Autonomic Physiology

Question 1

Describe a simple reflex arc involving skeletal muscle

Answer 1

Sensory information is relayed from periphery to the central nervous system via afferent neurons

The neuronal circuit is found within the spinal cord and sensory fiber synapse on motor neurons (alpha motor) which relay signal to the muscle

Question 2

Where are autonomic responses processed?

Answer 2

Processed in hypothalamus

Question 3

What takes places of alpha motor neurons in autonomic (visceral reflexes)?

Answer 3

The autonomic nervous system

Question 4

How many neurons make up the autonomic nervous system? The somatic motor system?

Answer 4

Autonomic= two neurons:

• pre synaptic (pre ganglionic) neuron= cell body in CNS which terminates in ganglion in periphery
• post synaptic= cell body in ganglion terminates on end organ

Somatic= 1 neuron

Question 5

Where is the first synapse of the autonomic nervous system?

Answer 5

in the ganglion, between sympathetic and parasympathetic systems

Question 6

What neurotransmitter is released at synapse #1 and what is its receptor? Are parasympathetic and sympathetic the same?

Answer 6

They are the same

Acetylcholine –> Nicotinic cholinergic receptor

Question 7

How does the sympathetic and parasympathetic systems differ in synapse #2?

Answer 7

Parasympathetic: Acetylcholine –> muscarinic cholinergic receptors on the target cells

Sympathetic: Norepinpehrine –> alpha and beta adrenergic

Question 8

What G-protein is M1R coupled to? What is its role?

Answer 8

Gq= increased in intracellular Ca++

Increase secretion in salivary glands and acid secreting cells of the stomach

Non autonomic function= memory

Question 9

What G-protein is M3R coupled to? What is its role?

Answer 9

Gq

Smooth muscle contraction
Exocrine gland secretion including sweat

Question 10

What G-protein is M5R coupled to? What is its role?

Answer 10

Gq

unknown aka can’t be answer to question

Question 11

What G-protein is M2R coupled to? What is its role?

Answer 11

Gi= decreased cAMP

Found on Cardiac muscle specifically SA node slow heart rate by opening K+ channels causing decrease in membrane potential and depol/hyperpolarization

Question 12

What G-protein is M4R coupled to? What is its role?

Answer 12

Gi

Don’t know role

Question 13

What G-protein is alpha-1 receptor coupled to? What effects does it have on the body?

Answer 13

Gq= increased Ca++ intracellularly

Contract smooth muscle of blood vessels, urinary and reproductive tracts
Promote glycogenolysis and gluconeogensis in liver
Promote lipolysis in adipose tissue
Reduce water secretion in lacrimal glands
Contract radial muscle of iris –> dilation of pupil

Question 14

What G-protein is alpha-2 receptor coupled to? What effects does it have on the body?

Answer 14

Gi= decreased in AC and cAMP

Contract GI sphincters
Pancreas: Glucagon increased insulin decreased
Dilation of smooth muscles of BV
Increased clotting of platelets= if get hurt don’t bleed as much

Question 15

What G-protein is beta-1 receptor coupled to? What effects does it have on the body?

Answer 15

Gs

Cardiac tissue: SA node –> increased heart rate, Ventricular muscle –> increased strength of contraction
Cause dry mouth, viscous secretion of salivary glands
Lipolysis in adipose tissue

Question 16

What G-protein is beta-2 receptor coupled to? What effects does it have on the body?

Answer 16

Gs

Smooth muscle relaxation in bronchioles, GI, urinary/repro, vascular
Glycogenolysis in liver
Flatten lens of ciliary muscle aka focus eye

Question 17

What G-protein is beta-3 receptor coupled to? What effects does it have on the body?

Answer 17

Gs

Brown adipose heat production
White adipose lipolysis

Question 18

How does the sympathetic system and adrenal medulla interact?

Answer 18

Instead of synapsing in paravetbral ganglion some sympathetic axons go through the ganglion and synapse on adrenal medulla
- pre-gang release Ach which binds to nicotinic receptors on chromaffin cells which then release epinephrine into the blood stream

Question 19

What is the rest and digest (parasympathetic) response?

Answer 19

Plenty of oxygen
Slow heart beat
Low BP 
Digesting food so intestine get bllod
Fueling up with GI

Question 20

What is the flight or flight (sympathetic) response?

Answer 20

Need lots of O2 for muscles
Heart beating fast and hard
Aren’t going to worry about digesting (won’t matter if you die)