Arteries, Arterioles, Veins, Venules, & Capillaries

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Arteries, Arterioles, Veins, Venules,
Capillaries
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Arteries

• Large hose-like vessels
• Carry blood away from the heart.
• Have thick, multi-layered muscular walls.
• Walls are capable of stretching to accommodate
  the pulse of blood when the heart beats.

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Arteries

• Capable of expanding and contracting to change
  and maintain the blood pressure.
• NO valves
• Blood spurts
• Blood inside them is high in oxygen low in
  carbon dioxide except in pulmonary artery.

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Arteries

• Blood inside is bright red
• Blood inside is under High pressure
• Examples
• Coronary (heart),
• Brachial (arms),
• Carotid (head),
• Femoral (legs),
• Renal (kidney).

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Arterioles

• Tiny branches off of the arteries.
• Cannot be seen with unaided eye - microscopic
• Thinner, less muscular walls (compared to
  arteries)
• Feed blood into the capillaries.
• Narrower than arteries, but wider than
  capillaries.

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Capillaries

• Flow and pressure of blood is controlled by
  sphincters that are outside of the capillaries.
• Microscopic vessels 8 µm in diameter.
• Erythrocytes (rbcs) pass through in single file.
• Walls are only one cell thick (to facilitate
  diffusion of materials/exchange).

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Capillaries

• Thinness allows for easy diffusion outward or
  inward through the single cell layer.
• Form capillary beds - networks of vessels linking
  arterial and venous blood.

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Capillaries

• Oxygen , nutrients and other materials move out
  of the capillaries and into the extra-cellular
  fluid and then into cells.
• Carbon dioxide, wastes and other materials are
  picked up and move into the capillaries (both
  involve diffusion for the movement).

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Venules

• Vessels larger than capillaries but smaller (i.e.
  narrower and thinner walls) than veins.

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Veins

• Larger inside diameter compared to arteries
• Take blood towards the heart
• Thinner, less muscular walls than arteries, but
  still 3 layers
• No stretching or contracting of walls except by
  external muscles.
• Contain valves to help return the blood to the
  heart (compensate for lower venous pressure, less
  muscle in walls, and large diameter).

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Veins - Valves
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Veins

• Blood
• Moves smoothly.
• Low in oxygen except pulmonary circulation.
• Dull red.
• Low pressure.
• Examples cardiac (heart), brachial (arms),
  jugular (head), femoral (legs), renal (kidney).

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Varicose Veins (copy this)

• When the valves dont function properly, blood
  leaks backwards and pools in veins
• Veins sag, stretch and swell, creating bulging
  knarled vessels

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The END!!