Lecture 71

Question 1

organization of the nervous system

Answer 1

• CNS: brain and spinal cord
• PNS: neurons outside brian and spinal cord; enter CNS (afferent) or leave CNS (efferent)
• efferent subdivided into: somatic neurons (voluntary functions) and autonomic neurons (functions outside of conscious control)

pg 1842

Question 2

autonomic vs somatic efferent neurons

Answer 2

Autonomic

• have ganglia (NT → acetylcholine, receptor → N_n (neuronal))
• post-ganglionic neurotransmitter and receptor varies depending on sympathetic vs parasympathetic

Somatic

• NO ganglia
• NT: acetylcholine
• Receptor: N_m (muscle)

pg 1844

Question 3

structure of the efferent neuron

Answer 3

• autonomic: preganglionic and postganglionic neuron
• somatic: 1 neuron from CNS to muscle

pg 1845

Question 4

sympathetic vs parasympathetic neuron

Answer 4

Sympathetic

• short pre-ganglionic neuron (branched), long postganglionic neuron
• 1st NT → acetylcholine, 1st receptor → N_n
• 2nd NT → norepinphrine/noradrenaline, 2nd receptor → α/β adrenergic receptor
• ganglion in sympathetic chain, close to spinal cord

Parasympathetic

• long pre-ganglionic neuron, short post-ganglionic neuron
• 1st NT → acetylcholine, 1st receptor → N_n
• 2nd NT → acetylcholine, 2nd receptor → muscarinic receptor
• ganglion very close to or within the organ

pg 1847

Question 5

sympathetic innervation to adrenal medulla

Answer 5

• adrenal medulla thought of as a modified ganglion
• has nicotinic receptor for acetylcholine from preganglionic neuron
• releases epinephrine/adrenaline that travels in the blood to go where needed (and act on adrenergic receptors)

pg 1849

Question 6

sympathetic nervous system

Answer 6

• fight, fright or flight response
• increases all heart functions
• vasoconstricts BVs in skin and splanchnic, vasodilates skeletal BVs
• decreases GI motility and secretions, contracts sphincters
• bronchodilation, decreased respiratory secretions
• bladder relaxation, urinary sphincter contracts
• pupil dilation, accommodation for far vision

pg 1860

Question 7

parasympathetic nervous system

Answer 7

• rest and digest response
• opposite functions as sympathetic nervous system

pg 1860

Question 8

dual innervation

Answer 8

• received by most organs
• relationship between two components of ANS is dynamic and continuously fine tuned to achieve homeostasis

pg 1864

Question 9

neurotransmission at cholinergic neurons

Answer 9

1. synthesis of acetylcholine
2. uptake into storage vesicles
3. release of neurotransmitter
4. binding to the receptor
5. degradation of acetylcholine
6. recycling of choline

pg 1866

Question 10

cholinergic receptors

Answer 10

• bind to acetylcholine → cholinergic receptors
• further classified into nicotinic and muscarinic

pg 1867

Question 11

muscarinic recptors

Answer 11

• found in effector organs receiving parasympathetic innervation
• GPCRs
• M1 through M5

pg 1868

Question 12

nicotinic receptors

Answer 12

• N_n found in ganglia and adrenal gland
• N_m found in skeletal muscle
• ion channel-linked receptors

pg 1868

Question 13

distribution of muscarinic receptor subtypes

Answer 13

• M2 found in heart
• M3 in glands and smooth muscle
• N_m found in skeletal muscle neuromuscular junction
• N_n found in postganglionic cell body

pg 1869

Question 14

examples of actions mediated by cholinergic (muscarinic) receptor stimulation

Answer 14

• rest and digest actions
• bronchoconstriction, lung secretion, increased GI motility, etc…

pg 1870

Question 15

acetylcholinesterase (AChE)

Answer 15

responsible for termination of acetylcholine action at nerve terminals by breaking down acetylcholine (important drug target to elicit a parasympathetic response)

pg 1872

Question 16

drugs targeting cholinergic receptors

Answer 16

• enhance cholinergic signaling: receptor agonists (direct approach) or cholinesterase inhibitors (indirect approach)
• inhibit cholinergic signaling: receptor blockers

pg 1873-1874

Question 17

adrenergic neurotransmission

Answer 17

• unlike cholinergic neurotransmission, the major pathway to terminate noradrenergic transmission is the agonist’s removal and reuptake into the presynaptic neuron
• reuptake system is target of pharmacotherapeutic agents

pg 1881

Question 18

adrenergic receptors

Answer 18

• all GPCRs
• separated into alpha and beta, alpha and beta further separated
• alpha 1 (blood vessels of skin and splanchnic vessels)
• alpha 2 (CNS)
• beta 1 (heart)
• beta 2 (bronchial smooth muscles)
• beta 3 (bladder detrusor muscle)

pg 1882-1884