Blood Vessels in the
Cardiovascular System
Cause the heart can’t do it alone!
Recap!
• Cardiovascular system → Responsible for transporting gases and
nutrients throughout the body
• Composed of
• Heart
• Blood Vessels
• Blood
Blood Vessels
• Three Types
1. Arteries, which transports blood away from the heart
2. Veins, which transports blood to the heart
3. Capillaries, where exchange of gases and nutrients take place
Colour and label the diagram of blood vessels below
Red: Oxygenated blood, Blue: Deoxygenated blood, Purple: Gas Exchange
Characteristics of Arteries
• Thick, muscular walls; able to withstand high pressure of blood
being pumped from the heart
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Usually carry oxygenated blood (except Pulmonary Artery)
Split into arterioles, which have a smaller diameter than arteries
Arterioles lead into capillaries
Blood pressure in aorta: 120 mmHg
Characteristics of Veins
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•
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Thin walls; blood pumped through veins have a low pressure
Veins have valves to prevent backflow
Usually carry deoxygenated blood (except Pulmonary Vein)
Venules receive blood from capillaries, and blood flows into veins,
Venules have smaller diameter than veins
Blood pressure in vena cava: 8 mmHg
Characteristics of Capillaries
• Extremely thin walls; allow for diffusion of gases to take place
• Extremely small diameter; only large enough for one red blood
cell to pass at a time
• Receives oxygenated blood from arterioles, sends deoxygenated
blood to venules
Diffusion
• Exchange of substances by concentration difference through a
semi-permeable membrane
• Exchange is always from high concentration to low
concentration
Did you know?!?!
• Your body has approximately 96 500 km of capillaries in your body! (That’s
¼ the distance from the Earth to the Moon, or flying Montreal – Sydney 6
times in a row!)
• The total surface area of all the capillaries in your body is between 800 and
1000 m2 (That’s the area of 2.4 basketball courts!)