Introduction into the structure and function of blood Flashcards
What are the components of the blood?
- Plasma (fluid)
2. Cells including RBCs, WBCs and platelets
What happens when you centrifuge the blood?
From the top, you get plasma (fluid), buffy coat (white cells), Red cells (RBCs and platelets).
Describe the basic features of RBCs and their dimensions
- Biconcave discs
* No nucleus and do not contain DNA, RNA or mitochondria
What are the most common WBC (leukocytes)?
- Neutrophils
* Lymphocytes
Describe polymorphonuclear and granulocytes, and other types of granulocytes
• Polymorphonuclear
Irregular, multi-lobed nucleus
having a nucleus with several lobes and a cytoplasm that contains granules, as in an eosinophil or basophil.
• Granulocyte
prominent cytoplasmic granules
i.e. a neutrophil, basophil, or eosinophil.
• People often say “granulocytes” or “polymorphs” when they mean neutrophils
• However, there are two other types of granulocyte:
Describe Mononuclear cells
• Lack granules
• Large, regular nuclei
• Two types:
Monocytes and Lymphocytes
Give a brief overview of platelets
- Cytoplasmic fragments
- No nucleus
- Membrane bound
- Contain granules
Where do Red 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
What does the plasma fluid contain?
• fluid containing water salts proteins organic molecules e.g. metabolites carbohydrates lipids
What ions are present in the blood?
• Positive ions (cations)
sodium (Na+)
Also potassium, calcium, magnesium and hydrogen ions
• Negative ions (anions)
Chloride (Cl-)
Also bicarbonate, phosphate, sulphate & organic anions
Describe serum and plasma
- 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
Describe Plasma proteins (3)
- Normal: 7-9% of plasma is protein
- Complex- thousands of different proteins
- But > 90% is a single protein: albumin
What are the functions of the 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
• DEFENCE
• HOMEOSTASIS
What do erythrocytes do?
• 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 from the tissues
Come out of solution in the lungs
• Major constituent is the protein haemoglobin (Hb)
• Hb binds oxygen
• Carries it from the lungs to the tissues
Describe 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
• The haem holds a ferrous (Fe++) iron atom.
• Oxygen binds reversibly to the iron atom by a coordination bond.
• Oxyhaemoglobin
Fully saturated with O2 = bright red
• Deoxyhaemoglobin
Lost all O2 = dark red
• Basis of pulse oximetry, Measures the colour of the haemoglobin, Determines if patient is hypoxic
• 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
what are the functions of plasma proteins?
• 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.
Ca++
Fe++
Cu++
Describe defence as a function of the blood
• DEFENCE Immunity WBC and plasma proteins Clotting (aka haemostasis) Platelets and plasma proteins
Describe the function so each of the WBCs
White Blood Cells (WBCs) • Neutrophils Phagocytose and kill bacteria & fungi Main mediators of innate immunity • Lymphocytes Main mediators of adaptive (acquired) immunity Produce antibodies Kill virus infected cells Other White blood cells • Eosinophils Kill parasites Involved in allergic responses • Basophils Kill parasites Involved in allergic responses Involved in inflammation • Monocytes (macrophages) Phagocytosis of dead cells and pathogens
What do Immunoglobulins (Ig) do and Complement proteins do?
• Immunoglobulins (Ig) Made by B-lymphocytes Act as antibodies against pathogens • Complement proteins kill bacteria and other pathogens cooperate with Ig and WBC
What is the function os platelets?
• Major role: Primary Haemostasis
Recognise damage at the blood vessel wall
Form a platelet plug
Prevent/stop bleeding
• Platelet plug stops bleeding– but insecure & temporary.
Describe fibrinogen (4)
- Fibrinogen is a major plasma protein
- Converted to Fibrin, forms a blood clot
- Clotting factors control process
- Fibrin clot reinforces primary platelet plug
Describe homeostasis as a function of the blood in further detail
• HOMEOSTASIS- keeping the internal environment of the body constant Maintaining pH (7.4) Controlling distribution of water and solutes Distributing heat Plasma pH, ion concentrations and protein concentrations must be kept within safe limits Otherwise bad things happen • Disturbed by disorders of: Kidney Liver Lungs Cardiovascular system Endocrine organs
Describe the blood in numbers
On image
Discuss the types of blood tests that can be carried out
Full blood count (FBC) which determines the concentration of haemoglobin in the blood, used to diagnose anaemia. This also includes the full white blood cell count, no of neu and lym - important for disease
Mean Red cell Volume (MCV) used to calculate the size of RBCs.
Mean Red cell haemoglobin count (MCHC) used to calculate the number of haemoglobin molecules in each red cell to diagnose the type of anaemia.
