B3- keeping internal conditions constant

controlling internal conditions

• controlling internal conditions is called homeostasis
• temp, blood glucose, water, ion content must all be controlld
• waste products needed to be removed are- co2, urea 
• too mcuh water in cells can cause them to burst and too little the inside can pull away from the membrane

human kidney

• two kidneys filter the blood
• urine is produced by;
• 1. filtering the blood
• 2. reabsorbing ions and water
• 3.releasing urea and excess ions and water
• if glucose is in urine you may have diabetes
• urine is tempory stored in bladder before removal

dialysis

• if a person suffers with kidney failure they use dialysis
• in a dialysis machine blood flows between partically permeable membranes
• dialysis process:
• 1.blood taken from arm
• 2.thinners prevent clotting
• 3.dialysis fluid removes urea
• 4.clean blood flows through bubble trap
• 5.blood returns to vein
• in the dialysis fluid there is the same concentration of useful substances as the persons blood substances dont diffuse out
• urea diffuses out of blood
• needs to be carried out a regular intervals 

kidney transplant

• kidneys can be donated or taken from someone who died or was in an accident
• they must be a good…