Module 2 - Monitoring the Heart

Question 1

Why monitor the heart?

Answer 1

• Heart disease and vascular disease are the biggest causes of death in the UK and other western countries.
• Many risk factors associated with Coronary Heart Disease (CHD) so monitoring is one way of determining the effect and implications of these risk factors on an individual.

Question 2

Stroke volume:

Answer 2

• The volume of blood pumped out of the left ventricle during the cardiac cycle.
• Approx 60-80 cm^3.

Question 3

Heart rate:

Answer 3

• The number of beats per minute (bpm).

- Average at rest = 72 bpm.

Question 4

Cardiac output:

Answer 4

• The volume of blood pumped out of the left ventricle each minute.
• Approx 4-8 dm^3 min^-1.
• Cardiac output = stroke volume x heart rate

Question 5

Measuring heart rate…

Answer 5

-Heart rate can be easily measured by taking a pulse - count the number of pulses felt in an artery in one minute.

Question 6

What is a pulse?

Answer 6

• Pulse is an expansion of the artery wall.
• As blood is forced into the main arteries with each ventricular systole, the artery wall stretches.
• Then when the blood pressure in the ventricle drops during diastole there is elastic recoil in the artery wall.

Question 7

Radial pulse:

Answer 7

-radial pulse is felt on the wrist, just under the thumb.

Question 8

Carotid pulse:

Answer 8

-carotid artery is a branch of the aorta which carries blood to the brain.

Question 9

Effect of exercise on cardiac output: Heart rate…

Answer 9

• skeletal muscles require more energy.
• so there is an increase in demand for oxygen and glucose by skeletal muscles.
• due to increased aerobic respiration.
• which results in an increased heart rate.

Question 10

Effect of exercise on cardiac output: Stroke volume…

Answer 10

• Exercise increases venous blood flow to the heart, which causes an increase in heart rate.
• The volume of blood in the heart also increases, resulting in extra stretching of the left ventricular wall.
• This results in a stronger contraction and hence stroke volume.

Question 11

Effect of training on cardiac output:

Answer 11

• Aim of training is to increase the cardiac output of the trained person without increasing heart rate.
• If heart rate is the same and the cardiac output is higher, the stroke volume must therefore have increased.
• Increased ventricular wall stretching and stronger contractions cause the muscle in the left ventricle wall to increase in thickness.
• So at rest, the stroke volume is higher in a trained athlete than one untrained hence it takes less beats per minute to deliver the same cardiac output.