Introduction to the circulatory system

Question 1

What is the purpose of the cardiovascular system?

Answer 1

fluid transportation system

Question 2

What is being transported

Answer 2

Red blood cells: O2 and CO2 to and from the lungs, white blood cells and antibodies to sites of infection, nutrients to the liver to cells throughout the body, hormones for endocrine organs to target

Question 3

Aorta –> arteries and arterioles

Answer 3

thick walled, more muscular, smaller diameter, high pressure

Question 4

Vena cava –> veins

Answer 4

Thin walled, collapse easily, large diameter, low pressure

Question 5

Macrovessels

Answer 5

aorta, artery, vein, vena cava, arteriole

Question 6

Microcirculatio

Answer 6

terminal arteriole, capillary, venule, holds more than half of our blood volume

Question 7

Arterial vessels and large veins

Answer 7

have elastic tissue, have smooth muscle, have fibrous tissue (help keep shape)

Question 8

Capillaries and venules

Answer 8

do not have elastic tissue (do not stretch), do not have smooth muscle (do not contract), do not have fibrous tissue (collapse and close)

Question 9

Small arteries (SA) and arterioles (ART) are

Answer 9

resistance vessels

Question 10

Resistance

Answer 10

= deltaP/Flow –> mmHg/L/min

Question 11

Conservation of Mass

Answer 11

Flow = velocity * area = V * A + ~5 L/min

Question 12

Blood pumps

Answer 12

from the left ventricle into the aorta to the large artery, small artery, arteriole, capillaries, venule, vein, vena cava and then the right atria

Question 13

Large arteries

Answer 13

fast flow with little pressure drop, high pressure conduits

Question 14

Small arteries and arterioles

Answer 14

large pressure drop - control flow, resistance vessels

Question 15

capillaries

Answer 15

diffusion - exchange

Question 16

venules and small veins

Answer 16

capacitance - hold a large volume at low pressure, low pressure capacitance/volume

Question 17

large veins

Answer 17

low resistance conduits back to the heart

Question 18

Baroreceptor reflex system

Answer 18

controls blood pressure

Question 19

Poiseuille’s law

Answer 19

F = P1-P2/R, flow is proportional to the pressure/voltage gradient, flow is inversely proportional to the resistance

Question 20

R (resistance to flow) =

Answer 20

8etaL/pir^4

Question 21

The only parameter we can change is

Answer 21

radius

Question 22

The dominant contributors to flow resistance are

Answer 22

small vessels

Question 23

Small amounts of this can have dramatic effects

Answer 23

arterial occlusion

Question 24

Flow regulation is accomplished by

Answer 24

vasodilation and vasoconstriction in the arterioles

Question 25

How do small arteries and arterioles control resistance

Answer 25

local (metabolic and myogenic, shear stress), neural/hormonal – signals

Question 26

Startling’s Law of Filtration

Answer 26

Flux = K[(Pc - Pi) - (pic - pii)]
K = filtration coefficient
Pc = capillary pressure
Pi = interstitial pressure
pic = capillary oncotic pressure
pii = interstitial oncotic pressure

Question 27

Venous compliance

Answer 27

C = change in volume/change in pressure

Question 28

Arteries and arterioles

Answer 28

very stiff, if you add a little volume (delta V), you get a large change in pressure (deltaP)

Question 29

Veins and venules

Answer 29

very compliant, if you add a lot of volume to the veins (deltaV), you only get a small change in pressure (deltaP)

Question 30

Ca

Answer 30

«Cv

Question 31

Flow is (arterioles)

Answer 31

constant, deltaP is largest for the arterioles

Question 32

Resistance is

Answer 32

largest for the arterioles

Question 33

R =

Answer 33

deltaP/flow

Question 34

Flow is (veins)

Answer 34

constant, deltaP is tiny for the small veins and venules, resistance is negligible for the small veins

Question 35

TPR (total peripheral resistance)

Answer 35

= Ra + Rv = deltaP/flow

Question 36

Va

Answer 36

= Voa + CaPa

Question 37

VV

Answer 37

= Vov + CvPv

Question 38

decrease in (venous capacitance) or making veins stiffer Cv or smaller in diameter, Vov

Answer 38

Pv increase, preload increase, move more blood to the arteries