Excretion Flashcards
What is excretion?
The removal of metabolic waste from the body. The removal from the body of unwanted products of cell metabolism.
What is metabolic waste?
A substance that is produced in excess by the metabolic processes in the cells; it may become toxic.
What products of metabolism must excreted?
Carbon dioxide
Nitrogen containing compounds such as urea (nitrogenous waste)
Other pigments such as bile compounds in faeces
Name the excretory organs.
Lungs Liver Kidneys Skin Bladder
What do the lungs do?
The excrete carbon dioxide through gaseous exchange
What does the liver do?
It has many metabolic roles and some of the products are passed into the bile for excretion with the faeces for example the pigment bilirubin.
The liver also converts excess amino acids into urea.
How are amino acids broken down?
Through the process of deamination.
What makes up urea?
A nitrogen containing part of the amino acid and carbon dioxide.
What do the kidneys do?
Urea is passed into the bloodstream to be transported into the kidneys. Urea is then removed from the blood stream to become part of urine.
What is excreted by the skin through sweat?
Salts, urea, water, uric acid and ammonia.
Why is excretion important?
Allowing the products of metabolism to build up could be fatal. Some metabolic products such as carbon dioxide and ammonia are toxic due to the fact that they alter the pH of the bloodstream.
Name the ways that carbon dioxide can be transported throughout the body?
Hydrogencarbonate ions
Haemoglobinic acid
Carbonic acid
Carbominohaemoglobin
Where do hydrogen carbonate ions come from?
The dissociation of carbonic acid
What is the name of the enzyme that causes the dissociation of carbonic acid inside the red blood cells?
Carbonic anhydrase
What bonds with haemoglobin to form haemoglobinic acid?
Hydrogen ions from the dissociation of carbonic acid.
