excretion in humans T13

• Kidneys regulate levels of ions water and waste products in the blood stream
• The main role of the kidney is to filter the blood and remove the waste we don’t want
• The main waste product is urea
• Urea is made in the liver during the process of deamination (where excess amino acids that we don’t need anymore are converted to fats and carbohydrates for storage)
• Urea is produced by the liver from amino acids that are not needed anymore
• The kidneys other role is to regulate the levels of ions and water
• We get ions like sodium and potassium ions from our diet.
• If levels of ions get too high or too low it can begin to damage our cells and cause problems
• Ions are lost naturally through sweating and kidneys
• Water gained from our diet.

  Water lost through sweat and our lungs when we breathe. Mainly lost through are kidney in the form of urine
• Water regulation is important because our cells lose or gain water through osmosis depending on the amount of water stored in  the body. An excess of water in our body can lead to cells swelling and possibly bursting. A deficiency of water in our body can lead to cells shrinking.
• As blood passes through the kidneys the tubules absorb anything small (water, glucose, amino acids, urea) and NOT large things (cells and proteins) which is called filtration process
• The kidney tubules reabsorb the things we want (reabsorb all glucose, some water, no urea) this process is called selective reabsorption.
• The main roles of the kidney is removing waste product (urea) from blood, regulate the level of ions and to regulate the amount of water in the blood.
• Blood constantly cycles into the kidney, in trough the renal arteries and out through the renal veins. 

  From the blood the kidney produces urine which passes down the ureters and stored in the bladder. Urinated out through the urethra. 
•    The tubule in the kidney carries the filtered fluid that becomes urine.
• Filtration where some of the liquid part of the blood is forced from the glomerulus (tangle of blood vessels) into the Bowmans capsule (start of the tubule).
• Only very small substances can be filtered through  to the Bowmans capsule (water, amino acids, urea, glucose and ions).
• Fluid passes through the tubule absorbing only what they want back into the blood vessels (reabsorb almost all glucose and amino acids and only some water and ions and none of the urea)  this process is called selective reabsorption which happens throughout the entire nephron (the tubules and blood vessels)
• Fluid passed through the collecting duct is classed as urine.
• If too little water is taken in or if too much is lost through sweating or diarrhoea, dehydration occurs. Dehydration causes an increase in concentration of solutes in the blood plasma.
• Kidney failure results in waste substances build up in the blood stream, unable to regulate water and ion levels making the person become sick and is possible death.
• Treatment for sever kidney failure is dialysis or a kidney transplant (unlike mild kidney disease which can be treated with medication.
• Dialysis machines act as artificial kidneys that can filter a patients blood for them helping their blood filter.
• Dialysis fluid contains the same concentration of water and other molecules as healthy blood does. (Glucose, ions and amino acids)
• s the blood passes through the machine it loses all the waste it doesn’t want like any extra ions and amino acids and all the urea. Once it’s passed through it’s then much cleaner and can go back into the patient.
• In a kidney transplant there is a main risk that the organ will be rejected. (Transplanted organ is attacked by patients immune system) to suppress their immune system medication is prescribed however might not work.