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| 8000475152 | Body temperature | 37 C - temperature at which enzymes work best | 0 | |
| 8000475153 | How is body temperature controlled | By the thermoregulatory centre in hypothalamus in the brain. It contains receptors sensitive to the temperature of the blood. | 1 | |
| 8000475154 | The skin and the thermoregulatory centre | Contains temperature receptors and sends nerve impulses to the centre. The receptors are very sensitive detecting temperature differences of as small as 0.5 C | 2 | |
| 8000475155 | Vasodilation | The blood vessels that supply the surface skin capillaries dilate allowing more blood to flow through the capillaries. The skin flushes, so you transfer energy by radiation from the skin to the surroundings, cooling the body down | 3 | |
| 8000475156 | Cooling the body down | You produce more sweat from the sweat glands in the skin. The extra sweat cools the body down as water evaporates from the skin, transferring energy to the environment | 4 | |
| 8000475157 | Why is it harder to stay cool in humid weather | The water in sweat doesn't evaporate | 5 | |
| 8000475158 | When you lose more water through sweating you have to... | Take in more water and mineral ions through food and drink to balance the loss | 6 | |
| 8000475159 | Vasoconstriction | The blood vessels supplying the skin capillaries constrict, reducing blood flow through the capillaries. This reduces energy transfer by radiation through the skin surface | 7 | |
| 8000475160 | Sweat production when keeping warm | Reduced or stopped so less water from sweat evaporates so less energy is transferred to the environment | 8 | |
| 8000475161 | Skeletal muscles | Contract and relax rapidly, causing you to shiver. These muscle contractions needs lots of respiration, an exothermic process. The energy transferred from these exothermic reactions raises the body temp until shivering stops | 9 | |
| 8000475162 | Removing waste products | They can cause major problems for the body if their levels build up. The main poisonous ones are carbon dioxide and urea. Products of chemical reactions | 10 | |
| 8000475163 | Carbon dioxide | Produced during respiration and must be removed as dissolved CO2 produces an acidic solution affecting the enzymes in the cells. It diffuses out of the cells into the blood, then it diffuses into the alveoli in the lungs to be lost through exhalation | 11 | |
| 8000475164 | Urea | Urea is filtered out of your blood by the kidneys then passes out of the urine. Sweat | 12 | |
| 8000475165 | Water | Leaves the lungs through exhalation, through sweat and by the kidneys | 13 | |
| 8000475166 | Mineral ions | Sweat and excess mineral ions in the urine | 14 | |
| 8000475167 | Why is the loss of water and mineral ions carefully balanced | To maintain the water and mineral ion content of the blood as cells wont function properly if they lose or gain too much watee | 15 | |
| 8000475168 | No control | Sweat and exhalation | 16 | |
| 8000475169 | Control | Kidneys | 17 | |
| 8000475170 | Kidneys | Remove toxic urea from the blood in the urine along with excess water and mineral ions not needed by the body. | 18 | |
| 8000475171 | kidney function | Important for homeostasis - water balance of the body - and excretion | 19 | |
| 8000475172 | Nephron filter | Each kidney contains millions of nephrons and it is responsible for filtering the blood | 20 | |
| 8000475173 | ultrafiltration | Blood from the renal artery enters the glomerulus. Water, urea, salts and glucose are forced into the Bowman's capsule. Blood cells and large proteins can't pass through the partially permeable membrane as they are large and insoluble | 21 | |
| 8000475174 | Selective reabsorption | In the first coiled tube, 2/3 of the salts, water and all of the glucose move out of the nephron by active transport and are reabsorbed into the blood capillaries | 22 | |
| 8000475175 | Loop of Henle | section of the nephron tubule that conserves water and minimizes the volume of urine. | 23 | |
| 8000475176 | Collecting duct | Remaining substances move through the second coiled tubule into the collecting duct and the permeability of this part of the nephron to water is controlled by ADH | 24 | |
| 8000475177 | How is the water balance of the blood maintained | By the hormone ADH which changes the amount of water reabsorbed by the kidney tubules | 25 | |
| 8000475178 | If the water concentration is too low | Receptors detect the blood is too concentrated with solutes so the PG releases more ADH into the blood. This causes the tubules to reabsorb more water. This results in a small volume of concentrated urine and the concentration of the blood returns to normal | 26 | |
| 8000475179 | If water concentration is too high | If solute concentration is too dilute, less ADH is released into the blood. Less water is reabsorbed in the kidney tubules so a large volume of dilute urine is produced and the blood water conc. is back to normal | 27 | |
| 8000475180 | Exercise a lot, drink little | More water loss in sweat, little in urine | 28 | |
| 8000475181 | Kidney failure | when kidneys can no longer cleanse the blood and maintain homeostasis, which can damage the cells by osmosis. Toxins build up in the blood like urea and excess mineral ions | 29 | |
| 8000475182 | Dialysis | The function of the kidney is carried out artificially and restores concentrations of the dissolved substances to normal levels. The blood leaves the body and flows between partially permeable membranes. On the other side of these membranes is dialysis fluid which carries the waste products away | 30 | |
| 8000475183 | Dialysis and glucose | Dialysis fluid contains the same conc. of glucose as the blood of a person without kidney disease, ensuring that there is no net movement of glucose out of the blood | 31 | |
| 8000475184 | Dialysis and mineral ions | Contains normal plasma levels of mineral ions so any excess ions are removed out of the blood by diffusion. The excess moves out of the blood into the dialysis fluid by diffusion down a conc. gradient so the blood plasma conc. of mineral ions at normal levels | 32 | |
| 8000475185 | Dialysis and urea | Contains no urea creating a steep conc. gradient from the blood down to the fluid by diffusion so most of the urea leaves the blood as it relies on diffusion, not active transport | 33 | |
| 8000475186 | Kidney transplants | A healthy kidney from a donor replaces the function of the diseased or damaged kidney. | 34 | |
| 8000475187 | Rejection | The antigens on the donor kidney is different to those of the recipient. There is a risk that the antibodies of the immune system of the recipient will attack the antigens on the donor organ | 35 | |
| 8000475188 | Prevent rejection | The tissue types of the donors are matched as closely as possible because of the antigens | 36 | |
| 8000475189 | Immunosuppressants | Suppresses their immune system to prevent the rejection of the organ. Leaves them susceptible to other infections or diseases. For life | 37 | |
| 8000475190 | Disadvantages of dialysis | Strict diet due to salts and proteins in food. Regular long sessions attached to machine. Feel tired and unwell between sessions as toxins build up. Balance of substances become difficult to maintain over many years causing damage to the body | 38 | |
| 8000475191 | Advantages of dialysis | More readily available. Relatively normal life. | 39 | |
| 8000475192 | Advantages of transplant | Free from restrictions of diet and sessions. Travel. More of a normal life. Lasts for years | 40 | |
| 8000475193 | Disadvantages of transplant | Risk of rejection. Immunosuppressants can lead to illnesses and infectious diseases. Too high of a demand and too little kidneys | 41 |
