Lecture 2- The Blood PDF

LECTURE 2 Dr. Thaer AL.Mashhadani The Blood Blood is a fluid connective tissue. It circulate continually around the body, allowing constant...

LECTURE 2 Dr. Thaer AL.Mashhadani The Blood Blood is a fluid connective tissue. It circulate continually around the body, allowing constant communication between tissues distant from each other. Blood makes up about 7% of body weight (about 5.6 liters in a 72 Kg man). This proportion is less in women, while in children is greater (gradually decreasing until the adult level is reached). Functions of the Blood: 1. The main function of blood is to maintain intracellular homeostasis by: a). Carries O2 and nutrients (glucose, amino acids, lipids) to the cells. b). Carries CO2 and other wastes (nitrates, creatine) away from the cell. 1 LECTURE 2 Dr. Thaer AL.Mashhadani 2. Providing intercellular communication in the body: carries hormones (secreted by endocrine glands) to the target organs. 3. Protection and defense: it allows cells and immunological proteins to transport from place to place where need them. 4. Self repair mechanism: clotting cascade. 5. Regulating body temperature. 6. Blood brings waste products to the kidneys and liver. Blood Components: 1. Plasma: Plasma makes up about 55% of the body's total blood volume, the constituents of plasma are: 1. Water (90-92%). 2. Plasma proteins: make up about 7% of plasma. a. Albumins: (about 60% of total plasma protein): the main functions are: 1. They are responsible for maintain normal plasma osmotic pressure. 2. Act as carrier molecules as nutrient elements, free fatty acids, some drugs and steroid hormones. b. Globins: the main functions are: 1. As antibodies (immunoglobulins). 2. Transportation of some hormones and mineral salts. 2 LECTURE 2 Dr. Thaer AL.Mashhadani 3. Clotting factors. c. Fibrinogen: Produced in the liver, during tissue is injury, it is converted enzymatically by thrombin to fibrin and then to a fibrin-based blood clot. 3. Inorganic salts (electrolytes) like Ca, Na, Po4 which are responsible for muscle contraction, transmission of nerve impulses. 4. Nutrients: glucose, amino acid, fatty acids and glycerol. 5. Waste products like urea, creatinine and uric acid. 6. Hormones and gases transport. 2 Cellular Content of Blood :There are three types of blood cell: 1.Erythrocytes (Red Blood Cells =RBC). 2. Platelets (thrombocytes). 3 LECTURE 2 Dr. Thaer AL.Mashhadani 3. Leukocytes (white blood cells = WBC) they include Monocytes, Lymphocytes, Neutrophils, Eosinophils, and Basophils. Source of Blood Cells: 1. Mature blood cells have a relatively short life spine. 2. Blood cells are synthesised mainly in the red bone marrow. 3. Some lymphocytes, additionally are produced in lymphoid tissue. 1.Erythrocytes = (Red Blood Cells =RBC). Red blood cells are the most common type of blood cell, have no nucleus and cytoplasmic organelles. They contain a red coloured protein called hemoglobin. The main function of RBC is gas transport, mainly of O2 but they also carry some CO2. The biconcave shape increases their surface area for gas exchange, and the thinness of the central portion allows fast entry and exit of gases. The red blood cells count approximately (3.9- 5.5) million per microliter in women and (4.1-6 ) million per microliter in men. Erythrocytes are produced in red bone marrow (in the ends of long bones and in flat and irregular bones). Hemoglobin (Hb) : Hb is the most important constituent of red blood cells. It is responsible for transport of O2 from lungs to tissues and CO2 from tissues to lungs. The normal value of Hbin adult male adult )13-18 g\100ml( and in female is )11.5- 16.5 g\100ml(, the molecules structure of Hb are made up of heme and globin. 4 LECTURE 2 Dr. Thaer AL.Mashhadani Heme: is made up of iron (in ferrous form) and porphyrin. Globin: is a protein that has 4 polypeptides chains (2 alpha and 2 beta). Each unit of Hb contains 4 units of heme that are united together by the alpha and beta chains of globin. Each unit of heme can combine with one molecule of O2. So one molecule of Hb can carry 4 molecule of O2. Blood Groups: There are 4 main blood groups defined by the ABO system: 1. Persons of blood group A have antigen of type A on their red blood cells. serum contains antibodies of type B. 2. Persons of blood group B have antigen of B on their red blood cells. Their serum contains antibodies of type A. 5 LECTURE 2 Dr. Thaer AL.Mashhadani 3. Persons of blood group AB have antigens of both types A and B. they do not have type A or type B antibodies. 