Blood vessels

Question 1

list the features and properties of arteries

Answer 1

-smooth muscle - contractile power and regulates diameter of lumen.
-adventitia - structural support, tethers vessels in place.
- elastin- expand and recoil
- endothelium- filtering interface between blood and body

Question 2

list the features of arterioles

Answer 2

smooth muscle cells
lumen
endothelium
pre-capillary sphinchter- controls blood flow to specific capillary beds

Question 3

what is active hyperaemia?

Answer 3

the increase in blood flow according to the metabolic needs of the tissue
eg. a increase in metabolic activity leads to arteriolar dilation which increases blood flow

Question 4

what is flow autoregulation?

Answer 4

maintenance of blood flow rather than changing it.
eg. when the driving pressure drops the vessels dilate to restore normal value and when it increases the vessels constrict.

Question 5

what happens to the vessels when arterial pressure increases ?

Answer 5

blood vessels constrict

when MAP decreases vessels dilate

Question 6

with increasing sympathetic stimulation do vessels dilate or constrict?

Answer 6

vasoconstrict as norepinephrine is released

Question 7

which receptors does circulating epinephrine bind to to cause vasodilation?

Answer 7

beta receptors causes vasodilation of skeletal muscle arteries

Question 8

list the vessels in order

Answer 8

artery-arteriole-capillary-venule -vein

Question 9

what is fick’s law of diffusion?

Answer 9

flow of gas= area/thickness x D x (P2-P1)

Question 10

if hydrostatic pressure increases does this force fluid in or out of capillaries?

Answer 10

out of capillaries

Question 11

if colloid osmotic pressure of proteins within capillaries decreases do this pull fluid into or out of the capillary?

Answer 11

into the capillary

Question 12

what must occur for filtration to occur from the capillaries to the interstitial fluid?

Answer 12

hydrostatic pressure > osmotic pressure

Question 13

what must occur for absorption of fluid from the interstitial fluid into the capillaries?

Answer 13

colloid osmotic pressure > hydrostatic pressure

Question 14

how are veins different to arteries?

Answer 14

larger volume capacity
lie closer to the skin surface
larger diameter
have valves
less elastic tissue
less smooth muscle
more distensible (swell)
thinner walls

Question 15

whats the difference in pressure between the veins and arteries?

Answer 15

veins have a pressure of 10mmHg whereas arteries have a pressure of 100 mmHg

Question 16

are veins affected by hydrostatic pressure?

Answer 16

yes HP opposes blood flowing towards the heart

Question 17

what is the frank-starling mechanism?

Answer 17

SV increases with increasing venous return

Question 18

how is pressure in veins?

Answer 18

low and non-pulsatile

Question 19

how can compliance of a vein be changed?

Answer 19

neural - sympathetic stimulation releases norepinephrine to veins of smooth muscle causing vasoconstriction reducing vol of blood to those organs
hormonal- diameter of veins affected by circulating epinephrine

Question 20

how does the skeletal muscle pump send blood towards the heart?

Answer 20

compression of veins by muscle contraction empties veins of blood towards the heart

Question 21

what happens to the diaphragm during inspiration?

Answer 21

diaphragm contracts moving downwards, increasing the volume of the thoracic cavity and decreasing the volume of the abdominal cavity

Question 22

what happens to blood flow to the heart during inspiration?

Answer 22

flow increases due to the fall in intrathoracic pressure (chest expansion) and the rise in intraabdominal pressure (abdominal compression)

Question 23

what happens to blood flow to heart during expiration?

Answer 23

flow is impeded due to rise in intrathoracic pressure (diaphragm relaxes)

Question 24

what does the respiratory pump create in order to promote blood return to the heart?

Answer 24

a pressure difference between the abdomen and the thoracic cavity

Question 25

how does the lymphatic system contribute to the circulating blood volume?

Answer 25

lymph vessels collect filtered fluid from the interstitial space and return it to the circulating blood volume

Question 26

what results if the lymphatic system fails?

Answer 26

oedema