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Physiology 215 > Module 6: Vascular Physiology > Flashcards

Module 6: Vascular Physiology Flashcards

1
Q

T/F
Flow is proportional to the pressure gradient

A

True

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2
Q

T/F
Flow is proportional to resistance

A

False
It’s inversely proportional

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3
Q

Within the circulatory system, where is blood pressure the highest?

A

In the aorta

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4
Q

How is a pressure gradient formed?

A

As blood travels from the aorta to the rest of the body, the friction between the blood and blood vessel causes a decrease in pressure

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5
Q

What are the 3 factors that contribute to blood flow

A

The viscosity of the blood
Vessel length
Vessel radius

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6
Q

How does the viscosity of the blood contribute to blood flow?

A

The thicker the blood, the higher the frictional forces and therefore the resistance

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7
Q

How does the length of the vessel contribute to blood flow?

A

At a constant radius, a longer vessel has higher resistance

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8
Q

How does vessel radius impact blood flow?

A

Smaller radius creates more resistance

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9
Q

What are the 5 components to the vascular tree?

A

Systemic arteries
Arterioles
Capillaries
Venules
Systemic veins

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10
Q

T/F
The pulmonary system receives 80% of cardiac output

A

WRONG
It receives 100% bc all of the blood coming out of the right ventricle goes here

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11
Q

What are the 3 layers of a blood vessel?

A

The inner layer
The middle layer
The outer layer

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12
Q

Describe the structure of the inner layer of a blood vessel

A

Composed of a single layer of endothelial cells surrounded by a basement membrane

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13
Q

Describe the structure of the middle layer of a blood vessel

A

Made up of circular arrangements of smooth muscle cells and CT

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14
Q

Describe the structure of the outer layer of a blood vessel

A

Made of collagen-rich CT

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15
Q

Where is elastic fibre found in blood vessels

A

Between the outer and middle layer and the middle and inner layer

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16
Q

T/F
Maximum blood pressure occurs during systole

A

True

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17
Q

What is the systolic pressure in a healthy person?

A

120mmHg

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18
Q

What is passive recoil?

A

The un-stretching of the arteries that create a squeezing effect on the blood to keep arterial pressure higher

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19
Q

When does passive recoil occur?

A

During diastole

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20
Q

What is the normal diastolic pressure in a healthy person?

A

80mmHg

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21
Q

By what device is blood pressure measured?

A

By a sphygmomanometer

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22
Q

The sounds of blood flowing through blood pressure monitoring are called what?

A

Korotkoff sounds

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23
Q

When is the first kortkoff sound heard? What does this represent?

A

Occurs when cuff pressure is between 120-80mmHg
Represents peak systolic pressure

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24
Q

When is the last kortkoff sounds heard? What does this represent?

A

Occurs when cuff pressure is less than 80mmHg
represents minimum diastolic pressure

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25
Q

What is pulse pressure?

A

The difference between the systolic and diastolic pressures

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26
Q

What is mean arterial pressure (MAP)

A

The average pressure during the cardiac cycle

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27
Q

Large pressure swings occur where in the cardiovascular system?

A

In the ventricles during each heartbeat

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28
Q

Blood pressure steadily drops from the ___ to the ___ and ______

A

capillaries to the venules and large veins

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29
Q

How do arteriole walls differ from the walls in arteries?

A

They lack the high collagen content and elastin
Are also much smaller in size

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30
Q

What part of the circulatory system is deemed the “resistance vessels of the circulatory system”

A

The arterioles

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31
Q

T/F
Arteriolar resistance (total peripheral resistance) is not a constant value. Why?

A

True!
Because arterioles are very dynamic in the regulation of their radius

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32
Q

What is shunting

A

The decrease in arteriole radius in the digestive system to allow blood to go to different organs

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33
Q

Describe vasoconstriction

A

Occurs when arterioles contract and their radius becomes smaller
Increases pressure
Decreases blood flow

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34
Q

Describe vasodilation

A

Occurs when arterioles relax and radius increases
Decreases pressure
Increases blood flow

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35
Q

What is vascular tone?

