Blood Flashcards
What is blood composed of?
Cells (45% of blood volume)- ‘formed elements’
Red blood cells (erythrocyte)
White blood cells (leucocytes)
Platelets (thrombocytes)
Plasma (55% of blood volume) - extracellular fluid; water, electrolytes, organic molecules (glucose, fatty acids, glycerides, amino acids, etc); plasma proteins
Which proteins are present in the plasma?
Albumins (60%): oncotic pressure, transport of lipids
Globulins (35%): transport of ions, hormones, lipids. Immune function
Firbinogen (4%): key component of blood clot
Regulatory proteins (1%): enzymes and hormones
Red blood cells make up what percentage of all cells in the blood?
99%
What is the diameter of a red blood cell?
6-8 micrometers
What shape is a RBC and what does this confer?
Biconcave shape: gives large surface area relative to volume
This permits rapid gas (O2, CO2) transfer across cell membrane
Allows RBC to bend in narrow capillaries
Enables RBC to expand to accommodate fluid in hypotonic solutions
Where are RBCs formed?
In the red bone marrow
What is the average lifespan of a RBC?
120 days
How are old RBCs broken down?
Old RBCs are removed from circulation and broken down by MPS (monocyte/phagocyte system) - in the spleen, mainly
Breakdown products are recycled
What is haemoglobin made up of?
Protein - amino acid pool
Haem -> contains iron. Converted into biliverdin and bilirubin (waste products)
Where is bilirubin conjugated?
In the liver and excreted as bile pigment
What are the symptoms of excess bilirubin in the blood?
Jaundice (yellowing of skin) and itchy skin
What percentage of RBCs are non-functional?
10%
What happens to non-functional RBCs?
Broken down by haemolysis
Eliminated through urine or picked up by macrophages
What is transferrin?
A carrier protein made in the liver
Picks up iron and drops it off at the bone marrow -> transferrin circulates iron
What is anaemia caused by?
Iron deficiency in the blood
What is the main symptom of anaemia?
Chronic fatigue
How are RBCs formed?
Formed in red bone marrow, regulated by erythropoietin
Series of stages involved
During development there is a reduction in cell size and regression of nucleus
Requires folic acid and vitamin B12
Requires iron (for haemoglobin)
What are the stages in RBC formation?
Day 1: Proerythroblast (huge nucleus, big cell) Day 2: Basophilic erythroblast Day 3: Polychromatophilic erythroblast Day 4: Normoblast Days 5-7: Reticulocyte Day 7: Mature RBC
What happens if RBC numbers are low?
Decreased oxygen delivery to cells Decreased oxygen to kidney Erythropoietin released Acts on red bone marrow Increases production of RBCs
Why are RBCs never 100% saturated with oxygen?
Because they also carry CO2
What is the molecular weight of haemoglobin?
68,000 Da
Describe the structure of haemoglobin
2 alpha chains and 2 beta chains
4 hame groups (porphyrin ring, iron atom)
Fe reversibly binds O2
What type of haemoglobin does a foetus have?
Hb-F
How many molecules of haemoglobin does each RBC contain?
200-300 Hb molecules per RBC
What percentage of cells in the blood do white blood cells make up?
1%
What type of cells make up the majority of white blood cells?
Neutrophils (50-70%)
What do neutrophils do?
Fight infections
Non-specific
General immune response
Phagocytic
What do neutrophils do?
Fight infections
Non-specific
General immune response
Phagocytic
What are eosinophils?
Immune cells involved in allergy
What is the precursor for macrophages?
Monocytes
What are the 2 types of lymphocyte?
T cells and B cells
What are the 2 types of lymphocyte?
T cells and B cells
Produce a specific immune response
What are platelets derived from?
Megakaryocytes
What is the role of platelets?
Involved in haemostasis
Release vasoconstrictors (thromboxane A2)
Form platelet plug
Source of phospholipid (‘platelet factor’) for coagulation
What is the normal platelet count?
150-400 x 10^9/litre
What are blood groups?
RBCs carry antigens on their membranes
AB antigens and Rhesus antigens important for determining blood group/important in blood transfusions
A, B, AB, O
Rh+ or Rh-
What happens if a Rh- person receives Rh+ blood?
They will develop anti-Rh antibodies
What happens to a Rh- female if they conceive a Rh+ foetus?
Some of the foetal RBCs can enter maternal circulation during childbirth
Anti-Rh antibodies are formed
These can attack and haemolyse RBCs of a subsequent Rh+ foetus
Haemolytic disease of the newborn
Which blood group is the universal donor?
O
Which blood group is the universal recipient?
AB
