  4. Activation of a motor neuron
  5. Response by effector
Term
What are the 4 ways to classify reflexes? (Ch. 14 pg. 382)
Definition
  1. Based on their development (innate vs. aquired)
  2. Based on the response (somatic vs. visceral)
  3. Based on complexity of the circuit (monosynaptic vs. polysynaptic)
  4. Based on processing site (spinal reflexes vs. cranial reflexes)
Term
What is a stretch reflex? Give an example. (Ch. 14 pg. 382)
Definition
A monosynaptic spinal reflex, which provides automatic adjustment of muscle tone and automatic regulation of skeletal muscle length.  Example: knee jerk, or patellar reflex
Term
What do excitatory/inhibitory interactions among the extensively interconnected neuronal pools ensure? (Ch. 15 pg. 387)
Definition
Excitatory/inhibitory interactions among the extensively interconnected neuronal pools ensure that the response can vary to meet changing circumstances.
Term
What are the divisions of the brain and what are their basic functions? (Ch. 15 pg. 388)
Definition
  • Cerebrum (largest portion) - conscious thought processes, intellectual functions, memory storage/processing, conscious & subconscious regulation of skeletal muscle contractions
  • Diencephalon - Thalmus has relay & processing centers for  sensory info, hypothalmus has centers controlling emotions, autonomic functions and hormore production
  • Cerebellum - Coordinates complex somatic motor patterns, adjusts output of other somatic motor centers in brain and spinal cord

 and the brain stem made up of the:

  • Mesencephalon - Processing of visual & auditory data, generation of reflexive somatic motor responses, maintainance of consciousness 
  • Pons - Relays sensory info to cerebellum & thalmus, subconscious somatic & visceral motor centers
  • Medulla oblongata - Relays sensory info to thalmus and to other portions of the brain stem, autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)
Term
Describe the ventricles of the brain and their location. (Ch. 15, pg. 389)
Definition
Ventricles are fluid-filled cavities within the brain.  They are filled with cerebrospinal fluid & lined with ependymal cells.  There are 4 brain ventricles: one in each cerebral hemisphere, a third within the diencephalon, and the 4th between the pons and cerebellum, which extends into the superior portion of the medulla oblongata
Term
What is involved in protection, support, and nourishment of the brain? (Ch. 15, pg. 389)
Definition
  • Bones of the skull
  • Cranial meninges
  • Cerebrospinal fluid
  • Blood-brain barrier
  • Vessels of cardiovascular system
Term
What are the names of the cranial meninges and as what do they function? (Ch. 15, pg. 391)
Definition
The cranial meninges are the dura mater, arachnoid mater and pia mater (same as spinal meninges). They function as shock absorbers that prevent brain contact with the surrounding bones
Term
What does the choroid plexus in the brain do? (Ch. 15, pg. 394-5)
Definition
The choroid plexus produces cerebrospinal fluid, and acts as the selective membrane (made up of ependymal cells) which determines which ions/molecules are allowed into the CNS (blood-brain barrier)
Term
What are the 2 main points to keep in mind concerning the lobes of the cerebral hemispheres? How are these lobes named? (Ch. 15, pg. 396-8)
Definition
  1. Each hemisphere receives sensory info from & generates motor commands to the opposite side of the body
  2. The 2 hemispheres have some functinal differences, although anatomically they look identical

The lobes are names based on the bone that resides on them. They are separated by the sulci/gyri.

Term
What do basal nuclei do? (Ch. 15, pg. 401)
Definition
  • Subconscious control and intergration of skeletal muscle tone
  • the coordination of learned movement patterns
  • Processing, intergration, and relay of info from the cerebral cortex to the thalamus
  • Provide the general pattern and rhythm for movement
Term
What are the functions of the limbic system? (Ch. 15, pg. 401)
Definition
  • Establishment of emotional states and related behavior
  • Linking the conscious, intellectual functions of the cerebral cortex with the unconscious & autonomic functions of other portions of the brain
  • Facilitating memory storage and retrieval
Term
Where is the diencephalon and what pieces make it up? (Ch. 15, pg. 405-6)
Definition
The diencephalon is located at the top of the brain stem.  It is made up of the epithalamus, thalamus, and the hypothalamus
Term
What are the epithalamus, the thalamus, and the hypothalamus responsible for? (Ch. 15, pg. 405)
Definition
  • Epithalmus - controls circadian rhythm (day/night cycle)
  • Thalamus - final relay point for ascending sensory info, filters info  & passes on a small portion
  • Hypothalamus - Coordinates activities of the nervous & endocrine systems (which maintain homostasis), emotional & visceral processes (such as hunger/thirst, sex drive)
Term
What is the function of the mesencephalon? (Ch. 15, pg. 410)
Definition
It contains nuclei which process visual and auditory info and generate reflexive responses to these stimuli (primitive - reflexes)
Term
What are the functions of the pons ? (Ch. 15, pg. 410-12)
Definition
  • Coordinates involuntary skeletal muscle movement & muscle tone
  • Relays info to/from brain and spinal cord
  • Sensory & motor nuclei for 4 cranial nerves