4. Persons of blood group O did not has A nor B antigens. antibodies of both types A and B are present. 5. Rh factor or antigen (Rhesus factor), about 85% of people have this antigen own cell membrane of RBC. 2. Leucocytes = White Blood Cells (W.B.C.): Leucocytes are the largest blood cells. They account for only about 1% of the blood volume. There are two main types of (W.B.C.): 1. Granulocytes: Which contain granules in their cytoplasm: and they ( Neutrophils, Easinophils and Basophils. ) 2. Agranulocytes : did not contain granules in their cytoplasm: (Monocytes and lymphocytes). Granulocytes: 1. Neutrophils: *Represent 60-70% of total WBC. *Have short half life 6-7 hours in blood and 1-4 days in the tissues. * With nucleus consisting of 2-5 lobes. *Have phagocytic activity against bacteria and other small particles. 6 LECTURE 2 Dr. Thaer AL.Mashhadani 2. Basophils: * Constitute 2-4% of leukocytes in normal blood. * Live in circulation about 10 hours and 10 days in tissues. * Have bilobed nucleus, The cytoplasm contains large granules. Agranulocytes: `1. Lymphocytes: * Cpherical cells, and Constitute about 20-30%. * Nucleus of lymphocyte are large and rounded. * Lymphocytes vary in life; some live only a few days and other survive for many years. *Defending against invading microorganisms, and cancer cells. 2. Monocytes : * The largest of the white blood cells, and Constitute about 5% of total W.B.C. *The nucleus is horseshoe- or kidney-shaped. * Migrate into the tissues and develop into macrophages. * Monocytes live in the circulation is few days but 60-120 days in the tissues. 7 LECTURE 2 Dr. Thaer AL.Mashhadani Use of blood in forensic evidence Blood is one of the most important biological traces that are often found on the crime scen. Analysis of different aspects of bloodstains can contribute to clarify the circumstances under which some violent crimes have been committed. The technological state of blood evidence analysis has rapidly advanced in the last 20 years. In the early seventies, most crime labs relied upon the ABO blood grouping system to characterize bloodstains. This meant that the blood could have come from 49% of the population. In the 1990's, most crime labs are relying on DNA analysis to characterize bloodstains. A blood source can now be statistically narrowed down to one person out of several million or even several billion. The most important things when collecting a blood sample 1. Blood evidence must never be exposed to excessive heat or humidity. If possible, the bloodstained evidence should be refrigerated until it can be transported to the crime lab 2. The part of the body from which the blood has come can found out from the nature of extraneous matter. Thus, blood from nose, mouth, vagina or anus can be identified. 3. Diseases like leukaemia or syphilis can be detected microscopically. Blood Testing Mechanisms in Forensic Evidence: 1. Evidence collection: At the crime scene, investigators carefully collect blood samples using sterile tools to avoid contamination. Blood found on 8 LECTURE 2 Dr. Thaer AL.Mashhadani surfaces, clothes, the ground, or even on perpetrators and victims is collected. 2. Blood source identification tests: Testing to determine whether the blood is human: Special tests such as deoxyribonucleic acid (DNA) testing or serological tests are performed to determine whether the blood is human or animal. 3. Blood type testing: After confirming that the blood is human, the blood type (A, B, AB, O) can be analyzed to narrow down the circle of suspects. 4. DNA analysis: DNA analysis is considered one of the strongest pieces of evidence in criminal cases. DNA is extracted from blood cells, and then compared to the DNA of suspects or victims to determine whether it matches a specific person. 5. Detecting hidden blood: Sometimes, the blood is cleaned or wiped away, so chemicals such as Luminol are used that react with the hemoglobin in the blood, making the hidden stains glow under the light. 9