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A Level PE > 1.1 cardiovascular system > Flashcards

1.1 cardiovascular system Flashcards

1
Q

Describe the cardiac conduction system

A
  1. heart is myogenic it generates its own impulse
  2. impulse begins in the SAN
  3. impulse spreads through the heart in a wave of excitation
  4. from the SAN the electrical impulse spreads through the walls of the atria, causing them to contract
  5. impulse passes through the AVN, the AVN delays the transmission for 0.1 seconds (so atria fully contract)
  6. impulse passed down through the bundle of His (located in the septum) and spreads down the purkinje fibres that spread through the walls of the ventricles, causing them to contract
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2
Q

Define systole

A

when the heart contracts

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3
Q

Define myogenic

A

the capacity of the heart to generate its own impulses

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4
Q

Define diastole

A

when the heart relaxes and fills with blood

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5
Q

What is the sympathetic system?

A

a part of the autonomic nervous system that speeds up heart rate

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6
Q

What is the parasympathetic system?

A

a part of the autonomic nervous system that decreases heart rate

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7
Q

What is the medulla oblongata?

A

the most important part of the brain as it regulates processes that keeps us alive e.g. breathing and heart rate

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8
Q

What are chemoreceptors?

A

tiny structures in the carotid arteries and aortic arch that detect changes in blood acidity caused by and increase or decrease in carbon dioxide concentration

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9
Q

Where are chemoreceptors found?

A

carotid arteries and aortic arch

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10
Q

What happens if there is an increase in carbon dioxide concentration in the blood?

A

the chemoreceptors will detect an increase in blood acidity and will stimulate the sympathetic nervous system which will increase heart rate

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11
Q

What are baroreceptors?

A

special sensors in tissues in the aortic arch, carotid sinus, heart and pulmonary vessels that respond to changes in blood pressure to either increase or decrease heart rate

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12
Q

How do baroreceptors work?

A
  • nerve endings that respond to stretching of the arterial wall caused by changes in blood pressure
  • establish a set point for blood pressure
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13
Q

What happens if there is an increase in blood pressure?

A

baroreceptors detect the decrease in blood pressure above a set point results in a decrease of heart rate through parasympathetic system

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14
Q

What happens if there is a decrease in blood pressure?

A

decrease in stretch in the stretch of the baroreceptors and results in an increase in heart rate

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15
Q

What are proprioceptors?

A

sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement

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16
Q

What happens to the baroreceptor blood pressure set point before exercise?

A

increases so enough oxygen is still delivered to the working muscles

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17
Q

What happens if there is an increase in muscle movement?

A

proprioceptors detect increase in muscle movement, they send an impulse to the medulla, which sends an impulse through the sympathetic nervous system to the SAN to increase heart rate

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18
Q

What’s adrenaline?

A

a stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in HR

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19
Q

What node does adrenaline stiumlate?

A

sinoatrial node

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20
Q

How does adrenaline increase cardiac output?

A

stimulates SAN which results in an increase in the speed and force of contraction if the heart

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21
Q

What is stroke volume?

A

the volume of the blood pumped out by the heart ventricles in each contraction

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22
Q

What 3 factors does stroke volume depend on?

A
  • venous return: the volume of blood returning to the heart in the veins (increased venous return=increased stroke volume)
  • contractility of the cardiac tissue: the greater contractility, the greater the force of contraction= increase in stroke volume
  • elasticity of the cardiac fibres: greater stretch, the greater force of contraction and ejection fraction
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23
Q

Define the ejection fraction

A

the percentage of blood pumped out by the left ventricle per beat

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24
Q

What is starling’s law?

A

increased venous return —> greater diastolic filling of heart —> cardiac muscle stretched —> more force of contraction —> increased ejection fraction

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25
Q

How do you determine ejection fraction?

A

stroke volume/end diastolic volume (volume of blood in ventricles at rest

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26
Q

What is bradycardia?

A

a decrease in resting heart rate to below 60bpm

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27
Q

What is cardiac output?

A

the volume of blood pumped out by the heart ventricles per minute

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28
Q

Define cardiac hypertrophy

A

the thickening of the muscular wall of the heart so it becomes bigger and stronger; also can mean a larger ventricular cavity

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29
Q

How do you determine cardiac output?

A

stroke volume x heart rate

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30
Q

What is an average stroke volume?

