The Kidneys:
Excretory products:
- Urea is a waste product from excess amino acids. It is produced in the liver, then transported to
the kidneys in the plasma in the blood.The kidneys are the excretory organ for urea (as well as
ions and water) and they are all removed in urine.
- Carbon dioxide is an excretory product from respiration. This is produced in cells, and is
transported back to the lungs in the plasma in the blood. The lungs are the excretory organ
responsible for removing carbon dioxide from the body.
- The skin is also an excretory organ, which removes products when we sweat, which is mainly
water but also contains some waste products such as urea. Sweat also helps cool us down when
we are hot, we sweat more which evaporates from the skin transferring heat energy away from
the body.
- Waste products from respiration and photosynthesis in plants are removed through the stomata.
THE KIDNEYS:
The kidneys are excretory organs, and part of the urinary system. They have 3 jobs: Removal of urea
(excretion), Adjustment of ion levels in blood, Adjustment of water content in blood (osmoregulation).
The kidneys work by filtering out unwanted substances,
such as urea, from the blood, and reabsorbing useful things
into the blood. Anything remaining in the kidneys, is
removed from the body in urine, including water, urea and
ions.
Nephrons are found between the medulla and
the cortex layers - there are thousands of these.
The kidneys are also responsible for controlling
the level of water in the blood - osmoregulation.
Water is gained from food and drink, and is lost
in sweat, urine and breathing. This is stimulated
by ADH (antidiuretic hormone) which is produced
in the pituitary gland in the brain and travels to
kidneys in the blood. When we have low water
levels in the blood (blood is highly concentrated)
it results in more water reabsorption from
collecting ducts in kidneys, and a smaller volume
of more concentrated urine is produced. When
we have high water levels in the blood (low
concentration of blood) less water is reabsorbed,
and a larger volume of more dilute urine is
produced.
Excretory products:
- Urea is a waste product from excess amino acids. It is produced in the liver, then transported to
the kidneys in the plasma in the blood.The kidneys are the excretory organ for urea (as well as
ions and water) and they are all removed in urine.
- Carbon dioxide is an excretory product from respiration. This is produced in cells, and is
transported back to the lungs in the plasma in the blood. The lungs are the excretory organ
responsible for removing carbon dioxide from the body.
- The skin is also an excretory organ, which removes products when we sweat, which is mainly
water but also contains some waste products such as urea. Sweat also helps cool us down when
we are hot, we sweat more which evaporates from the skin transferring heat energy away from
the body.
- Waste products from respiration and photosynthesis in plants are removed through the stomata.
THE KIDNEYS:
The kidneys are excretory organs, and part of the urinary system. They have 3 jobs: Removal of urea
(excretion), Adjustment of ion levels in blood, Adjustment of water content in blood (osmoregulation).
The kidneys work by filtering out unwanted substances,
such as urea, from the blood, and reabsorbing useful things
into the blood. Anything remaining in the kidneys, is
removed from the body in urine, including water, urea and
ions.
Nephrons are found between the medulla and
the cortex layers - there are thousands of these.
The kidneys are also responsible for controlling
the level of water in the blood - osmoregulation.
Water is gained from food and drink, and is lost
in sweat, urine and breathing. This is stimulated
by ADH (antidiuretic hormone) which is produced
in the pituitary gland in the brain and travels to
kidneys in the blood. When we have low water
levels in the blood (blood is highly concentrated)
it results in more water reabsorption from
collecting ducts in kidneys, and a smaller volume
of more concentrated urine is produced. When
we have high water levels in the blood (low
concentration of blood) less water is reabsorbed,
and a larger volume of more dilute urine is
produced.
