how circulations works

the heart and its key elements

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  • Created by: Leigh. x
  • Created on: 17-09-12 11:25

cirulatory systems


heart pumps out blood into cavities

substances can diffuse between blood and cells

when the heart muscles relax blood is drawn back in


enclosed within tubes- higher blood pressures

narrow channels instead of large cavities

blood faster and more efficient

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Closed circ system


heart pumps deoxygenated blood to gills

gaseous exchange takes place(diffusion)- CO2 from blood to water/ O2 from water to blood

blood leaving the gills travels to the rest of the body then back to the heart.


R ventricle pumps deoxygenated blood to lungs (blood gains oxygen)

L ventricle pumps the returning oxygenated blood to the rest of the body

the heart gives the blood an extra boost reducing the time it takes to get around the body- efficient for high metabloic rate, O2 and nutrience gets to cells faster

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Arteries and viens

Thinest layer

a single layer of simple endothenlial cells

Tunica media (thickest layer)

circluarly arranged, elacstic fiber & smooth muscle

Tunica adventitia

mostly collagen

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tough and fibrous protein ( makes them strong and durable)

Elastic fiber

allows them to stretch and recoil

Smooth muscles

allow walls to constrict and dilate

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  • narrow luman
  • thicker walls
  • more collogen / elastic fiber / smooth muscles

-due to higher pressures of blood being pumped though

  • no valves
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  • wide luman
  • thinner walls
  • less collogen / less elastic fiber / less smooth muscles

- due to lower pressures of blood being pumped through

  • valves

- stop back flow due to blood travelling at a lower pressure and agaisnt gravity

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Stages of blood flow

From the heart

artery (aorta)



To the heart


vein (vena cava)

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except the pulmonary and aorta arteries (in the heart) 

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why the heart has its own blood supply

blood is suplied directly to the heart so that it always has a constant supply of oxygen and glucose for respiration.

the chambers of the heart have small volume to surface ares ratio- so diffusion rate would be to slow and not efficient

every celll needs to be close to a cappillery- for fast diffusion

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