Unit 6.2 - Circulatory system

Question 1

Explain the structure of the vein

Answer 1

Large central lumen, carries blood at a low pressure, thin muscle wall layer, low levels of elastin, endothelial layer, contains valves to ensure there isn’t backflow.

Question 4

Explain the structure of the artery

Answer 4

Small lumen, carries blood at a high pressure, thick muscle wall, high amounts of elastin to be able to withhold large amounts of stress induced by the heart cycle, endothelial layer.

Question 4

Explain the structure of capillaries

Answer 4

One cell thick vessel that carries blood at a low pressure to ensure material exchange, complete basement membrane.

Question 5

Explain how heart rate is controlled?

Answer 5

SAN (sinoatrial node) in the right atrium acts as a pacemaker by sending electrical impulses, which cause myogenic contraction in the myocytes, this impulse travels to AVN, then down bundle of his and purkinje fibres to cause ventricular contraction. Epinephrine and norepinephrine can either increase or decrease the heart rate, which is apart of the fight or flight respone. Medulla oblongata also controls heart rate through