arteries, veins and control of PVR

Question 1

structural feature of arteries

Answer 1

-thick muscular-to-elastic tunica media
-plentiful elastic fibres
-high compliance: walls stretch easily

Question 2

structural features of veins

Answer 2

-do not readily maintain shape
-slower pressure
-thinner wall
-less elastic
-collagenous and smooth muscle tissue
-bicuspid valves

Question 3

venules

Answer 3

-drain capillary blood

Question 4

tunica intima

Answer 4

inner lining of endothelial cells that makes contact with the blood
-another component is the basement membrane

Question 5

basement membrane

Answer 5

made of collagen fibres that provides tensile strength and stretch/recoil

Question 6

tunica media

Answer 6

middle layer primarily made of smooth muscle and elastic fibres
-smooth muscle regulates diameter of lumen

Question 7

Vasoconstrict/Vasodilate

Answer 7

controlled by smooth muscle and innervation from sympathetic innervation (ANS)

Question 8

elastic arteries

Answer 8

largest arteries (e.g., aorta) that branch into muscular arteries

Question 9

muscular arteries

Answer 9

branch into atrioles
-tunica media contains smooth muscle and fewer elastic fibres

Question 10

capillary

Answer 10

one cell thick and contain 5% of the total blood volume

Question 11

tunica adventitia

Answer 11

composed of mainly collagen and elastic tissue
-nerves and lymphatic vessels found within these layers
-small vessels supply blood to tissue through vessel (vasa vasorum)

Question 12

nitric oxide

Answer 12

inhibits platelet aggregation

Question 13

compliance

Answer 13

ability of an organ to distend in response to applied pressure
-declines with age and it can raise BP

Question 14

blood pressure

Answer 14

circulation of fluid contained within a space of definitive volume

Question 15

pressure falls during

Answer 15

systemic circulation and pulmonary circulation

Question 16

MAP

Answer 16

diastolic BP + 1/3 pulse pressure

Question 17

pulse pressure

Answer 17

systolic-diastolic

Question 18

MAP

Answer 18

DP - 1/3(DP-SP)

Question 19

arterial BP

Answer 19

blood ejected into the arteries from ventricles
-elastic artery wall stretch out by raised temp

Question 20

arteries

Answer 20

small amount of blood at high pressure - very thick walled

Question 21

arterioles

Answer 21

variable resistance system which distributes blood - dissipate most of pressure

Question 22

capillaries

Answer 22

vast surface area where interchange of fluid can occur in the ECF - one cell thick

Question 23

venules/veins

Answer 23

collecting/reservoir system which contains most of blood - very distensible

Question 24

factor influence transport

Answer 24

hydrostatic pressure and colloid pressure

Question 25

hydrostatic pressure

Answer 25

blood in capillaries exerts a pressure on capillary wall (favour movement out capillary) -decrease as BP drops

Question 26

colloid pressure

Answer 26

plasma has intrinsic osmotic pressure due to plasma proteins (favour movement into capillary)

Question 27

colloid pressure when BP is low

Answer 27

-remains the same as albumin is too big to leave capillary -therefore fluid moves out at arterial end and back in venous end

Question 28

tissue fluid net filtration

Answer 28

4 litres per day (not including kidneys)

Question 29

oedema

Answer 29

build up of tissue fluid: body moves fluid back into blood using lymph capillaries and vessels

Question 30

lymph vessels

Answer 30

contract to aid movement of fluid; also responsible for moving absorbed fat into the circulation

Question 31

alpha1 selective e.g., praxosin and doxazosin

Answer 31

decrease vasoconstrictor tone (PVR) no direct change in HR or CO

Question 32

alpha1 non-selective e.g., phentolamine

Answer 32

decrease vasoconstrictor tone (PVR) not used therapeutically

Question 33

noradrenaline mechanism

Answer 33

negative feedback to stop production at the terminal. -acts on alpha2 receptor to inhibit its own release

Question 34

issue with non-selective alpha agonist

Answer 34

blocks negative feedback of noradrenaline

Question 35

endothelial cells function

Answer 35

-release constrictors -proliferative state of tension -release free radicals -express molecules which tether inflammatory cells

Question 36

calcification

Answer 36

healing response to the presence of dead cells - increased risk of myocardial infraction

Question 37

normal BP

Answer 37

120/80 (systolic/diastolic)

Question 38

reactive hyperaemia

Answer 38

when blood flow is blocked

Question 39

active hyperaemia

Answer 39

changes in O2/CO2 can dilate arterioles

Question 40

evohaler

Answer 40

beta2 agonist - activate adenylate cyclase to relax bronchial smooth muscle

Question 41

factor controlling blood flow

Answer 41

- length of vessel - viscosity of liquid - pressure gradient

Question 42

venodilation

Answer 42

caused by nitrates - reducing filling on the heart so reducing cardiac work

Question 43

baroreceptors

Answer 43

present in cartoid sinus and aortic arch and are more sensitive around MAP

Question 44

vagus nerve X

Answer 44

aortic arch baroreceptor sends signal via this

Question 45

hering nerve IX

Answer 45

cartoid sinus baroreceptor

Question 46

clonidine

Answer 46

alpha2 agonist - activates presynaptic receptor in brain vasomotor centre to lower sympathetic output