Cardiovascular System: Blood PDF

CARDIOVASCULAR SYSTEM: BLOOD PREPARED BY ALARZAR CARDIOVASCULAR SYSTEM ¡ Consists of: ¡ Blood ¡ Heart ¡ Blood Vessels ¡ Connects the various tissues of the body ¡ The heart pumps the blood through a network of blood vessels which is refers to as the circulatory system ¡ Blood delivers nut...

CARDIOVASCULAR SYSTEM: BLOOD PREPARED BY ALARZAR CARDIOVASCULAR SYSTEM ¡ Consists of: ¡ Blood ¡ Heart ¡ Blood Vessels ¡ Connects the various tissues of the body ¡ The heart pumps the blood through a network of blood vessels which is refers to as the circulatory system ¡ Blood delivers nutrients and picks up waste products at the body tissues FUNCTIONS OF BLOOD 1. Transport of gases, nutrients and waste products 2. Transport of processed molecules 3. Transport of regulatory molecules 4. Regulation of pH and osmosis 5. Maintenance of body temperature 6. Protection against foreign substances 7. Clot formation COMPOSITION OF BLOOD ¡ Type of connective consisting of liquid matrix (PLASMA) with cells and cell fragments (FORMED ELEMENTS) ¡ Total blood volume is around ¡ Female: 4-5L ¡ Male 5-6 L COMPOSITION OF BLOOD Blood is a sticky, opaque fluid with a metallic taste Color varies from scarlet to dark red The pH of blood is 7.35–7.45 Temperature is 38°C Blood accounts for approximately 8% of body weight Average volume: 5–6 L (1.5 gallons) for males, and 4–5 L for females PLASMA ¡ Pale, yellow fluid that consists of around ¡ Ions 91% water and 9% other substances ¡ Nutrients ¡ Considered a colloid containing ¡ Waste Prodcuts suspended substances that do no settle out such as plasma proteins (7%) ¡ Gases ¡ Contains ¡ Regulatory Substances ¡ Water ¡ Plasma Proteins  PLASMA PROTEINS 1. ALBUMIN 1. important in regulating the movement of water between the tissues and blood (colloid osmotic pressure) 2. Bind and transport other molecules in the blood 2. GLOBULIN 1. Transport of substances in the blood 2. Includes ANTIBODIES that protect against microorganisms 3. FIBRINOGEN 1. Responsible for the formation of blood clots 2. SERUM – refers to plasma without clotting factors PRODUCTION OF FORMED ELEMENTS ¡ HEMATOPOIESIS – process of blood cell production ¡ After birth, occurs primarily in the red bone marrow ¡ For some WBC’s, maturation happens in the lymphatic tissue ¡ In adults, red bone marrow is found in the ribs, sternum, vertebrae, pelvis, femur and humerus ¡ All formed elements are derived from stem cells called HEMOCYTOBLASTS PRODUCTION OF FORMED ELEMENTS Most blood cells do not divide but are renewed by stem cells (hemocytoblasts) in bone marrow Hematopoiesis: blood cell production Occurs in different locations before and after birth Fetus Liver, thymus, spleen, lymph nodes, and red bone marrow After birth In the red bone marrow of the Axial skeleton and girdles Epiphyses of the humerus and femur Some white blood cells are produced in lymphatic tissues Hemocytoblasts give rise to all formed elements Growth factors determine the type of formed element derived from the stem cell PRODUCTION OF FORMED ELEMENTS ¡ Chemical signals regulate the development of the formed elements ¡ Includes Colony-Stimulating Factors (CSFs) and hormones transported to the bone marrow ¡ EPO (Eyrthropoietin), a hormone secreted by endocrine cells of the kidney stimulated myeloid stem cells to develop into RBCs RED BLOOD CELLS Biconcave discs, anucleate, essentially no organelles RBCs are dedicated to respiratory gas transport Filled with hemoglobin (Hb), a protein that functions in gas transport Biconcave shape has a huge surface area relative to volume Structural characteristics contribute to its gas transport function Biconcave shape also allows RBCs to bend or fold around their thin center Gives erythrocytes their flexibility Allow them to change shape as necessary  Hemoglobin (Hb) Accounts for about a third of the cell’s volume Consists of The protein globin, made up of two alpha and two beta chains, each bound to a heme group Each heme group bears an atom of iron, which can bind to one oxygen molecule Heme molecules transport oxygen (Iron is required) Oxygen content determines blood color Oxygenated: bright red Deoxygenated: darker red Globin molecules transport carbon dioxide One RBC contains 250 million Hb groups thus it can carry 1 billion molecules of O2 HEMOGLOBIN RBC TRANSPORT ¡ Oxygen attach to the heme group and combine with iron atoms ¡ Hemoglobin bound to O2 is called OXYHEMOGLOBIN ¡ Hemoglobin not bound to O2 is called DEOXYHEMOGLOBIN ¡ CO2 does not combine with iron atoms but attaches to the globin molecule ¡ CARBAMINOHEMOGLOBIN vs CARBOXYHEMOGLOBIN ¡ NO (Nitric Oxide) can also be transported