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ESA 2- Cardiovascular System > Introduction to the Cardiovascular System > Flashcards

Introduction to the Cardiovascular System Flashcards

1
Q

What is true of all living cells?

A

They are metabolically active

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2
Q

What is the result of living cells being metabolically active?

A

They use oxygen and nutrients, and produce carbon dioxide and other waste

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3
Q

How can single celled or tiny organisms get oxygen and nutrients?

A

Directly by diffusion from the environment

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4
Q

What is diffusion?

A

Random movement that results in an overall movement from high concentration to a low concentration

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5
Q

What is the result in small organisms being able to get oxygen and nutrients directly by diffusion?

A

They don’t require a cardiovascular system

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6
Q

How many cells are in the human body?

A

10^14 (100 million)

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7
Q

What is the problem with the human body having so many cells?

A

Most are far away from a source of oxygen and nutrients, and therefore can’t obtain them from diffusion

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8
Q

Why does the body cells being far away from a source of oxygen and nutrients mean that it can’t get them by diffusion?

A

Because diffusion is proportional to distance squared, so it works well over short distances, but not larger distances as it takes far longer to travel across

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9
Q

What is the result of large cells being unable to get oxygen and nutrients by direct diffusion?

A

They need a gas exchange and circulatory system to carry oxygen and nutrients to cells, and carry waste produces away

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10
Q

What does the right heart do?

A

Pumps blood to the lungs

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11
Q

What happens to blood at the lungs?

A

Gas exchange takes place and blood becomes oxygenated

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12
Q

What happens to blood once it has become oxygenated?

A

It passes from the lungs to the left heart

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13
Q

What does the left heart do?

A

Pumps blood to the body cells

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14
Q

What happens to blood at the body cells?

A

Oxygen is released

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15
Q

What does deoxygenated blood return to the right heart via?

A

The kidneys and the gut

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16
Q

Why does blood return via the kidneys?

A

Filtering

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17
Q

Why does blood return via the gut?

A

Nutrient acquisition

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18
Q

What is the pulmonary circulation?

A

The circulation of blood form right heart to lungs, to left heart

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19
Q

Where is blood pumped in the pulmonary circulation?

A

Alveoli

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20
Q

Why is blood pumped to the alveoli?

A

So gas exchange can take place by diffusion

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21
Q

What is the systemic circulation?

A

The circulation of blood form left heart, to body, to right heart

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22
Q

How does blood in circulation travel?

A

By convective transport (flow)

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23
Q

What is the advantage of convective transport?

A

It works quickly over long distances

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24
Q

What is essential to allow diffusion to take place?

A

The mechanism for transporting substances close to cells

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25
Q

What is the distribution system?

A

Vessels and blood

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26
Q

What is the heart?

A

Effectively, two pumps

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27
Q

What is the exchange mechanism?

A

The capillaries

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28
Q

What does blood transport around the body?

A

Oxygen
Metabolic substrates
Carbon dioxide
Waste product

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29
Q

How does exchange of substances between the blood and body cells occur?

A

By diffusion

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30
Q

What does the cardiovascular system provide?

A

The correct conditions for diffusion to take place at the tissues and lungs

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31
Q

Where does diffusion between blood and tissues take place?

A

Capillaries

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32
Q

What are capillaries composed of?

A

A single layer of endothelial cells, surrounded by a basal lamina

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33
Q

What is the advantage of capillaries being one cell thick?

A

There is a short distance for diffusion to take place

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34
Q

What molecules can directly diffuse through the lipid bilayer?

A

Those that are lipid soluble, e.g. oxygen and carbon dioxide

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35
Q

How do molecules that can’t diffuse through the lipid bilayer get through?

A

Small aqueous pores between endothelial cells in capillaries

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36
Q

What molecules can’t diffuse through the lipid bilayer?

A

Those that are hydrophilic and not lipid soluble, e.g. glucose, amino acids and lactate

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37
Q

In what direction do all molecules move?

A

Down their concentration gradient

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38
Q

What does how easily molecules diffuse through pores depend on?

A

Size and charge of molecule

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39
Q

Why are special transport molecules sometimes needed to get through pores?

A

In some places, e.g. the brain, the pores are tighter

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40
Q

What do leaky pores allow?

A

More molecules to move in and out of the capillary lumen

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41
Q

What does rate of diffusion depend on?

A

Area, diffusion ‘resistance’, and concentration gradient

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42
Q

What does a larger area available for exchange result in?

A

A faster rate of diffusion

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43
Q

What does the area of exchange between capillaries and tissues depend on?

A

Capillary density

44
Q

What will be true of a tissue that is more metabolically active?

A

It will have more capillaries (a higher capillary density)

45
Q

What does diffusion resistance pertain to?

A

The nature of the molecule, the nature of the barrier, and the path length

46
Q

Give an example of what is meant by the nature of the molecule?

A

Is it hydrophilic or lipophilic

47
Q

Give an example of what is meant by the nature of the barrier

A

Larger pores mean hydrophilic molecules and larger molecules can diffuse more readily

48
Q

What does a greater path length lead to?

A

A slower rate of diffusion

49
Q

What is the rate of diffusion proportional to?

A

The square of the distance it needs to travel

50
Q

What does the path length depend on?

A

Capillary density

51
Q

Where is path length shortest?

A

The most active tissues

52
Q

What is normally the rate limiting factor of diffusion?

A

Concentration gradient

53
Q

What does a greater concentration gradient lead to?

A

Greater rate of diffusion

54
Q

What is the concentration gradient that matters in the human body?

