Week 1- Normal erythrocytes (biochemistry) Flashcards
What is the life span of RBCs?
120 days
Where are red blood cells destroyed?
The spleen removes fragile old RBCs from the circulation.
Describe the structure of RBC’s?
They are packed with haemoglobin
They have no nucleus or mitochondria
They have no DNA/RNA so no cell replication.
What is the process of producing RBC’s called?
Erythropoiesis
Where are red blood cells produced?
Bone marrow.
What do red blood cells arise from?
Pluripotent stem cells.
What happens to old red blood cells?
The spleen and liver engulf old red blood cells.
What occurs to the globular proteins from RBC’s when they are broken down?
They are broken down into amino acids which enter the blood stream.
What occurs to the haem group in RBC’s when they are broken down?
The haem group (minus iron) is converted to bilirubin. Bilirubin is transported to the liver and secreted into bile. The bilirubin breakdown products colour urine and faeces.
What happens to the iron in RBCs when they are broken down?
Iron binds to transferrin in the blood and is recycled.
What hormone regulates erythrocyte production?
Erythropoetin (EPO)
What organ releases EPO?
The kidney
Describe how hypoxia affects EPO release and red cell production?
Hypoxia is detected by the kidney causing it to release EPO hormone into the circulation. EPO acts on bone marrow to increase red cell production (erythropoiesis). This increases the oxygen carrying capacity in the blood and counteracts hypoxia.
Describe how normal oxygen levels/too much oxygen will affect EPO release?
Kidneys will sense that oxygen saturations are normal and EPO levels will drop.
Describe the progression of erythropoiesis?
Myeloid stem cells
Proerythroblast
Polychromatic erythroblast (Hb appears in cytoplasm)
Orthochromatic erythroblast (nucleus shrinks, full Hb present)
Erythroblast gets rid of its nucleus
Reticulocyte into circulation
Mature erythrocyte
What is the difference between a reticulocyte and an erythrocyte?
A reticulocyte is an immature red blood cell, it still has some RNA. An erythrocyte is a mature red blood cell (no DNA or RNA).
Why are red blood cells shaped the way they are? Also what is this shape called?
Biconcave shape- allows maximum gas diffusion by increasing the surface area to volume ratio. It also has a flexible membrane to allow it to squeeze through capillaries.
What is haematocrit?
The volume of red blood cells as a percentage of total blood volume. (40-50% in males and 36-46% in females).
What percentage do red blood cells, plasma, platelets and white blood cells make up of blood?
Plasma- 55%
Red blood cells- (40-50% in males, 36-46% in females)
White blood cells and platelets <1%.
What makes up the Buffy coat when blood is separated into its constituents?
White blood cells and platelets.