The Vascular System

Question 1

Where does most of the blood sit at rest?

Answer 1

Venous system

inf. Vena cava

Question 2

How much blood sits in the venous system?

Answer 2

61%

Question 3

Answer 3

A = 12
B = 9%
C = 11%
D = 7%
E = 61%

Question 4

What does the heterogeneity of the vascular network allow?

Answer 4

Adapt to environment

blood vessels different in nerves (parallel), muscles (cork screw), lung for example

Question 5

What controls the blood pressure

Answer 5

Contractility of the vascular smooth muscle cells

Question 6

What are vascular smooth muscle cells embedded in?

Answer 6

Collagen and elastin

Question 7

Name the 2 cell types of smooth muscle

Answer 7

Question 8

What allows the contraction of a smooth muscle cell?

Answer 8

Actin and myosin

Question 9

What is the thick filament?

Answer 9

Myosin

Question 10

What happens if the smooth muscle cells are not flexible (no collagen and elastin matrix)

Answer 10

Damage to blood vessels

Question 11

What regulates cross bridging in smooth muscle?

Answer 11

MLCK

Myosin light chain kinase

Question 12

Answer 12

Myosin light chain

Question 13

What does the light chain inhibit?

Answer 13

The myosin binding to the actin via the heavy chain

Question 14

How do we activate myosin?

Answer 14

Calmodulin binds calcium = complex

This binds MLCK

Phosphorylated the myosin light chains

Confo change in the light chain and expose actin BS

Actin BS on myosin exposed

Contraction activated

Question 15

What muscle has myosin light chain?

Answer 15

Smooth muscle

Question 16

What receptor regulates smooth muscle contactility?

Answer 16

Voltage gated Ca2+ channels

Question 17

What does calcium into the cell activate?

Answer 17

Myosin light chain kinase

Question 18

What are 2 ways calcium can increase in the cell?

Answer 18

Extracellular via the voltage gated calcium channels

Intracellular calcium stores

Question 19

What activates the intracellular calcium stores?

Answer 19

PLC pathway

then IP3 activates the Ca2+ channels

Question 20

What does a drops in CO2 do to smooth muscle?

Answer 20

Dilation - allow ,ore blood to get into cerebral circulation

Question 21

Why do you pass out during hyperventilation?

Answer 21

Blood vessels contract

Question 22

What happens to blood vessels in decreased CO2?

Answer 22

Vasoconstriction

Question 23

What happens to cerebral blood flow during hyperventilation?

Answer 23

Cerebral blood flow halves

Question 24

In pulmonary circulation, during hypoxia what happens to blood vessels?

Answer 24

Vasoconstriction

As that part of the lung isn’t working properly

Question 25

In systemic circulation what is the effect of hypoxia on blood vessels?

Answer 25

Vasodilation Increase blood flow

Question 26

What are 4 factors which regulate vascular smooth muscle contractiliy?

Answer 26

Autonomic nervous system Endothelial derived factors Myogenic response Blood borne factors

Question 27

In the regulation of smooth muscle contractility, what is the ANS mostly?

Answer 27

Sympathetic

Question 28

What does NO released from?

Answer 28

Endothelial cells

Question 29

What is the effect of norepinephrine?

Answer 29

Contract

Question 30

What is the effect of epinephrine?

Answer 30

Relax

Question 31

What receptors does norepinephrine act upon?

Answer 31

Alpha adrenergjc

Question 32

What receptor does epinephrine act upon?

Answer 32

Beta-adrenergic

Question 33

What is the effect of NO?

Answer 33

Relax

Question 34

What is the effect of endothelin released from the endothelial cells?

Answer 34

Contract

Question 35

What are the endothelial-derived factors?

Answer 35

NO endothelin

Question 36

What is the half life of NO?

Answer 36

2-5 seconds

Question 37

What is the limiting factor in NO production?

Answer 37

NOS NO synathse

Question 38

What are the 3 forms of NOS?

Answer 38

eNOS iNOS - inducible form nNOS

Question 39

What are the activators of NOS?

Answer 39

Shear stress Thrombin ACh

Question 40

What does shear stress induce?

Answer 40

Activates a kinase enzyme (Akt) which stimulates eNOS

Question 41

what is the capacitance vessel?

Answer 41

vena cava

Question 42

what vessels regulate the blood pressure?

Answer 42

arterioles

Question 43

Do arteries or veins have a large gap between the endothelial cells?

Answer 43

arteries for exchange

Question 44

what produces the ECM in smooth muscle cells?

Answer 44

the smooth muscle cells, maintain their own flexibility

Question 45

how do you reverse the depolarisation of the smooth muscle cells?

Answer 45

calcium-activated potassium channels

Question 46

What agonists activate the intracellular calcium store pathway?

Answer 46

norepinepherine

Question 47

What is the myogenic response?

Answer 47

innate ability of vascular smooth muscle to respond to changes in pressure

Question 48

What activates shear stress?

Answer 48

blood flow over endothelial cells

Question 49

What does NO activate in smooth muscle cells to cause relaxation?

Answer 49

GC which makes cGMP = relaxation

Question 50

What enzyme makes edothelin-1?

Answer 50

endothelin-converting enzyme

Question 51

What stimulus causes the production and release of endothelin?

Answer 51

thrombin GF angiotensin II low shear forces

Question 52

What happens when you double the pressure in the arteries?

Answer 52

active contraction - lumen diameter decreases myogenic response

Question 53

What is the stimulus for myogenic response?

Answer 53

vessel wall tension

Question 54

What is the role of the myognic response?

Answer 54

maintain a constant tissue blood flow when blood pressure changes

Question 55

When does the myogenic response when blood pressure increases?

Answer 55

cause vascular smooth muscle increase contraction