CLS 224: Lecture 4 - Blood (King Saud University) PDF

CLS 224 (Basic Anatomy & Physiology) Lecture 4: Blood Contents: 1. Composition and Functions of Blood 2. Developmental Aspects of Blood 3. Hemostasis 4. Blood Groups and Transfusions Blood Blood Composition and Functions of...

CLS 224 (Basic Anatomy & Physiology) Lecture 4: Blood Contents: 1. Composition and Functions of Blood 2. Developmental Aspects of Blood 3. Hemostasis 4. Blood Groups and Transfusions Blood Blood Composition and Functions of Blood Objectives: Describe the composition and volume of whole blood. Describe the composition of plasma, and discuss its importance in the body. Blood Composition and Functions of Blood The only fluid tissue in the human body Classified as a connective tissue Components of blood A. Living cells Formed elements B. Non-living matrix Plasma  If blood is centrifuged – Erythrocytes sink to the bottom (45 percent of blood, a percentage known as the hematocrit) – Buffy coat contains leukocytes and platelets (less than 1 percent of blood) Buffy coat is a thin, whitish layer between the erythrocytes and plasma – Plasma rises to the top (55 percent of blood) Physical Characteristics of Blood: Color range – Oxygen-rich blood is scarlet red – Oxygen-poor blood is dull red pH must remain between 7.35–7.45 Blood temperature is slightly higher than body temperature at 38°C (100.4°F). In a healthy man, blood volume is about 5–6 liters or about 6 quarts Blood makes up 8 percent of body weight Blood Plasma: Composed of approximately 90 percent water Includes many dissolved substances – Nutrients – Salts (electrolytes) – Respiratory gases – Hormones – Plasma proteins – Waste products Blood Plasma: Plasma proteins: – Most abundant solutes in plasma – Most plasma proteins are made by liver – Various plasma proteins include Albumin—regulates osmotic pressure Clotting proteins—help to stem blood loss when a blood vessel is injured Antibodies—help protect the body from pathogens Blood Plasma: Acidosis – Blood becomes too acidic Alkalosis – Blood becomes too basic In each scenario, the respiratory system and kidneys help restore blood pH to normal Formed Elements: a. Erythrocytes – Red blood cells (RBCs) b. Leukocytes – White blood cells (WBCs) c. Platelets – Cell fragments Formed Elements: a. Erythrocytes (red blood cells or RBCs): – Main function is to carry oxygen – Anatomy of circulating erythrocytes Biconcave disks Essentially bags of hemoglobin Anucleate (no nucleus) Contain very few organelles – 5 million RBCs per cubic millimeter of blood – Average lifespan is 120 days Formed Elements: Erythrocytes (red blood cells or RBCs) Formed Elements: Hemoglobin: – Iron-containing protein – Binds strongly, but reversibly, to oxygen – Each hemoglobin molecule has four oxygen binding sites – Each erythrocyte has 250 million hemoglobin molecules – Normal blood contains 12–18 g of hemoglobin per 100 mL blood Formed Elements: Hemoglobin: Formed Elements: Homeostatic imbalance of RBCs – Anemia is a decrease in the oxygen-carrying ability of the blood – Sickle cell anemia (SCA) results from abnormally shaped hemoglobin – Polycythemia is an excessive or abnormal increase in the number of erythrocytes Formed Elements: b. Leukocytes (white blood cells or WBCs): – Crucial in the body’s defense against disease – These are complete cells, with a nucleus and organelles – Able to move into and out of blood vessels (diapedesis) – Can move by ameboid motion – 4,800 to 10,800 WBC per cubic millimeter of blood Formed Elements: b. Leukocytes (white blood cells or WBCs): -Can respond to chemicals released by damaged tissues Formed Elements: b. Leukocytes (white blood cells or WBCs): Types of leukocytes ii. Agranulocytes i. Granulocytes Lack visible cytoplasmic granules Granules in their cytoplasm can be stained Nuclei are spherical, oval, or kidney-shaped Possess lobed nuclei Include lymphocytes and Include neutrophils, monocytes eosinophils, and basophils Formed Elements: b. Leukocytes (white blood cells or WBCs): List of the WBCs from Easy way to most to least abundant remember this list – Neutrophils – Never – Lymphocytes – Let – Monocytes – Monkeys – Eosinophils – Eat – Basophils – Bananas Formed Elements: b. Leukocytes (white blood cells or WBCs): Types of granulocytes 1. Neutrophils Cytoplasm stains pale pink and contains fine granules Deep purple nucleus contains three to seven lobes Function as phagocytes at active sites of infection Numbers increase during infection (40–70% of WBCs) Formed Elements: b. Leukocytes (white blood cells or WBCs): Types of agranulocytes 1. Lymphocytes Cytoplasm is pale blue Dark purple-blue nucleus Functions as part of the immune response – B lymphocytes produce antibodies – T lymphocytes are involved in graft rejection, fighting tumors and viruses (20–45% of WBCs) Formed Elements: b. Leukocytes (white blood cells or WBCs): Types of agranulocytes (continued) 2. Monocytes Largest of the white blood cells Gray-blue cytoplasm Dark blue-purple nucleus is often kidney shaped Function as macrophages Important in fighting chronic infection (4–8% of WBCs) Formed Elements: b. Leukocytes (white blood cells or WBCs): Abnormal numbers of leukocytes: – Leukocytosis WBC count above 11,000 leukocytes/mm3 Generally indicates an infection – Leukopenia Abnormally low leukocyte level Commonly caused by certain drugs such as corticosteroids and anticancer agents – Leukemia Bone marrow becomes cancerous, turns out excess WBC Formed Elements: c. Platelets: – Derived from ruptured multinucleate cells (megakaryocytes) – Needed for the clotting process – Average lifespan is 9 to 12 days – Platelet count ranges from 150,000 to 400,000 per cubic millimeter of blood Blood Hematopoiesis Objectives: Explain the role of the hemocytoblast. Blood Hematopoiesis Blood cell formation Occurs in red bone marrow All blood cells are derived from a common stem cell (hemocytoblast) Hemocytoblast differentiation a. Lymphoid stem cell produces lymphocytes b. Myeloid stem cell produces all other formed elements Blood Hematopoiesis Blood A. Formation of Erythrocytes Unable to divide, grow, or synthesize proteins Wear out in 100 to 120 days When worn out, RBCs are eliminated by phagocytes in the spleen or liver Lost cells are replaced by division of hemocytoblasts in the red bone marrow Blood Hematopoiesis Blood B. Formation of White Blood Cells and Platelets Controlled by: – Colony stimulating factors (CSFs) and interleukins prompt bone marrow to generate leukocytes – Thrombopoietin stimulates production of platelets Blood Hemostasis Objectives: Describe the blood-clotting process. Name some factors that may inhibit or enhance the blood-clotting process. Blood Hemostasis Platelet plug formation – Collagen fibers are exposed by a break in a blood vessel – Platelets become “sticky” and cling to fibers – Anchored platelets release chemicals to attract more platelets – Platelets pile up to form a platelet plug Blood usually clots within 3 to 6 minutes The clot remains as endothelium regenerates The clot is broken down after tissue repair Blood Hemostasis Blood Hemostasis Blood Hemostasis Blood Blood Groups and Transfusions Objectives: Describe the ABO and Rh blood groups. Explain the basis for a transfusion reaction. Blood Blood Groups and Transfusions Large losses of blood have serious consequences – Loss of 15 to 30 percent causes weakness – Loss of over 30 percent causes shock, which can be fatal Transfusions are the only way to replace blood quickly Transfused blood must be of the same blood group Blood Human Blood Groups Blood contains genetically determined proteins Antigens (a substance the body recognizes as foreign) may be attacked by the immune system Antibodies are the “recognizers” Blood is “typed” by using antibodies that will cause blood with certain proteins to clump (agglutination) Blood Human Blood Groups There are over 30 common red blood cell antigens The most vigorous transfusion reactions are caused by ABO and Rh blood group antigens Blood ABO Blood Groups Based on the presence or absence of two antigens – Type A – Type B The lack of these antigens is called type O Blood ABO Blood Groups Blood ABO Blood Groups Blood ABO Blood Groups The presence of both antigens A and B is called type AB The presence of antigen A is called type A The presence of antigen B is called type B The lack of both antigens A and B is called type O Blood ABO Blood Groups Blood type AB can receive A, B, AB, and O blood – Universal recipient Blood type B can receive B and O blood Blood type A can receive A and O blood Blood type O can receive O blood – Universal donor Blood ABO Blood Groups Blood Group RBC Antigens Plasma antibodies Blood that can be received AB A, B None A, B, AB, O Universal recipient B B Anti-A B, O A A Anti-B A, O O None Anti-A, Anti-B O Universal donor Blood Rh Blood Groups Named because of the presence or absence of one of eight Rh antigens (agglutinogen D) that was originally defined in Rhesus monkeys Problems can occur in mixing Rh+ blood into a body with Rh– (Rh negative) blood Blood Rh Dangers During Pregnancy Danger occurs only when the mother is Rh– and the father is Rh+, and the child inherits the Rh+ factor RhoGAM shot can prevent buildup of anti-Rh+ antibodies in mother’s blood Blood Rh Dangers During Pregnancy Blood Rh Dangers During Pregnancy The mismatch of an Rh– mother carrying an Rh+ baby can cause problems for the unborn child – The first pregnancy usually proceeds without problems – The immune system is sensitized after the first pregnancy – In a second pregnancy, the mother’s immune system produces antibodies to attack the Rh+ blood (hemolytic disease of the newborn) References: