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3 blood vessels-arteries, veins and capillaries (Functions of the 3 blood…
3 blood vessels-arteries, veins and capillaries
Functions of the 3 blood vessels
Veins
Carry blood under low or negative pressure
Have thin walls - have less muscular tissue than arteries
Always carry deoxygenated blood, except for the pulmonary vein
Have less connective tissue than arteries
Always carry blood to the heart
Have a wide lumen
Capillaries
While the arteries and arterioles act to transport these products to the capillaries, it is at the level of capillaries where the exchange takes place.
The capillaries also function to receive carbon dioxide and waste products that are then delivered to the kidneys and liver (for wastes) and the lungs (for exhalation of carbon dioxide).
The capillaries are responsible for facilitating the transport and exchange of gasses, fluids, and nutrients in the body.
Arteries
Carry blood under high pressure
Have thick muscular and elastic walls to pump and accommodate blood
Carry oxygenated blood, except for the pulmonary artery
A type of supporting tissue called connective tissue provides strength
Always carry blood away from the heart
The channel in the blood vessel that carries blood - the lumen - is narrow
Name of the 3 blood vessel
Veins
Capillaries
Arteries
Relationship between the structure and functions of the 3 blood vessels
Veins
They have a very wide lumen (keeps pressure low and allows greater flow of blood)
The walls of tissue surrounding the vein are thin (blood is not travelling in rhythmic pulses)
Veins carry blood under low pressure (<10 mm Hg)
They have valves to prevent blood pooling at extremities (arteries do not have valves)
Capillaries
Their wall is made up a a single layer of cells to allow for ease of diffusion
Blood pressure in the capillaries is relatively low (~15 mm Hg) and they have a very small diameter (~5 micrometers wide)
Capillaries are involved with material and gas exchange with the surrounding body tissue
Capillaries may contain pores to aid the transport of material
Arteries
They have a narrower lumen (to maintain high pressure) surround by a thick wall made of two layers
The middle layer (tunica media) contains muscle and elastin to help maintain pulse flow (it can contract and stretch)
Arteries carry blood at high pressure (80 - 120 mm Hg)
The outer layer (tunica adventitia) contains collagen prevents the artery rupturing due to the high pressure blood flow