Autonomic NS

Question 1

Describe the three modes of innervation in the sympathetic division

Answer 1

1) Preganglionic neuron –> paravertebral ganglia (prevertebral ganglia)–> post-ganglionic neuron
2) Preganglionic neuron –> specialized ganglion (superior cervical, celiac, superior/inferior mesenteric ganglia) –> target organ
3) Preganglionic neuron –> organ: adrenal medulla

Question 2

Sympathetic

Answer 2

thoracolumbar - located in the lateral horn (intermediolateral cell column)
- ganglia lie

Question 3

Parasympathetic

Answer 3

Cranio-sacral

- ganglia lie close to target

Question 4

describe the cranial outflow of the parasympathetic division

Answer 4

Preganglionic fibers in certain cranial nerves:

• Oculomotor
• facial and glossopharyngeal nerves
• vagal nerve

Question 5

Describe the sacral outflow

Answer 5

• bladder
• descending large intestine
• rectum
• genitalia

Question 6

Describe the enteric nervous system

Answer 6

a system of ganglia sandwiches between the layers of the gut and connected by dense meshwork of nerve fibers

• myenteric plexus: motility of gut
• submucosal plexus: secretion of ion and fluid transport
• receives input from both the sympathetic and parasympathetic divisions
• can function normally without extrinsic input

Question 7

define dual innervation

Answer 7

Most organs receive both sympathetic and parasympathetic innervation –> actions controlled by both symptoms (not antagonistic)
EXCEPTIONS
- only symptahtic = hair follicles, thermoregulatory sweat glands, liver, adrenal gland, kidney
- two systems producing similar rather than opposing effects: salivary glands

Question 8

what is the main NT at Presynaptic

Answer 8

ACh

Question 9

What is the key postglanglionic NT for sympathetic sweat glands

Answer 9

ACh

Question 10

What is the key postglanglionic NT for symapthetic Cardiac and smooth muscles, gland cells, nerve terminals

Answer 10

NE

Question 11

What is the key postglanglionic NT for symapthic to renal vascular smooth muscle

Answer 11

Dopamine

Question 12

What is the key postglangionic NT for Parasympathetic to cardiac and smooth muscle, gland cells, nerve terminals?

Answer 12

ACh - for All parasympathetics

Question 13

describe Cholinergic Synthesis

Answer 13

1) Choline transporter (CHT) (transports choline into cell from Extracellular matrix)
- blocked by hemicholiniums (experimental Rx)
2) acetylCoA (mito) + Choline = Acetylcholine
- Choline acetyltransferase (ChAT) (conjugates it)

Question 14

Storage of Cholinergic

Answer 14

1) Vesicle-associated transporter (VAT) transports ACh into the lumen of a vesicle
- -> blocked by Vesamicol (experimental)

Question 15

Release of cholinergic

Answer 15

1) depolarization of the Nerve terminal
2) voltage-dependent Ca+ entry
3) Ca+-calmodulin association with vesicle-associated membrane protein (VAMP) and synaptosome-associated proteins (SNAP)
- -> BLOCKED BY Butulinum toxin
4) vesicles fusion and neurotransmitter released (exocytosis)

Question 16

Termination of action of cholinergic transmission

Answer 16

1) rapid hydrolysis of Ach
- Acetylcholine esterase (AchE) forms choline and acetate
- -> blocked by AchE inhibitors! (causes hyperactivation of AcH)
2) choline re-uptake into terminals

Question 17

What are the two types of choliergic receptors

Answer 17

Muscarinic - G protein coupled

Nicotinic - Ionotropic receptor (Na+ channel)

Question 18

Affects of M3 receptor in intact endothelium vs damaged endothelium

Answer 18

Intact endothelium = effects of M3 activation lead to VASODILATION
Damaged endothelium = effets of M3 activation on vascular smooth muscle cell causes VASOCONSTRICTION.

Question 19

M1 and M3 activate what receptors?

