Lecture 12: Autonomics (Heart and Lungs)

Question 1

What parasympathetic innervation does the SA Node have?

What effects does it have on the heart?

Answer 1

• Vagus N. releases acetylcholine on muscarinic receptors on the SA Node
• Slows down depolarization = slows down HR

Question 2

What type of sympathetic innervation does the SA and AV node have?
What effects does it have on the heart?

Answer 2

• T1 - T5 > sympathetic trunk > release Epi on Beta1 adrenergic receptors
• Faster depolarization = increase HR

Question 3

What parasympathetic innervation does the AV Node have?

What effects does it have on the heart?

Answer 3

• Vagus > release Ach > muscarinic receptors
• Decrease depolarization rate and pacemaker potential which decreases conduction velocity between AV node and ventricles

Question 4

What sympathetic innervation does the AV Node have?

What effects does it have on the heart?

Answer 4

• T1-T5 > sympathetic trunk > release epi on Beta1 receptors

- increase depolarization rate and pacemaker potential

Question 5

Should the AV Node be the primary pacemaker of the heart?

What happens to ventricular rate during sympathetic and parasympathetic control?

Answer 5

-No
-Sympathetic: increases ventricular rate
Parasympathetic: decreases ventricular rate

Question 6

What is the parasympathetic innervation of the atrial and ventricular myocytes? What are the effects?

Answer 6

Atrial: Vagus
Ventricles: unclear

-decrease atrial and ventricular contractility

Question 7

What is the sympathetic innervation of the atrial and ventricular myocytes? What receptors accept them? What are the effects?

Answer 7

T1-T5 sympathetic trunk > B1 and B2 receptors

Increase calcium and myocyte contractility

Question 8

What innervates cerebral vasculature? What is released and what happens?

Answer 8

Sympathetic > A1 adrenergic receptors > contracts vascular smooth muscle > vasoconstriction > decrease capillary blood flow to protect it

Question 9

When does sympathetic control of cerebral vasculature happen?

Answer 9

High systemic BP that may damage brain capillaries (brain looks out for itself and sacrifices systemic BP to keep brain BP low)

Question 10

What controls blood flow to the heart?

Answer 10

Metabolic needs over ANS. So metabolic needs can override ANS to increase/decrease blood flow to heart

Question 11

What is the parasympathetic innervation to the coronary arteries? What are the effects?

Answer 11

Vagus N. (cholinergic)

Relaxes smooth muscle which vasodilates the artery and increases blood flow

Question 12

What is the sympathetic innervation to the coronary arteries? What are the effects?

Answer 12

• T1-T5 sympathetics (A1 adrenergic)

- Contracts smooth muscle which vasoconstricts the arteries decreasing blood flow

Question 13

Why is the vasoconstriction on the coronary arteries short lived?

Answer 13

Vasoconstriction will increase metabolism = increase metabolites = feedback on the sympathetic effect (vasodilation)

Question 14

What is the major type of innervation to the cutaneous vasculature? What are the effects?

Answer 14

Sympathetic fibers from different places

Vasoconstriction

Question 15

How are sweat glands innervated? What are the effects?

Answer 15

Sympathetic muscarinic

Relaxes vascular smooth muscle, vasodilates and contributes to sweat production

Question 16

What is the major type of innervation to muscular vasculature? What are the effects?

Answer 16

Sympathetic (A1 and B2)
A1: vasoconstriction of arterioles
B2: vasodilation

Question 17

What are the major innervation of the splanchnic vessels? What are the effects?

Answer 17

Sympathetic (T5-L2)

Contraction of vascular smooth muscle = vasoconstriction

Question 18

From which ganglia does splanchnic vessel innervations arise from?

Answer 18

Celiac, superior mesenteric and inferior mesenteric

Question 19

What are two ways that splanchnic vessels be vasodilated?

Answer 19

1. Decrease sympathetic activity

2. Override by local control (metabolic needs)

Question 20

What are the major innervations to the veins? What are the effects?

Answer 20

Sympathetic (A1,A2, B2)
A1: smooth muscle contraction, increase in venous return
A2 and B2: relaxation, decrease venous return

Question 21

What is the arrangement of autonomic innervations in the pulmonary vasculature?

Answer 21

Decreases as you move closer to the alveoli

More sympathetic fibers than parasympathetic

Question 22

How is the lung vasculature parasympathetically innervated? What are the effects?

Answer 22

Vagus N (cholinergic) 
NO production > vascular smooth muscle relaxation = vasodilation

Question 23

How are the lung vasculature sympathetically innervated? What are the effects?

Answer 23

T1-T5 > A1 and B1
A1: vascular smooth muscle contraction = vasoconstriction of large vessels
B1: vascular smooth muscle relaxation = vasodilation of large vessels

Question 24

What activates sympathetic innervation to pulmonary vasculature?

Answer 24

Cold air exposure and detecting distension of the large airways

Question 25

How are the upper airways innervated parasympathetically? What are the effects?

Answer 25

Parasympathetic fibers from CN V and sphenopalatine ganglion

Vasodilation and increased mucus secretion

Question 26

How are the upper airways innervated sympathetically? What are the effects?

Answer 26

Sympathetic fibers from CN VII and superior cervical ganglion (A1)
Vasoconstriction and decreased mucus secretion

Question 27

What does intrinsic innervation mean?

Answer 27

Intrinsic nerve plexus that developed from the gut also innervate the trachea and large airways

Question 28

How are lower airways parasympathetically innervated? What are the effects?

Answer 28

Vagus N.

Contraction of bronchial smooth muscle and increased mucus synthesis

Question 29

How are lower airways sympathetically innervated? What are the effects?

Answer 29

T1-T5 (B2)

Relax bronchial smooth muscle and slightly increase mucus secretions