8d – The heart

Question 1

flow of blood

Answer 1

1. Superior vena cava brings deoxygenated blood from above the heart, and the inferior vena cava brings deoxygenated blood from below the body.
2. Blood then flows into the right atrium.
3. Blood then flows into the right ventricle
4. Blood then flows into the pulmonary artery, the only artery with deoxygenated blood. It then flows blood to the lungs, making the blood oxygenated.
5. Blood flows back to the heart via the pulmonary veins.
6. Blood then empties into the left atrium.
7. Blood then flows into the left ventricle.
8. Blood then flows into the aorta, and it is sent to different parts of the body.

Question 2

ventricle walls (left vs right)

Answer 2

• Wall of the left ventricle is thicker than the wall of the right ventricle as it has more muscle.
• This is because the left atrium needs more pressure to pump blood to the rest of the body, whereas right atrium only pumps blood to the lungs.

Question 3

valves

Answer 3

• Valves prevent the backflow of blood.
• Atrioventricular valves are found between the atriums and ventricles (Bicuspid on left, Tricuspid on right).
• Semi lunar valves found between the ventricles and arteries.

Question 4

stroke vol: fit vs unactive

Answer 4

Regular exercise increases strength of the muscles in the heart and ventricle size, so fitter people have bigger stroke volumes and their hearts beat slower while achieving the same cardiac output as a less fit person.

Question 5

stroke volume

Answer 5

the volume of blood pushed through the aorta per beat

Question 6

heart beat

Answer 6

number of times the heart beats per minute

Question 7

cardiac output

Answer 7

the volume of blood pushed through the aorta per minute

Cardiac output (L/min) = Stroke volume (L/beat) x Heart rate (beats/min)