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IB Biology > 6.2 The blood system > Flashcards

6.2 The blood system Flashcards

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1
Q

What is our modern understanding of circulatory system based upon?

A

The discoveries of william harvey

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2
Q

What were the beliefs of the circulatory system prior to harveys findings?

A
  • arteries and veins were separate blood networks
  • veins were though to pump natural blood
  • arteries were thought to pump heat via the lungs
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3
Q

What were the three findings Harvey proposed?

A
  • arteries and veins were part of a single connected blood network
  • arteries pumped blood from heart
  • veins returned blood to the heart
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4
Q

What is the heart?

A

A four chambered organ

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5
Q

What are the four chambers of the heart?

A

Right ventricle
Left ventricle
Right Atria
Left atria

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6
Q

What do the atria act as?

A

Resevoirs

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7
Q

How do atria act as reservoirs?

A

By which blood returning to the heart is collected via veins

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8
Q

What do the ventricles act as?

A

Pumps

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9
Q

How do the ventricles act as pumps?

A

Expelling the blood from the heart at high pressure via arteries

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10
Q

Why are there two sets of atria and ventricles?

A

As there are two distinct locations for blood transport

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11
Q

What does the left side of the heart do?

A

Pump oxygenated blood around the body

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12
Q

What does the right side of the heart do?

A

Pump deoxygenated blood to the lungs

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13
Q

What are the two types of circulation?

A

Systemic and pulmonary circulation

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14
Q

What side of the body is systemic circulation?

A

Left

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15
Q

What side of the body is pulmonary circulation?

A

Right

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16
Q

Why does the left side of the heart have a much thicker muscular wall?

A

As it must pump blood much further

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17
Q

What is the function of the arteries?

A

To convey blood at high pressure from the heart ventricles to the tissues of the body and lungs

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18
Q

What is the three structures of arteries to match their functions?

A
  • narrow lumen to maintain a high bp
  • thick wall with an outer layer of collagen to prevent artery from bursting under the high pressure
  • arterial wall has an inner layer of muscle and elastic fibres to maintain pulse flow
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19
Q

When is blood expelled from the heart?

A

Upon ventricular contraction

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20
Q

How does blood flow from the heart?

A

Through the arteries in repeated surges called pulses

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21
Q

What helps maintain the pressure in arteries?

A

Muscle and elastic fibres

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22
Q

What do the muscle fibres help to form in arteries?

A

A rigid arterial wall capable of withstanding the high bp without bursting

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23
Q

What do the elastic fibres allow the arterial wall to do?

A

Stretch and expand upon the flow of a pulse through the lumen

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24
Q

What happens when the lumen is narrowed in the arteries?

A

Pressure increases between pumps to maintain bp throughout cardiac cycle

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25
Q

When is the pressure exerted on the arterial wall returned to the blood?

A

When the artery returns to its normal size

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26
Q

What does the elastic recoil in arteries help to do?

A

Push the blood forward through the artery as well as maintain arterial pressure between pump cycles

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27
Q

What is the function of capillaries?

A

To exchange materials between the cells in tissues and blood travelling at low pressure

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28
Q

What do arteries split into?

A

Arterioles

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29
Q

What do arterioles split into?

A

Capillaries

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30
Q

What decreases as total vessel volume is increased?

A

Arterial pressure

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31
Q

What does the branching of arteries into capillaries ensure?

A

Blood is moving slowly and all cells are located near a blood supply

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32
Q

What do capillaries pool into after material exchange?

A

Venules which in turn collate into larger veins

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33
Q

What are the four key structures of capillaries?

A
  • small diameter
  • capillary wall is made of a single layer of cells
  • surrounded by a basement membrane
  • may contain pores
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34
Q

What does the fact capillaries have a small diameter allow?

A

Passage of only a single red blood cell at a time

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35
Q

Why does the capillary wall being a single layer of cell minimise?

A

Diffusion distance for permeable materials

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36
Q

What is the basement membrane surrounding capillaries permeable to?

A

Necessary materials

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37
Q

What do the pores in capillaries aid with?

A

The transport of materials between tissue fluid and blood

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38
Q

What are the three types of capillary structure?

A

Continuous
Fenestrated
Sinusoidal

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39
Q

What is a continuous capillary wall?

A

Continuous with endothelial cells held by tight junctions

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40
Q

What do the tight junctions limit?

A

Permeability of large molecules

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41
Q

When will the capillary be fenestrated?

A

In tissues specialised for absorption

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42
Q

What do sinusoidal capillaries have?

A

Open spaces between cells and may be permeable to large molecules and cells

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43
Q

How does blood flow through capillaries?

A

Very slowly and at low pressure

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44
Q

Why does blood flow through capillaries at slowly and at low pressure?

A

To maximise material exchange

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45
Q

What is the high blood pressure in arteries dissipated by?

A

The extensive branching of vessels and narrowing of the lumen

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46
Q

What does the higher hydrostatic pressure at the arteriole end of the capillary force?

A

Material from the bloodstream into the tissue fluid

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47
Q

What are examples of materials that exit the capillaries at body tissues?

