Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Circulatory System -Cardiovascular & LymphaticsChapters 17 - 19 Chapter 17 - BLOOD Components Only fluid connective tissue Formed elements – living cells Fluid matrix – plasma Spun tube – 45% RBC’s, 1% buffy coat (WBC’s, Platelets), 55% plasma Characteristics Salty Alkaline (7.35 – 7.45 pH) Varied in color due to O2 content 5-6 L in males; 4-5 L in females 8% of body weight Functions (transportation &/or protection) Distribution O2 and food nutrients Wastes to lungs and kidneys Hormones from endocrine glands to target organs Maintains body temperature (absorbs and distributes body heat) Protection Maintains pH (reservoir for bicarbonate ions) Maintains fluid volume Prevents blood loss (through platelet action and blood proteins) Prevents infection (through WBC’s and antibodies) Formed Elements Erythrocytes (RBC’s) Characteristics Lacks nucleus and organelles – “bag of hemoglobin molecules”; 33% of RBC is hemoglobin ~ 8 mm in diameter; look like flat discs with depressed centers Shape provides large surface area ideal O2 transport Flexible due to spectrin (fibrous protein) which allows Rouleaux movement (stacking) when traveling through capillaries 800:1 RBC’s : WBC’s = blood viscosity 4.3 – 5.2 million cells/cc RBC count in women 5.1 – 5.8 million RBC count in men Number of cells correlates with viscosity; more RBC’s = more viscous blood = slower moving Function Carry O2 through their contained hemoglobin Hemoglobin consists of “globin” protein bound to red “heme” iron pigment Each hemoglobin contains 4 ringlike heme groups Each globin protein consists of 4 polypeptide chains; each chain is bound to a heme group Each iron atom can combine with one O2 Thus each hemoglobin can carry 4 O2’s Each RBC contains 250 million hemoglobin molecules = transporting 1 billion O2’s. Also carries CO2 on the globin so there is no competition for binding sites ~ 20% of CO2 is carried this way Production of RBC’s In red bone marrow of long and flat bones Arise from stem cells “Hemocytoblasts” which reside in bone marrow Hemocytoblast is transformed into a proerythroblast Proerythroblast give rise to early erythroblast (produce large amounts of ribosomes) Early erythroblast transforms into late erythroblast as hemoglobin production increases Late erythroblast transforms into normoblast when hemoglobin content reaches 34% Nucleus ceases functions and is ejected causing the center of cell collapse (thus the depressed center or disc shape) Normoblast transforms into reticulocyte (named for remaining rough ER) Up to this point takes 3-5 days Reticulocytes enter circulation and become mature erythrocytes in ~ 2 days. Process is balanced between production and destruction (about 2 million/sec) under hormonal control and with adequate amounts of iron and B vitamins. Hormonal Control RBC production is directly linked to erythrocyte hormone (which is in system at low levels all the time to maintain production as basal levels) Erythropoietin hormone is produced when kidney cells release REF (renal erythropoietin factor) in response to cell hypoxia. Hypoxia is due to Declining # of RBC’s due to hemorrhaging or excessive RBC destruction Reduced availability of O2 due to altitude or pneumonia Increased O2 demands by tissues during exercise It’s not the number of cells that controls erythropoietin, but the cell’s ability to transport O2 Erythropoietin stimulate red marrow to MATURE already committed cells at a faster rate than otherwise (1-2 days faster) Testosterone can stimulate kidneys to release REF (accounting for high RBC levels in men than women; conversely those with kidney failure have RBC counts less than half of normal individuals Dietary needs for erythropoietin production Need carbs, proteins, lipids, iron B-complex vitamins 65% of body’s iron supply is in hemoglobin, the rest is stored in liver, spleen and marrow (because free iron is toxic to tissues) as ferritin, hemosiderin, or transferrin Iron loss is 1.7 mg and 0.9 mg per day in women and men respectively B-12 and folic acid are needed for DNA synthesis in immature RBC’s Destruction of RBC’s Because they are anucleate, they cannot synthesize proteins, reproduce, grow, etc. Lifespan of 100-120 days Dying cells become trapped in capillaries of spleen and are engulfed by roaming phagocytes Hemoglobin is degraded into billirubin and secreted in the bile by the liver Released iron is salvaged and recycled Disorders (anemias or polycythemia) Anemias – reduced O2 carrying ability of blood (really a symptom rather than a disease) Hemorrhagic anemia – results from blood loss; corrected by blood replacement Hemolytic anemia – erythrocytes are ruptured prematurely (hemoglobin abnormalities, blood mismatch, bacterial or parasitic infection, congenital defects in plasma membrane) Aplastic anemia – destruction or inhibition of red marrow (cancer and the drugs used to treat cancer can cause marrow to be replaced by connective tissue); blood transfusions are used until a bone marrow transplant can be performed Iron deficiency anemia – inadequate intake of ironcontaining foods, impaired iron absorption Pernicious anemia – deficiency in vitamin B-12, usually due to lack or intrinsic factor necessary to absorb B-12 from the diet Thalassemia – genetic in origin, RBC count is less than 2 million cells/cc, RBC’s are small and delicate due to hemoglobin molecule abnormality Sickle-cell anemia – abnormal hemoglobin is spiky and sharp causing cells to become crescent shaped; cells rupture prematurely causing vessels to dam up and cause clots. Polycythemia – excessive or abnormal increase in the number of erythrocytes. Viscosity is increased causing sluggish blood flow. Usual cause is bone cancer. Secondary polycythemia – normal in those living at high altitudes due to secretion of erythropoietin in response to reduced O2 levels. Leucocytes (WBC’s) 800: 1 RBC’s:WBC’s 4,000-11,000 WBC/cc (anymore = leukocytosis) 1% of total blood volume Contain nuclei and organelles Protect from damage caused by viruses, bacteria, toxins, parasites, cancer Display diapedesis (slip in and out of blood vessels) by amoeboid movement Can respond to chemical distress signals given out by damaged and dying tissues (positive chemotaxis) 2 major categories based on structural and chemical characteristics: Granulocytes – lobed nuclei and stained granules – appears “grainy” Neutrophils most numerous 2x RBC size ½ of WBC population 3-5 lobes, hard to see granules digest bacteria #’s elevate with staph, salmonella, systemic yeast, and appendicitis infections Basophils Least numerous Slightly larger than RBC’s, U or S shaped nucleus Few purple granules When found in tissues are called “mast cells” When bound to antibodies release heparin (anticoagulant) and histamine (vasodilator) to help WBC migration Eosinophils 2x RBC size 1-4% of WBC population Nucleus is bi-lobed Large, coarse red granules Eat antigen-antibody complexes Elevation can indicate allergic reactions, parasitic worm or protozoan infections Reside in intestines, lungs and skin Agranulocytes – lack granules Lymphocytes 2nd most numerous Found in lymph tissue Small portion in bloodstream Immune cell (T and B cells) production Large, dark, purple nucleus which occupies most of the cell May have a thin rim of pale blue cytoplasm Act against virus infected cells and tumors Monocyte Largest WBC Also called “macrophages” Gray-blue cytoplasm, dark blue-purple U or kidney shaped nucleus Elevation may indicate a chronic viral or bacterial infection such as leprosy or tuberculosis 3 Monocyte 1 Basophil 4 2 Lymphocyte 5 Neutrophil Eosinophil Production of WBC’s Leukopoiesis – hormonally triggered All arise from hemocytoblasts Some mature in the thymus gland; others in the bone marrow Disorders Leukemia – “white blood” Abnormal WBC’s which fail to respond to regulatory mechanisms Remain unspecialized Enhanced lymphoblastic ability to divide Impair or suppress normal bone marrow function Named according to cell type: “myelocytic” or “lymphocytic” leukemias promyelocytic Infectious mononucleosis Viral (Epstein-Barr virus) Elevated monocytes and lymphocytes Leukopenia – decreased number of WBC’s; usually due to chemotherapy Platelets (Thrombocytes) Not true cells; are fragments Anucleated Arise from stem cells, become megakaryocyte then fragment 250,000 – 500,000 /cc Essential for clotting Degenerate in 10 days Hemostasis – (stopping blood flow) Vasconstriction – Constriction of blood vessels triggered by injury to smooth muscle wall of vessel, compression of vessel by escaping blood, chemicals released by platelets, pain receptors being stimulated 20-30 minutes of reduced blood flow More efficient when vessel is crushed rather than blunt cut . Blunt cuts have less tissue damage and more profuse blood flow Platelet Plug (+) charged platelet clings to the (-) charged collagen tissue under the endothelium Platelets develop swollen, spiky processes Platelet granules degenerate and release chemicals This sets up a series of clotting events which calls more platelets to the injury site Aspirin inhibits plug formation Takes about 1 minute Plug Formation Coagulation (blood clotting) Prothrombin ------> thrombin Thrombin + fibrinogen = fibrin mesh 30 different factors involved; + each require Ca Most are plasma proteins made in the liver Absence of any one of these factors results in the inability to coagulate blood (hemophilia is an example) Takes about 3-6 minutes COAGULATION Clot Retraction Within 30 – 60 minutes, platelets shrink and pull fibrin fibers closer together, further sealing edges of wound Fibrinolysis – Clot disposal Within 2 days, plasmin enzyme (activated by healing endothelium and factors in the clot itself) will begin to eat away at the clot Fibrinolysis Pathology Thrombus – undesirable clot in an unbroken vessel Embolus – thrombus that has broken free and is traveling in the circulatory system Any roughening of vessel walls can exacerbate this (atherosclerosis, burns, inflammation, immobilization, etc) Ruptured cholesterol plaque with thrombus Thrombocytopenia – decrease in the number of platelets, causes numerous, small, hemorrhages body wide (petechiae). Caused by anything that would destroy bone marrow (drugs, radiation). Diagnosed with a platelet count under 50,000/cc. Often need blood transfusions Impaired Liver Function – can’t manufacture coagulants due to vitamin K deficiency, hepatitis, cirrhosis, etc Hemophilia Type A – lack Factor VIII – 83% Type B – lack Factor IX Type C – lack Factor X Plasma 90% water 10% “other stuff” – gases, hormones, nutrients, wastes, ions, proteins (albumin, clotting proteins, globulins), etc. Transfusions Losses of 15 – 30 % causes paleness and weakness; more than 30% = severe shock RBC’s have specific antigens (flags) on their surface Plasma has agglutinogens (soldiers) floating in it which attach to and clump foreign antigens Foreign blood will be agglutinated (clumped) and destroyed Type A – A antigens, Anti-B agglutinogens – can receive A and O blood Type B – B antigens, Anti-A agglutinogens – can receive B and O blood Type AB – A & B antigens, no agglutinogens – can receive all blood types (universal recipient) Type O – no antigens, Anti-A & Anti-B agglutinogens – can receive only O (universal donor) Rh factor is another type of antigen Transfusion reactions can involve lowered oxygen carrying ability, blocked blood vessels, renal shut down from liberated hemoglobin in the system, fever, chills, nausea, vomiting Any Questions?