Lecture 7

Question 1

Blood vessel wall structure: 3 layers

Answer 1

1. tunica intima- barrier, secretes vasoactive mediators
2. tunica media- mechanical strength and contractile power
3. tunica adventitia- tethers vessels to surrounding tissues (in larger arteries contains vasa vasorum)

Question 2

Conducting arteries (the really big ones) (4)

Answer 2

elastic arteries-large and thick walled(act as pressure reservoir)
very distensible (elastin)
recoil when stretched-temporary blood storage vessels
Most compliant arteries- aorta, pulmonary

Question 3

Compliance

Answer 3

degree of volume change when distending pressure inc

Question 4

small inc in venous pressure=

Answer 4

large inc in venous volume

Question 5

veins are…

Answer 5

capacitance vessels- can hold 70% of blood volume

Question 6

Arterial compliance important in…

Answer 6

important in converting pulsatile flow from heart to steady flow through peripheral vascular beds

Question 7

Distributing arteries (5)

Answer 7

muscular arteries
more smooth muscle than conducting
primary role to conduct flow to smaller arteries
Rich sympathetic innervation- change diameter actively
includes most arteries: internal carotid, femoral

Question 8

Resistance vessels (4)

Answer 8

control local blood flow to tissues
main source of peripheral resistance
major fall in BP occurs across resistance vessels
includes all arterioles and metarterioles

Question 9

Microcirculation- arterioles and metarterioles (2)

Answer 9

regulate TPR

control of blood flow to capillary beds

Question 10

peripheral vascular resistance (2)

Answer 10

BP dec in consecutive segments of the vascular tree

largest drop in arterioles- pulsatile flow also disappears here

Question 11

TPR

Answer 11

resistance to flow through the entire systemic circulation

MAP= CO x TPR

Question 12

Determinants of arterial pressure (3)

Answer 12

MAP= CO x TPR
CO = SV x HR
MAP= diastolic pressure + 1/3 of pulse pressure

Question 13

Exchange vessels (3)

Answer 13

metabolic exchange takes place across walls
low resistance, high cross sectional area
capillaries, sinusoids, post capillary venules

Question 14

Arteriovenous shunts (3 types)

Answer 14

simple- connects arteriole with a muscular venule-sphincter like action
thorough fare channel-metarteriole to post capillary venule
Glomeriform arteriovenous anastomosis- role in thermoregulation

Question 15

Capacitance (reservoir) vessels (3)

Answer 15

large volume and low pressure
return blood to heart
includes all muscle venules and veins

Question 16

peripheral venous pool

Answer 16

largest volume of blood is stored in veins of systemic organs

Question 17

central venous pool

Answer 17

blood also stored in great veins of the thorax and R atrium

Question 18

venous return controls…

Answer 18

SV coming out of heart

Question 19

factors controlling venous return (4)

Answer 19

smooth muscle contraction- sympathetic NS
skeletal muscle pump effect
one way valves
thoracic and cardiac pressure (between veins and heart)

Question 20

Valves in the lumen of veins

Answer 20

composed of 2 cusps
present in medium sized veins- especially limbs
reduce hydrostatic pressure and aids the muscle pump