P: Red blood cells Flashcards
Types of red blood cells:
- Red blood cells (erythrocytes)
- White blood cells (leucocytes)
- Platelets (thrombocytes)
Haematocrit:
fractional contribution of erythrocytes to blood.
Plasma components:
- Water: 90%
- Proteins: 8%, mostly synthesised by liver
- Albumin: 60% of proteins, transport
- Globulin: 36% of proteins, immune response
- Fibrinogen: forms blood clots
- Nitrogenous waste products (urea, uric acid)
- Organic nutrients: glucose, amino acids, glycerol etc…
- Electrolytes (ions)
Serum
plasma sample without fibrinogen + other clotting proteins .
Where are blood cells produced
Blood cells are made in pluripotential hematopoietic stem cells in bone marrow.
What do PHSCs divide into?
- Some remain as PHSCs
- Most differentiate into intermediate committed stem cells or progenitor cells
- Each progenitor cell differentiates into specific cell type
Red, white and platelet formation names?
Red cell formation = erythropoiesis
White cell formation = leucopoiesis
Platelet formation = thrombopoiesis
Function of erythrocytes
most abundant cell type in the body 5x 10^12 cells/L blood
Function: transport O2 and CO2 in blood
Very flexible, squeezes through capillaries, contains haemoglobin.
Erythropoiesis: what are proerythroblasts formed by? How are erythrocytes formed? What does DNA synthesis require? What do RBCs lack?
- Proerythroblasts are formed from CFU-E (colony forming unit-erythroid) stem cells
- Reticulocytes pass into capillaries from bone marrow and differentiate into erythrocytes
- High rate of DNA synthesis requires vitamin B12 and folic acid (folate)
- RBCs lack nuclei, mitochondria + ribosomes
- If there is low oxygen in tissues (hypoxia), hypoxic kidney cells secrete ___ which promotes ___ production in ___
- ___ production under normal oxygen conditions
- Increases production of ___, ___ synthesis + production and release of ____
- erythropoietin (EPO), RBC production, bone marrow.
- Basal
- proerythroblasts, haemoglobin, reticulocytes
RBC destruction:
- RBC lifespan = ___ days.
- Rely on ____ for ATP
- Decrease of ___ –> reduced ___ –> reduced ___ so RBCs cannot squeeze through capillaries. They self-destruct in ___
- Haemoglobin absorbed by ____: iron recycled to ___, ___ converted to ___, protein subunits degraded to ____.
- 120
- glycolysis
- glycolysis, ATP, membrane flexibility, red pulp of spleen, macrophages, bone marrow/liver, bile pigment bilirubin, amino acids
What’s anaemia? What’s the causes and consequences?
deficiency on oxygen carrying capacity of blood caused by
- Low haematocrit (low RBC abundance)
- Haematocrit is normal but low haemoglobin in RBCs
Anaemia results in hypoxia - insufficient oxygen to perform metabolic functions in the tissues.
Causes of iron deficiency anaemia?
- Blood loss
- Increased blood demands (growth, pregnancy…)
- Malabsorption
- Poor diet
Polycythaemia
abnormal increase in RBC count - 6-7 x 10^12 cells/L
Polycythaemia vera
Genetic aberration resulting in excessive proliferation of erythroblasts. Causes excess production of white blood cells + platelets. Haematocrit = 60-70%.
Secondary polycythaemia
Increased RBC caused by hypoxia.
Blood group antigens
A antigen: alpha-N-acetylgalactosamine (GalNAc) added to D-galactose end of H antigen.
B antigen: D-galactose added to D-galactose end of H antigen
O antigen: no change to H antigen.
Blood group antibodies
Type A blood: anti-B antibodies
Type B blood: anti-A antibodies
Type O blood: anti-A and anti-B antibodies
Type AB blood: no anti-A or anti-B antibodies.
Mismatching of blood causes and consequences?
anti-A/anti-B plasma mixed with A or B antigens cause antibodies to agglutinate, which plugs small blood vessels and white blood cells destroy membrane of agglutinated cells, releasing haemoglobin into plasma (haemolysis).
Rh antigens: what are the transmembrane proteins and which is most abundant? What’s Rh positive/negative blood + % of each?
transmembrane proteins:
- C, D, E, c, d, e
- Type D is most prevalent + most antigenic
- Rh positive blood ( DD, Dd) 85-100%
- Rh negative blood (dd) 0-15%
Infusion of Rh+ve donor blood to Rh-ve recipient
- Recipient blood develops anti-D antibodies
- Triggers agglutination.
Scenario if mother is Rh-ve and father is Rh+ve –> foetus inherits Rh+ve paternal antigen:
- Mother develops anti-Rh antibodies from exposure to foetus’ Rh antigen
- Diffuse through placenta into foetus and cause red blood cell agglutination (haemolysis + excess bilirubin)
- Conditions affects 2nd and subsequent foetuses
- Jaundiced infant is usually anaemic at birth
- Anti-D antibodies administered during pregnancy to inhibit maternal production of anti-Rh agglutinins
Universal donor
Type O blood
Universal recipient
Type AB+
