Anatomy + physiology of vascular system

Question 1

3 layers of arteries and veins

Answer 1

tunica interna, tunica media, tunica externa

Question 2

Describe elastic (conducting) arteries

Answer 2

thick-walled arteries near heart (aorta + major branches)
- large lumen = low-resistance conduction of blood
- contain elastin in all 3 tunics
withstand and smooth out large BP fluctuations
- allow blood to flow fairly continuously through the body

Question 3

Describe muscular (distributing) arteries and arterioles

Answer 3

distal to elastic arteries
- thick tunica media with more smooth muscle and less elastic tissue
- active in vasoconstriction

arterioles:
- smallest arteries, lead to capillary beds
- control flow into capillary beds via vasodilation and constriction

Question 4

What special adaptations do veins have?

Answer 4

large diameter lumens = little resistance to flow
valves = prevent backflow of blood

Question 5

What are venous sinuses?

Answer 5

specialised, flattened veins with extremely thin walls (eg. coronary sinus of heart, dural sinuses of brain)

Question 6

What is blood flow?

Answer 6

actual volume of blood flowing through a vessel, an organ or the entire circulation in a given period

Question 7

Define blood pressure

Answer 7

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

Question 8

What are the main factors that influence BP?

Answer 8

cardiac output
peripheral resistance
blood volume

Question 9

Define systolic pressure

Answer 9

pressure exerted on arterial walls during ventricular contraction

Question 10

Define diastolic pressure

Answer 10

lowest level of arterial pressure during a ventricular cycle

Question 11

Define pulse pressure

Answer 11

the difference between systolic and diastolic pressure

Question 12

How does blood coming from a cut vein differ from blood coming from an artery?

Answer 12

vein = even blood flow
artery = flows in spurts

Question 13

What factors aid venous return?

Answer 13

respiratory pump (pressure changes created during breathing suck blood toward the heart by squeezing local veins)

muscular pump (contraction of skeletal muscles milk blood toward the heart

valves prevent backflow

Question 14

What is ABPI?

Answer 14

ankle:brachial pressure index

objective measurement of the vascular supply to the lower limbs

Question 15

Define autoregulation

Answer 15

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

Question 16

Describe 3 overarching causes of arterial vascular disease

Answer 16

narrow and block:
- atherosclerosis
- dissection
- rarities

expand and pop:
- aneurysm

things travel down them:
- embolus

Question 17

What is an embolus?

Answer 17

a mass of clotted blood or another material brought by the blood from one vessel and forced into a smaller one, obstructing the circulation

Question 18

What compensatory mechanisms can arise as a result of decreased perfusion?

Answer 18

vasodilation
development of collateral vessels
anaerobic metabolism