anatomy + physiology of vascular disease

Question 1

what are the 3 layers of a blood vessel

Answer 1

tunica interna; tunica media; tunica externa

Question 2

what is the lumen

Answer 2

central blood-containing space surrounded by tunics

Question 3

what are capillaries composed of?

Answer 3

endothelium with sparse basal lamina

Question 4

components of tunica interna

Answer 4

endothelium; subendothelial layer; internal elastic lamina

Question 5

why are valves important to consider in surgery

Answer 5

when using veins in bypasses, the valves must be facing the correct way

Question 6

differences between veins and arteries

Answer 6

veins have a thinner tunica media, wider lumen and valves

Question 7

where are elastic arteries located

Answer 7

near the heart - the aorta and its major branches

Question 8

characteristics of elastic arteries (4)

Answer 8

large lumen to allow low resistance conduction of blood; contain elastin in all three tunics; withstand and smooth out large blood pressure fluctuations between systole and diastole; allows blood to flow fairly continuously through the body

Question 9

what are muscular artieries

Answer 9

arteries distal to elastic arteries that deliver blood to body organs; active in vasoconstriction

Question 10

characteristics of muscular arteries (2)

Answer 10

thick tunica media; more smooth muscle and less elastic tissue

Question 11

role of arterioles (2)

Answer 11

lead to capillary beds; control flow into capillary beds vis vasodilation/contriction

Question 12

veins characteristics (5)

Answer 12

formed when venules converge; composed of three tunics (thin interna + media, thick externa made of collagen and elastic networks); are capacitance vessels (blood reservoirs); have much lower blood pressure; have large diameter lumens to decrease flow resistance; have valves to prevent backflow

Question 13

what are venous sinuses

Answer 13

specialised, flattened veins with extremely thin walls

Question 14

what is blood flow

Answer 14

the actual volume of blood flowing through a vessel/organ/entire circulation in a given period (mL/min); equivalent to cardiac output if whole vascular system is considered

Question 15

blood flow characteristics (2)

Answer 15

relatively constant at rest (5 mL/min); varies widely through individual organs according to immediate needs

Question 16

blood flow/tissue perfusion is involved in… (4)

Answer 16

delivery of oxygen and nutrients/removal of waste from tissue cells; gas exchange in the lungs; absorption of nutrients from the digestive tract; urine formation by the kidneys

Question 17

poiseuille’s law

Answer 17

ΔP = (8μLQ)/πr^4

Question 18

what is blood pressure

Answer 18

force per unit area exerted on the wall of a blood vessel by its contained blood

Question 19

what provides the driving force within the vascular system

Answer 19

differences in BP keeps blood moving from high to low pressure areas

Question 20

main factors affecting blood pressure (3)

Answer 20

cardiac output; peripheral resistance; blood volume

Question 21

blood pressure equation

Answer 21

CO x PR

Question 22

why may older people be more at risk from bleeds (BP)

Answer 22

atherosclerosis decreases vessel flexibility; volume is depleted; certain medications (e.g. B-blockers)

Question 23

blood flow/ blood pressure relationship

Answer 23

F ∝ ΔP

Question 24

blood flow/ resistance relationship

Answer 24

F∝ 1/R; R is more important than ΔP in influencing BP

Question 25

systolic pressure

Answer 25

pressure exerted on arterial walls during ventricular contraction

Question 26

diastolic pressure

Answer 26

lowest level of arterial pressure during a ventricular cycle

Question 27

pulse pressure

Answer 27

the difference between systolic and diastolic pressure

Question 28

mean arterial pressure

Answer 28

pressure that propels the blood to tissues; diastolic pressure + 1/3 pulse pressure

Question 29

average pressure gradient in venous system

Answer 29

20 mmHg (changes little); blood flow will be even if cut

Question 30

factors aiding venous return (3)

Answer 30

respiratory pump (pressure change from breathing sucks blood towards the heart); muscular pump (contraction of skeletal muscles help push blood towards the heart); valves (prevent backflow)

Question 31

what is autoregulation

Answer 31

automatic adjustment of blood flow to each tissue in proportion to its requirements at any given point in time

Question 32

how is organ blood flow control

Answer 32

intrinsically controlled by modifying the diameter of local arterioles feeding its capillaries; MAP remains constant while local demands regulate the amount delivered to areas in need

Question 33

what is an end organ

Answer 33

and organ with a singular blood supply

Question 34

what is Amaurosis fugax

Answer 34

“fleeting vision”; temporary loss of vision in one or both eyes

Question 35

different types of AAA (location)

Answer 35

supra renal; juxta renal; infra renal

Question 36

what is an aneurysm

Answer 36

permanent, abnormal dilation of a BN to 150% of normal

Question 37

what arterial diseases result in vessel blockage (3)

Answer 37

atherosclerosis; dissection; rarities

Question 38

what arterial diseases result in expansions/burst

Answer 38

aneurysms (different cytokine released here than in athersclerosis)

Question 39

what arterial diseases occur via travel through vessels

Answer 39

embolisms

Question 40

areas commonly atherosclerosed (6)

Answer 40

carotid bifurcation; LAD; aortic bifurcation; common femoral; superficial femoral; aorta (distal to left subclavian)

Question 41

common aneurysm areas (2)

Answer 41

abdominal aorta; popliteal arteries

Question 42

what does decreased blood tissue perfusion result in?

Answer 42

vasodilation; collateral vessel formation; anaerobic metabolism; ischemia if compensatory mechs are unable to meet O2 demand