Cardiovascular System - Lecture 3

Question 1

What is blood pressure?

Answer 1

the force exerted by blood on the walls of blood vessels

Question 2

What is the value for systemic blood pressure?

Answer 2

120/80 mmHg

Question 3

What is the value for central venous pressure?

Answer 3

5-15 cm H2O (6-12 mmHg)

Question 4

What region does blood move to and from?

Answer 4

from high pressure to low pressure

Question 5

What is the formula for pressure?

Answer 5

Pressure = Force/Area

Question 6

What kind of velocity and pressure is needed for diffusion to happen?

Answer 6

low velocity and low pressure

Question 7

The pressure is ___ in the arteries and arterioles than in the capillaries, venules and veins.

Answer 7

higher

Question 8

Why is the pressure in the arteries and arterioles higher than in the capillaries, venues, and veins?

Answer 8

because resistance is much greater in the arteries and arterioles than in the capillaries, veins and venules

Question 9

What kind of resistance do arteries and arterioles have?

Answer 9

high resistance

Question 10

What kind of resistance do veins and venules have?

Answer 10

low resistance

Question 11

Why do arteries contract?

Answer 11

because they have more muscle than veins

Question 12

Is pressure higher in the systemic circulation or the pulmonary circulation?

Answer 12

systemic circulation

Question 13

Is pressure higher in systole or diastole?

Answer 13

systole

Question 14

Which vessels have less significant pressure differences between systole and diastole?

Answer 14

arterioles and capillaries

Question 15

Which vessels does the oscillation of pressure between systole and diastole diappear in?

Answer 15

venules and veins

Question 16

What is the formula for perfusion pressure?

Answer 16

perfusion pressure = inlet pressure (arterial pressure) - outlet pressure (venous pressure)

Question 17

What is perfusion pressure normally equal to?

Answer 17

arterial pressure

Question 18

What happens to flow if there is no perfusion pressure?

Answer 18

there is none

Question 19

What is the formula for flow?

Answer 19

Flow = Perfusion Pressure/Resistance

Question 20

Which vessel regulates flow: arteries or veins? How?

Answer 20

arteries by changing the cross-sectional area, diameter and resistance

Question 21

Flow is proportional to perfusion pressure, which in turn is approximately the ___ ___.

Answer 21

arterial pressure

Question 22

What occurs between vessel walls and the blood?

Answer 22

friction

Question 23

What happens to flow when internal surface area and resistance of a vessel doubles?

Answer 23

it halves

Question 24

Where is the resistance greatest in a vessel?

Answer 24

near the surface (slowest flow)

Question 25

Where is the resistance the least in a vessel?

Answer 25

at the center

Question 26

What is laminar flow?

Answer 26

the entire fluid that flows in the same direction

Question 27

Where is fluid speed greater in a vessel?

Answer 27

in the middle

Question 28

What does the flow speed depend on?

Answer 28

the viscosity of the fluid

Question 29

The greater the viscosity, the ___ the resistance to flow.

Answer 29

greater

Question 30

In blood, what does viscosity vary depending on?

Answer 30

hematocrit

Question 31

The more red blood cells there are, the more ___ the blood.

Answer 31

viscous

Question 32

Why is blood viscosity generally constant?

Answer 32

because hematocrit varies very little under normal conditions

Question 33

What is the length of blood vessels in an organism?

Answer 33

constant

Question 34

What is resistance equal to?

Answer 34

8 x viscosity x length / radius

Question 35

What is the main determinant of resistance variation in blood vessels?

Answer 35

viscosity, length of the vessel and cross-sectional area

Question 36

What controls the resistance in vessels (4)?

Answer 36

1. local metabolites 2. hormones 3. neurotransmitters 4. endothelial cells

Question 37

What happens to levels of Ca2+ in muscle cells when contraction occurs?

Answer 37

they increase

Question 38

What happens to levels of Ca2+ in muscle cells when relaxation occurs?

Answer 38

they decrease

Question 39

What happens to the resistance when cross-sectional area of a vessel increases?

Answer 39

it decreases

Question 40

In a situation where the vessels are in series, the total resistance of the 2 vessels is equal to...

Answer 40

the sum of the resistances of vessel 1 and vessel 2

Question 41

When vessels are in series, the total resistance is ___ than the resistance of each vessel taken individually.

Answer 41

greater

Question 42

In a situation where the vessels are organized in parallel, the resistance at the entry and exit of the system is ___ than the resistance in each of the vessels.

Answer 42

lower

Question 43

Why is the resistance inversely proportional to the radius in parallel vessels?

Answer 43

because the radius of the vessels at the entrance/exit is greater than the radius of each individual vessel

Question 44

Which vessels have the most blood?

Answer 44

veins and venules

Question 45

Why do veins and venules have most of the blood?

Answer 45

because of the high compliance they have

Question 46

Why don't arteries and arterioles have as much blood as veins?

Answer 46

because they have more resistance

Question 47

Why are arteries able to contract very well?

Answer 47

because veins are able to relax very well

Question 48

What does compliance depend on?

Answer 48

variations in vessel volume

Question 49

What is the formula for compliance?

Answer 49

compliance = V/P

Question 50

Why are veins more compliant then arteries?

Answer 50

because they have little smooth muscle and few elastic layers

Question 51

What kind of change happens in volume when the pressure of arteries increases?

Answer 51

minimal change

Question 52

What kind of change happens in volume when there is a slight pressure change in veins?

Answer 52

it increases a lot

Question 53

Venous compliance is much more ___ than arterial compliance.

Answer 53

important

Question 54

Blood pressure in the venous system is much ___ than the arterial system.

Answer 54

lower

Question 55

Blood pressure in peripheral venules is <___ percent of that in ascending aorta.

Answer 55

10

Question 56

What are the 2 mechanisms needed to maintain flow of blood in veins against force of gravity?

Answer 56

1. valves 2. contraction of skeletal muscles

Question 57

What is the function of valves?

Answer 57

ensure one-way flow of blood toward heart

Question 58

Valves superior to the contracting muscle ___, allowing blood to move toward the heart.

Answer 58

open