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PHGY-210 > Cardiovascular System - Lecture 3 > Flashcards

Cardiovascular System - Lecture 3 Flashcards

1
Q

What is blood pressure?

A

the force exerted by blood on the walls of blood vessels

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2
Q

What is the value for systemic blood pressure?

A

120/80 mmHg

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3
Q

What is the value for central venous pressure?

A

5-15 cm H2O (6-12 mmHg)

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4
Q

What region does blood move to and from?

A

from high pressure to low pressure

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5
Q

What is the formula for pressure?

A

Pressure = Force/Area

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6
Q

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

A

low velocity and low pressure

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7
Q

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

A

higher

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8
Q

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

A

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

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9
Q

What kind of resistance do arteries and arterioles have?

A

high resistance

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10
Q

What kind of resistance do veins and venules have?

A

low resistance

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11
Q

Why do arteries contract?

A

because they have more muscle than veins

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12
Q

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

A

systemic circulation

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13
Q

Is pressure higher in systole or diastole?

A

systole

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14
Q

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

A

arterioles and capillaries

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15
Q

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

A

venules and veins

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16
Q

What is the formula for perfusion pressure?

A

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

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17
Q

What is perfusion pressure normally equal to?

A

arterial pressure

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18
Q

What happens to flow if there is no perfusion pressure?

A

there is none

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19
Q

What is the formula for flow?

A

Flow = Perfusion Pressure/Resistance

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20
Q

Which vessel regulates flow: arteries or veins? How?

A

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

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21
Q

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

A

arterial pressure

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22
Q

What occurs between vessel walls and the blood?

A

friction

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23
Q

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

A

it halves

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24
Q

Where is the resistance greatest in a vessel?

A

near the surface (slowest flow)

25
Q

Where is the resistance the least in a vessel?

A

at the center

26
Q

What is laminar flow?

A

the entire fluid that flows in the same direction

27
Q

Where is fluid speed greater in a vessel?

A

in the middle

28
Q

What does the flow speed depend on?

A

the viscosity of the fluid

29
Q

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

A

greater

30
Q

In blood, what does viscosity vary depending on?

A

hematocrit

31
Q

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

A

viscous

32
Q

Why is blood viscosity generally constant?

A

because hematocrit varies very little under normal conditions

33
Q

What is the length of blood vessels in an organism?

A

constant

34
Q

What is resistance equal to?

A

8 x viscosity x length / radius

35
Q

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

A

viscosity, length of the vessel and cross-sectional area

36
Q

What controls the resistance in vessels (4)?

A
  1. local metabolites
  2. hormones
  3. neurotransmitters
  4. endothelial cells
37
Q

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

A

they increase

38
Q

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

A

they decrease

39
Q

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

A

it decreases

40
Q

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

A

the sum of the resistances of vessel 1 and vessel 2

41
Q

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

A

greater

42
Q

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.

A

lower

43
Q

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

A

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

44
Q

Which vessels have the most blood?

A

veins and venules

45
Q

Why do veins and venules have most of the blood?

A

because of the high compliance they have

46
Q

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

A

because they have more resistance

47
Q

Why are arteries able to contract very well?

A

because veins are able to relax very well

48
Q

What does compliance depend on?

A

variations in vessel volume

49
Q

What is the formula for compliance?

A

compliance = V/P

50
Q

Why are veins more compliant then arteries?

A

because they have little smooth muscle and few elastic layers

51
Q

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

A

minimal change

52
Q

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

A

it increases a lot

53
Q

Venous compliance is much more ___ than arterial compliance.

A

important

54
Q

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

A

lower

55
Q

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

A

10

56
Q

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

A
  1. valves
  2. contraction of skeletal muscles
57
Q

What is the function of valves?

A

ensure one-way flow of blood toward heart

58
Q

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

A

open

PHGY-210 (36 decks)

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