by hemoglobin ¡ Chemical messenger that induces the relaxation of smooth muscle of blood vessels ¡ Binds to the cysteine amino acid in the 𝛽-globin RBC TRANSPORT Transport of Oxygen and Carbon Dioxide Oxygen Transported bound to hemoglobin ~98.5% Dissolved in plasma ~1.5% Each Hb molecule binds four oxygen atoms in a rapid and reversible process Carbon dioxide Dissolved in plasma ~7% Transported as bicarbonate(HCO3–) ~70% Chemically bound to hemoglobin ~23% TRANSPORT AND EXCHANGE OF CARBON DIOXIDE Carbon dioxide diffuses into RBCs and combines with water to form carbonic acid (H2CO3), which quickly dissociates into hydrogen ions and bicarbonate ions In RBCs, carbonic anhydrase reversibly catalyzes the conversion of carbon dioxide and water to carbonic acid FORMATION OF RBC RBC PRODUCTION Circulating erythrocytes: The number remains constant and reflects a balance between RBC production and destruction Too few RBCs leads to tissue hypoxia Too many RBCs causes undesirable blood viscosity Erythropoiesis is hormonally controlled and depends on adequate supplies of iron, amino acids, and B vitamins (folate and B12) Erythropoietin (EPO) release by the kidneys is triggered by Hypoxia due to decreased RBCs Decreased oxygen availability Increased tissue demand for oxygen Enhanced erythropoiesis increases the RBC count in circulating blood Oxygen carrying ability of the blood NEGATIVE FEEDBACK MECHANISM FOR ERYTHROPOIESIS RBC LIFE CYCLE The life span of an erythrocyte is 100–120 days Old RBCs become rigid and fragile, and their Hb begins to degenerate Dying RBCs are engulfed by macrophages located in the spleen or liver Heme and globin are separated and the iron is salvaged for reuse Globin chains are broken down to individual amino acids and are metabolized or used to build new proteins Iron released from heme is transported to the red bone marrow and is used to produce new hemoglobin Heme becomes bilirubin that is secreted in bile In the intestines bilirubin is converted by bacteria into other pigments Gives feces its brown color Gives urine its yellow color HEMOGLOBIN BREAKDOWN WHITE BLOOD CELLS Only blood components that are complete cells Are less numerous than RBCs Make up 1% of the total blood volume Two functions of WBCs Protect the body against invading microorganisms Remove dead cells and debris from tissues by phagocytosis Named according to their appearance in stained preparations Granulocytes: contain large cytoplasmic granules Agranulocytes: very small granules that cannot be easily seen with the light microscope WHITE BLOOD CELL - MOVEMENT 1. AMEBOID MOVEMENT – ability to move like amoeba by putting out cytoplasmic projections 2. DIAPEDESIS – WBCs become thin and elongated and slip between cells of blood vessel walls 3. CHEMOTAXIS – attraction to foreign materials or dead cells within the tissue BUFFY COAT WHITE BLOOD CELLS/ LEUKOCYTES WHITE BLOOD CELLS Granulocytes: neutrophils, eosinophils, and basophils Contain cytoplasmic granules that stain specifically (acidic, basic, or both) with Wright’s stain Are larger and usually shorter- lived than RBCs Have lobed nuclei Are all phagocytic cells WHITE BLOOD CELLS Neutrophils most common type of WBC Have two types of granules that: Take up both acidic and basic dyes Give the cytoplasm a lilac color Contain peroxidases, hydrolytic enzymes, and defensins (antibiotic-like proteins) Neutrophils are our body’s bacteria slayers Pus is an accumulation of dead neutrophils, cell debris and fluid at sites of infections WHITE BLOOD CELLS Basophils account for 0.5% of WBCs Have large, purplish-black (basophilic) granules that contain Histamine: inflammatory chemical that acts as a vasodilator and attracts other WBCs (antihistamines counter this effect) Heparin: prevents the formation of clots WHITE BLOOD CELLS Eosinophils account for 1–4% of WBCs Have red-staining, bilobed nuclei connected via a broad band of nuclear material Have red to crimson (acidophilic) large, coarse, lysosome-like granules Lessen the severity of allergies by reducing inflammation Lead the body’s counterattack against parasitic worms WHITE BLOOD CELLS Agranulocytes: lymphocytes and monocytes Lack visible cytoplasmic granules Are similar structurally, but are functionally distinct and unrelated cell types Have spherical (lymphocytes) or kidney-shaped (monocytes) nuclei WHITE BLOOD CELLS Lymphocytes account for 25% or more of WBCs Have large, dark-purple, circular nuclei with a thin rim of blue cytoplasm Are found mostly enmeshed in lymphoid tissue (some circulate in the blood) There are two types of lymphocytes: T cells and B cells B cells Stimulated by bacteria or toxins Give rise to plasma