Physiology of Circulation

Question 1

heart

Answer 1

pump

Question 2

arteries

Answer 2

pressure reservoirs and conduits

Question 3

aterioles

Answer 3

resistance vessels

Question 4

capillaries

Answer 4

sites of exchange

Question 5

veins

Answer 5

conduits and blood reservoirs

Question 6

blood flow

Answer 6

• volume of blood flowing through a vessel, organ, or circulation system in a period of time
• blood flow remains fairly constant, and it is relatively equivalent to CO

Question 7

blood pressure

Answer 7

• the force per unit area exerted on a vessel wall by the contained blood
• typically measured in the largest arteries near the heart

Question 8

resistance

Answer 8

• opposite to flow, the amount of friction that blood encounters
• most friction is encountered well away from the heart (total peripheral resistance)
• sources of resistance: blood viscosity, vessel length, and vessel diameter

Question 9

3 sources of friction

Answer 9

blood viscosity
blood vessel length
blood vessel diamater

Question 10

blood viscosity

Answer 10

internal resistance to flow that exists in all fluids

• thickness of fluid
• greater viscosity = less movement
• blood viscosity is fairly constant - exception being the anemias and polycythemias

Question 11

blood vessel length

Answer 11

longer vessel = greater resistances

Question 12

blood vessel diameter

Answer 12

smaller diameter = greater resistance

Question 13

Systolic pressure

Answer 13

blood is expelled into the aorta, the walls are stretched, aortic pressure peaks

120mmHg

Question 14

Diastolic pressure

Answer 14

aortic walls recoil, aortic valves closes, and pressure drops

80mmHg

Question 15

pulse pressure

Answer 15

difference in Systolic and diastolic pressure

Question 16

MAP

Answer 16

the pressure that propels blood into the tissues - useful tool for determining tissue perfusion

• because diastole lasts longer than systole, MAP is not simply the halfway point between SBP and DBP

Question 17

Why is it more difficult for blood to make its return trip to the heart via the veins?

Answer 17

Venous pressure is far less pulsatile – pressure gradients are less steep

Low venous pressure results from TPR – energy has been dissipated out

Despite valves, venous pressure is too low for adequate venous return

Question 18

3 functional adaptations

Answer 18

1. The muscular pump
2. the respiratory pump
3. the sympathetic vasoconstriction

Question 19

The muscular pump

Answer 19

activity of the skeletal muscles surrounding the deep veins squeezes the veins and propels blood towards the heart

Question 20

the respiratory pump

Answer 20

during breathing, pressure changes in the ventral body cavity propel blood towards the heart

Question 21

Sympathetic vasoconstriction

Answer 21

during SNS firing, veins constrict, venous volume is reduced, and blood is pushed towards the heart

Question 22

baroreceptors

Answer 22

pressure-sensitive mechanoreceptors that respond to changes in arterial pressure and stretch

inputs from baroreceptors are integrated into the cardiovascular center of the medulla oblongata

outputs travel via autonomic fibers to the heart and the vascular smooth muscle

Question 23

slide 19-20

Question 24

chemoreceptors slide 21

Answer 24

receptors that respond to changes in levels of CO 2+, H+, and O2 in the blood

Question 25

slide 20-30