Autonomic Functions Of The SC,BS, & Hypothalamus

Question 1

Functions of the ANS

Answer 1

1. Maintenance of homeostasis ( neg feedback on BP/ regulate PH
2. Integration of stress response ( exercise increases blood to limbs by VASODILATION. or fight/ flight makes sure energy is available
3. Inegration of visceral function (coord of GI organs after ingestion of food)

Question 2

How do we feel thirsty?

Answer 2

Function of hypothalamic nuclei that plays a major role in the activity of the ANS

Question 3

Difference in distribution of pre-ganglionic neurons

Answer 3

SNS : it’s in the MIDDLE
They are somewhere in the SC between T1 and L1/2 they send projections to ganglia chain, these ganglia have 2nd cell bodies called post-ganglionic neurons (either pre or paravertebral)
PSNS : it’s in the edges

Question 4

Neurotransmitters of the ANS

Answer 4

1. Acetylcholine : cholinergic ( degraded by cholinesterase) > SNS AND PSNS
2. Adrenaline/Noradrenaline : Adrenergic
   (degraded by monoamine oxidase or catecholamine O methyl transferase) > ONLY SNS
3. non-aderengergic/cholinergic : some postganglionic neurons of the GIT, VIP, Substance P, NO

Question 5

Non-adrenergic/cholinergic fibers use

Answer 5

ATP/VIP/NO
NO cannot be stored in the SV, Ca (required for vesicle docking and release) entry activates NO, NO diffuses across the synaptic cleft, relaxation of POSTSYNAPTIC SMC

Question 6

What neurons release Ach and what receptors do they act on in the PSNS and SNS ?

Answer 6

Pre-ganglionic neurons release Ach and they activate receptor if POST ganglionic neurons called NICOTINIC R
, post gang also release Ach to act on MUSCARINIC R

SNS only pre-gang release Ach act on NICOTONIC, post-gang release NA also to act on alpha or Beta R

Question 7

What are the to Ach receptors and their function ?

Answer 7

Nicotinic receptors :

1. Inotropic
2. Expressed in all postgang in SNS and PSNS
3. Ach binding to nic R is Stimulatory
4. Inhibited by curare (tuborcurare)
5. Fast AP/depol (NA/CA in, K out)
6. Post-synaptic membrane of all autonomic ganglia/NMJ/some CNS pathways

Muscarinic receptors :
G-protien coupled receptors aka METABOTROPIC (Gi, Gs, Gq, Go)
Expressed in effector cells stimulated by postganglionic cholinergic fibers
Stimulatory or inhibitory
Blocked by ATROPINE ( BELLADONA )
Causes relaxation of muscles of the iris (OPTHALMIC EXAM)
Slower activation than nicotinic R
Produces PSNS effect on heart,SMC, glands
EXCITATORY M3M5 IF CLOSED K CHANNEL (BUILDUP) > SMC contraction, glands secretion ( open Ca channels )
INHIB M2 OPEN K CHANNEL > Slows HR

Question 8

Alpha and beta

Answer 8

Alpha 1 and 2 :
Generally stimulatory just little are inhib
Beta 1 : stim in heart
Beta 2&3 : inhib ( b2 in lungs )