A

70ml

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31
Q

What is an average heart rate?

A

72bpm

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32
Q

How do you determine max heart rate?

A

220- age

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33
Q

Define anticipatory rise

A

an increase in heart rate prior to exercise, due to the release of adrenaline

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34
Q

What are the effects of cardiac hypertrophy

A
  • increased stroke volume

- resting heart rate will decrease (bradycardia)

35
Q

What is the effect of exercise on stroke volume?

A

it will increase as exercise intensity increases up to 40-60% max effort
after this, stroke volume plateaus because the increased HR results in shorter diastolic phases

36
Q

What is atherosclerosis?

A

Atherosclerosis occurs when arteries harden and narrow as they become clogged up by fatty deposits(atheroma)

37
Q

What are the causes of atherosclerosis?

A
  • high blood pressure
  • high levels of cholesterol
  • lack of exercise
  • smoking
38
Q

How does a heart attack occur?

A

Heart attacks can occur when a piece of fatty deposit (atheroma) breaks off to cause a blood clot which results in a blockage that can cut off the supply of oxygenated blood to the heart

39
Q

What is angina?

A

Angina is the pain and discomfort that occurs as a result of the coronary arteries narrowing because they are unable to deliver enough oxygen to the heart

40
Q

What are the benefits of exercise in terms of heart disease?

A

Benefits of regular exercise for reducing risk of heart attacks:

  • helps to keep the heart in shape
  • cardiac muscle bigger and stronger so increased stroke volume
  • maintains the flexibility of blood vessels which ensures good blood flow
  • low cholesterol levels
  • normal blood pressure
41
Q

What is blood pressure?

A

Blood pressure is the force exerted by the blood against the blood vessel walls

42
Q

What are the effects of high blood pressure?

A

High blood pressure puts extra strain on the arteries and the heart. If left untreated high blood pressure increases risk of heart attack, kidney disease, heart failure, stroke or dementia

43
Q

What is the effect of regular exercise on blood pressure?

A

Regular exercise can reduce blood pressure by:

Reducing the risk of heart attack by up to 20% because exercise lowers systolic and diastolic pressure by up to 5-10mmHg

44
Q

What are the two types of cholesterol?

A

Low density lipoproteins (LDLs)

High density lipoproteins (HDLs)

45
Q

What do LDLs do?

A

LDLs transport cholesterol in the blood to the tissues and are considered ‘bad’ cholesterol because they increase the risk of heart disease

46
Q

What do HDLs do?

A

HDLs transport cholesterol in the blood to the liver where it is broken down. Classed as ‘good’ cholesterol

47
Q

What is the effect of exercise on cholesterol levels?

A

Regular exercise increases HDLs and lowers LDL levels

48
Q

What is a stroke?

A

A stroke occurs when the blood supply to the brain is cut off

49
Q

Define disability

A

physical, sensory or mental impairment which adversely affects performacne

50
Q

What are the 2 main types of stroke?

A

2 main types of stroke:

  • Ischaemic (most common) when a blood clot stops blood supply
  • Haemorrhagic occurs when a weakened blood vessel supplying the brain bursts
51
Q

What is the effect of exercise on strokes?

A

Regular exercise can help lower your blood pressure and help you maintain a healthy weight which can reduce the risk of a stroke by 27%

52
Q

What is cardiovascular drift?

A

a progressive decrease in stroke volume and arterial blood pressure, together with a progressive rise in heart rate. this occurs during prolonged exercise (after 10 mins) in a warm environment and intensity of exercise remaining the same

53
Q

Why does cardiovascular drift occur?

A
  • some of plasma volume is lost as sweat which reduces venous return and stroke volume
  • HR increases to compensate and maintain higher cardiac output in order to create more energy to cool the body down
54
Q

How can cardiovascular drift be minimised?

A

maintain high fluid consumption before and during exercise

55
Q

What are the 2 types of circulation?

A

1) Pulmonary- deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart
2) Systemic- oxygenated blood from the heart round the body and deoxygenated blood back to heart

56
Q

Define systolic pressure

A

the pressure in the arteries when the ventricles are contracting

57
Q

Define diastolic pressure

A

the pressure in the arteries when the ventricles are relaxing

58
Q

Define venous return

A

the return of the blood to the right side of the heart via the vena cava

59
Q

What are the 3 mechanisms to aid venous return?

