4.5.3.3 Maintaining water and nitrogen balance in the body Flashcards
What is osmosis?
Osmosis is the movement of water from a
dilute solution to a concentrated solution
through a partially permeable membrane.
In what ways is water lost from the body?
● During exhalation via the lungs
● Sweating
● Urine (some reabsorbed in the kidney)
In what ways are ions lost from the body?
● Sweating
● Urine (some reabsorbed in the kidney)
How are excess amino acids excreted from the
body?
● Excess amino acids are deaminated in the liver to
form ammonia.
● Ammonia is toxic, therefore it is converted into urea
● Urea is excreted from the body via sweat and urine.
How do the kidneys maintain the balance of water
and other substances in the body? (
● Filter blood in order to remove waste
products eg. urea.
● Selectively reabsorb useful molecules eg.
glucose, water, ions
What is the full name of the hormone ADH?
Anti-diuretic hormone
Where is ADH secreted in the body?
The pituitary gland of the brain
How does ADH affect the reabsorption of water in
the kidneys?
● When the blood is too concentrated, the pituitary
gland secretes more ADH.
● ADH travels in the bloodstream to the kidney and
increases the permeability of kidney tubules to water.
● More water is reabsorbed in the kidneys, resulting in
a smaller volume of more concentrated urine.
Why is kidney failure dangerous?
When the kidneys are damaged, they may be unable
to filter the blood properly. This may lead to:
● A build-up of toxic molecules (eg. urea) in the
body.
● An uncontrolled ion and water balance and cells
being damaged as a result of osmosis.
What are the two main ways of treating kidney
failure?
● Dialysis
● Transplant
What is kidney dialysis?
Kidney dialysis is the use of a specialist machine
to carry out the function of kidneys. Dialysis fluid
contains the same concentration of glucose and
ions as healthy blood. As a result, only excess
and waste molecules are lost from the blood, and
glucose and ions remain.
