Veins, Arteries And Capillaries

Question 1

Pressure

Answer 1

Pressure decreasing ->

Arteries - arterioles - capillaries - venues - veins

Question 2

Why does pressure decrease?

Answer 2

The pressure of the blood decreases as it moves further away from the heart.
This is because capillaries are permeable - water and small substances lost from the blood.
And because there is resistance to flow (friction) between blood and the walls of the blood vessels.
For this reason, the walls of the lumen - made up of endothelial tissue - are smooth.

Question 3

Artery (and arterioles) structure

Answer 3

• colleges fibres
• lumen
• endothelium
• smooth muscles + elastic tissue
• 0.1 - 10 mm

Question 4

Capillary structure

Answer 4

• basement membrane (collagen)
• endothelium cell
• lumen (blood)
• red blood cell
• 8 micrometer

Question 5

Vein structure

Answer 5

• collagen and connective tissue
• thin layer of smooth muscle
• endothelium
• semilunar valve
• lumen
• 0.1 - 20mm

Question 6

Arteries and arterioles

Answer 6

• function is to carry blood away from the heart to the tissues
• thick walls with elastic layers to resist Hugh pressure and smooth muscle layer
• small lumen
• no valves (expect in heart)
• blood at high pressure
• blood usually oxygen (except in pulmonary circulation)

Question 7

Capillaries

Answer 7

• function is to allow exchange of materials between blood and the tissues
• very thin permeable walls, only one cell thick to allow efficient exchange of materials
• very small lumen, blood must distort to pass through
• no valves
• blood pressure falls in capillaries
• blood changes from oxygenated to deoxygenated ( except in pulmonary circulation)

Question 8

Veins and venules

Answer 8

• function is to carry blood away from tissues to heart
• thin walls, mainly collagen, since blood at low pressure
• large lumen to reduce resistance to flow
• many valves to prevent backflow
• blood at low pressure
• blood usually deoxygenated (except in pulmonary circulation)

Question 9

Elastic recoil

Answer 9

• this where the high pressure blood leaving the ventricles enters the arteries; because of the elastic tissue in their walls they stretch and then recoil
• because the pressure in the arteries now exceeds that in the ventricles the semilunar valves in the arteries close and blood pressure is maintained as the blood continues to move away from the heart