factors affecting blood flow

Question 1

what do beta 2 agonists do?

Answer 1

induce bronchodilation by binding to beta 2 receptors in the lungs, activating adenyl cyclase to relax bronchial smooth muscle

Question 2

what condition is characterised by narrowing/blockage of arteries, leading to reduced blood and oxygen flow to specific part of the body which is then damaged?

Answer 2

critical limb ischaemia

Question 3

what condition is characterised by the interruption or blockage of heart blood supply by a build up of fatty substances in coronary arteries?

Answer 3

coronary artery disease

Question 4

what factors affect blood flow?

Answer 4

. length of tube
. viscosity of liquid flowing through tube
. pressure gradient across length of tube
. cross sectional area of tube

Question 5

where is blood at its highest pressure?

Answer 5

leaving heart

Question 6

what may increase blood viscosity?

Answer 6

dehydration

Question 7

state the poiseuille equation

Answer 7

Q = delta P x pi x radius^4 / 8 x n x l

Question 8

what is ‘Q’ equal to in poiseuille’s equation?

Answer 8

volumetric flow rate

Question 9

what is ‘delta P’ equal to in poiseuille’s equation?

Answer 9

pressure change/difference

Question 10

what is ‘l’ equal to in poiseuille’s equation?

Answer 10

length of tube

Question 11

what is ‘n’ equal to in poiseuille’s equation?

Answer 11

viscosity

Question 12

what are the assumptions associated with poiseuille’s equation?

Answer 12

. blood flow is laminar
. flow is non-pulsative
. flow is through a uniform straight pipe

Question 13

what may cause deep vein thrombosis?

Answer 13

immobility, dehydration

Question 14

how may you reduce the risk of deep vein thrombosis?

Answer 14

moving, staying hydrated, wearing compression socks

Question 15

what is flow determined by?

Answer 15

. pressure gradient
. resistance
. branching

Question 16

what happens to blood flow and resistance as branching increases down arterial tree (arteries - arterioles - capillaries)

Answer 16

resistance increases and blood flow is reduced

Question 17

what is the function of slowed blood flow in capillaries?

Answer 17

allows more time for substance exchange

Question 18

in what areas is blood flow slowest?

Answer 18

areas with largest cross-section

Question 19

which areas have the largest cross-section?

Answer 19

capillaries

Question 20

blood flows from high pressure to low pressure, which vessels are carry blood at high pressure and which carry blood at low pressure?

Answer 20

artery - high

veins - low

Question 21

what happens to blood flow as blood exits capillaries into veins?

Answer 21

increases

Question 22

do veins have a small or large pressure gradient?

Answer 22

small

Question 23

what percentage of blood do veins hold at any one time?

Answer 23

70%

Question 24

which structure promotes venous return?

Answer 24

skeletal muscle pump

Question 25

which process aids venous return?

Answer 25

respiratory movement

Question 26

which hormone produced by sympathetic nerves constricts veins, increasing venous return to the heart?

Answer 26

noradrenaline

Question 27

what effect does noradrenaline opreoduced by sympathetic nerves have on the blood low to the heart?

Answer 27

increases

Question 28

what is the term for venous return to the right ventricle?

Answer 28

preload

Question 29

what are the effects of an increased preload?

Answer 29

heart has to work harder to pump blood out

Question 30

what 2 conditions may increased preload cause?

Answer 30

heart failure, coronary artery disease

Question 31

what class of drugs can be used to decrease preload

Answer 31

nitrates

Question 32

what effect do nitrates have on vessels?

Answer 32

vasodilation

Question 33

what effect does nitrates have on venous pressure?

Answer 33

decreased

Question 34

what effect do nitrates have on cardiac output?

Answer 34

decreased

Question 35

changes in oxygen/CO2/celluar metabolites can dilate arterioles, increasing organ blood flow, what is this known as?

Answer 35

active hyperaemia

Question 36

what does blocking blood flow induce?

Answer 36

reactive hyperaemia

Question 37

what is the name of the biological process which maintains blood flow?

Answer 37

flow autoregulation