Osmoregulation: The body can control water content of the blood using the kidney
Special cells in the hypothalamus of the brain detect the amount of water in the blood and they can then cause the pituitary gland to release a hormone called ADH.
What does ADH stand for? Anti-diuretic hormone
ADH travels to the kidney making the collecting duct walls more permeable therefore more water can be absorbed back into the blood.
Which part of the kidney does osmoregulation occur? Nephron
A runner is training hard on a hot day. Suggest how this could affect his urine. (5 marks)
He is losing water through sweat (1) and respiration in the lungs (1). This is detected by the hypothalamus in the brain (1) which stimulates the pituitary gland (1) sending more ADH to the kidneys (1). The ADH will make the collecting ducts in the nephron more permeable (1) so more water is reabsorbed into the blood making his urine more concentrated (1).
Name the fluid that travels from the kidneys to the bladder: Urine
Describe the function of the bladder: stores urine and empties it into the urethra
How is urea produced?
Urea is formed by deamination in the liver, removing the nitrogen containing part of excess amino acids to form urea.
Two waste substances that are removed from the blood by dialysis: urea/creatinine/uric acid/ammonia... (nitrogen, hormones)
One advantage and disadvantage of kidney transplant: Adv: there's no need to return to clinics for dialysis/patients can eat normally Dis: there's a risk of rejection/infection/death
Define active transport (2 marks)
The movement of ions/large molecules through the cell membrane using energy from respiration.
Explain how a dialysis machine filters blood (4 marks)
Minerals/salts/ions/urea is moved by diffusion (1) from high concentration to low concentration/down a concentration gradient (1) water moves by osmosis (1) glucose is not removed/same concentration (1) fresh dialysate maintains a concentration gradient (1).
Describe the function of the nephron:
Filtration of blood and glucose, reabsorption of water and ions, and secretion of urea
What is mutation?
A change in the DNA sequence of an organism. Mutation can be caused by mistakes during cell division.