Lecture 20 Flashcards
What are the general functions of blood?
Transport, immune response and coagulation.
What functions does blood transport involve?
Transport involves dissipation of heat, transport of oxygen, nutrients, carbon dioxide and other waste products, transports hormones which co-ordinate the activity of the organs of the body and also transports phagocytic cells, antibodies and coagulation factors.
What function does blood immune function involve?
What about coagulation?
Immune involves action via the phagocytes, antibodies and other white blood cells, these help for fighting infection and productions of the immune response.
Coagulation is done via platelets and endothelial cells and coagulation factors
How much blood do we have? What is it made up of?
Blood makes up about 6-8% of the total body mass, it is proportional to the lean body mass, the leaner you are (also if you are a woman) the higher % blood volume and vice versa.
The main components are: plasma (fluid portion of the blood, 90% is water, 10% is solutes which include plasma proteins and also some waste products (
What are the plasma proteins?
Plasma proteins are divided into 3 main groups:
albumins (maintain the osmotic pressure, buffere the blood and bind and transport insoluble substances, some of these are hormones, some are coagulation factors.)
Globulins: involves many different antibodies
Fibrinogen: the precursor of fibrin during blood coagulation.
What is haematocrit? What are common values?
haematocrit (packed cell volume) is worked ot using centrifuged blood (which seperates), it is the fraction of blood occupied by red cells. For men this is roughly 0.40-0.53, for women it is roughly 0.37-0.47.
Where do blood cells come from?
All blood cells are derived from a common All blood cells are derived from a common progenitor cell (Red blood cell production is stimulated by erythropoietin and requires folic acid, bitamin B 12, thymine and iron.
), either myeloid stem cells or lymphoid stem cells which subsequently differentiate into red blood cells, white blood cells (granulocytes) or platelets if myeloid. Or into lymphocytes (a type of white blood cell) if lymphoid stem cells.
What are the main white blood cells?
neutrophils are the most common granulocyte (65%), they last from hours to days and tend to engulf antigens. The next are basophils which make up less than 1% and play an important role in inflammation , they last fomr hours to days. Eosinophils are 2-5% and last a few days. Monocytes make up 3-8%, when they enter tissues they change into macrophages (which engulf antigens) and have life spans of months. There are also lymphocytes which have a uniform shape and make up 25% of the white blood cells, they secrete antibodies.
Why are red blood cells shaped the way they are? How much haemoglobin does it contain?
Red blood cells have a biconcave shape to give a large surface area to volume ration, allowing for more efficient diffusion and reasonable flexibility for movement through capillaries.
Roughly 1/3rd of the red blood cell is haemoglobin, range is 140-180 g/L of blood for men, 120-160 g/L for women
What is the rate of red blood cell production to destruction?
Equal.
How is erythropoietin secretion regulated?
A reduction in oxygen delivery is detected by the kidneys, these secrete erythropoietin which causes the bone marrow to produce more red blood cells.
How does destruction of red blood cells work?
red blood cells live roughly 120 days, breaking apart in the capillaries, these are removed by macrophages and the haemoglobin is broken down to amino acids, iron and bilirubin. The iron is transported to bone marrow, amino acids are used for energy and bilirubin is transported to the liver and excreted in bile.
What is anaemia? What are some causes?
Anaemia is a reduction in the oxygen carrying capacity typically due to lowered concentration of haemoglobin, for men this is less than 130 g/L for men or 115 g/L for women. This low haemoglobin concentration could be due to reduced production (e.g low iron or erythropoietin) or defective maturation. It could also be due to cellular defects or extracellular defects. bleeding is also a cause of anaemia.