A

The state of partial constriction in arterioles

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36
Q

Why is vascular tone important?

A

Allows the arterioles to either dilate or constrict as necessary

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37
Q

Intrinsic control can either be:

A

chemical or physical

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38
Q

Extrinsic control can either be:

A

neural or hormonal

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39
Q

List the local chemical influences that can lead to vasodilation (7)

A

Decreased oxygen
Increased carbon dioxide
Increased acid
Adenosine release
Increased potassium
Increased osmolarity
Prostaglandin release

40
Q

T/F
Chemical influences act directly on the smooth muscle cells

A

False
They trigger the endothelial cells to release chemical messengers that act directly on the smooth muscle cells

41
Q

T/F
Histamine causes vasodilation

A

True

42
Q

What are the local physical influences of blood vessels

A

Temperature
Shear stress
Myogenic response to stretch

43
Q

How does temperature influence blood vessel dilation/constriction?

A

Applying heat can cause vasodilation
Applying cold can cause vasoconstriction

44
Q

How does shear stress influence blood vessel dilation/constriction?

A

Increase in shear stress cause friction, which causes a release of nitric oxide to create vasodilation within the vessel to cause a reduction in the shear stress

45
Q

How does myogenic response to stretch influence blood vessel dilation/constriction?

A

When smooth muscle cells are passively stretched, their myogenic response causes vasoconstriction to oppose this stretch
The opposite is true if there is less stretch in the smooth muscle

46
Q

T/F
Chemical and physical influences often work at the same time

A

True

47
Q

T/F
Arteriolar smooth muscle is dual innervated

A

False
It’s only innervated by the sympathetic nervous system

48
Q

Increasing sympathetic activity does what to arteriolar tone?

A

Increases it

49
Q

Decreasing sympathetic activity does what to arteriolar tone?

A

Decreases it

50
Q

How does hormonal input cause arteriolar contraction?

A

The sympathetic nerves release norepinephrine, which bind to a1-adrenergic receptors that allow increased calcium entry into the smooth muscle

51
Q

T/F
norepinephrine release does not impact the arterioles in the brain

A

true

52
Q

How do you calculate mean arterial pressure (MAP)?

A

Total peripheral resistance (TPR) * cardiac output (CO)

53
Q

T/F
Vasopressin and Angiotensin II are vasoconstrictors

A

True

54
Q

What are the walls of capillaries made of?

A

A single layer of endohelial cells

55
Q

Exchange across the capillaries in all parts of the body (excluding brain) occur by what?

A

Diffusion

56
Q

In the brain, exchange occurs through what? Why?

A

carrier-mediated transport
due to the blood-brain barrier

57
Q

What factors make capillaries ideal for diffusion?

A

Short distance between them and other cells
Large surface area (provides many sites for exchange)
Slow velocity of blood (allows for more time for exchange)

58
Q

What are capillary beds?

A

Branching networks of capillaries

59
Q

What is the purpose of a metarteriole

A

To provide a bypass between the arterioles and venules

60
Q

What is the function of precapillary sphincters?

A

To control the flow of blood through a capillary bed

61
Q

When the precapillary sphincter is relaxed, how is blood flow act?

A

Blood flows through the metarteriole and entire capillary bed

62
Q

When the precapillary sphincter is contracted, how is blood flow affected?

A

Blood only flows through the metarteriole, bypassing the capillary bed

63
Q

What is bulk flow?

A

The movement of protein-free plasma from the capillary lumen into the interstitial space
Is the summation of filtration and reabsorption

64
Q

What is filtration? When does it occur?

A

Fluids are forced out of the capillaries
Occurs when outward forces are greater than inward forces

65
Q

What is reabsorption? When does it occur?

A

Fluid is forced into the capillaries
Occurs when inward forces are greater than outward forces

66
Q

What forces contribute to bulk flow? (4) (good luck w this one. hard)

A

Capillary blood pressure
Interstitial fluid colloid osmotic pressure
Interstitial fluid hydrostatic pressure
Plasma colloid osmotic pressure

67
Q

What is capillary blood pressure?

