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CHAPTER 1 : TRANSPORT
1.2 The Concept of Circulatory System
LEARNING OUTCOME
•Describe the structure of human blood vessels
STRUCTURE OF HUMAN BLOOD VESSELS
• Tubes that transport blood from one part to another in the human body
3 types of human blood vessels
•Transport blood away from the
heart
•Connect arterioles to
venules
• Transport blood to the heart.
ARTERIES• Carry blood away from the
heart• Branch into smaller vessels
arterioles capillaries• To transport blood quickly &
at high pressure to the tissues.
• Arteries walls consist of epithelial tissue, smooth muscle & connective tissue
• The muscle tissue enables the artery to constrict & dilate.
CAPILLARIES• The sites for the exchange
of nutrients, respiratory gases & waste products.
• Thin-walled blood vessels which allow rapid gaseous exchange to occur, only one-cell thick.
• Capillaries venules veins
VEINS• Transport blood back to
the heart• Consist of epithelial
tissue surrounded by smooth muscle (thinner than arteries) & connective tissue
• Blood flows under low pressure
• Have large lumens & valves that maintain the one-way flow of blood
Differences between arteries, capillaries & veins
Arteries Capillaries Veins
Transport blood away from the heart
Connect arterioles to venules
Transport blood to the heart
Transport oxygenated blood
(except the pulmonary artery)
Act as the sites for exchange of
substances with the cells
Transport deoxygenated blood
(except the pulmonary vein)
Thick muscular wall Thinnest wall, one cell in thickness
Thinner wall
No valves except semi-lunar valves at the base of the aorta & pulmonary artery
No valves Valves present to prevent back flow of
blood
Blood flows in pulse under high pressure
No pulses; pressure lower than arteries
but higher than veins
No pulses; blood flows under lower
pressure than arteries