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14 Cards in this Set
- Front
- Back
The cardiac cycle is controlled by the sinoatrial node (SAN) and the atrioventricular node (AVN). Describe how. (5 marks)
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1. SAN initiates heartbeat / acts as a pacemaker /myogenic;
2. (SAN) sends wave of electrical activity / impulses (across atria) causing atrial contraction; 3. AVN delays (electrical activity / impulses); 4. (Allowing) atria to empty before ventricles contract / ventricles to fill before they contract; 5. (AVN) sends wave of electrical activity / impulses down Bundle of His / Purkyne fibres; 6. (Causing) ventricles to contract (from base up) / ventricular systole; |
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What is atheroma and how may it cause myocardial infarction? (5 marks)
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1. Cholesterol / plaque / lipoprotein / LDL / fatty material / cells;
2. In artery wall / under lining / endothelium of artery / blood vessel; 3. Atheroma linked to blood clot / thrombosis; 4. (Blocks) coronary artery / artery supplying heart muscle / tissue / cells; 5. Reduces oxygen / glucose supply (to heart muscle / tissues / cells); 6. (Heart muscle / tissue / cells) unable to respire / dies; |
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Many different substances enter and leave a cell by crossing its cell surface membrane. Describe how substances can cross a cell surface membrane. (5 marks)
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1. (Simple / facilitated) diffusion from high to low concentration / down concentration gradient;
2. Small / non-polar / lipid-soluble molecules pass via phospholipids / bilayer; OR Large / polar / water-soluble molecules go through proteins; 3. Water moves by osmosis / from high water potential to low water potential / from less to more negative water potential; 4. Active transport is movement from low to high concentration / against concentration gradient; 5. Active transport / facilitated diffusion involves proteins / carriers; 6. Active transport requires energy / ATP; 7. Ref. to Na+ / glucose co-transport; |
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Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them. (5 marks)
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1. Many alveoli / alveoli walls folded provide a large surface area;
2. Many capillaries provide a large surface area; 3. (So) fast diffusion; 4. Alveoli or capillary walls / epithelium / lining are thin / short distance between alveoli and blood; 5. Flattened / squamous epithelium; 6. (So) short diffusion distance / pathway; 7. (So) fast diffusion; 8. Ventilation / circulation; 9. Maintains a diffusion / concentration gradient; 10. (So) fast diffusion; |
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Pulmonary tuberculosis is a disease of the lungs. Describe the transmission and course of infection of pulmonary tuberculosis. (5 marks)
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1. (Bacteria transmitted in) droplets / aerosol;
2. (Bacteria) engulfed / ingested by phagocytes / macrophages; 3. (Bacteria) encased in named structure e.g. wall / tubercle / granuloma / nodule; 4. (Bacteria) are dormant / not active / not replicating; 5. If immunosuppressed, bacteria activate / replicate / released; 6. Bacteria destroy alveoli / capillary / epithelial cells; 7. (Leads to) fibrosis / scar tissue / cavities /calcification; 8. (Damage) leads to less diffusion /less surface area / increases diffusion distance; 9. (Activation / damage allows bacteria) to enter blood / spreads (to other organs); |
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Emphysema is another disease of the lungs. People with emphysema may feel weak and tired. Explain why. (5 marks)
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1. Alveoli break down / collapse / rupture / walls thicken;
2. Less surface area / increases diffusion distance / less diffusion; 3. Loss of elastin / elastic tissue / elastase involved; 4. (Alveoli / lungs) cannot recoil / spring back / have reduced elasticity / more difficult to expel air; 5. Reduced diffusion gradient / air not replenished / less air leaves lungs; 6. Less oxygen enters blood / tissues; 7. Less respiration / less energy released / less ATP produced; |
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Different cells in the body have different functions. Some white blood cells are phagocytic. Describe how these phagocytic white blood cells destroy bacteria. (5 marks)
