KA 2.5 The structure and functions of arteries capillaries and veins

How does Blood circulate around the body?

Blood circulates from the heart through the arteries to the capillaries then to the veins and back to the heart.

What happens to blood pressure as Blood moves away from heart?

There is a decrease in blood pressure

What is the endothelium lining the central lumen surrounded by?

The endothelium lining the central lumen of blood vessels is surrounded by layers of tissue.

Describe arteries structure ( outer layer, middle layer)?

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

Why do the elastic walls in the arteries stretch and recoil?

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

How do the smooth muscle surrounding arteries control Blood flow?

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

How do capillaries allow exchange of substances?

Capillaries allow exchange of substances with tissues through their thin walls.

What are veins strcture compared to arteries and what do they contain to prevent blackflow of blood?

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 backflow of blood.

What does pressure filtration cause ?

Pressure filtration causes plasma to pass through capillary walls into the tissue fluid surrounding the cells.

What does tissue fluid supply the cells with? (1)

Tissue fluid supplies cells with glucose, oxygen and other substances.

What happens to carbon dioxide and other metabolic wastes in the cells? (2)

Carbon dioxide and other metabolic wastes diffuse out of the cells and into the tissue fluid to be excreted.

Where does much of the tissue fluid return to? (3)

Much of the tissue fluid returns to the blood.

What do lymphatic vessels do to excess tissue fluid? (4)

Lymphatic vessels absorb excess tissue fluid and return it as lymph to the circulatory system.

Tissue fluid and blood plasme are similar in composition with the exception of what?

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