Transporting substances around the body B3

Blood circulation system supplies the things need by your bodys cells, and removes the waste they produce. Double circulation- the right side pumps deoxygenated blood to the lungs, and the left side pumps oxygenated blood around the body.

The blood vessels, arteries- carry blood away from your heart to organs of your body (usually oxygenated blood, except for the pulmonary artery) and have thick walls and a small lumen, veins- carry blood towards your heart (usually deoxygenated blood, expect for the pulmonary vein) and have thin wall sand a large lumen and capillaries- narrow with thin walls so substances that are needed by cells can pass easily into the blood.

Blood plasma contains red blood cells, white blood cells and platelets. Blood plasma is a yellow liquid, which firstly transports carbon dioxide produced by organs to the lungs. Secondly transports urea (waste product formed in the liver) to the kidneys. Thirdly transports small soluble products of digestion to organs and cells which need them.

Red blood cell adaptations for efficiency in picking up oxygen,they are biconcave discs, giving them an increased surface area: volume ratio, packed full of haemoglobin, which carries oxygen and no nucleus, so more space to pack haemoglobin. Haemoglobin reacts to form oxyhaemoglobin with oxygen, and where oxygen concentration is lower, the oxyhaemoglobin reverses to form oxygen and haemoglobin again. Haemoglobin is based on iron, so if you lack iron, your body cannot make enough red blood cells and you suffer from anaemia (your pale and lack energy).

Muscle tissues made up of protein fibres which contract when they are supplied with energy from respiration, so the fibres contain many mitochondria. Muscles contain glycogen stores (can then be converted into glucose) which is used in respiration to provide energy. Glucose + Oxygen = Carbon dioxide + Water +Energy. You muscles use up some glucose at rest, because some fibres are always contracting to keep you in position against the pull of gravity.

During exercise, some changes take place, heart rate increases, and arteries supplying blood to the muscles dilate, increasing blood flow to muscles and this increases the supply of oxygen and glucose- this also increases the removal of carbon dioxide and breathing rate increases and the depth of breathing increases- increases amount of oxygen brought into the body, and more carbon dioxide is removed. Exercising results in an increased delivery rate of oxygen to the muscles.

Your muscles switch to anaerobic respirations when they become fatigued. Glucose = lactic acid + energy. The oxygen debt is the amount of oxygen needed to break down lactic acid. Lactic acid + oxygen = carbon dioxide + water.

Kidneys filter urea out of the blood, and get rid of it in the urine. Kidneys control water balance, by removing excess water through urine , and if you are short of water, your kidneys conserve it by producing little urine. Kidneys control ion concentration- some are lost through the skin, excess mineral ions are lost through the urine.

Liver produces urea. Ureter is the tube through which urine passes from the kidney to the bladder. Urethra- tube through which urine passes to the outside of your body.

Kidneys filter the blood, and take back everything useful- glucose, amino acids, mineral salts and urea all move out of the blood into the kidney tubules by diffusion. All glucose is reabsorbed back by active transport, but water and mineral ions that are reabsorbed varies- selective reabsorbtion. Sugar and mineral ions move back into the blood by diffusion and active transport to ensure that all glucose is reabsorbed, and the right amount of mineral ions is reabsorbed.

Nephrons are filtration units in the kidneys- high pressure is built so water, urea, ions and sugar are diffused into the Bowman’s capsule (proteins and blood cells are to large). The liquid flows through the nephron, and useful substances (sugar, sufficient ions and water) are reabsorbed into the blood against a concentration gradient (active transport). Remaining substances (urea, excess water and ions) continue out the nephron, into Ureter and down the bladder. Dialysis machine carries out the functions of the kidney.

Person’s blood leaves body and flow between partially permeable membranes. Other side of membranes is dialysis fluid, and the concentration of this fluid means that unwanted substances in the blood pass into the fluid (urea, excess ions and water). Dialysis fluid contains same concentration of glucose and mineral ions (so no net movement of glucose, but excess mineral ions are lost). Dialysis fluid contains no urea, so strong concentration gradient form blood to fluid.

A kidney transplant is you replace failed kidneys with a health kidney form a donor. To reduce the risk of rejection, match between donor and recipient made as close as can be, e.g. same blood group and immunosuppressant drugs are given to stop the immune system from working. Kidney Transplant Advantages, free from any restrictions- you can live a normal life. Kidney transplant disadvantages, risk of rejection, have to take medicine daily, need regular check-ups and may never get the chance of a transplant. Dialysis advantages, much more readily available. Dialysis disadvantages, have to follow carefully controlled diet and regular, long sessions hooked up to the machine.