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Biology > Peak Performance - Heart And Lungs > Flashcards

Peak Performance - Heart And Lungs Flashcards

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1
Q

What type of muscle is cardiac muscle?

A

Myogenic

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2
Q

What does myogenic mean?

A

It can contract and relax without receiving signals from neurons

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3
Q

Give three factors for why people have different resting heart rates

A
  • Size of heart due to different body sizes
  • How much exercise someone does

Genetic factors

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4
Q

What happens when a person exercises their heart over a long period of time?

A
  • The heart muscle walls thicken
  • More blood is pumped each time/increased stroke volume
  • Resting heart rate is lower
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5
Q

How does a heart beat?

A
  • The SAN, located on the right atrium wall, generates an electrical impulse
  • This spreads across the left and right atria, causing them to contract at the same time
  • A band of collagen tissue prevents the impulse being passed directly from the atria to the ventricles
  • The impulse also travels to the AVN which conducts the impulse to the bundle of His
  • During this there is a delay of about 0.13 seconds
  • The bundle of His splits into right and left Purkyre fibres
  • These Purkyre fibres carry the impulse to the apex of the ventricles
  • The fibres divide into even smaller branches that penetrate the ventricular muscle
  • Ventricular muscle cells at the apex of the heart are depolarised, causing contraction
  • The impulse travels up the ventricles in a wave of contraction, pushing blood into the aorta and the pulmonary artery
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6
Q

What does SAN stand for?

A

Sinoatrial node

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7
Q

What is the sinoatrial node also known as?

A

The pacemaker

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8
Q

Why is there a delay of about 0.13 seconds when an impulse is travelling from the AVN to the ventricles?

A
  • To ensure that the atria have finished contracting

- To ensure that the ventricles have filled with blood before they contract

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9
Q

What does AVN stand for?

A

Atrioventricular node

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10
Q

How is electrical activity measured?

A

On an electrocardiogram (ECG)

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11
Q

How does an ECG work?

A
  • Electrodes are attached to a person’s chest
  • There is a change of polarisation of cardiac muscle when they contract
  • This causes a small electrical​current on the skin’s surface
  • This is what is measured
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12
Q

When might an ECG be performed?

A
  • When the patient is at rest, lying down

- In a stress test when an ECG is done before and after a period of exercise

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13
Q

What four things does an ECG trace show?

A
  • P wave - depolarisation of the atria
  • PR interval - The time taken for impulses to be conducted from the SAN to the ventricles
  • QRS complex - The contraction (depolarisation of the ventricles)
  • T wave - Repolarisation of the ventricles during diastole
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14
Q

What does an ECG not show? Why not?

A
  • Artial repolarisation

- Because it generates small signals that are hidden by the QRS complex

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15
Q

What does the P wave show?

A

Depolarisation of the atria

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16
Q

What does the PR interval show?

A

The time taken for impulses to be conducted from the SAN to the ventricles

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17
Q

What does the QRS complex show?

A
  • The contraction (depolarisation) of the ventricles

- It is the main peak of the ECG

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18
Q

What does a T wave show?

A

Repolarisation of the ventricles during diastole

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19
Q

What is the heart problem called when the heart is beating too fast? What might be causing this and what might it lead to?

A
  • Tachycardia
  • Heart can’t pump blood efficiently so heart rate increases to increase amount of blood being pumped
  • Increases risk of a heart attack
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20
Q

When might someone be described as being tachycardic?

A

When their heart rate is greater than 100 beats per minute

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21
Q

What might an ECG that shows p waves without any waves in between suggest is wrong with a person?

A
  • Atria are contracting as there are p waves
  • No QRS complex which means impulses aren’t travelling from the atria to the ventricles
  • This suggests there’s a problem with the AVN
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22
Q

What does fibrillation mean?

A

Irregular heartbeat

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23
Q

How is fibrillation shown on an ECG?

A

Irregular waves of various sizes

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24
Q

How long does a large square on an ECG represent?

A

0.2 seconds

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25
Q

How long does a small square on an ECG present?

A

0.04 seconds

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26
Q

How many squares make up 1 second on an ECG?

A
  • 5 large squares (0.2 seconds each)

- 25 small squares (0.04 seconds each)

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27
Q

What does the vertical axis on an ECG show?

