Blood And Its Components Lecture Notes PDF

Blood and its components By the end of this lecture: Describe components of the blood; cells and plasma Identify constituents of plasma and function Describe types of blood cells and their functions Discuss blood groups and importance Blood Blood is a specialized body fluid that flows...

Blood and its components By the end of this lecture: Describe components of the blood; cells and plasma Identify constituents of plasma and function Describe types of blood cells and their functions Discuss blood groups and importance Blood Blood is a specialized body fluid that flows throughout the body to carry oxygen, CO2, nutrients, hormones and others  Properties of Blood 1. Color: Blood is red in color.  Arterial blood: is scarlet red ( has more oxygen)  venous blood: is purple red ( carbon dioxide). 2. Volume: Average volume of blood in a normal adult is 5 L 3. Reaction:alkaline 4. PH: in normal conditions is 7.4. Properties of Blood 4. Specific gravity: Specific gravity of total blood: 1.052 to 1.061 5. Viscosity: Blood is five times more viscous than water. It is mainly due to red blood cells and plasma proteins The Functions of Blood Distribution and transport Delivers oxygen from lungs and nutrients from gastrointestinal tract to entire body Transfers metabolic waste products from cells to elimination sites (lungs and kidneys) Transports hormones from endocrine glands to target organs Maintenance of body temperature Absorbing and distributing metabolic heat Blood maintains temperature homeostasis with variable blood flow through the skin Regulation and maintenance of normal pH Buffers (proteins and ions) Maintenance of water content of cells with blood osmotic pressure Components of blood are involved in clot formation, thus preventing excessive blood/fluid loss Protection Blood carries components of the immune system to prevent infection The Composition of Blood Blood is composed of:  Cells 1) Erythrocytes ( RBC ) 2) Leukocytes ( WBC ) 3) Platelets 4) Plasma proteins  Plasma Plasma The liquid part of the blood Composed of water and a mixture of organic and inorganic substances  92% water  7% plasma proteins  < 1% other material  Electrolytes, buffers, nutrients, gases, hormones, wastes, etc. Functions of plasma:  Transports nutrients and gases  Regulates fluid and electrolyte balance  Helps maintain stable pH Serum  Plasma without plasma proteins Plasma Proteins Functions: Maintain plasma osmotic pressure  Very important for maintaining blood volume Maintain proper blood pH Clotting Immunity Plasma Proteins - 3 Groups Albumins Comprise 55% of plasma proteins Functions:  Maintain osmotic pressure  Transport hormones and fatty acids in the blood Globulins Comprise 36% of plasma proteins Functions:  Transport iron, fats, and fat-soluble vitamins in the blood.  Gamma globulins function as antibodies in providing immunity Fibrinogen Comprises 7% of plasma proteins The largest plasma proteins, but least numerous Function:  Clotting  SERUM Serum is the fluid that formed of blood clot (after about 45 minutes). When the blood is shed or collected in a container, it clots. In this process, the fibrinogen is converted into fibrin and the blood cells are trapped in this fibrin forming the blood clot. It is different from plasma only by the absence of fibrinogen, i.e. serum contains all the other constituents of plasma except fibrinogen. Serum = Plasma – Fibrinogen Formed Elements All blood cells are the formed elements:  Erythrocytes (RBC)  Leukocytes (WBC)  Platelets Synthesized in bone marrow  In children, the marrow of all bones produce blood cells  In adults, only the marrow of the flat bones of the skull. Erythrocytes (RBC) The RBC is one of the most specialized cell type in the body carry hemoglobin (Hb)  Hb comprises ~ 1/3 of the RBC’s total weight In an adult male, there are 5 - 6 million RBCs/mm3  ~ 30 trillion RBCs circulating in blood Women and children have about 4.5 - 5 million RBCs/mm Erythrocytes (RBC) - Characteristics Tiny size (8 microns) and flexible  Able to pass through the narrow lumen of the smallest blood vessels Flexible, biconcave disks No nucleus or other organelles Life span of RBC – 120 days Function – Transport of gases ( O2and CO2 ) from lungs to other parts of body Hemoglobin (Hb) Hb is the oxygen carrying component of RBCs Hb binds reversibly to oxygen Hemoglobin is found in two forms: Oxyhemoglobin  Gives blood its bright red color.  Hb + O2 —> HbO2 Deoxyhemoglobin  Has a dark red color and gives veins a bluish tint  HbO2 —> Hb + O2 Hemoglobin (Hb) Hb is composed of 4 globin molecules  Each globin molecule contains a heme group FUNCTION OF HEMOGLOBIN Carries oxygen and carbon dioxide. Oxygen from the lungs to tissues (oxyhemoglobin). Carbon dioxide from tissues to lungs (carbamino- hemoglobin.). Normal Hemoglobin Content Average hemoglobin (Hb) content in blood is 14 to 16 g/dL, the value varies depending upon the age and sex of the individual TYPES OF NORMAL HEMOGLOBIN 1. Adult hemoglobin – HbA 2. Fetal hemoglobin – HbF Replacement of fetal hemoglobin by adult hemoglobin starts immediately after birth. Leukocytes (WBC) Represent only ~ 1% of total blood volume WBCs are Synthesized in bone marrow WBCs are unlike RBCs the following ways: 1. Contain a nucleus and organelles 2. Do not contain hemoglobin 3. Not always contained in blood vessels 4. Diapedesis: WBCs are able to move in and out of blood vessels with amoeboid motion 5. Chemotaxis: WBCs follow a chemical trail leading to the site of tissue damage Function – Defense mechanism and immunity Leukocytes (WBC) – 2 Groups Classified based on structure and function Granulocytes  Lobed nuclei  Granules in cytoplasmic  Very short average life span, about 12 hours Agranulocytes  Spherical or oval nuclei  Lack granules in cytoplasmic  Long life span, greater than 12 hours White blood cells White blood cells Different types of blood cells White blood cell count Total leucocyte count is 4,000 - 10,000/cu mm Increase in WBC is known as leukocytosis Decrease in WBC is known as leukopenia Life span – 12 – 20 days Neutrophils – 54% - 70% Basophils – 0 – 1 % Eosinophils – 2 – 4% Monocytes – 3 – 8 % (largest of all WBC ) Lymphocytes – 22 – 30 % Platelets (Thrombocytes) Anucleate cell fragments  Formed from the fragments of a larger cell, a megakaryocyte 1) Megakaryocytes are derived from stem cells in bone marrow Life span of about 10 days Contain many cytoplasmic granules  These granules are loaded with enzymes Function:  Stop bleeding through the process of hemostasis or clotting of blood  Platelets play a vital role in blood loss by the formation of platelet plugs blood clotting.  Blood groups (types) There are 4 main blood groups (types of blood) – A, B, AB and O. Type A Type B Type AB Type O Rhesus antigen Blood transfusion m Summary Blood consists of plasma and cells Blood cells are white blood cells, red blood cells and platelets Hemoglobin carries oxygen and CO2 White blood cells are important for defense and consist of many types Platelets are small components for clotting Blood groups A, B, AB and O Rhesus factor R+ and R-