7.2 Neurotransmitters

Question 1

Whatdo cholinergic fibers release

Answer 1

• acetylcholine (Ach)
• released at:
• > sympathetic preganglionic axons
• > parasympathetic pre and post ganglionic axons
• > somatic motor neurons

Question 2

what do adrenergic fibers release

Answer 2

• norepinephrine or epinephrine

*released from most sympathetic postganglionic axons

exceptions: sympathetic postganglionic fibers secrete ACh at sweat glands & some blood vessels in skeletal muscles

Question 4

what do cholinergic receptors bind? what are the types

Answer 4

• bicotinic and muscarinic receptors bind ACh

Question 5

where are nicotinic receptors found? what is the effect of Ach binding

Answer 5

found on

• > Motor end plates of skeletal muscle cells
• > All ganglionic neurons (SNS & PSNS)
• > Hormone-producing cells of adrenal medulla

*effects of Ach at nicotininc receptors is always stimulatory

Question 6

where are muscarinic receptors found? what is their effect when Ach binds?

Answer 6

• found on all effector cells stimulated by postganglionic cholinergic fibers
• effect can be inhibitory or excitatory

Question 7

what are the types of adrenergic receptors?

Answer 7

1. Alpha = Generally stimulatory
2. Beta = Generally inhibitory (except heart)

(effects depend on receptor subclass of targer organ

Question 8

action of epinephrine and norepinephrine at beta and alpha adrenergic receptors

Answer 8

NE: alpha > beta

E: Alpha = beta

Question 9

what happens when NE or E binds α₁

Answer 9

acts on: blood vessles serving skin, ucosae, abdominal viscera, kidneys, and salivary glands

*vitally all sympathetic target organs except the heart

effect of binding: contricts blood vessels and visceral organ sphincters; dilates pupils of the eyes

*think α looks like a blood vesel if errase the tail

Question 10

what happens when NE or E binds α₂

Answer 10

• binds the membrane of adrenergic axon terminals, pancrease, and blood platlets
• inhibits NE release from adrenergic terminals, inhibits insulin secretion by pancreas and promotes blood clotting

Question 11

what happens when NE or E binds β₁

Answer 11

binds to: heart predominantly but also kidneys and adipose tissue

• increases HR and strength, stimulates renin release by kidnys

*β1 = heart, β2 = lungs bc have 2 lungs

Question 12

what happens when NE or E binds β₂

Answer 12

• binds to lungs and most other sympathetic target organs
• abundant on blodo vessels serving the heart, liver and skeletal muscle

effects are mostly inhibitory: dilates BV and bronchioles, relax smooth muslce walls of digestive and urinary organs, relax uterus

*relas bronchioles to have more air going in and out

Question 13

what happens when NE or E binds β3

Answer 13

acts on adipose tissue

0 stimulates lipolysis by fat cells

Question 14

why are there interactions of the autonomic divisions

Answer 14

Most visceral organs have dual innervation

􏰀 Dynamic antagonism allows for precise control of visceral activity

Question 15

what receptors are found in dilator, sphincter, cilary muscle and cilary epithelium of the eye

Answer 15

dilator: alpha

Sphincter: M

cilary epithelium: Beta

cilary muscle; M

Question 16

what is parasympathetic tone

Answer 16

PSNS normally dominates heart & smooth muscle of digestive & urinary tract organs

• >Slows heart
• > Dictates normal activity levels of digestive & urinary tracts

* SNS can override these effects during times of stress

Question 17

describe sympathetic tone

Answer 17

aka vasomotor tone

• dont have dual innervation, BV only have 1 input
• keeps blood vessel in a continual state of partial constriction

Question 18

what organs do not have dual inneration? what are they responsible for?

Answer 18

*these only have sympathetic inneravation

1. sweat glands and arrector pili muscles: thermoregulatory response
2. kidneys: release renin
3. most blood vessels: reg blood presure
4. adrenal medulla: metabolic effects
   
   • inc metabolic rate of cells
   • inc blood glucose
   • metabolize fats as fuels

Question 19

describe localized vs diffuse effects in PSNS and SNS

Answer 19

PSNS: short-lived, highly localized control over effectors

SNS: long-lasting, bodywide effects

Question 20

what are the effects of sympathetic activation

Question 21

duration of sympathetic activation

Answer 21

• long lasting because:
• > NE is inactivated more slowly than ACh
• > NE & E released into blood & remain there until destroyed by liver

Question 22

components of visceral reflexes

Answer 22

same as comatic reflexes

1. stimulus deteceted by sensory receptor in viscerea
2. visceral sensory neuron
3. integration center: amy be preganglionic neuron (as shown), doral horn interneuron, or within walls of GI tract
4. efferent pathway (two neuron chain): pre and post ganglionic neuron
5. visceral effector -> response

*can have short relfexe that bypasses CNS

Question 23

Question 25

what controls ANS functioning

Answer 25

Cerebral cortex (frontal lobe) limbic system (emotional input) hypothalamus (overall integration of ANS) —> Brain stem —–> spinal chord

*brain stem: reg pupil size, respiration, heart, BP, swallowing

*spina chord: reg urination, defication, erection and ejactualtion reflexes

Question 26