Page 156 - Primary Six Notes

BLOOD VESSELS

Blood vessels are muscular tubes running from the heart to

the whole blood to circulate blood.

Types of blood vessels.

There are basically three types of blood vessels namely

1. arteries,

2. veins

3. capillaries.

1. Arteries.

 Arteries are mainly blood vessels that carry blood away

from the heart.

 They have thick walls and narrow blood passage or lumen.

 They lack valves.

 Blood in arteries flows at a high pressure.

 Most arteries carry oxygenated blood apart from pulmonary

artery.

2. Veins

 These are blood vessels that carry blood towards the heart.

 they have valves, wider lumen and thin walls.

 Valves in veins open in one direction to prevent back ward

flow of blood.

 Blood in veins flows at a low pressure.