1.controls smooth muscle, cardiac muscles and glands, is involuntary.

2.Regulates the activities of cardiac muscle, smooth muscle, and glands which are typically involuntarily controlled.

Contains two neurons in the pathway from the spinal cord to its target, preganglionic neuron and postganglionic neuron that synapse in a ganglion

Preganglionic autonomic neurons originate in the CNS.

Postganglionic neurons originate from an autonomic ganglion (a collection of neuron cell bodies located outside the CNS).

 responds to emergencies and also exercise

axons leave the cord at T₁ to L₂ ; have ganglia near the cord

three ways that sympathetic neurons reach their target: the preganglionic neurons

• synapse in paravertebral ganglia (for blood vessels, sweat glands, arrector pili muscles and thoracic organs);

• pass through paravertebral ganglia and synapse in prevertebral (collateral) ganglia for urinary, digestive and reproductive systems;
• pass through both types of ganglia and innervate the adrenal medulla

Preganglionic neurons originate primarily in the thoracolumbar division (T1-L2).

• Synapse w/ postganglionic neurons in the sympathetic chain ganglia (paravertebral ganglia) or in other collateral (prevertebral) ganglia.

• Postganglionic axons are generally longer than preganglionic axons; they lead to the target organ.

• Preganglionic neurons release ACh (which binds to a cholinergic synapse);

•   postganglionic neurons release NE (which binds to an adrenergic synapse).

• Craniosacral division (cranial nerves 3, 7, 9, 10 and sacral nerves S2-S4).

• Synapse w/ postganglionic neurons in the target organs or near the target organs in the terminal ganglia.

• Preganglionic axons are very long compared to the postganglionic neurons they innervate because the latter are confined to the target organs.

• Preganglionic neurons release ACh; postganglionic neurons release ACh.

axons leave the CNS at the brainstem and sacral part of the cord (S_{2, 3,4} ); have terminal ganglia near the target organs

long preganglionic neurons and short postganglionic neurons, doesn't allow for interconnections and mass activation; unlike sympathetic system which has short preganglionic neurons and long postganglionic neurons

cranial contribution: cranial nerves III, VII, IX, and X

CN III, lens focusing and pupillary constriction

CN VII, lacrimal glands, submaxillary and submandibular (salivary) glands

CN IX, parotid (salivary) gland

CN X, vagus nerve, major parasympathetic supplier: thoracic and abdominal cavity organs through first half of large of large intestine

parasymathetic 

sacral contribution

sacral contribution: S _2-4 supplying distal half of large intestine, urinary and reproductive organs

sympathetic system

sympathetic system, increased: heart rate and contraction strength, blood pressure, blood glucose; pupil dilation, bronchiole dilation; digestion shuts down, blood shunted to muscles.

parasympathetic system

parasympathetic system, most effects are antagonistic to sympathetic system

 neurotransmitters

adrenergic refers to NE, cholinergic refers to ACh

1. all preganglionic neurons release ACh
2. parasympathetic postganglionic neurons release ACh
3. sympathetic postganglionic neurons release NE

adrenergic receptors, two major classes, alpha and beta

alpha-adrenergic receptors generally stimulate contraction ("a" as in contraction) of smooth muscle

beta-adrenergic receptors generally inhibit ("b" as in inhibit) contraction, i.e. cause relaxation

major beta exception: heart, which is stimulated to contraction faster and with more force and has beta-receptors. Called beta-1 receptors as compared to other organs, such as lung bronchioles, which have beta-2 receptors

antagonists prevent action of neurotransmitters, agonists intensify them

beta blockers (NE antagonists) are used to slow down the heart, but its important to be specific for beta-1 and not affect beta-2

Nerves that release norepinephrine are called adrenergic nerves. Adrenergic nerves are part of the postganglionic sympathetic nerve system** and parts of the central nervous system. (**A nerve that carries the impulse from the ganglion to the effecter cell is a postganglionic nerve.)

 nicotinic and muscarinic

example of a muscarinic blocker (antagonist): atropine, produces pupil dilation, also used to decrease respiratory secretions and intestinal activity

Nerves that release acetylcholine are called cholinergic nerves. Cholinergic nerves are part of the parasympathetic system, somatic motor nerves, preganglionic sympathetic nerves* and central nervous system. (*The nerve that carries the message from the central nervous system to a ganglion - junction for a group of nerve cells - is a preganglionic nerve.)

ANS Receptor Types:

• Adrenergic - alpha (α), beta (β); subtypes 1 and 2

• Cholinergic - muscarinic, nicotinic

Compounds have been developed that selectively bind to these receptors and either promote (an agonist) or inhibit (an antagonist) the cholinergic or adrenergic effect.

