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
Chapter 14 Blood Structure & Function • Blood is a type of connective tissue (consists of cells in a matrix) • Function – transports O2 & nutrients, maintains homeostasis, protection from blood loss & infection • pH – 7.35-7.45 • Volume – 5L (in avg. adult male) • Temp. – 100.4 º F. • Accounts for 8% of body weight • Color varies from scarlet (O2 rich) to dark red (O2 poor) Structure • Composition – • composed of 3 types of cells (called solid portion): • 1. RBCs – erythrocytes • 2. WBCs – leukocytes • 3. platelets - thrombocytes Structure • The solid portion makes up 45% of a blood sample • Called the hematocrit (HCT) or packed cell volume (PCV) • Matrix (liquid portion) – plasma; clear, straw-colored • Makes up remaining 55% of sample; mostly H2O, nutrients, etc. Hematopoiesis – Production of blood cells (RBCs, WBCs & platelets) Hematopoiesis Video • Hematopoiesis Video Erythrocytes (RBCs) • Structure: • 1. biconcave disks • three advantages: A. increase SA B. no point within the cytoplasm is far from the surface; ideal for gas exchange C. flexible; can squeeze thru tiny b.v. Erythrocytes • Structure: • 2. Contain hemoglobin (Hb); allows them to carry resp. gases more efficiently • 3. Mature RBCs lack nuclei; allows more room for Hb (each RBC is 1/3 Hb by volume) • Normal RBC count: 4-6 million/mm³ of blood (in avg. adult) (slight incr. after meals or exercise; decr. from anemia, leukemia, or hemorrhage) Hemoglobin • Hb consists of the protein globin→ • Each has 4 polypeptide chains & 4 heme groups (pigment) where O2 binds • Hb combines easily w/O2 – called affinity ( or attraction) for O2 • Produces oxyhemoglobin; makes blood bright red • When O2 is released from the RBC, deoxyhemoglobin is produced; makes blood dark bluish-red • Erythropoietin – hormone that stimulates erythrocyte formation. High altitudes and blood loss stimulate process. Hemoglobin • Normal Hb levels – 14-18 gm/100 ml of blood (in avg. adult male) • Cyanosis – occurs when O2 is deficient (hypoxia) & levels of deoxyhemoglobin incr. • Symptoms – bluish lips & nail beds, dizziness, fainting, fatigue, muscle weakness Destruction RBC • RBC break down from wear and become ruptured when travelling through the kidney and spleen. Live 100-120 days. • Macrophages break down RBC and their contents. • Hemoglobin breaks down into 4 globin groups and heme groups • Heme breaks down into biliverdin (green pigment) Destruction of RBC cont. • Biliverdin breaks down into bilirubin (orange) • The iron gets reused to make more hemoglobin or is stored in the liver as ferritin. White Blood Cell in Action • white blood cell chasing bacteria Immune System Video • Immune System Crash Course Leukocytes- WCBs • 2 main classes: • Granulocytes – have a grainy cytoplasm • Agranulocytes – have a clear cytoplasm Types There are 5 types of white blood cells: Granulocytes • Neutrophils 40-75% • Eosinophils 5% • Basophils 0.5% Agranulocytes • Lymphocytes 20-50% • Monocytes 1-5% The range is because the requirement for different types of WBCs vary from time to time. Neutrophils Structure: • Multilobed nucleus • Inconspicuous granules Amount: • 3-7,000/mm³ Functions: • Engulfing bacteria & viruses (phagocytosis) Life Span: • hours → days Eosinophils Structure: • Bilobed nucleus • Large, red granules Amount: • 100-400/mm³ Functions: • phagocytosis • Protects against parasitic infections • Neutralize histamines (their amts. incr. during hay fever & allergy attacks) Life Span – hours → days Basophils Structure: • Lobed nucleus • Large granules, but fewer Amount: • 20-50/mm³ Functions: • Become mast cells when they leave b.v. & produce histamines • Respond to allergens rapidly (anaphylactic shock) • Produce heparin (anticoagulant) Life Span – hours → days Monocytes Structure: • Largest WBC • U-shaped nucleus • Grayish blue cytoplasm Amount: • 100-700/mm³ Functions: • Phagocytosis • Become macrophages & remove dead cells Life Span – weeks → months Lymphocytes Structure: • Most numerous in children; 2nd most in adults • Spherical nucleus • Small “ring”of cytoplasm; pale blue Amount: • 1500-3000/mm³ Functions: • T cells – attack foreign antigens directly • B cells – produce antibodies for immunity Life Span – months → lifetime White Blood Cell Count • Normal adult has 5,000-10,000 cells/mm3 • Leukocytosis- WBC count above 10,000 cells/mm3 – Can be a sign of acute infection – Occurs during times of stress and vigorous exercise. • Leukopenia- WBC below 5,000 cells/mm3 – Can be a sign of virus such as influenza, measles, mumps and HIV Thrombocytes- Platelets • Fragments of giant cells (megakaryocytes) (each produces b/t 5-10,000 platelets) • Pieces break off these cells in bone marrow • Enter circulation – live for approx. 1 wk.; destroyed by spleen & liver • Disk-shaped, w/o nucleus • ½ the size of an RBC • Release serotonin to contract blood vessel walls. Function • Normal platelet count – 130,000-360,000/mm³ • Stem blood flow (hemostasis) 2 ways: 1. Form a platelet plug 2. Initiate the clotting process Platelet Plug Formation 1. B.V.damaged 2. Some blood escapes 3. Platelets adhere to each other & rough surfaces 4. When platelets come in contact w/collagen from connective tissue, they develop spiny projections; helps them adhere -Serotonin is released to cause vasoconstriction 5. Eventually platelet plug is formed & bleeding stops Hemostasis • Blood Clotting video Blood Clots • Thrombus – blood clot that forms in a b.v. abnormally • Embolus – blood clot or fragment of one that dislodges & travels to major organ Plasma • Clear, straw-colored fluid; matrix of blood • 92% water • Functions: 1. transport 2. maintain fluid balance 3. maintain pH Contents of Plasma • Contains 3 plasma proteins (all produced in the liver): 1. Albumin – accounts for 60% of all plasma proteins maintains osmotic pressure (keeps concentration of H2O & solutes in plasma stable - example – a decrease in albumin causes cells to lose H2O; it collects in interstitial spaces (b/t cells) & causes edema Plasma Proteins 2. Globulins – Accounts for 36% of all plasma proteins - transports lipids & vitamins 3. Fibrinogen – Accounts for 4% of all plasma proteins - responsible for blood clotting Other Substances Plasma also contains: • nonprotein nitrogenous substances – amino acids, urea, uric acid • electrolytes – release ions when dissolved in H2O; maintain osmotic pressure & pH; include Na, K, Cl, Ca Mg, bicarbonate, PO4 & SO4 ions Blood Types • Antigen – protein on surface of RBC’s • Determined by genes • Determines blood type • Possible antigens – A or B • Antibody – protein in plasma • Possible antibodies – A or B Human Blood Types Intrinsic Clotting (Agglutination) • Occurs when antigen comes in contact with foreign antibody (example – b.t. A receiving a transfusion of b.t. B) • Effects – RBC’s burst, hemoglobin released • Symptoms – anxiety, difficulty breathing, chest pain, pain in neck & lumbar area Rh Blood Group • 85% of humans have an additional protein on their RBCs; called the Rh factor • Named after the species of monkey it was discovered in (Rhesus) • Termed Rh+ • Remaining 15% of humans don’t have this protein • Termed Rh• Rh- individuals cannot receive Rh+ blood Erythroblastosis Fetalis Erythroblastosis Fetalis • 85% of people are rH positive and they are not affected by erythroblastosis fetalis. • If a rH negative mother has an rH positive child the mother will build up antibodies against the rH positive blood. • If the mother has another rH positive child the mother’s antibodies will attack the developing baby’s RBCs. • Can be easily treated with Rhogam.