A

The hydrostatic pressure exerted by the blood on the capillary walls that try to force fluid out of the capillary

68
Q

What is interstitial fluid colloid osmotic pressure?

A

The osmotic pressure created by the presence of proteins in the interstitial fluid.

69
Q

What forces of bulk flow want to push fluid out of the capillary?

A

Capillary blood pressure and interstitial fluid colloid osmotic pressure

70
Q

What forces of bulk flow want to move fluid into the capillary?

A

Interstitial fluid hydrostatic pressure and plasma colloid osmotic pressure

71
Q

What is interstitial fluid hydrostatic pressure?

A

The hydrostatic pressure exerted on the outside of the capillary by fluids in the interstitial space

72
Q

What is the plasma colloid osmotic pressure?

A

The presence of protein in the plasma creating an osmotic pressure that tries to bring fluid into the capillary lumen

73
Q

T/F
Interstitial fluid colloid osmotic pressure is usually at 0mmHg

A

True

74
Q

T/F
In a normal, healthy individual, there is balance between filtration and reabsorption

A

False
In a healthy individual, there is an imbalance

75
Q

What does the lymphatic system consist of?

A

The spleen, thymus, lymph nodes, lymph channels and tonsils

76
Q

What are the functions of the lymphatic system (4) ?

A

Return of excess fluid
Defense against disease
Transport of absorbed fat
Return of filtered proteins

77
Q

How does the lymphatic system create a defence against disease?

A

Lymph passes by lymph nodes on its way to the heart, which contain phagocytes and lymphocytes

78
Q

T/F
Venules generate little resistance to blood flow

A

True

79
Q

Decreasing venous capacity does what to blood circulation?

A

Increases the amount of blood circulating

80
Q

Increasing venous capacity does what to blood circulation?

A

Decreases the amount of blood circulating

81
Q

What factors affect venous return (6)?

A

Sympathetic activity
The skeletal muscle pump
Gravity
Venous valves
Respiratory activity
Cardiac suction

82
Q

How does sympathetic activity impact venous return?

A

Increasing sympathetic activity decreases venous capacity, therefore increases venous return

83
Q

How does the skeletal muscle pump impact venous return?

A

When the skeletal muscle pump is being actively used, the veins are compressed by the skeletal muscles contracting; reducing venous capacity and increasing venous return

84
Q

How does gravity affect venous return?

A

When laying down, there is less hydrostatic pressure, making venous return greater
When standing, the veins must fight gravity and the greater hydrostatic pressure, therefore increasing venous capacity and decreasing venous return

85
Q

How do venous valves affect venous return?

A

Help to reduce hydrostatic pressure when standing, therefore increase venous return

86
Q

How does respiratory activity affect venous return?

A

Increases venous return by increasing the pressure gradient between the venules and the heart

87
Q

How does cardiac suction affect venous return?

A

The rapid expansion of the ventricular walls creates a suction effect during ventricular relaxation than even affects the atria, allowing for the atria to suck in blood, therefore increasing venous return

88
Q

What is the function of baroreceptors?

A

To initiate a response that will return MAP back to its homeostatic set point

89
Q

Where are baroreceptors located?

A

In the carotid sinus and aortic arch

90
Q

If mean arterial pressure in increased, what happens to the baroreceptor’s firing rate?

A

It increases

91
Q

If MAP decreases, what happens to the baroreceptor’s firing rate?

A

It decreases

92
Q

Where is the cardiovascular control centre located?

A

In the medulla

93
Q

What is hypertension?

A

Chronic high blood pressure levels

94
Q

What is the most common type of hypertension?

A

Primary hypertension

95
Q

T/F
Hypertension progression can be slowed through medication

A

False
Medication can help normalize MAP, but the disease will still progress

96
Q

Describe secondary hypertension

A

The cause of hypertension is secondary to another problem

Physiology 215 (6 decks)

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