ANS: sympathetic and parasympathetic

neurotransmitters

Most organs receive dual innervation by both divisions of the ANS.

The 2 divisions are usually regarded as being antagonistic.

However, the effects can be:

• Antagonistic - Effects are opposite.  Examples: Heart, pupils, ...

• Complementary - Effects are similar.  Example: Salivary gland secretion

• Cooperative (synergistic) - Effects are different, but they work together to promote one action.  Example: Male reproductive system

• Penile erection is under parasympathetic control

• Ejaculation is under sympathetic control

ANS: sympathetic and parasympathetic

• Some structures do not receive dual innervation and receive only sympathetic input: the adrenal medulla, arrector pili muscles in the skin, most blood vessels, and sweat glands in the skin are examples.  Regulation is achieved by variations in the firing rate of sympathetic neurons.

Medulla oblongata of the brain stem most directly controls the activity of the ANS.  However, it is also influenced by sensory input and input from the hypothalamus.

Ch. 10 Sensory Physiology start at p. 280, Eyes and Vision

sensory receptors as transducers, changing a stimulus into an action potential

sclera, cornea, pupil, iris

All receptors are transducers, that is they respond to a stimulus by changing (transducing) it into a generator or receptor potential. A receptor potential is like the graded potentials which occur at a synapse. Graded potentials can result in an action potential produced in a neuron leading to the brain. Various stimuli can often produce a generator potential including electrical, physical, chemical, and others. But receptors can be classified according to the stimulus  to which they normally respond:

circular smooth muscle of the iris which produces constriction (parasymp.)

radial smooth muscle which produces dilation (sympathetic enervation)

pupillary response can be protective: constriction in bright light

iris and eye color

Glaucoma is a group of diseases that can damage the eye's optic nerve and result in vision loss and blindness. Glaucoma occurs when the normal fluid pressure inside the eyes slowly rises. However, with early treatment, you can often protect your eyes against serious vision loss.

What is a cataracts?

A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.

A cataract can occur in either or both eyes. It cannot spread from one eye to the other.

vitreous humor

The vitreous humor is a clear gel which occupies the posterior compartment of the eye, located between the crystalline lens and the retina and occupying about 80% of the volume of the eyeball.  Light initially entering the eye through the cornea, pupil, and lens, is transmitted through the vitreous to the retina.

retina, has three layers of neurons, rods and cones (photoreceptors), bipolar cells and ganglion cells whose axons form the optic nerve

blind spot at the optic disc where the optic nerve leaves the eye

Accommodation, lens changes shape to allow both near and distant objects to be focused on the retina lens will be thin for distance vision and bulging for near visionshape controlled by the smooth muscle of the ciliary body near point of vision and presbyopia

photoreceptors: rods and cones

rods: vision in low light; no color vision, images are fuzzy (low visual acuity)

rod photopigment is rhodopsin, consists of opsin and retinene

light causes 11-cis-retinene to become all-trans-retinene and dissociate from opsin (bleaching of the photopigment)

free opsin activates a G-protein which eventually leads to an ion channel closing à change in neurotransmitter à graded potential in bipolar cell à action potential in the ganglion cell, whose axon is part of the optic nerve; optic nerve à à occipital lobe of brain

cones: color vision ("c" for color and cone), sharp details, requires high light intensity

red, blue and green cones, all have same retinene but different opsins (proteins) called photopsins

the gene for the red and green photopsin is on the X chromosome; colorblindness is more common in men

cones are more centrally located on the retina and rods are more peripheral

fovea centralis, in the macula lutea, is the area of highest visual acuity (sharpness)

contains only cones; bipolar cells and ganglion cells are parted to give direct access to incoming light (fovea = pit); cones have a 1:1 connection to bipolar cells and ganglion cells (no convergence)

Ears: Hearing and Balance pg. 269-280

sound waves 1

outer ear funnels sound in to tympanic membrane, which vibrates

Ears: Hearing and Balance

ossicles in middle ear

1. auditory tube (eustachian tube) for pressure equalization

2. stapes sets up pressure waves in the fluid in cochlea the pressure waves produce vibrations of the basilar membrane

Ears: Hearing and Balance

Ears: Hearing and Balance

pitch discrimination:

 pitch discrimination: high pitched sounds cause the basilar membrane closer to the oval window to vibrate maximally; low pitched sounds cause the basilar membrane closer to the apex to vibrate maximally

hair cells have "hairs" embedded in the tectorial membrane; when basilar membrane vibrates, the pull on the hairs opens ion channels à à neurotransmitter release à action potential in the associated sensory neuron à à à temporal lobe of the brain

