Week 8: Local and hormonal regulation

Question 1

What is the O₂ content of arterial blood?

Answer 1

200 ml/l

Question 2

What is the O₂ content of venous blood?

Answer 2

150 ml/l

Question 3

What is the arteriovenous O₂ difference (AVDO₂)

Answer 3

50 ml/l

Question 4

What are the three types of local control?

Answer 4

1. Bayliss-effect autoregulation
2. Metabolic Regulation
3. Endothelium Mediated Regulation

Question 5

Describe the Bayliss-effect

Answer 5

• works through endothelium
• small arteries, arterioles
• smooth muscle

Question 6

Describe the graph showing the relationship between pressure and flow

Answer 6

P↓ ⇒ r↑ ⇒ R↓ Q is maintained

P↑ ⇒ r↓ ⇒ R↑ Q is maintained

Question 7

What happens when pressure is increased in regards to the Baylis-effect?

Answer 7

P↑ ⇒ T↑

mechanosensitive ion channels open

↓

depolarization

↓

L type Ca2+ channels

↓

Ca2+ ↑

↓

constriction of vessels

Question 8

Describe metabolic regulation

Answer 8

self regulating

• precapillary sphincters
• smooth muscle of terminal- and meta- arterioles
  
  • no sympathetic regulation

Question 9

How does the metabolic regulation work?

Answer 9

↑ function of tissue cells ⇒ ↑ metabolism

in general all the molecules have vasodilation effect on the smooth muscle (local flow ↑)

Question 10

What changes in the environment will lead to relaxation (dilation) of smooth muscle and hence ↑ flow

Answer 10

PO₂ ↓

PCO₂ ↑

lactic acid, pH ↓

adenosine

[K+] ↑

Question 11

What happens when there is an ↑ in [metabolites] and ↑ Q

Answer 11

functional hyperemia

reactive hyperemia

Question 12

What are the two types of endothelium mediated regulation?

Answer 12

1. metablism ↑
2. histamine and seratonin

Question 13

What are the vasodilators of endothelium mediated regulation?

Answer 13

PGl₂ → activates Gs receptors → cAMP↑ → PKA → relaxation of SM

NO → cGMP → PKG → relaxation of SM

Question 14

Endothelium mediated regulation: What happens when metabolism is increased?

Answer 14

* retrograde vasodilation *

[metabolites] ↑

↓

R↓

↓

Q↑

↓

shear stress ↑

↓

endothelial cells

↓

NO production ↑

↓

vasodilation

Question 15

Endothelium mediated regulation: What does histamine and seratonine do?

Answer 15

activated endothelial cells

↓

vasodilation

Question 16

What does angiotensin II provoke?

Answer 16

vasoconstriction

Question 17

What is another option for regulation?

Answer 17

hormonal, humoral regulation (slow)

has direct effect on smooth muscle

Question 18

What are the vasoconstrictors that aid in hormonal regulation?

Answer 18

1. Norepinephrine
2. Angiotenstin II
3. Vasopressin (ADH)
4. Histamine, seratonine

Question 19

Describe Norepinephrine

Answer 19

Sources: sympathetic system

adrenal gland

alpha adrenergic receptor → activates Gq → [Ca²⁺]↑ → vasoconstriction

Question 20

Describe Angiotensin II

Answer 20

Angiotensin II is a peptide

composed of: angiotensin I

angiotensinogen

renin production → AT1R → Gq

Question 21

Describe Vasopressin (ADH)

Answer 21

V2R → Gs → kidney function; water reabsorption

V1R → Gq → kidney function; water reabsorption

Question 22

What G protein is associated with Histamine, seratonine?

Answer 22

Gq

Question 23

What are vasodilators in regards to hormonal regulation?

Answer 23

1. Epinephrine
2. ANP
3. PGl₂

Question 24

Describe epinephrine

Answer 24

Source: adrenal gland

binds to beta 2 receptor w/ higher affinity

[Epinephrine] ↓

↓

activates Gs

↓

relaxation

vise versa if [E] ↑ more alpha 1 activated → vasoconstriction

Question 25

Describe ANP

Answer 25

(atrial natriuretic peptide)

volumetric regulation

• produced when
• ↑ cGMP