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Mammals have double circulation and a 4 chambered heart
Every 1 circuit of the body blood passes through the heart twice
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Advantages of double circulation
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Veins: Carry blood towatds the heart
Arteries: Carry blood away from the heart
Septum: Muscle wall that seperates two sides of the heart preventing the mixing of oxygenated and deoxygenated blood
Ventricles: Have a thicker muscle wall than the atria because they pump blood at higher pressure
Atria: The right and left atrium contracts to pump blood into the right and left ventricles respectively
Valves: Prevent the backflow of blood and ensure one way flow
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Coronary heart disease
Partial blockage of coronary arteries creates restricted blood flow to heart muscle cells; angina
Complete blockage leads to a heart attack; cells in the area of the heart cannot respire/ contract
Risk Factors
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Treatment
Aspirin: Dilutes blood and so reduces blood clotting
Angioplasty: Catheter threaded through the groin up the blocked vessel
Balloon inserted into catheter pushed up blocked vessel and inflated
Flattens plaque against wall of artery clearing blockage
Stent inserted to keep artery clear
Sometimes coated with drug to prevent further build up
Coronary bypass surgery: Piece of blood vessel is taken from patients lef or arm
Used to create new passage to cardiac muscle BYPASSING the blocked area
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Carry blood at low pressure towards the heart
Carry deoxygenated blood (except pulmonary veins)
Thin walls
Large lumen to reduce resistance to blood at low pressure
Have valves that prevent the back flow of blood as its under low pressure
Carry blood at low pressure
Both oxygenated and deoxygenated
One cell thick walls for easy diffusion in and out
‘Leaky’ walls allow blood plasma to leak out and forn tissue fluid surrounding cells
Connects arteries and veins
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Arterioles: Smaller branches of an artery that eventually form capillaries
Venules: Small vessels formed from the joining of the capillaries and combine to form a vein.
Shunt vessels: Connect blood directly from arterioles to venules forming an alternative route dor blood flow
Organ | Towards Organ | Awat from organ |
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Heart | Vena Cava, Pulmonary Vein | Aorta, Pulmonart Artery |
Lungs | Pulmonary artery | Pulmonary vein |
Kidney | Renal Artery | Renal Vein |
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Walls of capillaries are thin; water dissolved substances can easily leak out of them
==Plasma is forced out of the capillary to become tissue fluid==
Cells exchange materials across membranes with tissue fluid
If fluid leaked out i smore than fluid returned
Lymphatic system: Tubes which flow from tissues to heart
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==White Blood cells:==
==Multilobed nucleus and non granular cytoplasm==
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Lymphocytes: produces antibodies and antitoxins
==Large round nucleaus and clear non granular cytoplasm==
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==Plasma:== Transporting carbon dioxide, digested food, urea, hormones and heat
==Plateles====:== Blood clotting
Blood Clotting
Process
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