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Title: The cirulatory system
Description: These are my notes from my first year of A level biology on arteries, veins and capillaries, sequence of blood flow and the difference between the right and left atriums and ventricles
Description: These are my notes from my first year of A level biology on arteries, veins and capillaries, sequence of blood flow and the difference between the right and left atriums and ventricles
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Arteries, veins and capillaries
Arteries- carry blood away from the heart
Veins- Carry blood to the heart
Capillaries- Fine networks of tiny tubes linking arteries and veins
Arteries
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Collagen fibres (outer layer)- provides strength
Thick middle layer (elastic fibres, smooth involuntary muscle)- elasticity
Endothelium
No valves
Blood leaves at a high pressure (in waves/pulses)- so they have thicker walls
Elasticity- walls of arteries stretch when blood arrives at high pressure
Energy stored as potential energy in elastic walls
Stored energy used to maintain flow until ventricles contract when pressure of blood falls
Elastic recall of arteries- pressure fluctuations of blood smoothed to give a continuous flow
Veins
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Contain valves to prevent backflow
When surrounding muscles contract and press against veins, valves force blood from one
valve to the next (return flow)
Blood is at a lower pressure
Collagen fibres (outer layer)
Thin middle layer (elastic fibres and smooth involuntary muscle)
Endothelium
Capillaries
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Branch profusely and bring blood circulation close to cells
Blood is at a lower pressure by the time blood reaches capillaries- so they have thinner walls
No collagen fibres
No middle layer (elastic fibres)
Endothelium
No valves
Right side of the heart= pumps deoxygenated blood to lungs
Left side of the heart= pumps oxygenated blood to rest of the body
Pulmonary circulation- Pathways of arteries, veins, capillaries carrying blood from heart to lungs and
back to the heart
Systematic circulation- Pathways of arteries, veins, capillaries carrying blood from the heart to all
body tissues and back to the heart
Difference in thickness of walls of right atrium and right ventricle
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Right atrium pumps blood to right ventricle
Ventricle needs to maintain high pressure that is greater than the right atrium
Atrium is thinner than the ventricle
Ventricle needs to pump blood out of the heart to the lungs at a greater pressure
Sequence of blood flow
Vena Cava, Pulmonary artery, Pulmonary vein, Aorta
Title: The cirulatory system
Description: These are my notes from my first year of A level biology on arteries, veins and capillaries, sequence of blood flow and the difference between the right and left atriums and ventricles
Description: These are my notes from my first year of A level biology on arteries, veins and capillaries, sequence of blood flow and the difference between the right and left atriums and ventricles