Structure of blood vessels

Question 1

What do the arteries do ?

Answer 1

Carry blood away from the heart to the various organs of the body.

Question 2

What do the veins do ?

Answer 2

Carry blood from the organs of the body towards the heart.

Question 3

What do the capillaries do ?

Answer 3

Connect arteries and veins.

Question 4

Name some arteries adaptations.

Answer 4

• Carry oxygenated blood to the body tissues (other than the pulmonary artery)
• Have a small lumen to maintain high blood pressure Smooth inner
• endothelial lining (a smooth surface means there’s less resistance to blood flow)
• Thick layer of smooth muscle (contract and relax to dilate and constrict blood vessels * controlling their diameter) and elastic fibres (stretch and recoil)
• Lots of collagen fibres (for strength and support)

Question 5

Name some Veins adaptation

Answer 5

Blood is flowing at a much lower pressure so veins have a large lumen and much thinner walls containing little elastic fibres or muscle tissue.

Valves prevent the slow-moving blood from flowing backwards.

Large lumen (minimises resistance to flow)

Reduced collagen fibres

Question 6

Capillaries adaptations

Answer 6

• walls are only one endothelial cell thick, meaning their walls are very thin
• Additionally bc the lumen of the capillaries are only slightly wider than a red blood cell. Red blood cells therefore travel in a single file. Causing them to move more slowly, increasing the time available for molecules to diffuse in and out of the blood.
• Small holes between the endothelial cells
  (pores) enable the exchange of substances. It also allows fluid to pass out of the (tissue fluid).

Question 7

What do we call a network of capillaries

Answer 7

Capillary bed