Structure and function of blood vessels

Question 1

Function of arteries

Answer 1

Arteries are blood vessels that transport blood away from the heart, usually at high pressure

Question 2

Function of arterioles

Answer 2

-Arterioles are narrower branches of arteries that transports blood to capillaries

Question 3

Function of veins

Answer 3

-Veins are blood vessels that transports blood towards the heart, usually at a low pressure

Question 4

Function of capillaries

Answer 4

-Capillaries are microscopic blood vessels that transport blood to cells

Question 5

Endothelium

Answer 5

-Endothelium is a layer that is once cell thick and lines the lumen of all blood vessels

Question 6

Structure of arteries

Answer 6

-Arteries have a narrow lumen which maintains high blood pressure
-Arteries have a smooth endothelium, which reduces friction for free blood flow
-Arteries have a highly folded endothelium, which expands under high blood pressure
-Arteries have a thick layer of smooth muscle, this gives the artery strength, helping it to withstand high blood pressure
-This smooth muscle layer also enables constriction of the lumen, which is important for controlled blood flow
-Elastic tissure helps to maintain high blood pressure (enables stretch and recoil which enables pulse)
-Arteries have an outer layer of collagen (strong protein that protects the blood vessels)

Question 7

Structure of veins

Answer 7

-Veins have low blood pressure as they receive blood from the capillaries
-Veins have a thin smooth muscle and elastic layer
-Veins have no pulse
-Veins have a wider lumen than arteries, which enables blood to flow at the correct speed
-The wider lumen also reduces friction between the blood and the endothelium which helps to maintain free blood flow
-Veins have valves; these prevent backflow of blood

Question 8

Structure of capillaries

Answer 8

-Capillaries have very thin walls (once cell thick); this shortens the diffusion distance which allows substances to diffuse from the blood to the tissues and vice versa
-A network of capillaries forms a capillary bed which is a very important exchange surface within the circulatory system
-A large network of capillaries increases the speed of diffusion by shortening the diffusion distance
-Capillaries have a very narrow lumen; this means that red blood cells can only pass through capillaries in single-file - this slows down the movement of blood, providing more time for diffusion to occur
-Capillaries also have gaps in their walls called pores; white blood cells can squeeze out of these pores to combat infection at affected tissues