Ears: Hearing and Balance

balance:

vestibular apparatus = vestibule and semicircular canals contain hair cells, whose hairs are held by a gelatinous membrane

vestibule contains utricle and saccule which detect linear acceleration; hair cell hairs are embedded in the otolithic membrane

changing head position causes the hairs to move à à action potentials in the vestibular nerve à à cerebellum and medulla of the brain; from medulla to midbrain for controlling eye movements; and to spinal cord for regulating postural reflexes

Ch. 11 Endocrine Glands and Hormones

1

like the nervous system, the endocrine system is a regulatory system that releases effector molecules, but they are hormones rather than neurotransmitters

Ch. 11 Endocrine Glands and Hormones

2

nervous system is reactions are rapid and short-lived; endocrine system is slower and more prolonged

• hormones are released to the tissue spaces and carried through the body by the circulatory system

Ch. 11 Endocrine Glands and Hormones

3

hormones only affect target cells, cells with receptors

Ch. 11 Endocrine Glands and Hormones

4

organs other than the traditional endocrine glands can secrete hormones, such as the kidney which secretes erythropoietin which stimulates red blood cell formation in the bone marrow

Ch. 11 Endocrine Glands and Hormones

5

1. chemically, hormones can be lipophilic (lipid soluble); can be steroid hormones from the adrenal cortex or ovaries and tests, or thyroid hormones; will enter the target cell and have intracellular receptors

2. or hormones can be polar, not lipophilic and usually are proteins or related molecules; can't enter target cells and have receptors on the plasma membrane.

Ch. 11 Endocrine Glands and Hormones

6

 steroid hormones: carried by a protein carrier in the blood; intracellular receptor has two domains, ligand-binding domain and DNA-binding domain; hormone receptor complex binds to the DNA at a specific region of the DNA, the hormone-response element; nearby gene is activated to produce mRNA à new protein specific for the hormone's response

Ch. 11 Endocrine Glands and Hormones

7

protein hormones, hormone combines with receptor which is part of the cell membrane à G- protein is activated à adenylate cyclase is activated à cyclic AMP is produced; cyclic AMP is a "second messenger" that carries out the hormone's response by activating a protein kinase that activates other (pre-existing) enzymes à the hormone's response; example, epinephrine and the increase of blood glucose; this gives a faster response than steroid hormones which result in new protein synthesis;

Ch. 11 Endocrine Glands and Hormones

8

pituitary gland, anterior lobe, posterior lobe, both with different hormones, different mechanisms to control them and different embryological origin.

anterior pituitary hormones: trophic (tropic) ]hormones which stimulate (prevent atrophy) target glands or organs

Ch. 11 Endocrine Glands and Hormones

9

growth hormone (GH) stimulates protein synthesis and growth of bones, indirectly, by stimulating the liver to produce IGF (somatomedin) which causes muscle and bone growth via cartilage growth; Laron dwarfism, lacking GH receptors in the liver

hyposecretion of GH in children results in pituitary dwarfism; hypersecretion results in gigantism; in adults hypersecretion produces acromegaly

Hormones Activity

TSH: Thyroid-stimulating hormone

TSH: increases the activity of the thyroid gland.

Thyroid-stimulating hormone, or thyrotropin: influences the growth and activity of teh thyroid gland.

FSH and LH are gonadotropins and stimulate the ovaries and testes.

1.Follicle-Stimulating Hormone (FSH)

2.Luteinizing Hormone (LH)

LH is synthesized within the same pituitary cells as FSH and under the same stimulus (GnRH). It is also a heterodimeric glycoprotein consisting of

the same 89-amino acid alpha subunit found in FSH and TSH (as well as in chorionic gonadotropin); a beta chain of 115 amino acids that is responsible for its properties.

ACTH stimulates the adrenal cortex to produce hydrocortisone.

Adrenocorticotropic hormone, as its name implies, stimulates the adrenal cortex. More specifically, it stimulates secretion of glucocorticoids such as cortisol, and has little control over secretion of aldosterone, the other major steroid hormone from the adrenal cortex.

