blood pressure and volume

Question 1

what is blood flow to tissues governed mainly by and what does it alter

Answer 1

intrinsic factors which alter the vascular resistance of organs.

Question 2

what are the essential organs

Answer 2

the brain, the coronary circulation and working skeletal muscle.

Question 3

what is autoregulation

Answer 3

intrinsic mechanisms maintain essential organ blood flow in spite of alterations in systemic arterial blood pressure.

Question 4

what is arterial blood pressure maintained by

Answer 4

extrinsic mechanisms

Question 5

examples of intrinsic mechanisms

Answer 5

metabolic control
paracrine control

Question 6

what is active hyperaemia

Answer 6

increase in metabolic rate which brings about an increase in blood flow.

Question 7

what does increased metabolic rate in the cells of tissues result in?

Answer 7

increased oxygen consumption, increased production of waste products eg co2 and lactic acid and increased K outflow from cells.

Question 8

what is oxygen in relation to blood vessel diameter?

Answer 8

vasoconstrictor

Question 9

what induces vasodilation to increase blood flow to an area

Answer 9

CO2, lactic acid and K+ in the interstitial fluid

Question 10

what does vasodilation of the arterioles lead to

Answer 10

opening of more capillaries, increasing oxygen delivery to the tissue and removing the metabolic waste products.

Question 11

what is ischaemia

Answer 11

reduced blood flow to the tissue

Question 12

what can ischaemia result in

Answer 12

cell damage - infarction
cell death - necrosis
reduces the strength of muscular contraction

Question 13

what can poorly applied bandages lead to

Answer 13

tissue necrosis

Question 14

what can cause ischaemia

Answer 14

sustained contraction of skeletal muscle (weightlifting)
reflex increase in arterial blood pressure which increases perfusion pressure to the muscle (also workload on heart)

Question 15

what controls blood flow to non-essential organs

Answer 15

extrinsic factors

Question 16

what are extrinsic mechanisms governed by

Answer 16

central nervous system which coordinates responses via the autonomic nervous system.

Question 17

what part of the brain contains the cardiovascular centre

Answer 17

medulla oblongata

Question 18

function of the medulla oblongata

Answer 18

coordinates the blood flow of the non-essential organs to enable the intrinsic controls to manage the essential organs

Question 19

what does the cardiovascular centre maintain

Answer 19

cardiac output and vascular resistance so that arterial blood pressure is kept within normal limits.

Question 20

what are baroreceptors

Answer 20

stretch receptors that detect blood pressure situated in the aortic arch and carotid sinuses.

Question 21

what do baroreceptors do

Answer 21

deliver action potentials to the CV centre in response to stretch.

Question 22

what is the baroreflex

Answer 22

when the CV centre compares the information received to its reference value and makes changes as necessary
= maintains blood pressure

Question 23

what is the response of the baroreflex to a decrease in blood pressure

Answer 23

decreased stretch detected by the baroreceptors.
decreased frequency of action potentials sent to the brain
CV centre causes increased sympathetic activity
increased contractility of the heart, increased heart rate with shortening of systole to preserve diastolic filling time and faster conduction speed
vasoconstriction of peripheral blood vessels and dilation of vessels supplying essential organs
causes decreased parasympathetic activity which causes further vasoconstriction and increased heart rate.
these changes cause increased TPR and CO which raises arterial blood pressure.

Question 24

what is the response of the baroreflex to an increase in blood pressure

Answer 24

opposite to decrease

Question 25

what does the baroreflex do to the kidney

Answer 25

increase in sympathetic activity which causes release of a hormone called renin from juxtaglomerular apparatus

Question 26

what does renin cause the conversion of in the liver

Answer 26

angiotensinogen to angiotensin I

Question 27

what enzyme in the lungs converts angiotensin I to angiotensin II

Answer 27

angiotensin converting enzyme (ACE)

Question 28

what does angiotensin II cause

Answer 28

vasoconstriction and causes the release of aldosterone from the adrenal gland.

Question 29

what does aldosterone cause the kidney to do and what is the name of this process called

Answer 29

conserve sodium and water which increases the blood volume.
renin-angiotensin-aldosterone system

Question 30

what does angiotensin II cause the hypothalamus to do in response to reduced blood pressure/volume

Answer 30

increases sensation of thirst so animal takes in more water which increases blood volume.

Question 31

what does increased sympathetic activity and presence of angiotensin II cause the pituitary gland to release

Answer 31

a hormone called anti-diuretic hormone

Question 32

functions of anti-diuretic hormone

Answer 32

reduces urine formation
causes kidney to conserve water
increasing blood volume
causes further vasoconstriction

Question 33

what is long term control of blood pressure mediated by

Answer 33

the kidney