The heart

Question 1

What are the properties of veins?

Answer 1

They have valves to prevent backflow.
They are less stretchy, and operate at a lower pressure.
Carry deoxygenated blood.
Thinner walls.
Wider lumen.
Less collagen, elastic fibres and smooth muscle.

Question 2

What are the properties of arteries?

Answer 2

Carry oxygenated blood.
They don’t have valves, the higher pressure is enough to prevent backflow.
Narrow lumen, which expands to accommodate blood.
More collagen, smooth muscle and elastic fibres.
Thicker walls.

Question 3

What are the properties of capillaries that help with diffusion?

Answer 3

Walls only one cell thick.
High surface area to volume ratio.
Blood flow slows in capillaries.
Pores allow fluid carrying substances into tissues.

Question 4

What is atrial and ventricular diastole?

Answer 4

1. Blood flows into atria.
2. Elastic recoil of atrial walls generates low pressure in the atria.
3. This helps to draw blood from the heart.
4. As ventricles relax, blood falls back from the pulmonary artery and aorta.
5. So semilunar valves close.

Question 5

What is atrial systole?

Answer 5

1. Atria fill with blood, increasing pressure.
2. Atrioventricular valves pushed open and blood flows into ventricles.
3. Atria contract to force remaining blood into ventricles.

Question 6

What is ventricular systole?

Answer 6

1. Ventricles contract, increasing pressure.
2. This closes atrioventricular valves.
3. Semilunar valves opened, blood forced into the aorta and pulmonary artery.
4. Atria are relaxed, they begin to fill with blood from the vena cava and pulmonary vein.