Autonomic Nervous System

Question 1

PNS divided into

Answer 1

ANS and somatic

Question 2

ANS divided into

Answer 2

SNS and PNS

Question 3

Somatic nervous system divided into

Answer 3

Sensory (afferent) and motor (efferent)

Question 4

Effectors of Somatic System

Answer 4

skeletal muscles

Question 5

ANS effectors

Answer 5

cardiac, smooth muscle, glands

Question 6

Efferent pathways of somatic system

Answer 6

thick, heavily myelinated, somatic motor fiber makes pathway from CNS to muscle

Question 7

Efferent pathway of ANS

Answer 7

2 neuron chain
preganglionic- thin, lightly myelinated preganglion axon
ganglionic neuron has unmyelinated postganglionic axon that extends to effector organ

Question 8

Somatic NT effects

Answer 8

all somatic motor neurons release ACh- always stimulatory

Question 9

ANS NT Effects

Answer 9

PREganglionic fibers release ACh
POSTganglionic fibers release NE or ACh at effectors
effect is either stim/inhibitory depending on receptor

Question 10

SNS fibers

Answer 10

originates in thoracolumbar (T1-L2) region of SC
short pre and long post
ganglia close to spinal cord

Question 11

PNS fibers

Answer 11

Origin in craniosacral spinal cord
long pre and short post
ganglia in visceral effector organs

Question 12

sympathetic neurons produce ? of the spinal cord

Answer 12

lateral horns

Question 13

Upon entering sympathetic trunk ganglion, preganglionic fiber may do one of following:

Answer 13

1) synapse with ganglionic neuron within same ganglion
2) ascend or descend sympathetic trunk to synapse in another trunk ganglion
3) pass through trunk ganglion and emerge without synapsing

Question 14

T1-T4 fibers

Answer 14

cardiac accelerator fibers

Question 15

Pathways with synapses in adrenal medulla

Answer 15

some preganglionic fibers pass directly to medulla without synapsing- stimulates medullary cells to secrete NE and epi into blood

Question 16

Cholinergic fibers

Answer 16

release ACh

all ANS preganglionic axons and all PNS postganglionic axons

Question 17

Adrenergic Fibers

Answer 17

release NE

most sympathetic postganglionic axons

Question 18

Nicotinic Receptors

Answer 18

• end plates of SKELETAL muscle cells, all ganglionic neurons, hormone producing cells of adrenal medulla
• always stimulatory

Question 19

Muscarinic Receptors

Answer 19

• found on all effector cells stimulated by postganglionic cholinergic fibers (parasympathetic target organs)
• effect either inhibitory or excitatory (depends on organ)

Question 20

B1 receptors

Answer 20

• heart, kidneys, adipose

- NE increases HR contractility, stimulates renin release

Question 21

B2 receptors

Answer 21

• lungs, most other sympathetic organs

- NE effects mostly inhibitory- dilates BV and bronchioles, relax smooth muscle walls of digestive/urinary organs/uterus

Question 22

A1 receptors

Answer 22

• blood vessels, almost all sympathetic target organs except heart
• NE constricts BV and visceral organ sphincters, pupil dilation

Question 23

A2 receptors

Answer 23

• membrane or adrenergic axon terminals; pancrease; platelets
• inhibits NE release from adrenergic terminals, inhibits insulin secretion, promotes blood clotting

Question 24

Atropine

Answer 24

• anticholinergic; blocks muscarinic receptors

- prevents salivation, dilate pupils

Question 25

Neostigmine

Answer 25

• inhibits acetylcholinesterase

- reverses NMBs, used to treat MG

Question 26

alpha blocker drugs

Answer 26

interfere with vasomotor fibers, used to treat HTN

Question 27

PNS vs SNS length of effects

Answer 27

PNS- short lived

SNS- long lasting (NE inactivated more slowly than ACh)

Question 28

Main integrative center of ANS activity

Answer 28

hypothalamus