cells, which produce antibodies T cells Protect against viruses and other intracellular microorganisms Attack and destroy the cells that are infected WHITE BLOOD CELLS Monocytes account for 4–8% of leukocytes They are the largest leukocytes They have an abundant pale-blue cytoplasm They have purple-staining, U- or kidney- shaped nuclei They leave the circulation, enter tissue, and differentiate into macrophages Are highly mobile and actively phagocytic Activate lymphocytes to mount an immune response PLATELETS Fragments of megakaryocytes with a blue-staining outer region and a purple granular center Function in clotting by two mechanisms 1. Formation of platelet plugs, which seal holes in small vessels 2. Formation of clots, which help seal off larger wounds in the vessels Their granules contain ADP and thromboxanes HEMOSTASIS A series of reactions for stoppage of bleeding Three phases occur in rapid sequence 1. Vascular spasms: immediate vasoconstriction in response to injury * Thromboxanes and endothelin can cause vascular spasms 2. Platelet plug formation 3. Coagulation (blood clotting) VASCULAR SPASM ¡ Immediate but temporary constriction of a blood vessel ¡ Occurs when smooth muscle within the wall of the vessel contracts ¡ Damage can activate the nervous system and release chemicals that cause vascular spasm ¡ ENDOTHELIN – produced by endothelial cells ¡ THROMBOXANES – released by platelets  ¡ PLATELET PLUG – accumulation of platelets that can seal small breaks in PLATELET PLUG blood vessels. Smalls tears occur many times in the body each day and FORMATION platelet plug formation quickly closes them COAGULATION (BLOOD CLOTTING) ¡ When a blood vessel is severely damaged, coagulation results ¡ BLOOD CLOT – network of threadlike protein called fibrin that traps blood cells, platelets and fluids ¡ Depends on clotting factors found in plasma CLOT FORMATION BLOOD CLOTTING Blood clotting begins with the extrinsic or intrinsic pathway Both pathways end with the production of activated factor X Extrinsic pathway begins with the release of thromboplastin from damaged tissue Intrinsic pathway begins with the activation of factor XII BLOOD CLOTTING Activated factor X, factor V, phospholipids, and Ca2+ form prothrombinase Prothrombin is converted to thrombin by prothrombinase Fibrinogen is converted to fibrin by thrombin Insoluble fibrin strands form the structural basis of a clot Fibrin causes plasma to become a gel-like trap Fibrin in the presence of calcium ions activates factor XIII that: Cross-links fibrin Strengthens and stabilizes the clot Away from the site of injury anticoagulants in the blood, such as antithrombin and heparin, prevent clot formation CLOT RETRACTION AND FIBRINOLYSIS Clot retraction: stabilization of the clot by squeezing serum from the fibrin strands Results from the contraction of platelets, which pull the edges of damaged tissue closer together Serum, which is plasma minus fibrinogen and some clotting factors, is squeezed out to the clot Thrombin and tissue plasminogen activator activate plasmin, which dissolves fibrin (fibrinolysis) BLOOD GROUPING RBC membranes have glycoprotein antigens on their external surfaces These antigens are: Unique to the individual Recognized as foreign if transfused into another individual Promoters of agglutination and are referred to as agglutinogens Presence or absence of these antigens is used to classify blood groups ABO BLOOD GROUP The ABO blood groups consists of: Two antigens (A and B) on the surface of the RBCs Two antibodies in the plasma (anti-A and anti-B) RH BLOOD GROUP Rh-positive blood has certain Rh antigens (the D antigen), whereas Rh-negative blood does not Antibodies against the Rh antigen are produced when a Rh-negative person is exposed to Rh- positive blood The Rh blood group is responsible for hemolytic disease of the newborn, which can occur when the fetus is Rh-positive and the mother is Rh- negative DIAGNOSTIC BLOOD TESTS Laboratory examination of blood can assess an individual’s state of health Microscopic examination: Variations in size and shape of RBCs: prediction of anemia Type and number of WBCs: diagnostic of various diseases Chemical analysis can provide a comprehensive picture of one’s general health status in relation to normal values NORMAL VALUES DIAGNOSTIC BLOOD TESTS ¡ TYPE AND CROSSMATCH ¡ Determines ABO and Rh Blood groups ¡ Necessary for blood transfusions ¡ Donor should match the recipient CLOTTING BLOOD CHEMISTRY ¡ The composition of materials dissolved or suspended in plasma (e.g., glucose, urea nitrogen, bilirubin, and cholesterol) can be used to assess the functioning and status of the body’s systems.