Physiology of Autonomic Nervous System Flashcards
Stimulation of the autonomic nervous system is noted to produce an increase in the secretion of acid by gastric parietal cells. Activation of what receptor type is most likely to have occurred?
a) Nicotinic cholinergic receptors (NAchR)
b) Muscarinic cholinergic receptor, type 3 (M3 receptor)
c) Alpha2 adrenergic receptors
d) Beta1 adrenergic receptors
b) Muscarinic cholinergic receptor, type 3 (M3 receptor)
Where are you most likely to find nicotinic cholinergic receptors (NAchR) related to the autonomic nervous system?
a) Cardiac conduction tissues such as the SA node
b) Chromaffin cells of the adrenal medulla
c) Sweat glands
d) Ganglia found in the sympathetic chain (paravertebral column)
e) liver
b and d
During an asthmatic episode, Student Doctor Seuss takes a drug designed to relax bronchiole smooth muscle. What receptors are activated by this drug?
a) Beta2 adrenergic receptors
b) Nicotinic cholinergic receptors (NAchR)
c) Alpha1 adrenergic receptors
d) M2 cholinergic receptor
a) Beta2 adrenergic receptors
After his asthma attack subsides, SD Seuss notes that his heart rate remains elevated. Activation of which receptor type will reverse that?
a) Alpha1 adrenergic receptors
b) Beta3 adrenergic receptors
c) Muscarinic cholinergic receptor, type 2 (M2 receptor)
d) Nicotinic cholinergic receptors (NAchR)
c) Muscarinic cholinergic receptor, type 2 (M2 receptor)
Where is the ganglia located in the parasympathetic system?
At or near the target organ
(except for the 4 paired ganglia in the head and neck)
Where is ganglia located in the sympathetic system?
Paravertebral ganglia are located in the sympathetic trunk (chain) that runs lateral to the spinal cord down the spine
What is the neurotransmitter used between the first synapse (between the pre-ganglionic and post-ganglionic neurons)?
What channel does it bind to?
What is an exogenous analogue of this neurotransmitter?
- acetylcholine
- nicotinic cholinergic channels (on dendrites of post-ganglionic cell)
- nicotine
(both acetylcholine and nicotine bind to the channel and open it, allowing Na+ into the cell causing depolarization)
What is the neurotransmitter used between the second synapse (post-ganglionic cell and target tissue) within the parasympathetic system?
What is the receptor?
- acetylcholine
- muscarinic cholinergic receptor (5 types), second messenger is G-proteins
What G-proteins do the odd numbered muscarinic cholinergic receptors (M1R, M3R, M5R) activate?
Gq proteins
(Gq/11 activation causes increase in IP3 and DAG which causes an increase in Ca2+)
What is the M1R function in the parasympathetic ANS?
increase secretion in salivary glands and parietal cells in stomach
What is the M3R function in the parasympathetic ANS?
- increase contraction of smooth muscle
- increase secretion of exocrine glands (sweat glands)
What G-proteins do the even numbered muscarinic cholinergic receptors (M2R, M4R) activate?
Gi proteins
(Gi/0 activation causes decrease in adenylyl cycle and cCAMP)
What is the M2R function in the parasympathetic ANS?
causes K+ efflux which results in hyperpolarization of the cell, causing decrease in heart rate and heart conduction
What is the neurotransmitter used between the second synapse (post-ganglionic cell and target tissue) within the sympathetic system?
What is the receptor?
- norepinephrine
- adrenergic receptors (alpha 1, alpha 2, beta 1, beta 2)
What is the alpha 1 function within the sympathetic ANS?
activates Gq/11 proteins, increasing intracellular Ca2+
- contraction and vasoconstriction in vascular smooth muscle
- contraction in smooth muscle of GU
- glycogenolysis and gluconeogenesis within liver
- lipolysis within adipose tissue
- decreased tear production in lacrimal glands
- increased contraction and dilation of pupil in the radial M. of the eye
