week 5: cardiac physiology: blood vessels and hemodynamic

Question 1

functions of human vascular network

Answer 1

-blood flow
-supply of O2 and nutrients
-removal of metabolic byproducts
-hormonal regulation
-thermal regulation
-immune responses to infection
-fluid balance
-route for infection
-utilised in drug delivery

Question 2

systemic system

Answer 2

oxygenated blood leaves aorta
arteries carry oxygenated blood to tissues
gas exchange occurs by diffusion in capillaries

Question 3

veinous system

Answer 3

deoxygenated blood returned to the right atrium via vena cava

Question 4

pulmonary system

Answer 4

pulmonary arteries carry deoxygenated blood to lungs
gas exchange occurs at capillaries surrounding alveolae
pulmonary arteries carry oxygenated blood back to left atrium

Question 5

how are blood vessels arranged

Answer 5

parallel or series depending on location and function

Question 6

variations in blood pressure occurs due to

Answer 6

contractions of heart, ejecting blood out into systemic circulation
systemic: left side
pulmonary: right side

Question 7

pressure of systemic vs pulmonary system

Answer 7

systemic: higher
pulmonary: lower

Question 8

relationship between total cross sectional area and velocity of flow of blood vessels

Answer 8

greater total cross-sectional area= lower velocity of blood flow

Question 9

blood leaves via aorta to >

Answer 9

elastic arteries> muscular arteries > arteriole> continuous capillary

Question 10

blood passes form continuous capillary back to rhs of heart through

Answer 10

fenestrated capillary> venules> medium sized- veins > large veins

Question 11

windkessel effect

Answer 11

recoil of large elastic blood vessels during diastole helps maintain flow even though heart is not actively pumping

Question 12

3 distinct layers of arteries and veins

Answer 12

tunica adventitia
tunica media
tunica intima

Question 12

tunica adventitia

Answer 12

connective tissue- collagen fibres

Question 12

tunica media

Answer 12

smooth muscle and elastin

Question 13

tunica intima

Answer 13

squamous endothelium

Question 14

what does capillaries only having a single endothelial layer enable

Answer 14

efficient bidirectional diffusion of nutrients and metabolites between blood and tissues

Question 15

walls of arteries

Answer 15

thick, muscular and elastic
high pressure, carries blood away from heart, maintains blood flow during idastolic period

Question 16

vein walls

Answer 16

thin and elastic
return blood to heart at low pressure
valves facilitate unidirectional blood flow

Question 17

major arteries and precapillary arterioles are innervated by

Answer 17

sympathetic nerves

Question 18

what do venules and capillaries not have

Answer 18

smooth muscle

Question 19

are venules and capillaries directly innervated by sympathetic nerves

Answer 19

no

Question 20

fur distinct layers of an artery

Answer 20

(lumen)
endothelium (inner lining)
elastic and connective tissue
muscle fibres and elastic
protective outer coat

Question 21

what does elastic layer of artery allow

Answer 21

vessel walls to stretch without tearing in response to increase in pressure
operate at highest blood pressure (80-120mm Hg)

Question 22

atherosclerosis

Answer 22

fat and lipid lesions in vessel wall, leads to arterial narrowing and blockage,
reduce or loss of oxygenated blood flow
causes arterial dysfunction

Question 23

how can a blocked coronary artery be repaired

Answer 23

insertion of stent by angioplasty restores oxygenated blood flow

Question 24

what organs have more extensive capillary networks

Answer 24

organs with more metabolic requirements e.g heart, liver

Question 25

pressure over capaillary bed from arteriole end to venule end

Answer 25

pressure decreases

Question 26

at any given time, capillary beds hold to ....% of total blood volume

Answer 26

25

Question 27

capillary wall

Answer 27

endothelial cells surrounded by thin basement membrane

Question 28

feature of continuous capillaries

Answer 28

porous water filled pores

Question 29

continuous capillaries being porous allows

Answer 29

exchange between blood and tissues small, water-soluble substances can pass through pores

Question 30

how can lipid soluble substances pass between blood and tissues (continuous capillaries)

Answer 30

pass through endothelial cells

Question 31

how are exchangeable proteins passed between blood and tissues (continuous capillaries)

Answer 31

vesicular transport

Question 32

can plasma proteins cross continuous capillary wall

Answer 32

no

Question 33

how do fenestrated capillaires increase their exchange rate

Answer 33

larger openings

Question 34

where are fenestrated capillaries found

Answer 34

kidneys, small intestine and endocrine glands

Question 35

why is important capillary blood pressure is low

Answer 35

capillaries are very fragile 0-10 mmHg

Question 36

what can pulmonary hypertension in lungs lead to

Answer 36

damage of capillaries that surround the alveolae

Question 37

layers of veins

Answer 37

adventitia smooth muscle basement membrane endothelium valve lumen

Question 38

why is muscular later of veins and venules thinner than aerteriole system

Answer 38

operate at low pressure 0-10mm Hg

Question 39

venous blood flow during exercise

Answer 39

facilitated by intermittent compression due to skeletal muscle contraction when muscles contract, veins squashed, pushing blood back towards the heart- skeletal muscle pump

Question 40

varicose veins

Answer 40

veins become stretched and lose elasticity, valves weaken blood collects in veins, become swollen and large underlying causes unclear

Question 41

action of endothelial cells

Answer 41

sense and respond to a number of substances and stimuli responses regulate blood pressure

Question 42

how does the endothelium regulate blood pressure

Answer 42

receptor-ligand complexes activate signal transduction pathways leads to synthesis of gaseous NO in a process involving L-arginine NO is second messenger which regulates blood pressure and cell function

Question 43

how does receptor signalling lead to NO synthesis

Answer 43

-substances in intravascular compartment interact with receptors on endothelial surface - activation of receptors lead to signalling cascade, ultimatly induced activation of eNOS - eNOS hydrolyses L-arginine producing NO and L-citrulline

Question 44

eNOS

Answer 44

endothelial nitric oxide synthase

Question 45

VEGF

Answer 45

vascular growth factor

Question 46

PIGF

Answer 46

placental growth factor

Question 47

Akt

Answer 47

serine/ threonine protein kinase

Question 48

qithin pathways

Answer 48

Akt Ca2+

Question 49

a rise in intercellular calcium activates

Answer 49

eNOS

Question 50

what can eNOS also be activated by

Answer 50

shear stress: tangential force caused by blood flow acting on the surface of the endothelium

Question 51

shear stress eNOS activation involves

Answer 51

Akt or PKA induced phosphorylation

Question 52

how does NO regulate vascular smooth muscle relaxation

Answer 52

NO diffuses out of activated endothelium NO targets soluble guanylate cyclase (sGC) in VSMCs NO stimualtes sGC to convert GTP into cGMP cGMP binds and activates protein kinase G (PKG)

Question 53

VSMCs

Answer 53

vascular smooth muscle cells

Question 54

what does protein kinase G cause

Answer 54

VSMC relaxation and reduce blood pressure

Question 55

protein kinase G action

Answer 55

PKG phosphorylates and activates myosin light chain phosphatase (MLCP) MLCP de-phosphorylates contractile myosin causes relaxation of vascular smooth muscle cell relaxation increases dilation of blood vessel, reducing blood pressure