Answer 19

Gq coupled receptors –> phospholipase C which cleaves PIP2 into:
- IP3 = increases Calcium
- DAG = increaes PKC
THINGS SPEED UP

Question 20

M2 activates what receptors

Answer 20

Gi coupled receptors –>inhibits adenylyl cyclase causes decrease cAMP which Decreases PKA activity
THINGS SLOW DOWN

Question 21

Nicotinic receptor location?

Answer 21

Nicotinic receptor are located at the presynaptic terminal that causes release of Ach on postsynaptic neuron

Question 22

Describe effect of Nn on adrenal medula

Answer 22

secretions of epinephrine and NE

Question 23

Describe effect of Nn on autonomic ganlgia

Answer 23

stimulation - net effects dependent on PANS/SANS innervation and dominance

Question 24

Describe effect of Nm on NMJ

Answer 24

stimulation - twitch/hyperactivity of skeletal muscle

Question 25

catecholamine synthesis

Answer 25

1) tyrosine hydroxylase converts tyrosine to Dopa and eventually dopamine. - -> blocked by metyrosine

Question 26

Catecholamine storage

Answer 26

1) vesicular monoamine transporter (VMAT) - -> blocked by Reserpine 2) synthesis continues in vesicles

Question 27

Catecholamine release

Answer 27

1) similar exocytosis mechanism as Ach release | - -> VAMP inhibited by bretylium

Question 28

Termination of action of adrenergic transmission

Answer 28

1) Diffusion at synapse and metabolized by liver (via catechol-O-methyl transferase (COMT) 2) Autoreceptor --> decreases release 3) reuptake via NET1 (NE transporter) and repackaged in vesicles or - -> metabolized by mitochondrial monoamine oxidase (MAO)

Question 29

Mechanisms of alpha1 receptor activation

Answer 29

G-protein coupled receptor (Gq) | - leads to increase in calcium and end results in vasoconstriction (hypertension)

Question 30

Mechansims of beta and alpha 2 receptor activation

Answer 30

Beta activates Gs and activates adenylyl cyclase --> increases cAMP --> increases biologic effects alpha2 activates Gi and inhibits adenylyl cycles (similar to M2)

Question 31

Homotropic interactions

Answer 31

the transmitter, by binding to presynaptic autoreceptors, affects the nerve terminals from which it is being released. - inhibits the release of the same NT

Question 32

Heterotropic interactions

Answer 32

one NT affects the release of another via actions on heteroreceptors e.g. NE affects Ach release and vice-versa.

Question 33

Denervation supersensitivity (withdrawal rebound hyperactivity)

Answer 33

Phenomena: Nerve cut --> supersensitive downstream structure - sustained block of ganglionic transmission/postsynaptic receptors --> target organs become super sensitive when the blocker is removed MECHANISM: - proliferation of receptors - loss of mechanism for removal of transmitter

Question 34

Co transmission

Answer 34

Neurons release more than one transmitter or modulator, each of which interacts with specific receptors and produces effects, often both pre and postsynaptically.

Question 35

what are the main functions of the ANS

Answer 35

1) assist the body in maintaining a constant internal envornment 2) accommodates coordinated responses to external stimuli (ex. pupil response to ambient light)

Question 36

Response to sympathetic/parasympathetic activation

Answer 36

Sympathetic activation = ergotropic = fight or flight | parasympathetic activation = trophotropic = rest and digest

Question 37

Describe autonomic feedback loop controlling arterial blood pressure

Answer 37

increase in blood pressure (sympathetic activation) increases baroreceptor discharge --> activates vasomotor center --> activates SANS --> decrease in sympathetic tone --> decreases vasoconstriction, decrease cardiac contraction (M2), decrease heart rate (M2)

Question 38

Whenever you have an increase in peripheral resistence you have...

Answer 38

(increase alpha1) a reflex bradycardia (tries to correct itself) - same is true for opposite.

Question 39

describe hormonal autonomic feedback loop

Answer 39

Decrease blood pressure --> decreases renal blood flow --> increases renin production --> increases angiotension --> increase aldosterone --> increase blood volume --> increases cardiac output --> increases blood pressure. Decrease blood pressure --> increase sympatetic drive --> increase total peripheral resistance. ATTEMPTS TO BRING BLOOD PRESSURE UP.