A

Electrical activity

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28
Q

What is it called when a resting heart rate is lower than 60 beats per minute?

A

Bradycardia

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29
Q

What might cause bradycardia?

A
  • Hypothermia
  • Heart disease
  • Drugs - beta blockers
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30
Q

What might tachycardia be caused by?

A
  • Fear
  • Fever
  • Exercise
  • Drugs
  • Heart failure
  • Fluid loss
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31
Q

What happens in atrial fibrillation?

A
  • Abnormal electrical impulses start firing from sites in the atria
  • The SAN can no longer control the rhythm of the heart
  • Atria contracts randomly and too quickly
  • Heart muscles can’t relax properly between contractions which reduces their efficiency
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32
Q

Explain how the electrical activity of the heart ensures that the ventricles begin contracting from apex of the heart

A
  • There is a delay at the AVN
  • The impulse is then carried across the bundle of His and along the Purkyre fibres to the base
  • The impulse travels from the base up through and stimulates contract of cardiac muscle
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33
Q

What controls heart rate? Where is it located?

A
  • Cardiovascular control centre

- In the medulla oblongata region of the brain

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34
Q

What does the cardiovascular control centre detect?

A
  • CO2 levels
  • Lactate in the blood
  • Reduction in oxygen
  • Increase in temperature
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35
Q

How is heart rate increased?

A
  • Mechanical activity in muscles and joints is detected by sensory receptors in muscles
  • Impulses are sent to the cardiovascular control centre
  • An impulse is sent from the cardiovascular control centre down the sympathetic nerve to the SAN
  • SAN increases heart rate by increasing the frequency of impulses it produces
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36
Q

What does the sympathetic nerve do?

Where does it come from and where does it go to?

A
  • Increases heart rate

- From the cardiovascular control centre to the SAN

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37
Q

A runner is about to start a race. Describe what changes occur in their body when they hear the starting pistol

A
  • Skeletal muscles contract
  • Stretch receptors in the muscles and tendons are stimulated
  • They send impulses to the cardiovascular control centre
  • Impulse is sent along sympathetic nerve
  • This increases heart rate
  • Increased venous return leads to higher stroke volume
  • Increased heart rate + greater stroke volume result in a higher cardiac output
  • This means oxygen and fuel is transported to muscles faster
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38
Q

What is a negative factor when cardiac output increases? How can it be controlled?

A
  • Blood pressure increases
  • Pressure receptors in the aorta and the carotid artery send impulses back to the cardiovascular control centre
  • Impulses are then sent from the cardiovascular control centre to the SAN along the vagus nerve
  • This decreases the amount of impulses sent by the SAN
  • This is an example of negative feedback
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39
Q

What is result of sympathetic stimulation of the intercostal muscles?

A

Increases breathing rate

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40
Q

What is the effect of parasympathetic stimulation of the heart?

A

Decreases heart rate and stroke volume

41
Q

The carotid artery at the side of the neck is sometimes used for measuring heart rate.
Explain why pressing on the carotid artery might reduce pulse rate, thereby giving a false reading

A
  • Pressing on neck causes an increase in blood pressure in the carotid artery
  • Blood pressure sensors in the carotid artery signal to the cardiovascular control centre
  • This would stimulate the vagus nerve
  • This would reduce heart rate and therefore pulse rate
42
Q

Explain why the heart rate rises before the start of exercise and why this may be an advantage

A
  • Anticipatory rise due to the effect of adrenaline on the heart
  • This increases oxygen supply to muscles in preparation of activity
43
Q

Describe and explain the changes that occur in blood distribution after a person has started to exercise

A
  • Increased blood flow to active skeletal muscles
  • Reduced blood flow to non-essential organs such as digestive system
  • This means more oxygen and glucose goes to respiring muscle cells
44
Q

What is one complete heartbeat equal to?

A

One complete cardiac cycle

45
Q

What does a cardiac cycle consist of?

A
  • Atrial systole
  • Ventricular systole
  • Diastole
46
Q

What is the purpose of valves in the heart?

A

To prevent the back flow of blood

47
Q

What does an impulse consist of?

A

A wave of depolarisation followed by a wave of repolarisation

48
Q

What happens if parasympathetic stimulation is increased?

