Structure and function of blood Flashcards
What are the major cellular components of blood? Describe them
Red blood cells (erythrocytes) - biconcave, no nucleus, transport oxygen, remove CO2, contain Hb, porphyrin ring surrounding central Ferrous (iron) ion.
White blood cells (leukocytes) - colourless, involved in immune response , can be granulated or not granulated
Platelets (thrombocytes) - cytoplasmic fragments, no nucleus, membrane bound, granulated
How are white blood cells classified morphologically?
Into granulocytes and granulocytes:
Granulocytes are neutrophils, basophils, eosinophils
Agranulocytes - Monocytes, lymphocytes, macrophages
Describe the structure and function of neutrophils
Phagocytes, kill bacteria and fungi
Main mediators of innate immunity
Polymorphonuclear- irregular, multi-lobed nucleus
Prominent cytoplasmic granules
Describe the structure and function of eosinophil
Bi-lobed nucleus, granules stain red with eosin
Involved with allergic responses
Describe the structure and function of basophils
Bi-lobed nucleus, granules stain blue/purple with basic dyes
What are the mononuclear white blood cells?
- Monocytes
- Lymphocytes
These have NO granules, and large, regular nuclei
What is the function of lymphocytes?
- Main role in adaptive immunity
- B lymphocytes - produce specific antibodies
- T lymphocytes - produce cytotoxic granules that eat up tissue
What is the structure of haemoglobin?
Porphyrin ring with central ferrous ion, protein tetramer made of 4 polypeptide chains, each polypeptide chain has a haem group attached to it
What is the role of plasma?
Transports essential materials, waste products, carbohaydrates, lipids
What is plasma?
Fluid containing:
Water
Salts
Proteins
Organic molecules e.g. metabolites, carbohydrates, lipids
Clotting factors
Positive ions Na and potassium, calcium, magnesium
What is serum?
Fluid left after blood clotting
How do blood cells develop from haematopietic stem cells?
- begin with multipotent haematopoietic stem cells
Through series of steps cells develop through targeted processes to specific cell type they will later become
Cells develop into myeloid/lymphoid progenitor cells or red blood cells or platelets
What is the average red blood cell life span?
120 days
What is the normal value for blood volume?
5 litres
What is the normal value for plasma volume
2.5/3 literes
What is the normal value for haematocrit reading
0.4/0.5
Describe the appearance of blood after centrifuging
Bloody splits into red cell at bottom, buffy white layer of white blood cells , and plasma on top
What are the components of a full blood count test?
- Haemoglobin (Hb): concentration of haemoglobin within the blood. Low haemoglobin = ‘anaemia’.
- Mean corpuscular volume (MCV): mean volume of the red blood cells (‘-cytic’). Main method used to classify anaemia (macrocytic = large cells; normocytic = normal cells; microcytic = small cells).
- Reticulocyte count: number of immature red blood cells. Increased in blood loss and haemolytic anaemia bcs bone marrow works harder to replace lost cells. Decreased if there is impaired red blood cell production in the bone marrow.
- Red cell count (RCC): the concentration of red blood cells within the blood
It may be increased due to: reduced plasma volume (e.g. dehydration), or increased red blood cell production (e.g. polycythaemia rubra vera)
It may be decreased due to: increased plasma volume (e.g. pregnancy), or reduced red blood cell production/red blood cell loss (e.g. bone marrow failure, bleeding, anaemias) - Haematocrit (HCT)/packed cell volume (PCV): percentage of the total volume of blood accounted for by red blood cells. Causes of abnormalities are similar to the RCC but the haematocrit is based on volume so is also affected by the red cell volume (MCV).
- Mean corpuscular haemoglobin (MCH)/haemoglobin concentration (MCHC): the mean quantity/concentration of haemoglobin within the red bloods cells. This affects the colour of the cells (‘-chromic’: hypochromic = pale; normochromic = normal red).
Most normocytic and macrocytic anaemias are normochromic
Most microcytic anaemias are hypochromic (except anaemia of chronic disease)
Red blood cell distribution width (RDW): measure of the variation of red blood cell volumes. It is used in conjunction with MCV to determine if anaemia is due to a mixed cause or a single cause. Raised red cell distribution width = ‘anisocytosis’.
