overview of cardiovascular system

Question 1

Function of CVS (3)

Answer 1

Transport respiratory gases, nutrients and waste
Signalling system - distributes hormones, inflammation molecules etc to target issues
Temperature regulation through
cutaneous heat conservation / dissipation

Question 2

diffusion - distance related to time relationship

Answer 2

t proportional to x2

Time t needed to diffuse a net distance x is proportional to the square of distance

Question 3

how does cvs provide fast and directional transport?

Answer 3

convection (movement by pressure gradient)

Question 4

how does the heart achieve fast and directional transport?

Answer 4

Output of blood at high pressure
Creates a pressure difference with distance blood vessels
Aorta (>100mmHg), Large veins (5-10 mmHg)
Pressure difference drives blood flow

Question 5

what is cardiac output?

equation?

Answer 5

volume of blood ejected from ventricles per minute

heart rate x stroke volume

Question 6

what has highest cardiac output in the body?

Answer 6

liver + gi = 25%

Question 7

what organs are relatively under-perfused?

Answer 7

coronary and brain

Question 8

clinical importance of under perfusion?

Answer 8

clinical problems e.g. angina, MI, stroke triggered by a relatively moderate fall in perfusion
Need to carefully control cardiac output

Question 9

what controls cardiac output? (3)

Answer 9

1) Filling pressure (starling’s Law - in to out)
2) sympathetic/parasympathetic autonomic nerves controls CO by regulating HR and contractility (SV)
3) chemical factors - hromones (adrenaline)

Question 10

how does the velocity of the blood change from aorta? And why? importance of this?

Answer 10

Velocity greatly reduces and is very slow at capillaries because then more time to exchange molecules.
veolicity decreases because CSA increases from 1 aorta to many arterioles and many more capillaries

Question 11

why does velocity increase from capillaries to veins?

Answer 11

as the CSA decreases, velocity increases therefore blood has momentum to get blood back to heart

Question 12

why is the increase in velocity in blood flow of veins important?

Answer 12

low pressure in veins so less drive to get blood back to heart so relies on kinetic energy

Question 13

blood pressure equation

Answer 13

BP = CO x TPR

Question 14

relationship between blood flow and blood pressure

blood flow equation

Answer 14

proportional to pressure across blood vessel
inversely proportional to resistance of blood vessel
Blood flow = (Pa - Pv) / Resistance
↑ Resistance = ↓ blood flow

Question 15

what determines blood velocity?

equation?

Answer 15

Blood flow (cm3/s) / Cross-sectional area (cm2) 
                                  number x πr2 per vessel

Question 16

why does velocity decrease?

Answer 16

goes from Aorta, 1 large vessel with low cross-sectional area TO Capillaries made up of billions of small vessels with Huge cross-sectional area

Question 17

why is slow velocity at capillaries important?

Answer 17

Velocity is much slower in capillaries allowing gaseous/nutrient exchange to occur

Question 18

what is meant by dual system?

importance of this?

Answer 18

right blood flow goes to lungs and left goes to rest of the body at the same time
hence can oxygenate and remove co2 WHILST ejecting oxygenated blood via circulatory system

Question 19

parallel blood supply

importance?

Answer 19

CO is split up hence safeguards the o2 supply in organs - most organs supplied this way

Question 20

series blood supply

medical significance?

Answer 20

same blood supply between organs hence lower perfusion -> medical significance of under-perfusion in 1st organ

Question 21

series blood supply examples

Answer 21

liver + kidney

Question 22

liver series - why?

Answer 22

blood goes to spleen + intestine to pick up nutrients and then go to liver hence liver recieves de-oxygenated blood due to the exchange at before organs BUT liver recieves o2 from hepatic arteries

Question 23

what part of kidney can be under perfused and why?

Answer 23

Tubules of kidney may recieve less o2 due to being in series once filtered

Question 24

structure of artery and veins? (3)

Answer 24

Intima
Media
Adventitia

Question 25

what is in adventitia layer? (3)

Answer 25

provides collagenous connective tissue for mechnanical support
has vasa vasorum -> small blood supply for wall of blood vessels
autominc nervous system innervation

Question 26

media layer

what is in it and what does it do?

Answer 26

vascular smooth muscle cells + elastin

controls the size of the lumen

Question 27

intima layer (3)

Answer 27

fenestrated elastic lamina
basal lamina
endothelial cell -> interaction between blood flow and blood vessel hence info via blood to contract or dilate

Question 28

4 functional groups of blood vessels

Answer 28

elastic vessels, resistance vessels, capacitance vessels, exchange vessels

Question 29

elastic vessels

what? role (2)?

Answer 29

large arteries, e.g. aorta

Accommodate stroke volume And Convert intermittent ejection into continuous flow

Question 30

resistance vessels

what? role (2)?

Answer 30

(arterioles)
Control arterial BP
Control local blood flow

Question 31

exchange vessels

what? role (3)?

Answer 31

(capillaries, only endothelium layer)
Nutrient delivery to cells
Tissue water & lymph formation
Removal of metabolic waste

Question 32

capacticance vessels

what? role (2)?

Answer 32

(venules, veins)
Control filling pressure
Reservoir of blood

Question 33

distribution of blood volume

Answer 33

10% - lungs
10% - heart
10% - arteries
5% - capillaries
65% - systemic veins and venules therefore serves as a reservoir