2.5 - The Structure Of Arteries, Veins & Capillaries

Question 1

Describe the pathway of blood

Answer 1

Blood circulates from the heart through arteries to the capillaries then to the veins and back to the heart. There is a decrease in pressure as blood moves away from the heart.

Question 2

3 main types of blood vessels

Answer 2

Arteries

Capillaries

Veins

Question 3

What is the lumen

Answer 3

The central channel which blood flows through in a blood vessel is called the central lumen.

Question 4

What surrounds the central lumen

Answer 4

Endothelium lining which is a single layer of cells

Question 5

What surrounds the central lumen and endothelium lining

Answer 5

The central lumen and the endothelium lining are then surrounded by layers of tissue which differ in each type of blood vessel.

Question 6

Function of the artery

Answer 6

The function of the artery is to carry blood away from the heart at high-pressure

Question 7

What is the structure of an artery

Answer 7

Arteries have a thick outer layer of connective tissue containing elastic fibres and a middle layer of smooth muscle cell with more elastic fibres.

The narrow central lumen is surrounded by the endothelium lining.

Question 8

How do arteries accommodate the surge of blood after each contraction of the heart

Answer 8

The elastic walls of the arteries stretch and recoil to accommodate the surge of blood after each contraction of the heart

Question 9

How is bloodflow controlled in arteries

Answer 9

To control blood flow the smooth-muscle surrounding arteries can contract causing vasoconstriction or relax causing vasodilation.

Question 10

What do the arteries do during exercise

Answer 10

During exercise, arteries leading to working muscles undergo vasodilation.

The central lumen becomes wider allowing for an increased bloodflow to the muscles involved

Question 11

Function of capillaries

Answer 11

The function of capillaries is to allow the exchange of substances with tissues.

Capillaries form dense networks around body tissues and have very thin walls which allows substances to diffuse through with ease

Question 12

Veins function

Answer 12

The function of veins is to carry deoxygenated blood towards the heart at lower pressure

Question 13

Veins structure

Answer 13

The endothelium lining surrounds the wide central lumen

Veins have an outer layer of connective tissue containing elastic fibres but a much thinner muscular wall than arteries. They contain valves to prevent the back flow of blood.

Question 14

What does blood consist of

Answer 14

Red blood cells, white blood cells, plasma

Question 15

What is plasma

Answer 15

Plasma is a watery yellow liquid which transports the red and white blood cells along with: 
glucose 
oxygen 
carbon dioxide 
proteins 
fat

Question 16

What is the process of pressure filtration

Answer 16

Pressure filtration is the process by which plasma passes through the capillaries walls in the tissue fluid surrounding the cells.

Question 17

When does pressure filtration occur

Answer 17

As blood travels at high pressure in arteries towards the capillaries pressure filtration occurs

Question 18

 What does tissue fluid provide cells with

Answer 18

Tissue fluid supplies cells with glucose, oxygen and other useful substances. Carbon dioxide and other metabolic wastes diffuses out of the cells and into the tissue fluid to be excreted.

Much of the tissue fluid returns to the blood at the venous end of the capillary by osmosis.

Question 19

How is tissue fluid and blood plasma similar

Answer 19

Tissue fluid and blood plasma are similar in composition, with the exception of plasma proteins which are only found in plasma as they are too large to be filtered through the capillary walls.

Question 20

What happens to excess tissue fluid

Answer 20

Excess tissue fluid is absorbed by lymphatic vessels which return it as lymph to the circulatory system