Prolactin (PRL)

prolactin causes synthesis of milk in women shortly after birth.

is a protein of 198 amino acids. During pregnancy it helps in the preparation of the breasts for future milk production. After birth, prolactin promotes the synthesis of milk. Prolactin secretion is:

• stimulated by TRH

• repressed by estrogens and dopamine

ex: pregnant mice, prolactin stimulates the growth of new neurons in the olfactory center of the brain

The Posterior Lobe

posterior pituitary hormones (stored hormones)

ADH, targets kidney to reabsorb water from the urine to prevent dehydration

ADH is a peptide of 9 amino acids. It is also known as arginine vasopressin. ADH acts on the collecting ducts of the kidney to facilitate the reabsorption of water into the blood. This it acts to reduce the volume of urine formed (giving it its name of antidiuretic hormone).

Oxytocin
Oxytocin is a peptide of 9 amino acids.
It acts on certain smooth muscles:

oxytocin, targets uterus to stimulate uterine contractions during childbirth; responsible for the "let-down" reflex in nursing, parental bonding to children, and is released during orgasm (a cuddle hormone)

• stimulating contractions of the uterus at the time of birth;
• stimulating release of milk when the baby begins to suckle.

Oxytocin is often given to prospective mothers to hasten birth.

Oxytocin also acts on the nucleus accumbens and amygdala in the brain where it enhances:

• bonding between males and females after they have mated;
• bonding between a mother and her newborn;
• and, in humans, increases the level of one's trust in other people.

Relationship between the posterior pituitary and the hypothalamus:

Hormones are produced in the cell bodies in the hypothalamus and travel down the axons to be stored in the axon terminals in the posterior pituitary.

hypothalamo-hypophyseal tract

ADH & Oxytocin

ADH is synthesized in the supraoptic nucleus and oxytocin is made in the paraventricular nucleus these neurons form the hypothalamo-hypophysealtract action potentials along this tract cause release of the hormones

Relationship between the anterior pituitary and the hypothalamus:

Anterior pituitary starts as oral epithelial tissue which breaks off and moves to the forming posterior pituitary hypothalamic neurons secrete releasing and inhibiting hormones that control the synthesis and release of anterior pituitary hormones

these releasing and inhibiting hormones are picked up by the hypothalamo-hypophyseal

portal system:

portal system, by the first (primary) capillary bed

portal venules drain that bed and lead to the secondary capillary bed which is in the anterior pituitary gland this is a direct delivery system for the hypothalamic hormones 

Examples: of releasing and inhibiting hormones: TRH, GnRH, CRH, GHRH, and PIH anterior pituitary is also controlled by its target organs via negative feedback

low levels of T₄ will result in high levels of TSH which will produce an increase in T₄

 adrenal gland: cortex and medulla have different hormones, different origins, and somewhat different functions

medulla: secretes E and NE as a result of sympathetic activation

 cortex: has three layers or zones (think GFR)

zona glomerulosa secretes aldosterone which controls Na+/K+ balance zona fasciculata secretes glucocorticoids such as cortisol which increase blood glucose levels, and at very high concentrations depress the immune system zona reticularis secretes (probably) sex steroids and glucocorticoids

stress, via the sympathetic system, increases the secretion of the adrenal medulla; and via CRH à ACTH à increased glucocorticoids from the cortex;

Thyroid gland: contains follicles willed with colloid (thyroglobulin) follicle cells take in the thyroglobulin and use it to produce T₃ and T_4. 

The Roles of T₃ and T₄: control basal metabolism, stimulate nervous system development hyposecretion in adults results in fatigue, obesity, and lethargy

hyposecretion in infants results in severe retardation, called cretinism

hypersecretion results in nervousness, weight loss, irritability and intolerance of heat

lack of sufficient iodine in the diet can produce endemic goiter: decreased I-à decreased T₃ , T_{4 _}à increased TSH à hypertrophy of the gland.

parathyroid gland: secretes parathyroid hormone which increases blood calcium levels

Ca++ is an important cellular signal, necessary for exocytosis of neurotransmitters, muscle contraction, and also can act as a second messenger hormone targets bone to release calcium, or the kidney to secrete less

 pancreas mixed gland, both exocrine (digestive enzymes) and endocrine (insulin and glucagon)

islets of Langerhans secretes glucagon in the alpha cells and insulin in the beta cells glucagon increases blood sugar (glucose) by stimulating glycogenolysis

insulin decreases blood glucose by stimulating cells to take up the glucose and store it

diabetes mellitus results from insufficient insulin secretion, or from the secretion of insulin that is ineffective results in high blood sugar, which produces high glucose levels in the urine; glucose in the urine produces polyuria (by osmosis), increase in urinary output and polydipsia, increase in water intake; two types of diabetes: type 1, usually starts in childhood; due to autoimmune destruction of the beta cells and resulting in no insulin production type 2, usually starts in adulthood; insulin is produced but the tissues are no longer sensitive to it

