Arteries and red blood cells

Describes the structure of capillaries, arteries and veins including exceptions

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  • Created by: Sal
  • Created on: 27-11-08 14:18

Blood vessels

Open cirulatory system - blood bathes tissues directly

Closed circulatory system- Stays inside vessels

Arteries-- Lumen is small for high pressure, thick wall withstands high pressure elastic tissue to stretch and recoil smooth muscle narrows the lumen limits flow.

Veins-- Veins carry blood back to the heart, exception = pulmanary vein--The lumen is relatiively large to ease the pressure of the thinner layers of collegen that do not recoil contains valves that prevent back flow.

Capillaries-- Thin walls that allow material exchange walls consist of flattened endothelial cells narrow lumen same as that of a red blood cell helps them retain oxygen presses them close to the capillary walls reducing the diffusion path to tissue.

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Red blood cells

Produced by stem cells in marrow Oxygen is absorbed into the blood by haemoglobin oxygen pressure must be high before the oxygen can be absorbed, total oxygen = 4 molecules. Difficult to absorb 1st and 4th oxygen atom, fetal haemoglobin has a greater affinity for oxygen.

Red blood cells gives up more oxygen to working muscles than tissue at rest.

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