W9 Intro to blood Flashcards
RBC
AKA Erythrocytes
Biconcave discs
No nucleus and do not contain DNA, RNA or mitochondria (still metabolically glucose by glycolysis)
WBC
AKA leukocytes
Colourless
Neutrophils
Polymorphonuclear
Irregular, multi-lobed nucleus
Granulocyte
prominent cytoplasmic granules
Two other types of granulocyte
Eosinophil (granules stain red w/eosin) = 1-4% of WBC
Granules contain substances that are going to be released from the cell
Basophil (granules stain blue/purple w/basic dyes) = <0.5% of WBC
In basophil can’t see nucleus because of granules
Mononuclear cells
Lack granules Large, regular nuclei Two types: Monocytes Lymphocytes
Platelets (a.k.a. “thrombocytes” )
Cytoplasmic fragments
No nucleus
Membrane bound
Contain granules
Where do blood cells come from?
Mature blood cells are produced from stem cells in the bone marrow
Bone marrow contains many immature cells
Some blood diseases can be treated by bone marrow transplantation
Plasma fluid contains…
Water Salts Proteins Organic molecules e.g. Metabolites Carbohydrates Lipids
Ionic constituents of plasma
Positive ions (cations)
Sodium (Na+)
Also potassium, calcium, magnesium and hydrogen ions
Negative ions (anions)
Chloride (Cl-)
Also bicarbonate, phosphate, sulphate & organic anions
Plasma V serum
Plasma is the fluid component of whole blood
Serum is the fluid left after blood clotting
Some blood tests require unclotted blood
Use anticoagulant e.g. EDTA
Other tests work better with serum than plasma (as proteins removed)
Plasma proteins
Normal: 7-9% of plasma is protein
Complex- thousands of different proteins
But > 90% is a single protein: albumin (or = serum albumin)
Function of blood - transport
Carry oxygen / nutrients to tissues
Remove CO2 / other waste products from tissues
Transport other substances (e.g. hormones) from sites of production sites of action
Erythrocytes - function
Transport oxygen from lungs → body tissues
Help in removal of CO2 from body tissues → lungs:
- Most CO2 carried as bicarbonate in plasma
- Red cell enzyme carbonic anhydrase helps CO2:
- To dissolve in plasma in the tissues (because CO2 doesn’t readily dissolve in water → forms carbonic acid)
- Come out of solution in the lungs
Erythrocytes - major consituent
Major constituent is the protein haemoglobin (Hb)
Hb binds oxygen
Carries it from the lungs to the tissues
Haemoglobin
Haemoglobin is a protein tetramer made up of 4 polypeptide chains-
2 alpha globin chains
2 beta globin chains
Each globin chain carries a haem molecule
Haem group not prosthetic + extra group carried by protein
Haemoglobin - saturated/unsaturated
Oxyhaemoglobin
Fully saturated with O2 = bright red
Deoxyhaemoglobin
Lost all O2 = dark red
Haemoglobin - binding to ferrous ion
The haem holds a ferrous (Fe2+) iron atom
Oxygen binds reversibly to the iron atom by a coordination bond
Basis of pulse oximetry
Measures the colour of the haemoglobin = measures SATS
Determines if patient is hypoxic
[Hb] in RBC
There are about 300,000,000 Hb molecules in each RBC
Very high concentration
Almost 50% of the space in a red cell is taken up by Hb
Plasma transport
Plasma carries soluble metabolites in solution
Plasma proteins carry substances which are poorly soluble in water e.g.
- lipids
- lipid soluble hormones and vitamins
Plasma proteins also carry metal ions e.g.
Ca2+
Fe2+ (needed for bacterial growth)
Cu2+
All ions above toxic
Plasma transport - examples
Albumin acts as a general purpose carrier
But many substances have a specialised carrier e.g.
Thyroxine binding globulin (TBG) = as thyrohormones not v.water soluble
Transferrin
Transferrin
Binds to ion in blood + carries to tissue
Keeps it away from bacteria
Cells have receptor which binds to transferrin
Ion taken up
WBC function
Neutrophils
Phagocytose and kill bacteria & fungi
Main mediators of innate immunity
Lymphocytes
Main mediators of adaptive (acquired) immunity
Produce antibodies
Kill virus infected cells
Eosinophils - function
Kill parasites
Involved in allergic responses
Basophils - function
Kill parasites
Involved in allergic responses
Involved in inflammation
Monocytes (macrophages) - function
Phagocytosis of dead cells and pathogens
Show antigens to antigen presenting cells
Plasma- immune defense
Immunity
Immunoglobulins (Ig)
Made by B-lymphocytes
Act as antibodies against pathogens
Complement proteins
kill bacteria and other pathogens
cooperate with Ig and WBC
Platelets - function
Major role: Primary Haemostasis
Recognise damage at blood vessel wall
Form a platelet plug
Prevent / stop bleeding
Platelet plug stops bleeding– but insecure & temporary
Blood clotting in plasma
Fibrinogen is a major plasma protein
Converted to Fibrin, forms blood clot
Clotting factors control process
Fibrin clot reinforces primary platelet plug
Homeostasis
Keeping the internal environment of the body constant
Maintaining pH (7.4)
Controlling distribution of water and solutes
Distributing heat
Plasma - homeostasis = tests
“U and Es”- urea and electrolytes
- Check kidney function
“LFTs” – Liver function tests
Analysis of plasma = essential part of diagnosis & treatment
Blood in numbers
Total blood volume ~ 5 litres “for a 70Kg male”
(70 ml.kg-1 body weight)
Plasma volume ~ 2.5-3 litres
Haematocrit
H (aka packed cell volume = PCV) = Vol of cells/Total vol
Normal ~ 0.4-0.5
Ratio by volume of cells to plasma
RBC life span + measurements
Average life span ~ 120 days
Diameter ~ 8 μm
Thickness ~ 2 μm
FBC includes…
Haemoglobin concentration (Hb in g/l)
Overall concentration of haemoglobin in the blood
Used to diagnose anaemia
Mean (red) cell volume (MCV)
Size of the rbcs
Mean (red) cell haemoglobin content (MCHC)
How much Hb in each red cell
Haematocrit (Ht or Hc)
These help to diagnose the type of anaemia
Total white blood cell count (WBC)
Neutrophil count
Lymphocyte count
IMPORTANT FOR DIAGNOSING INFECTION
LFTs
Liver function tests
Albumin concentration
Liver enzymes (released from damaged liver cells)
Clotting factors
Urea and electrolytes (U&E) “you and ees”
Test kidney function and metabolic abnormalities
Blood glucose test
Tests for diabetes mellitus
Lipid profile - test
Triglycerides
Cholesterol
LDL and HDL
Risk of cardiovascular disease
