DSA & CIS: Autonomics

Question 1

Somatic reflex

Answer 1

sensory information goes back to the spinal cord via a fiber, which will enter the SC via a DRG and synapse directly onto an alpha motorneuron

Question 2

Goals of the sympathetic nervous system

Answer 2

(fight or flight)

need to get oxygen to the right parts of the body, direct the blood to the right tissues, need more fuel into the muscles, eyes need to see clearly to visualize threats, decrease ability of the liver to store glucose (glucogenolysis), increase lypolysis by adipose tissue

Question 3

parasympathetic nervous system

Answer 3

(rest and digest)

do not need as much oxygen as the tissues (slow HR down), storage of stuff being ingested, need food to be directed to the digestive tract

Question 4

What is the NT released by pre-ganglionic fibers in PARASYMPATHETIC NS?

Answer 4

Acetylcholine (Ach)

Question 5

What is the mechanism of Ach?

Answer 5

Ach binds to nicotinic AchR (nAchR) in the post ganglionic dendrites, this allows sodium into the post ganglionic cell which causes it to depolarize

Question 6

Post-ganglionic synapse in parasympathetic NS?

synapse between the parasympathetic post-ganglionic neuron and the target

Answer 6

similar to first synapse where Ach is released from the post ganglionic neurons, difference is that the receptor that binds Ach is a MUSCARINIC CHOLINERGIC receptor which activates 2nd messenger system

Question 7

Post-ganglionic synapse in sympathetic NS?

Answer 7

NT released by post-ganglionic axon is norepinephrine (NE)

Question 8

What are the 2 receptors NE can bind to?

Answer 8

• alpha adrenergic and beta adrenergic receptors

- these are metabotropic receptors that activate second messenger systems

Question 9

Different effects of NE binding to receptors?

Answer 9

• alpha adrenergic: cause vasoconstriction of smooth muscle

- beta adrenergic: cause vasodilation of the blood vessels

Question 10

what happens when there is an increase need for oxygen in the tissues?

Answer 10

• bronchodilation occurs via B2 adrenergic receptors
• increase oxygen to the lungs
• decrease secretion from glands

Question 11

How do you increase cardiac output?

Answer 11

increase oxygen to tissue lead to an increase in activity in ventricular myocytes, which will activate beta adrenergic receptors, which increases calcium in myocytes which increases cardiac output

Question 12

How do you increase the heart rate?

Answer 12

with increase oxygen need int he tissues, there is an increase in the activity of the SA/AV node, which increases the activity of B-1 receptors, this influences phase 4 of the AP - funny sodium channels open and increase depolarization which increases heart rate

Question 13

What are the effects of needing to direct blood to the right tissues during sympathetic response?

Answer 13

increase blood in skeletal muscle, redirect blood where it needs to be and away from gut, kidneys and salivary glands, brain/heart/lungs blood flow is activity dependent

Question 14

How does blood flow increase?

Answer 14

increase blood to skeletal muscle leads to an increase in sympathetic activitation, which increases B2 receptors to dilate in smooth muscle which increases blood flow

Question 15

alpha receptor activity in muscle

Answer 15

constriction

Question 16

B2 activity in SM

Answer 16

relaxation

Question 17

What leads to pupil dilation?

Answer 17

alpha 1 adrenergic fibers activate, constriction happens in the eye muscles

Question 18

How does one increase ability to see from afar?

Answer 18

Relax the ciliary muscle to increase far vision, B2 receptors are activated, flattening of the lens which leads to an increase in ability to see from a distance

Question 19

Effects of sympathetic NS on glucose in liver/skeletal muscle

Answer 19

increase glycogenolysis from the liver, increase glucose into the skeletal muscle, alpha and beta receptors are activated

Question 20

Effects of sympathetic NS on glucose in adipose tissue

Answer 20

beta receptors are activated, liploysis occurs, increase of free fatty acids int the blood which allows the rest of the body to function

Question 21

Effects of sympathetic NS on glucose in the pancreas

Answer 21

decrease insulin via alpha receptors

Question 22

if it has receptors what does that usually mean

Answer 22

sympathetic NS is acting

Question 23

What happens to motility in the GI during sympathetic NS?

Answer 23

decrease motility via B2 receptors, relaxation fo smooth muscle

Question 24

Sphincters in the GI during sympathetic response?

Answer 24

increase contraction of the smooth muscle via alpha 1 receptors, decrease movement of contents in the GI, decrease digestion

Question 25

secretion in the GI during sympathetic response?

Answer 25

in many cases there is a decrease in blood flow to the glands thus a decrease in secretion which is reinforced by the alpha receptors