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11 Cards in this Set
- Front
- Back
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Explain why many animals have a heart and circulation (mass transport to overcome limitations of diffusion in meeting the requirements of organisms). |
Small animals have large SA:V ratios, and can therefore survive by diffusion of CO2 and O2. Large animals have low SA:V ratios, and therefore need circulatory systems to circulate substances within the body. Fick's Law: (Surface Area x Concentration Gradient) ÷ (Diffusion distance) |
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Explain the importance of water as a solvent in transport, including its dipole nature. |
> Water is a polar molecule: - Liquid at normal temperatures; can "sheath" polar and ionic compounds, causing them to dissolve and aiding in transport, e.g. in blood. - Adhesive and cohesive. > High specific heat capacity, e.g. blood resists temperature change. > High specific latent heat, e.g. lots of energy can be lost in sweat. > Change in density with temperature, e.g. ice floats in the arctic. |
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Explain how the structures of blood vessels (capillaries, arteries and veins) relate to their functions. |
- Arteries carry blood away from the heart. High pressure so walls are thick; muscle tissue and elastic fibres; narrow lumen. - Veins carry blood under low pressure to the heart. Wide lumen; less muscle and elastic tissue than an artery. - Capillaries walls one cell thick; small lumen (10μm); designed for the exchange of chemicals through the walls by diffusion. |
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Describe the cardiac cycle (atrial systole, ventricular systole and diastole). |
- Atrial systole: Atria contract, forcing bicuspid and tricuspid valves open, sending blood into ventricles. - Ventricular systole: Ventricles contract, forcing bicuspid and tricuspid valves shut, and semilunar valves open, sending blood into the aorta and pulmonary artery. - Diastole - Blood drawn into atria by low pressure; all valves shut and blood begins to leak into the ventricles. |
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Relate the structure and operation of the mammalian heart to its function, including the major blood vessels. |
- Atria have this walls, as they only need to generate a low contractile force. - Ventricle walls are thicker, hence they can generate a bigger contractile force. The left side is the thicker of the two, as it needs to send blood a greater distance. - Valves prevent backflow. - Coronary arteries supply blood to the heart. |
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Explain the course of events that leads to atherosclerosis. |
Artery wall damaged --> Cholesterol accumulates --> Inflammatory response --> White blood cells enter wall --> White blood cells engulf cholesterol and become foam cells --> Atheroma formed --> Ca2+ salts and fibrous tissues accumulate --> Hard plaque forms --> Wall elasticity reduced --> Artery narrows --> Rising blood pressure --> Positive feedback --> Atherosclerosis |
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Describe the blood clotting process |
Artery wall damaged --> Collagen exposed --> Platelets contact damaged wall -->Platelets become "sticky" --> Platelet plug forms --> Thromboplastin released --> (Prothrombin > Thrombin, Fibrinogen > Fibrin) --> Tangled mesh formed --> Red blood cells trapped --> Blood clot formed |
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Analyse and interpret qualitative data on illness and mortality rates to determine health risks. |
Correlation - When an increase/decrease in one variable is accompanies by an increase/decrease in another. Causation - When a change in one variable is responsible for a change in another. |
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Explain why people's perceptions of risks are often different from the actual risks. |
- People tend to overestimate risks if something is involuntary, unnatural,unfamiliar, dreaded, unfair or very. - Sometimes, if the risk is far intothe future - e.g. a heart attack - one will underestimate the chance of it happening. |
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Evaluate design of studies used to determine health risk factors. |
Cohort studies - A group of people are followed over time to see who develops the disease. Case-control studies - A group of people who have the disease are compared with a group of people who do not have the disease (their histories are observed). A good study should have a clear aim, a representative sample and valid and reliable results. |
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Describe the factors that increase the risk of CVD |
Hypertension - Increased likelihood of break in artery wall; atherosclerosis. Obesity - High cholesterol, and high blood pressure. Diet - High sat fat, LDLs, atherosclerosis, salt, hypertension. Smoking - CO and nicotine leads to hypertension, other chemicals damage the artery wall. Genetics - e.g. Familial Hypercholesterolaemia. Alcohol - Damage to liver, brain, heart, arteries. Ethanol --> Ethanal in the liver, producing VLDLs. |
