Biology - Topic 7.3 - Peak Performance

Front 1

What is aerobic capacity?

Back 1

The ability to take in, transport and use oxygen

Front 2

What is VO2?

Back 2

When we are rest we consume 0.2-0.3 litres of oxygen per minute

Front 3

What is VO2(max) ?

And the units

Back 3

This is the max amount of oxygen consumed per minute during aerobic exercise.

ml min-1 kg-1

Front 4

What is VO2 max dependent on?

Back 4

The efficiency of uptake and delivery of oxygen by the lungs and cardiovascular system and the efficient use of oxygen in the muscle fibres.

So a fit person can work for longer at a higher intensity using aerobic respiration without accumulating lactate than someone who doesn't undertake regular exercise

Front 5

What is cardiac output?

Back 5

Volume of blood pumped by the heart in a minute

Front 6

When running, what is adequate oxygen supply maintained by?

Back 6

Increasing cardiac output

Faster (ventilation rate) rate of breathing - to obtain more oxygen and to get rid of more carbon dioxide

Increasing heart rate - to deliver oxygen to the muscles faster and remove extra CO2 produced by the increased rate of respiration in muscle cells

Front 7

What is cardiac output dependent on?

Back 7

The volume of blood ejected from the left ventricle (the stroke volume)

Heart rate

Front 8

What is the equation for cardiac output

Back 8

Stroke volume (SV) x Heart rate (HR)

Front 9

What is a venous return?

Back 9

When there is greater muscle action due to exercise so more blood returns to the heart.

Front 10

In diastole during exercise what happens to the heart?

Back 10

The heart fills with a larger volume of blood

The heart is stretched to a greater extent, causing it to contract with a greater force , and so more blood is expelled.

This increases stroke volume and cardiac output.

Front 11

What does it mean for the heart muscle to be myogenic?

Back 11

It means it can contract without external simulation

Front 12

How does the heart beat?

Back 12

1) Electrical impulses from the SAN (sinoatrial node) spread across the atria walls, causing contraction of both atrium. This is called atrial systole.

2) Impulses pass to the ventricles via the AVN after a short delay to allow time for the atria to finish contracting

3) Impulses pass down the Purkyne fibres to the heart apex

4) The impulses spread up through the ventricle causing contraction from the apex upwards. Blood is squeezed into the arteries. This is ventricular systole.

Front 13

Why is there a delay of the impulse between the SAN and AVN

Back 13

Because the delay ensures that the atria have finished contracting and that the ventricles have filled with blood before they contract.

Front 14

How can you measure electrical activity of the heart?

Back 14

The electrical currents caused by the spread of the electrical impulse during the cardiac cycle can be detected with an electrocardiogram (ECG).

Front 15

Explain the different peaks in ECG trace

Back 15

P wave - depolarisation of the atria, leading to atrial contraction (atrial systole)

PR interval - the time taken for impulses to be conducted from the SAN across the atria to the ventricles through the AVN

QRS complex - the wave of depolarisation resulting in contraction of the ventricles (ventricular systole)

T wave - repolarisation of the ventricles during the hearts relaxation phase (diastole)

Hint 15

Front 16

By using a ECG trace, how could you diagnose if a patient has Tachycardia - increased heart rate?

In addition what could results from the heart condition?

Back 16

The heartbeat would be too fast

This is a sign of heart failure, as the heart can't pump blood efficiently, so heart rate increases to pump blood around the body.

This can increase the chance of a heart attack

Front 17

How does the ventilation centre control the rate and depth of breathing during the exercise?

Back 17

1) It controls the rate and depth of breathing in response to impulses from chemoreceptors in the medulla and arteries which detect the pH and concentration of CO2 in the blood.

2) Impulses are sent to stimulate the muscles inclined involved in breathing.

3) A small increase in CO2 concentration causes a large increase in ventilation. It also increases in response to impulses from the motor cortex and from stretch receptors in tendons and muscles involved in movement.