Ch 12. Muscle

Skeletal muscle cells

skeletal muscle cells known as muscle fibers tendon, connective tissue wrappings (fascia, epimysium, perimysium, endomysium) muscle cells are multinucleate, striated and contain myofibrils A bands, I bands, Z lines (discs), sarcomeres: space between two Z lines sarcomere, cell membrane of a muscle cell

The combination of a motor neuron and all the muscle cells the neuron stimulates; can be large (powerful muscles, such as the gastrocnemius) or small (precise muscles, such as extraocular muscles)

Mechanism of  muscle contraction:

myofibril contains sarcomeres, which shorten during contraction; H zone is obliterated, I zone is obliterated, Z lines come closer together and A bands remain the same.

 A band: contains the protein myosin; like two golf clubs wrapped around each other; head has an actin binding site and an ATP binding site which is called myosin ATPase

 I band contains the protein actin whose subunits (globular components, G-actin) have a site for binding myosin; G-actin subunits form F-actin, filamentous actin, which consists of two chains of F-actin twisted around each other;

contraction: 1-3

1

Contraction: myosin heads attach to actin (and release Pi from the previous cycle) and pull the actin filaments towards the center of the sarcomere (power stroke); 

contraction: 1-3

2

this sliding of the actin filaments results in contraction; ADP is released; myosin binds ATP and releases actin; ATP is split; the energy is transferred to the myosin head and results in the head being in the "cocked" or energized position;

contraction: 1-3

3

one power stroke results in shortening 1% of the muscle's length; a contraction involves many asynchronous power strokes rigor mortis: muscle stiffening shortly after death; myosin attaches to actin and power strokes until there is no more ATP; but myosin can't release actin when there's no more ATP, hence stiffness;muscle contraction: Z lines move closer together due to myosin heads (cross bridges) pulling actin filaments toward the center of the sarcomere

Regulation of contraction

1

Regulation of contraction, tropomyosin and troponin associated with actin, control access of actin binding sites to myosin heads

regulation of contraction

2

tropomyosin covers actin's binding sites; when troponin binds Ca²⁺ it pulls tropomyosin off the binding sites; this allows contraction to occur

Regulation of contraction

3

Calcium is stored in the terminal cisternae of the sarcoplasmic reticulum;

Regulation of contraction

4

a motor neuron stimulates its muscle cells by releasing neurotransmitter; this starts an action potential down the muscle cell sarcolemma; the action potential spreads to the inside of the cell by the T (transverse) tubules; action potentials in the T tubules cause release of Ca²⁺ from the terminal cisternae

Regulation of contraction

5

use of a transducer, stimulator, and chart recorder to record the contractions of muscles muscle twitch, and the phases of contraction and relaxation.

 threshold voltage, the lowest voltage to produce a twitch

Increasing stimulus intensity leads to increased force of contraction:

whole muscle contraction is graded; due to activating more muscle fibers (via motor units); called multiple motor unit summation or recruitment

Leads to fused contractions and tetanus; this is how muscles normally contract in our body and leads to smooth sustained movements.

Summary of Steps in Muscle Contraction:

1

Action potential travels along a motor neuron

Summary of Steps in Muscle Contraction:

2

release of ACh

Summary of Steps in Muscle Contraction:

3

action potential moves down the muscle cell sarcolemma

Summary of Steps in Muscle Contraction:

4

Action potential moves along the T tubules

Summary of Steps in Muscle Contraction:

5

Voltage gated Ca ²⁺ channels open in the T tubules

Summary of Steps in Muscle Contraction:

6

Calcium release channels open in the associated terminal cisternae

Summary of Steps in Muscle Contraction:

7

Calcium diffuses into the sarcoplasm

Summary of Steps in Muscle Contraction:

8

Calcium binds to troponin

Summary of Steps in Muscle Contraction:

9

tropomyosin is moved off of actin's binding sites

Summary of Steps in Muscle Contraction:

10

myosin heads attach to actin's binding sites and release Pi

Summary of Steps in Muscle Contraction:

11

 Myosin heads do a power stroke and then release ADP

Summary of Steps in Muscle Contraction:

12

myosin heads bind a new ATP and release actin

Summary of Steps in Muscle Contraction:

13

Summary of Steps in Muscle Contraction:

14

Summary of Steps in Muscle Contraction:

15

tropomyosin covers actin's binding sites

Summary of Steps in Muscle Contraction:

16

Actin filaments slide back to their original position and muscle relaxes

Summary of Steps in Muscle Contraction:

2

Summary of Steps in Muscle Contraction:

2