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1. Phagocyte attracted to bacteria by chemicals / recognise antigens on bacteria as foreign;
2. Engulf/ingest bacteria; 3. Bacteria in vacuole / vesicle; 4. Lysosome fuses with / empties enzymes into vacuole; 5. Bacteria digested / hydrolysed; |
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The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how. (5 marks)
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1. Microvilli;
2. Large/increased surface area; 3. Many mitochondria; 4. (Mitochondria/respiration) produce ATP / release or provide energy (for active transport); 5. Carrier proteins for active transport; 6. Channel / carrier proteins for facilitated diffusion; 7. Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose; 8. Membrane-bound enzymes digest disaccharides / produce glucose |
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Vaccines protect people against disease. Explain how. (5 marks)
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1. Vaccines contain antigens / antigens are injected;
2. Dead pathogens / weakened pathogens; 3. Memory cells made; 4. On second exposure memory cells produce antibodies / become active / recognise pathogens; 5. Rapidly produce antibodies / produces more antibodies; 6. Antibodies destroy pathogens; 7. Herd effect / fewer people to pass on disease; |
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Oral rehydration solutions (ORS) are used to treat diarrhoeal disease. What does an ORS consist of and how does it work? (5 marks)
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1. Contains glucose/starch/ carbohydrate / sugar;
2. Sodium/salt; 3. Co-transport / symport; 4. Sodium and glucose taken up (from lumen); 5. Lowers water potential in cells/ increases water potential gradient; 6. Water taken up by osmosis; |
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The heart controls and coordinates the regular contraction of the atria and ventricles. Describe how. (5 marks)
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1. SAN initiates heartbeat / acts as a pacemaker /myogenic;
2. (SAN) sends wave of electrical activity / impulses (across atria) causing atrial contraction; 3. AVN delays (electrical activity / impulses); 4. (Allowing) atria to empty before ventricles contract / ventricles to fill before they contract; 5. (AVN) sends wave of electrical activity / impulses down Bundle of His / Purkyne fibres; 6. (Causing) ventricles to contract (from base up) / ventricular systole; |
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The diet of a person can increase the risk of coronary heart disease. Explain how. (5 marks)
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1. Too much saturated fat/ cholesterol in diet;
2. Increase in LDL/ cholesterol in blood; 3. Atheroma/ fatty deposits/ plaques in artery walls; 4. Reduces diameter of / blocks coronary arteries; 5. Less oxygen/ glucose to heart muscle /tissue/ cells; 6. Increase in blood pressure; 7. (Increased risk of )clot / thrombosis / embolism/ aneurysm; |
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Some substances can cross the cell-surface membrane of a cell by simple diffusion through phospholipid bilayer. Describe other ways by which substances cross this membrane. (5 marks)
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By osmosis (no mark)
1. From a high water potential to a low water potential/down a water potential gradient; 2. Through aquaporins/water channels; By facilitated diffusion (no mark) 1. Channel/carrier protein; 2. Down concentration gradient; By active transport (no mark) 3. Carrier protein/protein pumps; 4. Against concentration gradient; 5. Using ATP/energy (from respiration); By phagocytosis/endocytosis (no mark) 8. Engulfing by cell surface membrane to form vesicle/vacuole; By exocytosis/role of Golgi vesicles (no mark) 9. Fusion of vesicle with cell surface membrane; |
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Atheroma formation increases a person's risk of dying. Explain how. (5 marks)
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1. Atheroma is fatty material/cholesterol/foam cells/plaque/calcium deposits/LDL;
2. In wall of artery; 3. (Higher risk of) aneurysm/described; 4. (Higher risk of) thrombus formation/blood clot; 5. Blocks coronary artery; 6. Less oxygen/glucose to heart muscle/cells/tissue; 7. Reduces/prevents respiration; 8. Causing myocardial infarction/heart attack; 9. Blocks artery to brain; 10. Causes stroke/stroke described; |