Osmoregulation And Excretory System

Controls amount of water in blood and other body fluids Water has the potential to damage cells due to osmosis causing excessive movements of water Gain water by drinking and eating and cellular respiration Water lost through evaporation in lungs and sweat and through urine and faeces

The removal of metabolic waste substances from the body and the removal of toxic materials taken from the environment

The whole range of chemical reactions that occur within our cells Consists of anabolism and catabolism (build up and breakdown of substances)

Carbon dioxide - produced by cells during respiration Water - too much can dilute blood and cause cells to swell Salts - essential in certain quantities, can cause osmotic problems in large quantities Urea - poisonous - formed from the breakdown of amino acids in liver. Urea transported in the blood to the kidneys

Branch of the aorta Carries blood containing a high concentration of urea Carries nutrients and oxygen to the cells of the kidney

Carries blood to vena cava Blood has most of its urea removed and has the correct balance of salt and water

A tube that carries urine from the kidneys to the bladder to be stored

Muscular sac Can expand to store up to 400cm3 of urine for a short time

Ring of muscle which controls the release of urine from the bladder Relaxes to allow urine to pass through urethra and out of the body

Thw tube which carries the urine outside the body

3 main regions Outer cortex Inner medulla Central funnel - pelvic region Made up of millions of tubules called nephrons that filter blood and produce urine

Carey out filtration (ultrafiltration) of the blood Enters kidney through renal artery, when it reaches the cortex a lot of the liquid portion of blood and dissolved substances are filtered out into tubules Goes to medullary region useful substances are selectively reabsorbed

ADH instructs the kidneys how much water to reabsorb from the nephron during selective reabsorption ADH released into blood and travels to kidneys ADH release allows more water to be reabsorbed back into the blood by making the tubules more permeable. As a result, urine more concentrated and smaller in volume Less water - more ADH More water - less ADH

• kidneys reabsorb more water into blood • Less water passes to bladder as urine • More concentrated urine and blood concentration returns to normal

• Kidneys reabsorb less water into blood • More water passes to bladder as urine • Dilute urine and blood concentration returns to normal