A

Between the capillary blood and the tissues

55
Q

What must happen to the concentration gradients for exchange to continue

A

The gradient between capillary blood and tissues must be maintained

56
Q

What will happen to concentrations when a substance is used by tissues?

A

It will have a lower concentration in capillary blood that arterial blood

57
Q

What happens to the concentration of oxygen as it’s used by tissues?

A

It falls in the blood

58
Q

What does the extent of oxygen concentration decrease depend on?

A

Rate of use by tissue

Rate of blood flow through capillary bed

59
Q

What does a higher rate of flow through the capillary bed mean?

A

The more the concentration gradient can be maintained to match the rate of use in tissues

60
Q

What is the result of a lower blood flow at any rate of use?

A

The lower the capillary concentration

61
Q

What must the rate of blood flow do?

A

Be high enough to maintain a sufficient concentration gradient for diffusion

62
Q

What does the rate of blood flow determine?

A

The concentration gradient driving oxygen or nutrient diffusion into cells

63
Q

What must blood flow match?

A

The tissues metabolic needs

64
Q

What is the result of a higher rate of metabolism?

A

The greater the demand for oxygen and nutrients, and so an increase in blood flow

65
Q

What is the rate of blood flow known as?

A

Perfusion rate

66
Q

What is the perfusion rate of the brain?

A

Needs constant high flow

0.5ml per min per gram

67
Q

What is the perfusion rate of heart muscle?

A
  1. 9ml per min per gram at rest

3. 6ml per min per gram during exercise

68
Q

What is the perfusion rate of kidneys?

A

Need high, constant flow

3.5ml per min per gram

69
Q

Give two places where blood flow varies?

A

Skeletal muscle

Gut

70
Q

When is skeletal muscle blood flow high?

A

During exercise

71
Q

When is gut blood flow high?

A

After a meal

72
Q

What is the cardiac minimum flow in for a 70kg man?

A

5 litres per min

73
Q

What is the cardiac maximum flow in for a 70kg man?

A

24.5 litres per min

74
Q

What must the cardiovascular system do?

A

Supply between 5 and 25 litres per minute of blood to the tissue, whilst at all times maintaining perfusion to vital organs such as the brain, heart and kidneys

75
Q

How long would the heart have to stop beating for you to go unconscious?

A

2 to 4 secs

76
Q

What happens once the heart stops beating for a minute?

A

Neurones start to die

77
Q

What are the components of the cardiovascular system?

A

Pump- the heart
Distribution system- vessels and blood
Exchange mechanisms- capillaries
Flow control

78
Q

What acts as the flow control in the cardiovascular system?

A

Arterioles

Pre-capillary sphincters

79
Q

What do pre-capillary sphincters and specialised arterioles have?

A

Lots of smooth muscle cells

80
Q

How dopre-capillary sphincters and arterioles control flow?

A

The smooth muscle cells tense to restrict blood flow, or relax to increase blood flow to the area

81
Q

What would happen if there was no flow control?

A

Blood would only flow to the parts that are easier to perfuse

82
Q

What is the problem with blood flowing only to the easiest to perfuse areas?

A

The brain is harder to perfuse, due to gravity

83
Q

What needs to be added to the system to regulate blood flow?

A

Resistance

84
Q

What is meant by adding resistance to the system?

A

Reducing the ease with which some reasons are perfused, in order to direct blood flow to the more difficult to perfuse regions

85
Q

What are the resistance vessels?

A

Arterioles

86
Q

Why are the arterioles the resistance vessels?

A

As they narrow flow to one area, and therefore allow it to go to other areas

87
Q

What is the heart made up of?

A

Two pumps in series

88
Q

What does the left heart do?

A

Pumps blood around the systemic circulation

89
Q

What does the right heart do?

A

Pumps blood around the pulmonary circulation

90
Q

What does the heart pump to in the systemic circulation?

A

Arteries via the aorta

91
Q

What do the arteries supply?

A

Arterioles

92
Q

What do arterioles supply?

A

Capillaries

93
Q

What do capillaries produce?

A

A branching network

94
Q

What does the capillaries branching network provide?

A

A large surface area for diffusion

95
Q

What do capillaries drain into?

A

Venules

96
Q

What do venules drain into?

A

Veins

97
Q

What must the total flow in the system be able to do?

A

Change

98
Q

What does the ability to change the total flow in the system require?

A

A temporary store of blood, which can be returned to the heart at a different rate

99
Q

Why does a change in total flow in the system require a temporary store of blood?

A

The heart can only pump more blood through if it has more blood going into it

100
Q

What provides the temporary store of blood?

A

The capacitance of veins

101
Q

Why are veins able to provide a temporary store of blood?

A

Because they have thin walls with smooth muscle in them, so they can easily distend of collapse, enabling them to act as a variable reservoir

102
Q

In what direction does blood flow?

A

From high to low pressure

103
Q

How does the pressure of blood change as it goes through the system?

A

The heart increases the pressure of the blood to push it into the high pressure arterial system
Blood goes to resistance vessels, to exchange vessels, to capacitance vessels, resulting in blood being in the low pressure venous system

104
Q

What causes the highest drop in blood pressure?

A

Arterioles

105
Q

What is the result in drop in blood pressure caused by arterioles?

A

By the time that blood reaches capillaries, its at low pressure

106
Q

What is the distribution of blood in the body?

A

It varies, but it is approximately-
11% in arteries and arterioles

5% in capillaries

17% in heart and lungs

67% in veins

107
Q

Why can the distribution of blood in the body vary?

A

The veins are a temporary store, so can reduce a bit to put more blood back into the heart if needed

ESA 2- Cardiovascular System (18 decks)

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