A

Oxygen and nutrients

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48
Q

What does the lower hydrostatic pressure at the venule end of the capillary allow?

A

Materials from the tissue to enter the bloodstream

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49
Q

What are examples of materials that enter the capillaries at body tissues?

A

Carbon dioxide and urea

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50
Q

What is the function of veins?

A

To collect blood from the tissues and convey it at low pressure to the atria of the heart

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51
Q

WHat are the the three key structures veins have?

A
  • very wide lumen
  • thin wall with less muscle and elastic fibres
  • valves
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52
Q

Why do veins have a very wide lumen?

A

To maximise blood flow for more effective return

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53
Q

Why do veins have less muscle and elastic fibres?

A

As blood is flowing at a very low pressure

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54
Q

Why do veins have valves?

A

As pressure is low, to prevent backflow and stop blood pooling at the lowest extremities

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55
Q

Why can blood flow in veins be difficult to move against the downward force of gravity?

A

As blood is at a very low pressure

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56
Q

How do veins maintain the circulation of blood by preventing backflow?

A

Contain numerous one-way valves

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57
Q

Where do veins typically pass between?

A

Skeletal muscle groups

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58
Q

How do skeletal muscle groups facilitate venous blood flow?

A

Via periodic contractions

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59
Q

What happens when the skeletal muscles contract?

A

The squeeze the vein and cause the blood to flow from the site of compression

60
Q

In what direction do veins run to arteries?

A

Parallel

61
Q

How can an effect similar to skeletal muscle groups be caused by arteries?

A

By the rhythmic arterial bulge created by a pulse

62
Q

What blood vessels transport blood at low pressures?

A

Veins

63
Q

What blood vessels send blood at high pressure?

A

Arteries

64
Q

How many wall layers do veins and arteries have?

A

Three

65
Q

What does the left side of an image of the heart represent?

A

The right side of the heart

66
Q

What are the three overall main features of the heart structures?

A

Chambers
Heart valves
Blood vessels

67
Q

How many atria does the heart have?

A

Two

68
Q

What are the atria?

A

Smaller chambers near the top of the heart that collect blood from body and lungs

69
Q

What are ventricles?

A

Larger chambers near bottom of heart that pump blood to body and lungs

70
Q

Where are the atrioventricular valves?

A

Between atria and ventricles

71
Q

What is the atrioventricular valve on the left side?

A

Bicuspid valve

72
Q

What is the atrioventricular valve on the right side?

A

Tricuspid valve

73
Q

Where are semilunar valves found?

A

Between ventricles and arteries

74
Q

What is the semilunar valve on the left side of the heart?

A

Aortic valve

75
Q

What is the semilunar valve on the right side?

A

Pulmonary valve

76
Q

What are the four main blood vessels in the heart?

A

Vena cava
Pulmonary artery
Pulmonary vein
Aorta

77
Q

What does the vena cava do?

A

Feeds into the right atrium and returns deoxygenated blood from the body

78
Q

What does the pulmonary artery do?

A

Connects to the right ventricle and sends deoxygenated blood from the lungs

79
Q

What does the pulmonary vein do?

A

Feeds from the left atrium and returns oxygenated blood from the lungs

80
Q

What does the aorta do?

A

Extend from the left ventricle and send oxygenated blood around the body

81
Q

What word describes the contraction of the heart?

A

Myogenic

82
Q

What does myogenic mean?

A

That the signal for cardiac compression arises within the heart tissue itself

83
Q

Where does the signal for a heart beat initiate?

A

In the cardiomyocytes

84
Q

What is within the wall of the right atrium?

A

A cluster of specialised cardiomyocytes that direct the contraction of the heart

85
Q

What is the cluster of specialised cells in the right atrium called?

A

Sinoatrial node

86
Q

What does the sinoatrial node act as?

A

The primary peacemaker

87
Q

What does the sinoatrial node control?

A

The rate at which the heart beats

88
Q

How many cardiac contractions does the SA node trigger per minute?

A

60 - 100

89
Q

What happens if the SA node fails?

A

A secondary pacemaker maintains contractions at 40 - 60

90
Q

What would the interference of pacemakers lead to?

A

The irregular and uncoordinated contraction of the heart muscle

91
Q

How may normal sinus rhythm be re-established when fibrillation occurs?

A

With a controlled electrical current

92
Q

What causes the two heart sounds?

A

The delay between atrial and ventricular contractions

93
Q

What does the sinoatrial node send out?

A

An electrical impulse

94
Q

What does the electrical impulse from the SA node stimulate?

A

The contraction of the myocardium

95
Q

What does impulse directly cause the atria to do?

A

Contract and stimulare another node at the junction between the atrium and ventricle

96
Q

After the electrical impulse, what does the AV node do?

A

Sendss signals down the septum via a nerve bundle

97
Q

What causes ventricular contraction?

A

The bundle of his innervates nerve fibres in the ventricular wall

98
Q

What does the delay between atrial and ventricular contractions allow?

