Blood Vessels

Question 1

What are the features and their functions of an artery

Answer 1

• arteries carry blood away from the heart to the tissues of the body
• arteries contain a large proportion of elastic fibres, small amount of smooth muscle and medium amount of collagen
• elastic fibres allow the artery to withstand the force of the blood being pumped out of the heart and stretch
• collagen functions to maintain shape of the artery and prevent the elastic fibres from over stretching

Question 2

What are the features and their functions of an arteriole

Answer 2

• Arterioles also contain collagen, elastin and smooth muscle
• however they have a lot more smooth muscle than elastin compared to an artery
• this means they can contract and relax to allow vasoconstriction and vasodilation

Question 3

How are capillaries adapted for their role

Answer 3

• they provide a large surface area for diffusion of substances into and out of the blood
• the cross sectional area of a capillary is always larger than the arteriole supplying them so the rate of blood flow falls this gives more time for diffusion between blood and tissues
• walls are single endothelial cell thick, thin layer for diffusion

Question 4

What are the features of veins

Answer 4

• they have lots of collagen and relatively little elastin
• wide lumen
• smooth thin lining of endothelium cells

Question 5

What are the 3 ways veins manage to get blood back to the heart

Answer 5

• they have one way valves, these are infoldings that prevent blood from going backwards by closing and opening when blood flows towards the heart
• big veins in active muscle like arms and legs, muscular contractions squeezes blood towards the heart
• when you breath your chest acts as a pump, pressure changes and the squeezing action moves blood in the chest and abdomen to the heart

Question 6

How does the structure of the large vein related to its function

Answer 6

• thin walls as there is little pressure compared to arterial system,
• large lumen due to high volume of blood
• smooth muscle contracts and relaxes to change pressure of blood
• contain collagen and little elastin so there is a limit to blood flow
• wide lumen and smooth endothelial lining allow easy blood flow

Question 7

What is the role of capillaries and how are they adapted to their role

Answer 7

• they link arterioles to venules
• they are 1 cell in diameter
• substances pass through the gaps between the endothelial cells in the capillary into the cells
• they provide a large surface area for the diffusion of substances in and out of blood
• the total cross sectional area of the capillaries is greater than the arteriole supplying them so the rate of blood flow falls, this slow rate allows more time for diffusion
• walls are single cell thick, thin for diffusion

Question 8

What are the features and functions of veins

Answer 8

• thin walls due to low pressure and large Lumen too carry lots of blood
• smooth muscle for vaso constriction and dilation
• contain collagen but with very little elastin which limits amount of blood
• wide lumen and smooth walls to allow efficient blood flow

Question 9

What are the features and their function of venules

Answer 9

• venules have very little structure
• thin walls and little amount of smooth muscle to allow blood to flow into veins
• venules have no valves to control blood flow