Intro to structure + function of blood Flashcards
What is the structure of blood?
- CELLS ; red, white, platelets
- PLASMA (fluid)
What are the (3) functions of blood?
- Transport
- Defence
- Homeostasis
What does blood look like after centrifuging?
- Plasma at top (fluid)
- Buffy coat in middle (white cells + platelets)
- Red cells at the bottom
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What are red blood cells?
- Erythrocytes
- Biconcave discs
- No nucleus + do not contain DNA, RNA or mitochondria
What is the colour of white blood cells (AKA leukocytes)?
Colourless
What are the two commonest types of WBCs?
- Neutrophils
- Lymphocytes
Describe characteristics of neutrophils
- Polymorphonuclear: irregular, multi-lobed nucleus
- Granulocyte cell: prominent cytoplasmic ganules
What are the other two types of granulocytes apart from neutrophils and what do they stain?
- Eosinophil - stain red with eosin
- Basophil - stain blue with basic dyes
Neutrophil is the most common WBC, whereas eosinophils make up 1-4% of WBCs and basophils <0.5%.
What are mononuclear cells? Give examples
- Lack granules
- Large, regular nuclei
- Two types: monocytes + lymphocytes
What are platelets?
- Thrombocytes
- Cytoplasmic fragments
- No nucleus
- Membrane bound
- Contain granules
Where do blood cells come from?
- Mature blood cells produced from stem cells in bone marrow
- Bone marrow contains many immature cells
- Some blood diseases can be treated by bone marrow transplant
What does plasma generally contain?
- Water
- Salts
- Proteins
- Metabolites
- Carbohydrates
- Lipids
Which positive ions (cations) are present in plasma?
- Sodium
- Potassium
- Calcium
- Magnesium
- Hydrogen
Which negative ions (anions) are present in plasma?
- Chloride
- Bicabonate
- Phopshate
- Sulphate
- Organic anions
What is the difference between plasma and serum?
- Plasma is the fluid component of whole blood
- Serum is the fluid left after blood clotting
- Some blood tests require unclotted blood/plasma (use anticoagulant)
- Other tests work better with serum than plasma
What are the 4 major classes of serum proteins?
- Albumin
- Alpha globulins
- Beta globulins
- Gamma globulins
What is albumin?
- Single protein made in the liver
- >90%
- Maintaining plasma oncotic pressure (colloid osmotic pressure)
- Transport for substances w/ low water solubility
- General purpose carrier
What are alpha and beta globulins?
- Variety of proteins made in liver
- 1-4% of plasma proteins
- For transport + defence
What are gamma globulins?
- Produced by B-lymphocytes
- <0.5% of plasma proteins
- Immunoglobulins eg. IgA, IgG
- Antibodies which have a role in body’s defence against infection
What is fibrinogen?
- 2-5% of plasma protein
- Blood clotting
What does blood transport?
- Carry oxygen (from lungs) / nutrients to tissues
- Remove CO2 / other waste from tissues
- Transport other substances (eg hormones) from sites of prod to site of action
How is CO2 removed from body tissues? Where does it go?
- Goes to lungs from tissues
- Some CO2 carried by RBCs
- But most CO2 carried as bicarbonate in plasma
- Red cell enzyme carbonic anhydrase helps CO2 to dissolve
The major constituent of erythrocytes is haemoglobin. What is the structure of this and how does it carry oxygen?
- Haemoglobin is a tetramer of 4 polypeptide chains:
- 2 alpha globin chains
- 2 beta globin chains
- Each globin chain carries a haem as a prosthetic group
- The haem holds a ferrous (Fe2+) iron atom
- Oxygen binds reversibly to the iron atom by coordination bond
- 300,000,000 Hb molecules in each RBC
What do oxyhaemoglobin and deoxyhaemoglobin look like?
- Oxy = fully saturated with O2 = bright red
- Deoxy = lost all O2 = blue-purple
What is pulse oximetry?
- Measures colour of haemoglobin
- Determines if patient is hypoxic
What substances can plasma proteins carry?
- Poorly soluble in water - eg. lipids, lipid-soluble hormones + vitamins
- Metal ions - eg. Ca2+, Fe2+, Cu2+
In regards to white blood cells, what do neutrophils do?
- Phagocytose + kill bacteria and fungi
- Main mediators of innate immunity
What do lymphocytes do?
- Main mediators of adaptive (acquired) immunity
- Produce antibodies
- Kill virus infected cells
What do eosinophils and basophils do?
- Eosinophils and basophils both kill parasites and are involved in allergic responses
Basophils (mast cells) are also involved in inflammation!
What do monocytes/macrophages do?
Phagocytosis of dead cells + pathogens
What are immunoglobulins?
- Gamma globulins
- Made by B-lymphocytes
- Act as antibodies against pathogens
What are complement proteins?
- Kill bacteria + other pathogens
- Cooperate with Ig + WBC
How do platelets stop bleeding?
- Major role = primary haemostasis
- Recognise damage at blood vessel wall
- Form a platelet plug
- Prevent/stop bleeding
- But it is insecure + temporary
How does plasma protein fibrinogen contribute to haemostasis?
- Fibrinogen is a major plasma protein
- Converted to fibrin, forms blood clot
- Clotting factors control process
- Fibrin clot reinforces primary platelet plug
Homeostasis is keeping the internal environment of the body constant. Give examples of the blood’s role of homeostasis
- Maintaining pH (7.4)
- Controlling distribution of water + solutes
- Distributing heat
What is the total blood and plasma volume “for a 70kg male”?
- TBV = 5 litres
- Plasma volume = 2.5-3 litres
What is haematocrit and the normal value for it?
- Ht (haematocrit) AKA packed cell volume (PVC)
- HT = vol of cells / total volume
- Normal value: ~0.4 - 0.5
What is the average life span of a red blood cell?
120 days
What tests does a full blood count (FBC) include?
- Haemoglobin concentration (Hb in g/l)
- Mean (red) cell volume (MCV)
- White blood cell count (WBC)
- Haematocrit (Ht/Hc)
- Liver functon tests (LFTs)
- Urea + electrolytes (U + E)
- Blood glucose
From the full blood count, which counts are important for dignosing anaemia in comparison to infection?
FOR ANAEMIA:
- Hb conc
- MCV
- Ht
FOR INFECTION:
- WBC
- Neutrophil count
- Lymphocyte count
What do LFTs test/look for?
- Albumin concentration
- Liver enzymes (released from damaged liver cells)
- Clotting factors
Why are urea and electrolyte tests important?
- In diagnosing kidney function
- Also detect metabolic abnormalities
