W5-L6 microcirculation

Question 1

blood flow rate

Answer 1

volume of blood passing through a vessel per unit time

Question 2

State Darcy’s Law

Answer 2

pressure gradient = flow rate x resistance

Question 3

how to calculate pressure gradient

Answer 3

pressure gradient = pressure A - pressure B

Question 4

what is resistance

Answer 4

barrier to blood flow due to friction between moving fluid and stationary vascular walls

Question 5

how to calculate resistance

Answer 5

R = 8LN/pie x r^4

Question 6

what happens to pressure gradient, resistance and flow rate if BP increase?

Answer 6

increase in blood pressure and increase flow rate

Question 7

what happens to pressure gradient, resistance and flow rate if arterial constriction occurs?

Answer 7

decrease in resistance causing decrease in blood flow

Question 8

what are the characteristics of arterioles? why?

Answer 8

high capacity to constrict and dilate to provide the greatest resistance and therefore the greatest drop in pressure

Question 9

what happens to the radius, resistance and flow rate on arterial contraction?

Answer 9

radius decrease
resistance increase
flow rate decrease

Question 10

what happens to the radius, resistance and flow rate on arterial relaxation?

Answer 10

radius increase
resistance decrease
flow rate increase

Question 11

why are arteries in state of partial constriction

Answer 11

to allow for both constriction and relaxation when needed

Question 12

functions of arterial radii adjustments

Answer 12

match blood flow and metabolic needs- local control regulation independent of nervous or endocrine control
regulate arterial blood pressure-
extrinsic controls travelling via nerves or blood and centrally coordinated

Question 13

how arterioles match blood flow to metabolic needs?

Answer 13

vasodilation-driven by increase metabolites and oxygen usage
condition called active hyperaemia
vasoconstriction- driven by drop on body temperature or stretch due to increase BP
condition called myogenic auto regulation

Question 14

how arterioles regulates the blood pressure?

e.g. decrease in blood pressure

Answer 14

hormonal secretion- vasopressin, angiotensin II, adrenaline and noradrenaline

Question 15

function and adaptation of capillaries to functions

Answer 15

delivery of metabolic substrates to the cells of organism

incredibly narrow, thin walls and highly branched

Question 16

how do highly metabolically active tissues vary in capillary network

Answer 16

denser capillary network with massive flow to muscles for example

Question 17

how are pores through a capillary called?

Answer 17

fenestration

Question 18

types of capillaries

Answer 18

continuous, fenestrated or discontinuous

Question 19

type of capillary in blood brain barrier

Answer 19

continuous

Question 20

describe the change in substrate concentration at capilalries

Answer 20

refer to slides

Question 21

significance of ultrafiltration being effective the reabsorption

Answer 21

net loss of 1 hydrostatic pressure to the lymph node

Question 22

describe the build flow in capillaries

Answer 22

hydrostatic force push the fluid into the interstitial fluid leaving a concentrated protein fluid in the capillaries
the high fluid concentration then causes an oncotic force pulling the fluid back into the capillaries