Waste Disposal Flashcards
Excretion
Removing waste products made by body processes
Urea, carbon dioxide and sweat
What are excreted from the body
Urea- produced when excess amino acids are broken down by liver. Urea removed by kidneys, transferred to bladder before it is released
Sweat- contains water and salt, excreted by sweat glands onto skin surface. Evaporates and cools the skin
Carbon dioxide- produced by respiration, removed by lungs (toxic)
How is more carbon dioxide removed if there are high levels in the blood
If there are high levels of carbon dioxide in the blood, it is detected by the brain
Breathing rate increases to remove more carbon dioxide
What do kidneys do
Excrete urea, water and salt
They filter blood at high pressure to separate the small soluble molecules such as glucose,urea and water. The substances are now in the kidney tubules.
What is the amount and concentration of urine influenced by
Temperature of environment
Amount of water consumed and lost as sweat
Amount of exercise done
What are tubules (nephron)
Kidney tubules (filtering units) are found along each branch
Renal tubules in the kidneys contain millions of tiny renal tubules which are close to blood capillaries
What happens to the removed waste products in the kidney
Remaining fluid containing urea, salt and water passes from tubules out of the kidney and stored in the bladder as urine
What happens to useful molecules in the kidneys
Useful molecules such as glucose, water and fatty acids are re-absorbed back into the blood
How does the amount of urine produced vary depending on how much a person drinks and sweats
What does this maintain
Lots of water drank produces lots of pale dilute urine
Little water drank or water lost through sweating, produces small amount of concentrated urine
This maintains constant water concentration in the plasma
Describe the functions along each kidney branch
Ultrafiltration- lots of water and small molecule are squeezed out of the blood, under pressure, into tubules in the glomerulus and capsule
Selective reabsorption- useful substances reabsorb into blood from tubules
Regulation of water and salt- balance water and salt content in blood. Resulting urine passes from collecting duct to ureter, then to bladder
What controls amount of water re-absorbed by kidneys and
What does it do
What is this an example of
Anti-diuretic hormone (ADH)
Produced in pituitary gland in brain
ADH increases permeability (to water)of collecting duct and kidney tubes. It is released when water content in body is low
This is NEGATIVE FEEDBACK
With low blood water level, how does ADH regulate blood water level
This is detected by the brain and ADH released
Kidney tubules re absorb more water
Small amount of concentrated urine produced
Normal blood water level
With high blood water level, how does ADH regulate blood water level
This is detected by the brain and less ADH is released
Kidney tubules re absorb less water
Large amount of dilute urine produced
Normal blood water level
What does a Dialysis machine do
Used for patients with kidney failure
Removes urea
maintains levels of sodium and glucose in blood
How does a dialysis machine work
Blood taken from veins runs into machine
Comes in close contact with permeable membrane which separates blood from dialysis fluid
Waste diffuses from blood into dialysis fluid and sodium and glucose are replaced in the blood
