BLOOD VESSELS

ARTERIES

○   Carry blood from the heart to the tissues
○   Usually oxygenated blood, except in the arteries which carry blood from the heart to the lungs (pulmonary
arteries)
○   Have thick muscular walls
○   Do not have valves
○   May have a pulse

ARTERIOLES

○ Smaller versions of arteries
○ Connect arteries to capillaries

CAPILLARIES

○   Tiny, thin walled blood vessels - one cell thick and smaller in diameter than the diameter of an erythrocyte
○   Allow passage of nutrients and oxygen to tissues, and wastes products from tissues
○   Found in all tissues - in close contact with all cells

VENULES

○ Smaller versions of veins
○ Connect capillaries to veins

VEINS

○   Thinner-walled than arteries
○   Ferry blood from tissues to heart
○   Usually deoxygenated blood, except in the veins which carry blood from the lungs (pulmonary veins)
○   Have valves to stop backflow of blood
○   Do not have a pulse

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