A

Time for the ventricles to fill with blood following atrial contractions so as to maximise blood flow

99
Q

Whilst the heart rate can be determined within the heart what else can regulate it?

A

External signals

100
Q

How can nerve signals from the brain affect heart rate?

A

It can trigger rapid changes

101
Q

How can endocrine signals affect heart rate?

A

By triggering sustained changed

102
Q

What will bp levels or Co2 conces trigger changes in?

A

Heart rates

103
Q

What is the pacemaker under autonomic control from?

A

The brain stem

104
Q

How do the two nerves connected to the medulla regulate the heart rate?

A

By speeding it up or slowing it down

105
Q

How does the sympathetic nerve increase heart rate?

A

By releasing the neurotransmitter noradrenaline

106
Q

How does the parasympathetic nerve decrease heart rate?

A

By releasing the neurotransmitter acetylcholine

107
Q

What are hormones?

A

Chemical messengers released into the bloodstream that act specifically on distant target sites

108
Q

What can heart rate undergo in order to prepare for vigorous physical activity?

A

A sustained increase to hormonal signalling

109
Q

Where is the hormone adrenaline released from?

A

Adrenal glands

110
Q

How does adrenaline affect heart rate?

A

Increases it by activating the same chemical pathways as noradrenaline

111
Q

What does the cardiac cycle describe?

A

The series of events that take place in the heart over the duration of a single heart beat

112
Q

What is the cardiac cycle comprised of?

A

Systole and diastole

113
Q

Where will blood returning to the heart flow into?

A

The atria and ventricles

114
Q

Why will blood returning to the heart flow into the atria and ventricles?

A

As the pressure in them is lower

115
Q

What happens when the ventricles are 70% full?

A

Atria will contract

116
Q

When the atria contract what happens?

A

Increasing pressure in the atria and forcing blood into ventricles

117
Q

What happens to the ventricular pressure as the ventricles contract?

A

It exceeds atrial pressure and AV valves close to prevent back flow

118
Q

What happens to pressure when both sets of heart valves close?

A

Pressure rapidly builds in the contracting ventricles

119
Q

What happens when the ventricular pressure exceeds blood pressure in the aorta?

A

The aortic valve opens and blood enters the aorta

120
Q

What happens to ventricular pressure when blood exits the ventricle and travels down the aorta?

A

It falls

121
Q

What happens when ventricular pressure drops below aortic pressure?

A

The aortic valve closes to prevent back flow

122
Q

What happens when the ventricular pressure drops below the atrial pressure?

A

The AV valve opens and blood can flow from atria to ventricle

123
Q

Why does aortic pressure stay quite high throughout the cardiac cycle?

A

As muscle and elastic fibres in the artery wall maintain bp

124
Q

What are coronary arteries?

A

The blood vessels that surround the heart and nourish the cardiac tissue to keep the heart working

125
Q

What happens if the coronary arteries become occluded?

A

The region of heart tissue nourished by the blocked artery will die and cease to function

126
Q

What is athersclerosis?

A

The hardening and narrowing of the arteries due to the deposition of cholesterol

127
Q

What do atheromas do?

A

Develop in the arteries and reduce the diameter of the lumen

128
Q

In atherosclerosis, what does the restricted blood flow do?

A

Increases pressure in the artery causing arterial wall damage

129
Q

How is damaged region due to atherosclerosis repaired?

A

With fibrous tissue which reduces the elasticity of the vessel wall

130
Q

What happens as the smooth lining of the artery is progressively degraded?

A

Lesions form called atherosclerotic plaques

131
Q

What happens if the atherosclerotic plaque ruptures?

A

Blood clotting is triggered forming a thrombus which restricts blood flow

132
Q

What happens if the thrombus is dislodged?

A

It becomes an embolus and can cause a blockage in a smaller arteriole

133
Q

What can atherosclerosis lead to?

A

Blood clots, which cause CHD when in coronary arteries

134
Q

What does the myocardial tissue require to function?

A

The oxygen and nutrients transported via the coronary arteries

135
Q

What happens if a coronary artery becomes completed blocked?

A

A heart attack will happen

136
Q

How are blockages of coronary arteries typically treated?

A

By by-pass surgery or creating a stent

137
Q

What are the risk factors for CHD ( a goddess)

A

Age
Genetics
Obesity
Diseases
Diet
Exercise
Sex
Smoking

138
Q

How does age affect CHD?

A

Blood vessels become less flexible with advancing age

139
Q

How does genetics affect CHD?

A

Having hypertension predisposes individuals to developing CHD

140
Q

How does obesity affect CHD?

A

Being overweight places additional strain on the heart

141
Q

How does diseases affect CHD?

A

Certain diseases increase the risk of CHD

142
Q

How does diet affect CHD?

A

Diets rich in saturated fats, salts and alcohol increases the risk

143
Q

How does exercise affect CHD?

A

Sedentary lifestyles increase the risk of CHD

144
Q

How does sex affect CHD?

A

Males are at a greater risk due to lower oestrogen levels

145
Q

How smoking age affect CHD?

A

Nicotine causes vasoconstriction raising blood pressure

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