The structure of Arteries, Veins and Capillaries

How does blood flow through the body?

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

What happens to blood pressure as it moves away from the heart?

It decreases

Where do arteries carry blood?

away from the heart

What is the structure of an artery?

They have an outer layer of connective tissue containing elastic fibres and a middle layer containing smith muscle with more elastic fibres

What happens to arteries as the heart contracts?

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

What happens when arteries contract and relax?

The smooth muscle can contract causing vasoconstriction or relax causing vasodilation to control blood flow

Where do veins carry blood?

back to the heart

What is the structure of veins?

That have an outer layer of connective tissue containing elastic fibres but a mush thinner muscular wall than arteries.

What do valves do?

prevent back flow of blood

What do capillaries do?

Allow exchange of substances with tissues through their thin walls

What is pressure filtration?

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

What is tissue fluid?

The fluid that surrounds cells in tissues.

What is the difference between plasma and tissue fluid?

plasma contains proteins

What does tissue fluid supply cells with?

Glucose

What diffuses out of the cell and into the tissue fluid to be excreted?

Carbon dioxide and other metabolic wastes

What happens to the tissue fluid?

Most of it returns to the blood

What happens to the tissue fluid that doesn't return to the blood?

It's now referred to as lymph. It is absorbed into the lymphatic system via thin walled lymphatic vessels and returned to blood capillaries by osmosis