Cardiac Cycle Schemes

Question 1

How can blood clot cause heart attack?

Answer 1

It prevents oxygen reaching the cardiac muscle
Prevents aerobic respiration
Cardiac muscle cells die

Question 2

There is an increase in carbon dioxide concentration in the air. What happens to heart rate?

Answer 2

It will increase
Concentration of carbon dioxide in alveoli increases
Concentration of carbon dioxide in blood increases
Chemoreceptors in carotid artery
Change in carbon dioxide detected and response via medulla and parasympathetic nerves
More impulses to SAN and excitation rate increases

Question 3

During the cardiac cycle. Changes in pressure that occur in left atrium and left ventricle are different. Explain?

Answer 3

Pressure change is smaller in atria than ventricles
Atria have less cardiac muscle
Doesn’t need to pump blood as far as ventricles
Atrial systole happens before ventricular systole
Atrial pressure increases before ventricular pressure increases

Question 4

Explain importance of heart and circulation to large animal like giraffe?

Answer 4

Small SA to vol ratio
Diffusion not sufficient for gas exchange
Circulation allows oxygen to be transported to cells
Aerobic respiration
Heart has to pump the blood at a high pressure
Double circulatory system

Question 5

Explain the process of blood clotting?

Answer 5

Platelets release thromboplastin
This catalyses conversion of prothrombin to thrombin using Ca2+
Thrombin catalyses conversion of fibrinogen to fibrin which forms the clot