Introduction to the Cardiovascular System Flashcards Preview

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

Flashcards in Introduction to the Cardiovascular System Deck (107):
1

What is true of all living cells?

They are metabolically active

2

What is the result of living cells being metabolically active?

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

3

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

Directly by diffusion from the environment

4

What is diffusion?

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

5

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

They don’t require a cardiovascular system

6

How many cells are in the human body?

10^14 (100 million)

7

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

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

8

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

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

9

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

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

10

What does the right heart do?

Pumps blood to the lungs

11

What happens to blood at the lungs?

Gas exchange takes place and blood becomes oxygenated

12

What happens to blood once it has become oxygenated?

It passes from the lungs to the left heart

13

What does the left heart do?

Pumps blood to the body cells

14

What happens to blood at the body cells?

Oxygen is released

15

What does deoxygenated blood return to the right heart via?

The kidneys and the gut

16

Why does blood return via the kidneys?

Filtering

17

Why does blood return via the gut?

Nutrient acquisition

18

What is the pulmonary circulation?

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

19

Where is blood pumped in the pulmonary circulation?

Alveoli

20

Why is blood pumped to the alveoli?

So gas exchange can take place by diffusion

21

What is the systemic circulation?

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

22

How does blood in circulation travel?

By convective transport (flow)

23

What is the advantage of convective transport?

It works quickly over long distances

24

What is essential to allow diffusion to take place?

The mechanism for transporting substances close to  cells

25

What is the distribution system?

Vessels and blood

26

What is the heart?

Effectively, two pumps

27

What is the exchange mechanism?

The capillaries

28

What does blood transport around the body?

Oxygen 
Metabolic substrates 
Carbon dioxide 
Waste product

29

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

By diffusion

30

What does the cardiovascular system provide?

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

31

Where does diffusion between blood and tissues take place?

Capillaries

32

What are capillaries composed of?

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

33

What is the advantage of capillaries being one cell thick?

There is a short distance for diffusion to take place

34

What molecules can directly diffuse through the lipid bilayer?

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

35

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

Small aqueous pores between endothelial cells in capillaries

36

What molecules can’t diffuse through the lipid bilayer?

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

37

In what direction do all molecules move?

Down their concentration gradient

38

What does how easily molecules diffuse through pores depend on?

Size and charge of molecule

39

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

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

40

What do leaky pores allow?

More molecules to move in and out of the capillary lumen

41

What does rate of diffusion depend on?

Area, diffusion ‘resistance’, and concentration gradient

42

What does a larger area available for exchange result in?

A faster rate of diffusion

43

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

Capillary density

44

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

It will have more capillaries (a higher capillary density)

45

What does diffusion resistance pertain to?

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

46

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

Is it hydrophilic or lipophilic

47

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

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

48

What does a greater path length lead to?

A slower rate of diffusion

49

What is the rate of diffusion proportional to?

The square of the distance it needs to travel

50

What does the path length depend on?

Capillary density

51

Where is path length shortest?

The most active tissues

52

What is normally the rate limiting factor of diffusion?

Concentration gradient

53

What does a greater concentration gradient lead to?

Greater rate of diffusion

54

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

Between the capillary blood and the tissues

55

What must happen to the concentration gradients for exchange to continue

The gradient between capillary blood and tissues must be maintained

56

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

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

57

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

It falls in the blood

58

What does the extent of oxygen concentration decrease depend on?

Rate of use by tissue 
Rate of blood flow through capillary bed

59

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

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

60

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

The lower the capillary concentration

61

What must the rate of blood flow do?

Be high enough to maintain a sufficient concentration gradient for diffusion

62

What does the rate of blood flow determine?

The concentration gradient driving oxygen or nutrient diffusion into cells

63

What must blood flow match?

The tissues metabolic needs

64

What is the result of a higher rate of metabolism?

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

65

What is the rate of blood flow known as?

Perfusion rate

66

What is the perfusion rate of the brain?

Needs constant high flow 
0.5ml per min per gram

67

What is the perfusion rate of heart muscle?

0.9ml per min per gram at rest 
3.6ml per min per gram during exercise

68

What is the perfusion rate of kidneys?

Need high, constant flow 
3.5ml per min per gram

69

Give two places where blood flow varies?

Skeletal muscle 
Gut

70

When is skeletal muscle blood flow high?

During exercise

71

When is gut blood flow high?

After a meal

72

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

5 litres per min

73

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

24.5 litres per min

74

What must the cardiovascular system do?

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

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

2 to 4 secs

76

What happens once the heart stops beating for a minute?

Neurones start to die

77

What are the components of the cardiovascular system?

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

78

What acts as the flow control in the cardiovascular system?

Arterioles
Pre-capillary sphincters

79

What do pre-capillary sphincters and specialised arterioles have?

Lots of smooth muscle cells

80

How do pre-capillary sphincters and arterioles control flow?

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

81

What would happen if there was no flow control?

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

82

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

The brain is harder to perfuse, due to gravity

83

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

Resistance

84

What is meant by adding resistance to the system?

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

85

What are the resistance vessels?

Arterioles

86

Why are the arterioles the resistance vessels?

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

87

What is the heart made up of?

Two pumps in series

88

What does the left heart do?

Pumps blood around the systemic circulation

89

What does the right heart do?

Pumps blood around the pulmonary circulation

90

What does the heart pump to in the systemic circulation?

Arteries via the aorta

91

What do the arteries supply?

Arterioles

92

What do arterioles supply?

Capillaries

93

What do capillaries produce?

A branching network

94

What does the capillaries branching network provide?

A large surface area for diffusion

95

What do capillaries drain into?

Venules

96

What do venules drain into?

Veins

97

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

Change

98

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

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

99

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

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

100

What provides the temporary store of blood?

The capacitance of veins

101

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

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

In what direction does blood flow?

From high to low pressure

103

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

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

What causes the highest drop in blood pressure?

Arterioles

105

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

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

106

What is the distribution of blood in the body?

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


5% in capillaries


17% in heart and lungs


67% in veins

107

Why can the distribution of blood in the body vary?

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