A
  • pocket valves: to prevent backflow of blood
  • respiratory pump: when muscles contract and relax during breathing in and out, pressure changes occur in the thoracic and abdominal cavities which compress the nearby veins and assist blood return to the heart
  • skeletal muscle pump: when muscles contract and relax they change shape which presses on the nearby veins and causes a pumping effect to squeeze blood back to the heart
60
Q

What 3 other factors aid venous return?

A

1) gravity- helps return blood from the upper body
2) smooth muscle in the walls of veins- helps squeeze blood back to heart
3) suction pump action of the heart

61
Q

What is the effect of blood pressure on venous return?

A

when systolic pressure is increased there is an increase in venous return
when systolic pressure decreases there is a decrease in venous return

62
Q

How many oxygen molecules can haemoglobin take up when fully saturated?

A

4

63
Q

Define plasma

A

the fluid part of the blood (mainly water) that surrounds blood cells and transports them

64
Q

What is formed when oxygen combines with haemoglobin?

A

oxyhaemoglobin

65
Q

Define haemoglobin

A

an iron-containing pigment found in red blood cells, which combines with oxygen to form oxyhaemoglobin

66
Q

Define myoglobin

A

often called ‘muscle haemoglobin’ it’s an iron-containing muscle pigment in slow-twitch muscle fibres which has a higher affinity for oxygen than haemoglobin. it stores the oxygen in the muscle fibres which can be used quickly when exercise begins

67
Q

When does haemoglobin become fully saturated with oxygen?

A

when the partial pressure of oxygen is high in the blood e.g. in the alveoli

68
Q

What is oxyhaemoglobin dissociation?

A

the release of oxygen from oxyhaemoglobin to the tissues

69
Q

What is Bohr shift?

A

when an increase in blood carbon dioxide and a decrease in blood pH results in a reduction in the affinity of haemoglobin for oxygen. results in a shift to the right of the oxyhaemoglobin dissociation curve

70
Q

What are the 3 factors responsible for the increase in dissociation of oxygen from oxyhaemoglobin?

A
  • increase in blood temperature: means oxygen dissociates more easily
  • partial pressure of carbon dioxide increases: oxygen will dissociate faster
  • pH: lower pH results in faster dissociation
71
Q

Define vascular shunt mechanism

A

the redistribution of cardiac output

72
Q

Why should sports performers not eat less than an hour before competition?

A

blood would be directed to the stomach instead of the working muscles so less oxygen available for performance

73
Q

Why does blood flow to the brain remain constant?

A

ensure brain function is maintained as the brain needs oxygen for energy

74
Q

Where is the vasomotor centre located?

A

medulla oblongata

75
Q

Why does blood need to go to the skin during exercise?

A

energy is needed to cool the body down

76
Q

What does the vasomotor centre control?

A

blood pressure and blood flow

77
Q

Define vasodilation

A

the widening of the blood vessels to increase the flow of blood into the capillaries

78
Q

Define vasoconstriction

A

the narrowing of the blood vessels to reduce blood flow into the capillaries

79
Q

During exercise where does vasoconstriction and vasodilation occur?

A

vasodilation will occur at the arterioles supplying the working muscles with blood
vasoconstriction will occur at the arterioles supplying the non-essential organs e.g. intestines or liver

80
Q

What is the role of the chemoreceptors in vascular shunting?

A

detect chemical changes during exercise (increase in CO2 and lactic acid) and they stimulate the vasomotor centre in the medulla oblongata which redistributes blood through vasoconstriction or vasodilation

81
Q

What happens when sympathetic nerve stimulation increases in vascular shunting?

A

vasoconstriction occurs and blood flow is reduced

opposite for decrease in sympathetic nerve stimulation decreasing

82
Q

What are pre-capillary sphincters?

A

tiny rings of muscle located at the opening of capillaries. when they contract, blood flow is restricted, when they relax blood flow is increased

83
Q

Why is redistribution important?

A
  • increase supply of oxygen to working muscles
  • remove waste products from the muscles e.g. CO2 and lactic acid
  • ensure more blood goes to the skin during exercise to regulate body temperature and get rid of heat through radiation, evaporation and sweating
  • direct more blood to the heart as it requires extra oxygen during exercise
84
Q

Define arterio-venous difference

A

the difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles

A Level PE (31 decks)

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