 

Term
What are the functions of the cerebellum? (Ch. 15, pg. 414)
Definition
  • Adjusts the postural muscles of the body
  • Programs & fine-tunes  voluntary and involuntary movements  (stores memories of learned movement patterns)
Term
Where does the spinal cord connect to the brain stem? (Ch. 15, pg. 414)
Definition
Medulla oblongata physically connects the brain/stem with the spinal cord (most functions directly related to this connection)
Term
What are the functions of the nuclei of the medulla oblongata? (Ch. 15, pg. 414)
Definition
  • Relay stations along sensory or motor pathways
  • Nuclei of cranial nerves
  • Autonomic nuclei (vital functions including respiratory/cardiovascular - if medulla oblongata is severed, patient will likely die) 
Term
What is the pneumonic for the 12 cranial nerves? (Ch. 15, pg. 426)
Definition

Oh, Once One Takes The Anatomy Final, Very Good Vacations Are Heavenly

Olfactory

Optic

Oculomotor 

Trochlear

Trigeminal

Abducens

Facial

Vestibulocochlear 

Glossopharyngeal

Vagus

Accessory

Hypoglossal

Term
What are the primary functions of each cranial nerve? (Ch. 15, pg. 419)
Definition
  1. Olfactory - special sensory (smell)
  2. Optic - special sensory (vision)
  3. Oculomotor - motor (eye movement)
  4. Trochlear - motor (eye movement)
  5. Trigemenal - mixed (opthalmic/maxillary = sensory, mandibular = mixed)
  6. Abducens -  motor (eye movement)
  7. Facial - mixed (sensory & motor)
  8. Vestibulocochlear - special sensory (vestibular branch - balance & equilibrium, cochlear branch - hearing)
  9. Glossopharyngeal - Mixed (swallowing)
  10. Vagus - Mixed (motor is for somatic palate/pharynx and visceral respiratory, cardiovascular and deigestive organs) (only cranial nerve that extends beyond head/neck)
  11. Accessory - Motor (palate, pharynx, larynx, sternocleidomastoid, & traps)
  12. Hypoglossal - Motor (tongue movements)
Term
What is a sensory receptor? (Ch. 18, pg. 471)
Definition
A sensory receptor is a specialized cell or cell process that monitors conditions in the body or external environment.  Stimulation of the receptor directly or indirectly alters the production of action potentials in a sensory neuron.
Term
Define sensation, perception and general senses. (Ch. 18, pg. 471)
Definition
  • Sensation - sensory info arriving at the CNS
  • Perception - conscious awareness of a sensation (many sensations occur without perception)
  • General senses - refers to sensations of temp, pressure, pain, touch, vibration, proprioception (body position). General sensory receptors are distributed throughout the body 
Term
List the special senses.  Where are they located? (Ch. 18, pg. 471)
Definition
The special senses are: smell (olfaction), taste (gustation), balance (equilibrium), hearing, and vision.  The receptor cells are structurally more complex, and localized within complex sense organs (which, in humans, are all on the head)
Term
Define receptor specificity & receptor field. (Ch. 18, pg. 471)
Definition
  • Receptor specificity - Each receptor is sensitive to a specific characteristic sense. For example, a touch receptor is quite sensitive to pressure but relatively insensitive to chemical stimuli
  • Receptor field - the area monitored by a single receptor cell.  The larger the field, the poorer our ability to locate a stimuli.
Term
Explain the difference between tonic receptors and phasic receptors. (Ch. 18, pg. 471)
Definition
  • Tonic receptors - always active, with info sent to CNS based on frequency of action potential
  • Phasic receptors - normally inactive, but become active for a short time whenever there is a change in the conditions they are monitoring, with info sent to CNs based on intensity of stimulus.
Term
What is adaptation? Explain the difference between peripheral (sensory) & central adaptation. (Ch. 18, pg. 471)
Definition

Adaptation is a reduction in sensitivity in the presence of a constant stimulus.