A
  • Decreases the impulse frequency of the SAN
  • Increases the delay time at the AVN
  • This reduces the frequency and the forces of the heart beat
49
Q

What happens when parasympathetic stimulation is decreased?

A

-Impulse frequency of the SAN is increased

–Decreases delay time at the AVN

-This then increases the frequency and force of a heart rate

50
Q

What is the heart rate a balance of?

A

Sympathetic and parasympathetic stimulation

51
Q

What is tidal volume?

A

The volume of air we breathe in and out in each breath

52
Q

What is vital capacity?

A

The maximum volume of air we can inhale and exhale

53
Q

How can tidal volume and vital capacity be measured?

A

Using a spirometer

54
Q

How are accurate results ensured when using a spirometer?

A

A nose-clip is worn

55
Q

What happens to heart and breathing rate once you start to exercise? Why?

A
  • Heart rate increases to supply more oxygen and glucose to the muscles and to remove CO2 being produced
  • Breathing rate increases to increase oxygen uptake and CO2 removal
56
Q

Explain the effect of adrenaline on the body

A
  • Travels in the bloodstream as it is a hormone
  • Directly stimulates the SAN which causes an increase in heart rate
  • Causes dilation of the arterioles supplying skeletal muscles
  • Causes constriction of the arterioles going to the digestive system and other organs not involved in exercising
  • Causes an anticipatory increase in heart rate
57
Q

What controls breathing rate? Where is it?

A
  • The ventilation centre

- Medulla oblongata (brain)

58
Q

How does the medulla oblongata control breathing?

A
  • The ventilation centre sends nerve impulses to the external intercostal muscles and diaphragm muscles every 2-3 seconds
  • This causes these muscles to contract, increasing the volume of the lungs
  • This causes a decrease in pressure inside the lungs
  • Air from the outside enters the lungs due to this pressure difference
  • As the lungs inflate, stretch receptors in the bronchioles are stimulated
  • These send inhibitiory impulses back to the ventilation centre which stops the impulses to the muscles which then relax
  • The elastic recoil of the lungs and decreasing volume is why the air is forced out of the lungs
59
Q

What is the remaining air in the lungs called after exhalation?

A

Residual air

60
Q

What happens to the amount of residual air in the lungs during exercise?

A

-Decreases as more air is forced out

61
Q

What is the most important stimulus affecting breathing rate?

A

pH of blood

62
Q

What is the effect of a small increase in blood CO2 concentration on ventilation?

A

Big increase in ventilation

63
Q

How does CO2 effect ventilation?

A
  • CO2 dissolves in blood plasma, forming carbonic acid
  • Carbonic acid then dissociates into H+ ions and hydrogencarbonate ions, HCO3-
  • This causes a decrease in pH
  • Chemoreceptors in the medulla oblongata detect rise in H+ ions
  • Impulses are then sent from the ventilation centre to the intercostal and diaphragm muscles to stimulate them to contract faster and harder
64
Q

How else is CO2 concentration monitored apart from by the medulla oblongata?

A
  • Chemoreceptors in the carotid artery and the aorta

- These detect change in pH and send impulses to the ventilation centre

65
Q

What is the benefit of breathing deeply in terms of CO2 and O2?

A
  • Maintains a steep concentration gradient of CO2 between the air in the alveolar air and the blood
  • This ensures efficient removal of CO2 and uptake of O2
66
Q

How does a spirometer work?

A
  • As the person breathes in and out of the spirometer, the change in air volume inside causes the floating lid to rise and fall
  • The movement of the lid is recorded as a trace on a rotating drum
  • Soda lime in the tube absorbs CO2
67
Q

What does the trace produced by a spirometer show?

A
  • Depth and frequency of breathing

- Rate of oxygen consumption

68
Q

What does a fall on the trace produced by a spirometer represent?

A

-Consumption of oxygen by the person

69
Q

Why does the total volume of gas in a spirometer decrease over time?

A
  • Air breathed out is a mixture of CO2 and O2

- CO2 absorbed by soda lime

70
Q

How would you test the effect of exercise on the breathing rate and tidal volume of a person?

A
  • Connect a person to a spirometer using a mask so that continuous readings can be recorded
  • Record readings for one minute at rest
  • Have the person exercise for two minutes
  • Record readings for a further minute after exercise
71
Q

Equation for ventilation rate

A

Volume x breathing rate = ventilation rate

72
Q

What happens when there is less CO2 in the blood?

