Understanding:
• Components of red blood cells are recycled by the liver
In humans, red blood cells possess minimal organelles and no nucleus in order to carry more haemoglobin
- Consequently, red blood cells have a short lifespan (~120 days) and must be constantly replaced
The liver is responsible for the break down of red blood cells and recycling of its components
- These components are used to make either new red blood cells or other important compounds (e.g. bile)
Understanding:
• The breakdown of erythrocytes starts with phagocytosis of red blood cells by Kupffer cells
• Iron is carried to the bone marrow to produce haemoglobin in new red blood cells
Kupffer cells are specialised phagocytes within the liver which engulf red blood cells and break them down
- Kupffer cells break down haemoglobin into globin and iron-containing heme groups
- Globin is digested by peptidases to produce amino acids (which are either recycled or metabolised by the liver)
- Heme groups are broken down into iron and bilirubin (bile pigment)
The released iron must be complexed within a protein in order to avoid oxidation to a ferric state
- Iron can be stored by the liver within a protein shell of ferritin
- Iron can be transported to the bone marrow (where new haemoglobin is produced) within the protein transferrin
Process of Erythrocyte and Haemoglobin Recycling
