Blood Blood Composition Plasma Red blood cells -RBCs White Blood Cells- WBCs (leucocytes) Blood Platelets PLT (thrombocytes)
Functions of the blood 1. Respiration - transport of oxygen from the lungs to the tissues and of carbon dioxide (CO 2 ) from the tissues to the lungs 2. Nutrition - transport of absorbed food materials 3. Excretion - transport of metabolic waste to the kidneys, lungs, skin, and intestines for removal 4. Maintenance of the normal acid-base balance in the body 5. Regulation of water balance through the effects of blood on the exchange of water between the circulating fluid and the tissue fluid 6. Regulation of body temperature by the distribution of body heat 7. Defense of the body against infections and other foreign materials 8. Transport of hormones and regulation of metabolism 9. Transport of metabolites 10. Coagulation
If you centrifuge whole blood: the red cells settle to the bottom the white cells settle on top of them forming the "buffy coat". The fraction occupied by the red cells is called the hematocrit. Normally it is approximately 45%.
The formation of blood cells All the various types of blood cells are produced in the bone marrow arise from a single type of cell called a hematopoietic stem cell- hemocytoblast The path is regulated by: cytokines and/or hormones hemocytoblast proerythroblast myeloblast lymphoblast monoblast megakaryoblast erythrocytes progranulocyte lymphocyte monocyte megakaryocyte basophil eosinophil neutrophil granulocytes agranulocytes thrombocytes leukocytes
Plasma Plasma is the straw-colored liquid in which the blood cells are suspended. Plasma transports materials needed by cells and materials that must be removed from cells: various ions (Na +, K +, Ca 2+, Mg 2+, HCO 3, Cl etc. ) glucose amino acids organic acids cholesterol and other lipids hormones urea, uric acid and other wastes
Composition of blood plasma Component Percent Water ~92 Proteins 6-8 Inorganic ions 0.9 Organic substances 1.1
Inorganic Ions Inorganic ions play a very important role in the blood. Hence all the inorganic ions facilitate in a very important role as do other cells within the blood ION SYMBOL CONCENTRATION (mmol/l) Sodium Na + 135-146 Potassium K + 3.5-5.2 Calcium Ca +2 2.1-2.7 Magnesium Mg +2 0.7-1.1 Chloride Cl 98-108 Hydrogen Carbonate HCO - 3 23-31 Phosphate PO -- 3 0.7-1.4
Organic Substances Blood plasma carry organic substances such as nutrients: glucose and amino acids, glycerol, triglycerides, cholesterol and vitamins. Waste products of the body are also transmitted in the blood plasma. They include urea, uric acid and cellular waste that will be excreted out of the body. Hormones, such as cortisol and thyroxin are also transported around the body in plasma attached to plasma proteins. Medicine and drugs also circulate within the plasma.
Serum Proteins Serum is blood plasma without fibrinogen and other clotting factors. Plasma proteins are divided into serum albumins and 3 types of serum globulins: 1. Albumins - the main proteins of plasma, responsible for the colloidal osmotic pressure regulation of blood 2. Alpha globulins - the proteins that transport thyroxine, retinol (vitamin A) 3. Beta globulins - the metal transporting proteins: iron - transferrin, copper - ceruloplasmin 4. Gamma globulins - mostly antibodies, they are produced as a result of infections or immunizations
Protein functions: Transport of insoluble substances around the body Protein reserve for the body Blood clotting Responses in accordance to disease (inflammatory response) Protection from infection (the gamma globulins function) Keep balance for the ph of the blood
Serum Lipids The analysis of serum lipids has become an important health measure. LIPID Typical values (mg/dl) Desirable (mg/dl) Cholesterol (total) 150-200 < 200 LDL cholesterol 60-140 < 100 HDL cholesterol 35-85 > 40 Triglycerides 40-160 < 160 Total cholesterol is the sum of HDL cholesterol LDL cholesterol and 20% of the triglyceride value
Cardiac risk cardiac risk ratio = total cholesterol divided by HDL cholesterol high LDL values are bad, but high HDL values are good. A cardiac risk ratio greater than 7 is considered a warning.