  • Peripheral (sensory) adaptation occurs when the receptors or sensory neurons alter their level of activity.  They respond strongly at first, but thereafter the activity along afferent fibers gradually declines
  • Central adaptation involves active receptors but an inhibition of nuclei along a sensory pathway. In essence, the CNS "ignores" the action potential
Term
In what ways are our senses limited? (Ch. 18, pg. 472)
Definition
  1. Humans do not have receptors for every possible stimuli (ex. we cannot see heat)
  2. Our receptors have characteristic ranges of sensitivity (ex. visible wavelengths of light)
  3. A stimulus must be interpreted by the CNS.  Our perception of a particular stimulus is an interpretation and not always a reality (ex. phantom pains on amputee)
Term
What are the 3 types of receptors based on location? What are the 4 types of receptors based on the nature of the stimulus that excites them? (Ch. 18, pg. 472)
Definition

Location:

1. Exteroceptors - provide info about the external environment

2. Proprioceptors - monitor body position

3. Interoceptors - monitor conditions inside the body

 

Nature of stimulus:

  1. Nociceptors - respond to a variety of stimuli, usually associated with tissue damage.  Receptor activation causes the sensation of pain
  2. Thermoreceptors - respond to changes in temperature
  3. Mechanoreceptors - stimulated/inhibited by physical distortion, contact, or pressure on their plasmalemmae
  4. Chemoreceptors - monitor the chemical composition of body fluids and respond to the presence of specific molecules
Term
Explain referred pain. (Ch. 18, pg. 473)
Definition
Pain sensations from visceral organs are carried by sensory nerves that reach the spinal cord with the dorsal roots of spinal nerves.  These visceral pain sensations are often perceived as originating in more superficial regions that are innervated by the same spinal nerves, known as reffered pain.
Term
Explain the difference between unencapsulated and encapsulated mechanoreceptors. (Ch. 18, pg. 473-4)
Definition
  • Unencapsulated receptors are more easily activated (more sensitive), but they cannot give info about the degree of the stimulus (either on or off). Includes free nerve endings, root hair plexus, and merkel cells
  • Encapsulated receptors are less sensitive, but once they are activated, they are able to give info about the degree of the stimulus.  They include tactile corpuscles (aka Meissner's - sperm), ruffini corpuscles, and lamellated corpuscle's (aka pacinian - print)
Term
What are baroreceptors? (Ch. 18, pg. 475)
Definition
Mechanoreceptors, more specifically stretch receptors that monitor changes in pressure.
Term
Explain chemoreceptors. (Ch. 18, pg. 475)
Definition
Chemoreceptors are specialized neurons that can detect small changes in the concentration of specific chemicals or compounds
Term
What do the olfactory organs consist of? (Ch. 18, pg. 477)
Definition
  • A specialized neuroepithelium, the olfactory epithelium, which contains the bipolar olfactory receptors, supporting cells, and basal (stem) cells
  • An underlying layer of loose connective tissue known as the lamina propria.  This layer contains olfactory glands, which produce a thick, pigmented mucus, blood vessels, and nerves.
Term
What happens once compounds have reached the olfactory organs? (Ch. 18, pg. 477)
Definition
Water-soluble & lipid-soluble materials must diffuse into the mucus before they can stimulate the olfactory receptors
Term
Where are taste buds found? What are the 3 types of these structures? Where are taste receptors found? (Ch. 18, pg. 478, including fig. 18.7)
Definition

Taste buds lie along the sides of epithelial projects called papillae. The 3 types are:

  1. Filiform (thread-like)
  2. Fungiform (mushroom-shaped)
  3. Circumvallate (round walls)

Taste receptors are clustered within individual taste buds

Term
Aside from actual taste receptors, what other receptors effect taste perception?
Definition
The level of stimulation from the olfactory receptors
Term
What are the 4 primary taste sensations, and the other 2 recently described? (Ch. 18, pg. 479)
Definition
Sweet, salty, bitter, sour, umami (savory), water
Term
What are the 3 regions of the ear and what is housed in each? (Ch. 18, pg. 480)
Definition
  1. External ear - auricle, or pinna (flexible piece which funnels sound), which surrounds the external acoustic meatus.  The tympanic membrane (eardrum) facilitates the passage of sound and ends the external portion
  2. Middle ear - tympanic cavity (air-filled space) houses the auditory ossicles (malleous, incus, stapes) which conduct sound, and auditory tube(pressure equalizer)
  3. Inner ear - Cochlea (hearing-snail shell) and vestibule (equilibrium - snail head), and semicircular canals (snail antennae)
Term
How is the bony labrinth divided, and what make up the layers inside of it? (Ch. 18, pg. 482)
Definition
The bony labrinth is divided into vestibule, semicircular canals (which together form the vestibular complex), and the cochlea.  The bony labrinth surrounds (from outside to inside) the perilymph, membranous labrinth, and endolymph (fluid inside memb. labrinth)
Term
How do the semicircular canals operate? (Ch. 18, pg. 484)
Definition
The ampulla is filled with liquid endolymph (wind), which, when movement occurs, pushes the cupula (sail), which moves the hairs attached at the bottom (boat).  The hair movement stimulates the nerve cell attached to the hair, and sends info to CNS for sensation/perception of movement
Term
How is gravity perceived? (Ch. 18, pg. 484-6, including fig. 18.15)
Definition
Gravity is perceived using hair cells identical to those in the ampulla of semicircular canals, but atop the hair cells are statoconia (crystals) which together form the otolith.  The rocks move according the the angle of the head (i.e. if you are upside down, the rocks will not press on the hairs and your CNS will sense the position, regardless of motion) This allows us to achieve static balance
Term
How does the body get motion sickness? (Ch. 18, pg. 487)
Definition
In a space where one is moving but cannot see it, the vestibular complex senses motion, but that eyes do not agree.  Therefore the CNS is in confusion, making the person feel sick.
Term
List the steps in the production of an auditory sensation. (Ch. 18, pg. 490)
Definition
  1. Sound waves arrive at the tympanic membrane
  2. Movement of the tympanic membrane causes displacement of the auditory ossicles
  3. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct
  4. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct
  5. Vibration of the basilar membrane causes vibration of hair cells against the tectorial membrane, resulting in hair cell stimulation and neurotransmitter release
  6. Information concerning the region and intensity of stimulation is relayed to the CNS over the cochlear branch of N VIII
Term
In the cochlea, what are the 2 main ducts and how does sound travel in them? (Ch. 18, pg. 488)
Definition
The two ducts are the vestibular (scala vestibuli) and tympanic (scala tympani), split by the cochlear (scala media) where the tectorial membrane & hair cells are housed. Sound travels up through the scala vestibuli from the oval window plugged by stapes, and at apical turn, it travels back down through the scala tympani
Term
What is the function of the lacrimal apparatus and what is it made up of? (Ch. 18, pg. 492)
Definition
The lacrimal apparatus produces, distributes, and removes tears.  It is made up of : a lacrimal gland, superior & inferior canaliculi, a lacrimal sac, and a nasolacrimal duct
Term
What is the design of the eye? (Ch. 18, pg. 492)
Definition
3 layers make up the wall (outer fibrous tunic, or sclera - white part, middle vascular tunic, and inner neural tunic, or retina).  The eyeball is hollow, and the interior is divided into 2 cavities: Posterior (aka vitreous because it contains the gelatinous vitreous body) and Anterior, which itself is subdivided into anterior and posterior.  This shape is stabilized by the vitrious body and the clear liquid aqueous humor that fills the anterior cavity
Term
Describe the anatomy of front of the eye. (Ch. 18, pg. 496)
Definition
The cornea is a protective layer, which is most superficial, and forms the anterior chamber of the anterior cavity in front of the iris/lens.  The iris (colored portion) is underneath.  The pupil is the hole in the iris that allows the entrance of light, with the iris constricting to determine the intensity.  The lens resides behind the iris.
Term
Where has the highest concentration of cones and the greatest ability to focus? (Ch. 18, pg. 495)
Definition
The fovea (directly back from pupil).  Damage to the fovea leads to a difficulty in observing color (cones = color)
Term
Describe the layers of the retina for light to pass through, and explain the 2 types of photoreceptors. (Ch. 18, pg. 497-8)
Definition
Light starts by going through the ganglion cells, then bipolar cells, and only then reaches the photoreceptors at the back of the retina.  The two types of photoreceptors of rods and cones. Rods are light sensitive, but do not differentiate color.  Cones provide us with color vision
Term
Describe the way we are able to see in 3D. (Ch. 18, pg. 501, fig 18.26)
Definition
The optic nerve sends 2 tracts back from each eyeball, one to the lateral side of the eye and one to the medial side. The lateral tract of each eyeball goes to the same side of the brain, while the medial tract of each eye ball crosses to the opposite hemisphere of the brain.  The position of the tracts in the eyeball allows enough lines of sense to create a 3D view
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