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Physiology Y2S1-CVS > Intro to CVS physiology & hemodynamics > Flashcards

Intro to CVS physiology & hemodynamics Flashcards

1
Q

What is the main function of the cardiovascular system?

A

1) Delivering oxygen and nutrients

2) Removing CO2 and waste products

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2
Q

What are the other functions of the CVS?

A

1) Delivering hormones

2) Regulates body temperature

3) Maintains adequate blood supply

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3
Q

The cardiac output is equal to what?

A

In healthy individuals, it is equal to the venous return (about 5L/min)

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4
Q

Describe the normal blood distribution to the body

A

1) 25% GI

2) 25% Skeletal Muscles

3) 25% Renal

4) 15% Cerebral

5) 5% Skin

6) 5% Coronary (Heart)

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5
Q

In which part of the body the blood has the highest amount of pressure?

A

Aorta 120/80mmHg

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6
Q

What makes blood move?

A

The difference in pressure (PRESSURE GRADIENT)

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7
Q

Compare the pulmonary and systemic circulations

A

The Systemic circulation has a higher pressure compared to the pulmonary circulation with a pressure gradient of 93mmHg compared to 10mmHg in the pulmonary circulation

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8
Q

What helps to keep the valves open?

A

1) Papillary Muscles

2) Chordae Tendineae

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9
Q

Which artery carries deoxygenated blood?

A

Pulmonary Artery

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10
Q

Which vein carries oxygenated blood?

A

Pulmonary vein

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11
Q

Which part of the vascular system has the smallest internal radius?

A

The true capillaries

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12
Q

Which part of the vascular system has the smallest wall thickness?

A

Veins

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13
Q

Which part of the vascular system Has the most elastic fibers and the thickest wall?

A

Aorta

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14
Q

Which part of the vascular system has the most collagen fibers and the biggest radius?

A

Vena cava

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15
Q

What is the function of the arteries?

A

Carries blood from point A to B under high pressure

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16
Q

What is the function of the arterioles?

A

They are the smallest branch of the arteries and have the highest resistance (AKA resistors)

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17
Q

What is the function of the capillaries?

A

Exchange of fluid, nutrients, and gasses, facilitated by its tiny internal radius and wall thickness (the smallest of all)

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18
Q

What is the function of the venules?

A

Collects blood from the capillaries merging into larger veins

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19
Q

What is the function of the veins?

A

They transport blood back to the heart under low pressure, and thy hold most of the blood reserve (about 60%)

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20
Q

What is meant by compliance?

A

How easily a blood vessel can stretch (veins can stretch more than arteries)

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21
Q

What is meant by capacitance?

A

The amount of blood a vessel can hold (Veins have a higher capacitance when compared to arteries)

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22
Q

How to calculate compliance?

A

Compliance (C) = Change in volume / Change in pressure

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23
Q

Describe the relationship between the venous and arterial systems when the volume is changed

A

In the arterial system, a small change in volume will largely increase the pressure, on the contrary, veins are exactly the opposite

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24
Q

Describe the effect of age and sympathetic stimulation on the volume/pressure curves

A

With increased age and sympathetic stimulation, the smooth muscle will increase in tone increasing the pressure at each volume in the artery

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25
Q

Describe the relationship between the blood flow, Resistance & pressure

A

Blood flow (Q) = Change in pressure (P) / Vascular resistance (R)

  • Blood flow is inversely related to resistance and directly related to the change in pressure (the greater the more)
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26
Q

What are the types of blood flow?

A

1) Laminar flow

2) Turbulent flow

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27
Q

Describe the laminar flow

A

1) Fluid molecules flow in layers

2) It is Silent (you can’t hear it with a stethoscope)

3) The velocity is maximum in the center and minimum at the periphery due to the resistance by the BV

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28
Q

Describe the turbulent flow

A

1) It is when fluid molecules bounce around (due to an obstruction) like Vascular aneurysm, Stenosis & arteriovenous fistula (abnormal connections between arteries and veins), Anemia

2) It is noisy

3) It has a low velocity

29
Q

What is meant by Reynold’s Number (NR)?

A

It is a number that is calculated to determine whether the flow is laminar or turbulent

30
Q

How to calculate the Reynold’s Number?

A

NR= (Velocity * Diameter * Density) / Viscosity

  • NR > 2000 = Turbulent Flow
  • NR <2000 = Laminar flow
31
Q

What is the unit of blood flow?

A

Volume per unit time (ml/s)

32
Q

Describe the relationship between velocity and the cross-sectional area of the blood vessel

A

Velocity and the cross-sectional area are inversely proportional meaning that the higher the cross-sectional area of the blood vessel the lower the velocity

33
Q

Compare the Aorta to the Capillaries

A

The capillaries have a lower velocity due to the higher cross-sectional area of 2500cm^2 being the largest making it most suitable for exchange

34
Q

Which BV has the highest velocity?

A

The Aorta and thus it has the lowest cross-sectional area

35
Q

Compare the flow of blood (amount of blood) through the pulmonary circulation & Systemic Circulation

A

It is the same (CO = VR)

36
Q

What happens to the pressure in a vein when it losses blood?

A

The pressure will decrease, as the volume decreases (though minimal since vein have high compliance)

37
Q

What remains constant in the cardiovascular system?

A

The mean arterial pressure

38
Q

Compare the volume of blood pumped by the right and left ventricles

A

It is the same volume (Cardiac output “CO” = Venous Return “VR”)

39
Q

How is the resistance to blood flow calculated?

A

Resistance (R) = change in pressure (P) / Blood Flow ml/sec

40
Q

What are the units of resistance?

A

mmHg/ml/min or PRU (peripheral resistance unit

41
Q

Describe the different variables when calculating the resistance

A

1) Resistance in the systematic circulation is about 1PRU & in the pulmonary circulation is about 0.14PRU (less resistance)

2) Blood flow is about 5L/min or 100ml/sec

3) The change in pressure in the systematic arteries is about 100mmHg

42
Q

What is poiseulle’s law?

A

Resistance (R) = (Viscosity of BV * Length of BV (L)) / Radius (r) of BV ^ 4 * (8/PIE)

43
Q

Describe the relationship between the different factors in poiseulle’s law

A

1) Resistance is directly related to the viscosity of the BV and its length

2) Resistance in inversely proportional to the radius of the BV

3) If the radius decreases by half the resistance will increase by 16 folds, and if it doubles then vice versa

44
Q

What stimulates the vasoconstriction of the BV?

A

1) Increased myogenic activity (depending on the pressure “myogenic activity”)

2) Increased Oxygen

3) Decreased CO2 and other metabolites

4) Increased Endothelin

5) Increased sympathetic stimulation

6) Vasopressin

7) Angiotensin

8) Cold temperatures

45
Q

What stimulates the vasodilation of the BV?

A

1) Decreased myogenic activity (depending on the pressure “myogenic activity”)

2) Decreased Oxygen

3) Increased CO2 and other metabolites

4) Increased Nitric oxide

5) Decreased sympathetic stimulation

6) Histamine

7) Hot temperatures

46
Q

What are the characteristics of the series resistors?

A

1) The total resistance is calculated by adding all individual resistance together

2) Total resistance is always greater than any individual resistance

3) Adding a resistor in series increases the resistance of the system

4) Flow is equal in all points around the circulation (arteries, arterioles, capillaries, venules and veins)

5) Pressure decreases according to the resistance it has to overcome (the greatest being in the arterioles)

47
Q

What are the characteristics of the parallel resistors?

A

1) The total resistance is the sum of all the reciprocals of the individual resistance

2) The total resistance is always smaller than any individual resistance

3) Adding a resistor in parallel decreases the total resistance of the system

4) Increasing the resistance of an individual resistor will increase the total resistance

5) Vessels are arranged in parallel in various organs (coronary, cerebral and renal)

6) Flow in individual resistance can be adjusted independently

48
Q

What is meant by the hematocrit?

A

It is the percentage of RBC in the blood

1) Men usually 42 (42 percent of the blood volume is RBC), woman 38

49
Q

What is blood pressure and how can we calculate it?

A

It is the force exerted by the blood against any unit area of the vessel wall

  • Pressure = Force / area
50
Q

What is a systolic pressure?

A

It is the maximum pressure exerted in the aorta (usually during cardiac contraction)

51
Q

What is the diastolic pressure?

A

It is the minimum aortic pressure (usually during the relaxation of the heart)

52
Q

What is the pulse pressure?

A

It is the difference between systolic and diastolic pressure (systolic - diastolic) it gives us an idea about the compliance of the vessel (as we get old the compliance decreases (hence the pulse pressure increases), an indication of stiffness)

53
Q

What is meant by the mean arterial pressure (MAP)?

A

It is the (Mean/Average of systolic and diastolic BP) but given the heart spends more time in diastole we calculate it as (2/3 Diastolic pressure + 1/2 systolic pressure) or (Diastolic pressure + 1/3 pulse pressure)

54
Q

How is the MAP regulated? what is the equation regulating it?

A
  • MAP (mmHg) = CO (ml/min) * TPR (mmHg/ml/min)

If the CO goes up the TPR goes down and vice versa, and thus the MAP does not fluctuate and it is always maintained within a narrow range

55
Q

During exercise will the MAP increase?

A

No, yes the CO will increase but the TPR will decrease as the BV will dilate

56
Q

By how many folds does our CO increase during vigorous exercise?

A

from 5-6L/min to 35L/min so about 6 folds

57
Q

What is the Dicrotic notch (incisura)?

A

It is the slight change in pressure that occurs when the aortic valve closes

58
Q

What is the BP in various parts of the circulation?

A

Systemic Circulation:

  • Aorta & large arteries = 100 mmHg
  • Capillaries = 17mmHg
  • Veins = 0 mmHg

Pulmonary circulation:

  • Pulmonary arteries: 16mmHg
  • Pulmonary capillaries: 7mmHg
59
Q

What are the major factors that regulate arterial systolic pressure?

A

1) Stroke volume (volume of blood pumped out of the heart’s left ventricle during each systolic cardiac contraction)

2) Compliance of the arterial vessels

60
Q

What are the major factors that regulate the arterial diastolic pressure?

A

The total peripheral resistance

61
Q

What are the major factors that regulate the pulse pressure?

A

1) Stroke volume (volume of blood pumped out of the heart’s left ventricle during each systolic cardiac contraction)

2) Compliance of the arteries

3) TPR

62
Q

What is meant by the damping of the pressure pulses?

A

It is the progressive diminishment of the pulse pressure in the peripheral circulation due to the blood movement in the vessels and the compliance of the vessels

  • Resistance * compliance
63
Q

What type of blood flow can we hear in the stethoscope?

A

The turbulent

64
Q

What are the two main control mechanisms that change with age in regard to controlling BP?

A

1) The kidneys: As it regulates BP

2) The decrease in the elasticity of the arteries which increases the systolic blood pressure

65
Q

Where is the flow velocity the highest and where is it the lowest?

A

1) Arteries

2) Capillaries

66
Q

Where is the blood volume the highest and where is it the lowest?

A

1) Veins and venules

2) Arterioles

67
Q

Where is the BP the highest and where is it the lowest?

A

1) Arteries

2) Veins and venules

68
Q

Where is the vascular resistance the highest and where is it the lowest?

A

It is the highest in the arterioles

Physiology Y2S1-CVS (17 decks)

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