Red Blood Cells (erythrocytes) Structure of a Red Blood Cell Red blood cells have a diameter less than 0.01 millimeters and do not have a nucleus. Red blood cells contain a protein known as haemoglobin, which gives it the red color. Haemoglobin contains iron, which can easily transport gases such as oxygen and carbon dioxide.
Erythropoiesis = formation of erythrocytes the body must produce about 2.5 million new RBCs every second. In adults, erythropoiesis occurs mainly in the marrow of the sternum, ribs, vertebral processes, and skull bones begins with a cell called a hemocytoblast or stem cell (below). Rate is regulated by oxygen levels: Hypoxia (lower than normal oxygen levels) is detected by cells in the kidneys. Kidney cells release the hormone erythropoietin into the blood erythropoietin stimulates erythropoiesis by the bone marrow
Synthesis of erythrocyte
In adult humans the hemoglobin (Hb) molecule consists of four polypeptides: two alpha (α) chains of 141 amino acids and two beta (β) chains of 146 amino acids Fetal hemoglobin have a two alpha (α) chains and two gamma (γ) chains (in position 6 is Lys against Glu) Each of molecule protein is attached the prosthetic group heme. There is one atom of iron at the center of each heme. One molecule of oxygen can bind to each heme.
Functions of Red Blood Cells Respiration Red blood cells are responsible for the transport of oxygen and carbon dioxide Oxygen readily combines with haemoglobin to form oxyhaemoglobin in the lungs where there is high concentration of oxygen. However, oxy-haemoglobin is an unstable compound and will break down to release oxygen when there is low concentration of oxygen in the surroundings. Red blood cells also carry part of the carbon dioxide waste from the cells through most is transmitted through plasma as soluble carbonates
Erythrocytes Peoples - 4.5 5.5 million per cubic millimeters of blood (million/mm 3 = million/μl) Women average - 4.8 million of these cells per cubic millimeter (mm 3 ) Men average about 5.4 x 10 6 per µl.
Oxygen Transport 97% oxygen is bound to hemoglobin and is transport in oxyhemoglobin form Only 3% is dissolves in the plasma Oxygen is released to tissues, when low concentration of gas in surroundings occurs.
Carbon Dioxide Transport Into red blood cells CO 2 is converted following the equation above by the enzyme carbonic anhydrase. Carbon dioxide (CO 2 ) reacts with water forming carbonic acid, which dissociates into a hydrogen ion (H + ) and hydrogen carbonate (bicarbonate ions, HCO 3 ): CO 2 + H 2 O H 2 CO 3 H + + HCO 3 70% of the CO 2 in the plasma in bicarbonate form. Only about 10% of the CO 2 dissolves directly in the plasma. 20% of the CO 2 is carried by the red blood cells
Blood buffers Different buffers are responsible for maintaining of the correct ph of blood: In plasma: hydro carbonate (bicarbonate), albuminate phosphate In erythrocytes: hydro carbonate (bicarbonate), phosphate, oxyhaemoglobin and haemoglobin
The disturbances of acid-base equilibrium lead to acidosis or alkalosis: Metabolic acidosis generation of substances of acidic character is increased (lactic acid, acetylacetic acid). It can occur during untreated diabetes, renal insufficiency, chronic diarrhoea, starving. The amount of HCO 3- decreases. Respiratory acidosis occurs when the amount of excreted CO 2 is insufficient or its production is too great. It can be caused by: disturbances of respiratory system, drugs or alcohol poisoning as well as by changes of air composition.
Metabolic alkalosis occurs when the excess of HCO 3- occurs. It can be caused by chronic vomiting, treatment with diuretic agents and chosen endocrinological disorders. Respiratory alkalosis occurs in the case of excessive excretion of CO 2 through respiratory system. It can be caused by factors irritating respiratory centre e.g.: disturbances of central nervous system, poisoning, hepatic coma.
