Artery, Vein & Capillary Structure

Fluid containing plasma

(with nutrients, enzymes and hormones) diffuses from the capillary pores and into the cells to allow the exchange of such materials.

Capillary have a

Small diameter - 5-20 micrometers, one endothelial cell thick.

Using the serosa they are

able to secrete serosa fluid, preventing friction with tissue and other vessels.

Arteries branch into smaller

arteries - arterioles, which can change diameter to control blood flow & pressure.

Veins Carry blood to heart via

capillaries and venules.

Vein blood is always

deoxygenated apart from the pulmonary vein which carries oxygenated blood from the lungs to the heart.

Both veins and arteries have: A middle layer

of smooth muscle and elastic fibres (thin in veins)- tunica media (middle coat)

Artery blood is always

oxygenated apart from the pulmonary artery which takes deoxygenated blood from the heart to the lungs.

Both veins and arteries have: Capability of

resuming shape after stretching/contracting using elastin (elastic tissue)

Transported substances by capillaries can include

salts, water, oxygen, carbon dioxide and waste material from cells.

Both veins and arteries have: Lumen where

the blood flows through-from an artery is more narrow than that of a vein

Veins are a long way from

the heart and have little muscle so lower in pressure, pulse cannot be heard.

Vessels closest to the heart ventricles have

the most pressure - especially the pulmonary artery, which is why a pulse can be felt.

Both veins and arteries have: A lining of

thin cells (endothelium / endothelial cells)

Veins have

thin walls, blood flows at lower pressure and they have semi-lunar valves to prevent backflow of blood during circulation (to prevent waste materials returning because of the low pressure).

Blood is supplied to

tissue by capillaries.

Capillaries are a medium

to allow transfer of substances between blood and cells.

Capillaries have high resistance

to blood flow, reducing its speed. The delay allows more efficient exchange of chemicals to tissues in the body.

Muscular layer of arteries contracts

to help the blood flow around the body.

Both veins and arteries have: An outer covering of

tough collagen fibres (thin in veins)- tunica externa (outer coat)

Arteries process

transfer of blood from heart to rest of body.