A
  • pH rises

- Decrease in rate and depth of breathing

73
Q

What is the control of CO2 in the blood an example of?

A

Homeostasis

74
Q

What is the motor cortex?

A

The region of the brain that controls movement

75
Q

What effect does the motor cortex have on ventilation?

A
  • Impulses sent from motor cortex to the ventilation centre

- This causes a sharp increase in ventilation

76
Q

Apart from in the bronchioles, where else are stretch receptors found?

A

In tendons and muscles involved in movement

77
Q

During vigorous exercise, the concentration of O2 in the lungs is higher than when at rest. Give the reasons for, and advantage of, this elevates oxygen level

A
  • The depth and rate of breathing increases
  • This means there is a greater volume of air is inhaled which increases the amount of oxygen taken in
  • Increase in oxygen concentration creates a steeper concentration gradient between the alveolar air and the blood
  • This increases the rate of gaseous exchange
  • This increases metabolic rate
78
Q

Explain why it is beneficial that stimulation of stretch receptors in the muscles increases ventilation

A
  • Stretch receptors signal the start of movement
  • They stimulate an increase in ventilation before there is a build up of waste products eg CO2
  • This means these products are removed quicker than if the medulla oblongata noticed the change
79
Q

When a person breathes air containing 80% oxygen, the minute ventilation is reduced by 20%. Explain how is occurs

A
  • Increased oxygen levels in the blood
  • This is detected by chemoreceptors
  • This stimulates a decrease in breathing rate and depth
80
Q

What is cardiac output?

A

The volume of blood pumped by the heart in 1 minute

Cardiac output = stroke volume x heart rate

81
Q

What is stroke volume?

A

The volume of blood pumped out of the left ventricle each time the venticle contracts

82
Q

What is venous return?

A
  • Blood returning to the heart

- Increases during exercise

83
Q

Why would exercise increase stroke volume?

A
  • More blood fills heart during diastole
  • This means the heart muscle is stretched to a greater extent
  • Muscle contracts with greater force
  • More blood is expelled
84
Q

What is stroke volume measured in?

A

cm^3

85
Q

What is the average resting stroke volume for an adult?

A

Between 50-90 cm^3

86
Q

What determines how much blood is pumped out of the heart?

A
  • How much blood enters during diastole

- Force of contraction

87
Q

Which arteries are used to take a pulse?

A
  • Radial (wrist)

- Carotid (neck)

88
Q

A person has a resting stroke volume of 75 cm^3. They take their pulse rate and find that it is 70 beats per minute. Calculate their cardiac output

A

75 x 70 = 5250 cm^3 = 5.25 dm^3 min^-1

89
Q

Give the units for cardiac output

A

dm^3 min^-1

90
Q

What is the average cardiac output at rest?

A

5 dm^3 min^-1

91
Q

A patient’s stroke volume was found to be 67 cm^3 per heartbeat and her resting heart rate was 73 BPM. Calculate the patient’s cardiac output and suggest if it is within the normal range

A

67 x 73 = 4891 cm^3 min^-1 = 4.9 dm^3 min^-1

-Average cardiac output is about 5 dm^3 min^-1 so it is within the normal range

92
Q

A patient had a HR of 87 BPM. A dye was injected into blood circulation and sampled after circulation through the heart. Explain how cardiac output can be determined from the dye

A
  • Concentration of dye measures stroke volume
  • Lower the concentration of the dye in the sample, the larger the stroke volume
  • If heart rate is known then cardiac output can be calculated
93
Q

What is the cardiac output of the top end endurance athletes?

A

About 30 dm^3 min^-1

94
Q

What is aerobic capacity?

A

The ability to take in, transport and use oxygen

95
Q

What is VO2?

A

The volume of oxygen taken in per minute

96
Q

What is the average resting value of VO2?

A

0.2-0.3 litres

97
Q

What is VO2 max?

A

The maximum amount of O2 taken in per minute during aerobic exercise

98
Q

What are the units of VO2 max?

A

ml^-1 kg^-1

99
Q

What is VO2 max dependant on?

A
  • Efficiency of uptake and transfer of oxygen

- Efficient use of oxygen by muscle cells

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