Anemia Anemia is a shortage of RBCs and/or the amount of hemoglobin in them. Anemia has many causes. One of the most common is an inadequate intake of iron in the diet. Iron (Fe 2+ ) - heme vit. B 6 - coenzyme of synthase aminolevulinate acid vit B 12 and folic acid - synthesis purines vit. E - antioxidant protect membrane lipids Red Blood Cells lives about 120 days. When they die, they are destroyed by macrophages in the liver and spleen. This process releases iron to be stored in the liver and bile pigments to be excreted. Most of the iron in their hemoglobin is reclaimed for reuse. The remainder of the heme portion of the molecule is degraded into bile pigments and excreted by the liver. Some 3 million RBCs die and are scavenged by the liver each second.
White Blood Cells (leukocytes) White blood cells are much less numerous than red norm 5 000-10 000 per mm 3 have nuclei participate in protecting the body from infection consist of lymphocytes and monocytes with relatively clear cytoplasm, and three types of granulocytes, whose cytoplasm is filled with granules.
Types of WBCs: granular white blood cells include: neutrophils (50-70% of WBCs) eosinophils (1-4%) basophils (less than 1%) agranular (or non-granular) white blood cells include: lymphocytes (25-40%) monocytes (2-8%)
Lymphocytes The most common types of lymphocytes are B lymphocytes ("B cells ) responsible for making antibodies T lymphocytes ("T cells"): inflammatory T cells that enroll macrophages and neutrophils to the site of infection or other tissue damage cytotoxic T lymphocytes (CTLs) that kill virus-infected and tumor cells helper T cells that enhance the production of antibodies by B cells
- Lymphocytes produce anti-bodies against toxins secreted by bacteria and infecting germs. - These antibodies will be excreted into the plasma to kill bacteria in the blood as well as act as anti-toxins. - These antibodies will cause the foreign particles to cluster together, rendering them easily engulfed by the phagocytes.
Monocytes Both monocytes and macrophages are phagocytes which remove foreign invaders by phagocytosis. Monocytes act in blood and in tissues they are transformed to macrophages by the differentiation. Macrophages are large cells.
Neutrophils The most abundant of the WBCs Neutrophils kill the invaders (e.g. bacteria) removing them by phagocytosis. In healthy people, a lot of neutrophils are found in throat, nasal passages, and colon harbor, where a large number of bacteria are settled. High doses of radiation, chemotherapy and many other forms of stress can reduce the number of neutrophils.
Eosinophils Eosinophils are found during the attack of parasites and during infections. These cells are also responsible for allergic response within the blood and are also associated with asthma.
Basophils secrete anti-coagulant and antibodies, which mediate hypersensitivity reactions within the blood. The number of basophils increases during infection, where they release different mediators such as: histamine serotonin prostaglandins and leukotrienes These mediators are responsible for the increase in the blood flow and also play an important role in some allergic responses such as hay fever and an anaphylactic response to insect stings.
Platelets Platelets are cell fragments produced from megakaryocytes. Blood normally contains 150,000 400.000 per microliter (µl) or cubic millimeter (mm 3 ) Structure of Blood Platelets Blood Platelets are granular non-nucleated fragments of cytoplasm in the form of oval discs.
Functions of Blood Platelets They secrete a hormone called serotonin which constricts torn blood vessels. They are rich in activators that activate some proteins found in plasma. These proteins are thrown out in the form of fibers as a network. This network traps the escaping RBCs and forms a clot. This process is called coagulation or clotting. A blood clot consists of: network of insoluble fibrin molecules. a plug of platelets
Hemostasis- prevention of blood loss from broken vessel Formation of a platelet plug - platelets aggregate at the point where a vessel ruptures. This occurs because platelets are exposed to collagen. Upon exposure to collagen, platelets release ADP (adenosine diphosphate) & thromboxane. These substances cause the surfaces of nearby platelets to become sticky and, as 'sticky' platelets accumulate, a 'plug' forms
Blood coagulation (clotting)
Fibrinolysis: dissolution of clot mechanism = plasminogen (a plasma protein) is activated by many factors & becomes PLASMIN. Plasmin then breaks down fibrin meshwork & phagocytic WBCs remove products of clot dissolution
Excessive bleeding: Hemophilia genetic 'defect' inability to produce certain clotting factor(s) Thrombocytopenia abnormally low platelet count most persons have idiopathic thrombocytopenia (= unknown cause) while in others it's an autoimmune disease
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