14 capillary exchange

Question 1

how does erythropoietin affect cardiac output

for low bp

Answer 1

increases the number of rbc which increases the volume of blood and increases venous return which fills ventricles more efficiently
increases cardiac output

Question 2

describe the renin angiotensin system

for low bp

Answer 2

angiotensinogen is converted to angiotensin I by renin.

then converted to angiotensin II in the lungs by ACE

Question 3

what can angiotensin II do

for low bp

Answer 3

bind to angiotensin I receptors and cause vasoconstriction

stimulates aldosterone secretion which increases blood volume as increased Na absorption so more water

Question 4

describe the structure of capillaries for exchange

Answer 4

has thin walls for diffusion
slow blood flow to allow for exchange time
fenestrations for water to easily pass

Question 5

what happens at the arteriole end of capillary

Answer 5

the delivery of water, oygen, glucose, ions amino acids to the bodys tissues

Question 6

what happens at the venous end of capillary

Answer 6

the reabsorption water

removal of co2 waste molecules ion from the body cells into the venous end

Question 7

what is capillary hydrostatic pressure

Answer 7

blood pressure

force on walls of capillaries, pushes water and solutes into interstitial fluid

Question 8

what are osmotic forces

Answer 8

oppose capillary hydrostatic pressure

Question 9

formula for net filtration pressure

Answer 9

net hydrostatic pressure - net colloid osmotic pressure

Question 10

at the arteriole end what is the net hydrostatic pressure

Answer 10

thw capillary hydrostatic pressure (35mmHg arteriole to 18mmHg venous)
because there is no hydrostatic pressure in the interstitial fluid

Question 11

at the arteriole end what is the net colloid osmotic pressure

Answer 11

the blood colloid osmotic pressure (25mmHg)

there is no interstitial fluid colloid pressure because theres few proteins inside (stays in blood)

Question 12

at the arteriold end is the NFP + pr -

Answer 12

positive

the hydrostatic is greater than the osmotic

Question 13

at venous end is the NFP + or -

Answer 13

negative

slower blood flow decreases the hydrostatic while osmotic stays tge same

Question 14

why is NFP= closer towards the venous end

Answer 14

means grater distance across the capillary network is for net filtration, the delivery of materials to tissues
fast reabsorption at venous end

Question 15

what will happen to blood pressure in a haemorrhage

Answer 15

the blood volume will decrease which will decrease the blood pressure and lower the capillary hydrostatic pressure. this lowers the net filtration pressure so there is greater fluid absorption
the volume of the interstitial fluid increases, increases circulation, plasma volume increases
recall of fluids increases blood pressure

Question 16

how does the bbody protect against dehydration

Answer 16

plsma volume decreases due to water loss, the concentration of plasma porteins increases, which raises their osmotic potential. the blood colloid osmotic pressure increases for faster reabsorption and fluid recall

Question 17

high blood pressure

Answer 17

if capillary hydrostatic pressure Is too high or blood colloid osmotic pressure is too low this alters the blance of fluids and means there is net exit into peripheral tissue
fluid collects in extremities
systemic oedema

Question 18

is pulmonary arterial blood pressure higher or lower than systemic blood pressure

Answer 18

lower, as vascular resistance is very low

Question 19

describe what the pulmonary circulation does in low O2 and high O2

Answer 19

in low O2 pulmonary vessels constrict to shunt O2 to the alveoli cells
in high O2 the pulmonary vessels dilate and blood flow increases to absorb O2

Question 20

3 key characteristics of the brain

Answer 20

high blood flow rate for mass of tissue
blood flow is constant and preserved even in emergencies (cerebral vasodilation)
four arteries are used to supply brain and anastomoses inside the cranium

Question 21

key characteristics of the pulmonary circulation

Answer 21

coronary blood flow varies throughout thr cardiac cycle nd is influenced by heart rate
blood flow thorugh the coronary artery is interrupted during cardiac contraction as a result of compression

Question 22

how can we increase the pulmonary circulation to get more supply to the heart

Answer 22

vasodilator metabolites

adrenaline

Question 23

how is blood flow controlled in the skin

Answer 23

vasodilator metabolites
sensory stimulation by SNS
increase in body temp increases blood flow to skin by vasodilation