Net movement of molecules down a concentration gradient (high to low).
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Surface area : volume ratio
Surface area of an object divided by its volume.
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Gas exchange
Where gasses are transferred across cell membranes to leave or enter the blood.
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Alveoli
Tiny air sacs in the lungs that serve as the gaseous exchange surface. They have a large surface area, thin walls and a good blood supply.
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Concentration gradient
The difference in concentration between two areas. Proportional with rate of diffusion.
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Directly proportional
If one variable increases, the other increases by the same factor. This gives a graph with a straight line through the origin.
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Inversely proportional
When two variables are directly proportional to the reciprocal of the other. y∝1/x . This gives a curved graph.
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Fick's law
Rate of diffusion ∝ □(64&(surface area × concentration difference)/(thickness of membrane))
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Artery
Type of blood vessel which carries blood away from the heart under high pressure. Walls have thick layers of smooth muscle and elastic fibres.
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Vein
Type of blood vessel which carries blood to the heart under low pressure.
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Capillaries
Thin, narrow blood vessels that connect arteries to veins. Site of exchange of substances between blood and tissues.
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Valve
Structure in the heart which prevents backflow of blood.
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Pulse
Rhythmic contraction and dilation of the arteries from the beating of the heart.
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Erythrocyte
Red blood cell that is anucleate (no nucleus) and biconcave )(. It contains haemoglobin which enables the transport of oxygen and carbon dioxide to and from tissues.
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Lymphocyte
Type of white blood cell that produces antibodies and antitoxins.
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Phagocyte
Type of white blood cell that engulfs pathogens and digests the (in phagocytosis).
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Platelet
Small fragments of cells that are involved in blood clotting.
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Plasma
Main component of blood that carried red blood cells. It is a yellow liquid that contains proteins, nutrients, mineral ions, hormones, antibodies, antitoxins, dissolved gasses and waste.
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Haemoglobin
Enables the transport of oxygen and carbon dioxide to and from tissues.
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Antibodies
Produced by lymphocytes, bind to a specific antigen.
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Heart attack
When blood supply to the heart is cut off and the heart muscle begins to die.
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Coronary artery
Artery which supplies the heart muscle with oxygen.
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Atrium
Upper cavity of the heart where blood is pumped through to the ventricle.
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Right ventricle
Lower cavity of the heart, which pumps deoxygenated blood to the lungs.
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Left ventricle
Lower cavity of the heart, which pumps oxygenated blood to the rest of the body, through the aorta.
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Pulmonary veins
Veins that carry oxygenated blood from the lungs to the heart.
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Aorta
The artery that takes oxygenated blood away from the heart to the body.
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Vena cava
Vein that returns deoxygenated blood to the heart from the body.
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Pulmonary arteries
Arteries that carry deoxygenated blood away from the heart to the lungs.
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Bicuspid valves
Valves between left atrium and left ventricle (a.k.a. Left atrioventricular valves)
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Tricuspid valves
Valves between right atrium and right ventricle (a.k.a. Right atrioventricular valves)
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Cardiac output
Volume of blood pumped out of a ventricle in one minute. CO = heart rate x stroke volume.
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Stroke volume
Volume of blood pumped out of ventricle in one heart beat. SV = CO/HR.
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Heart rate
Number of times the heart contracts in one minute.
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Respiration
Exothermic reaction that releases energy from the breakdown of glucose.
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Exothermic
Gives out energy
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Aerobic respiration
Respiration in the presence of oxygen that releases energy from the breakdown of glucose.
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Anaerobic respiration
Respiration that takes place without oxygen, producing energy from the breakdown of glucose. In animals, lactic acid is produced and in plants, ethanol and carbon dioxide are produced. Less energy released than aerobic.
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Mitochondria
Organelle which releases energy in respiration.
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Lactic acid
Produced by animal cells in anaerobic respiration. Build up of it inhibits anaerobic respiration, resulting in cramp and fatigue.