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Lecture 25
Red Blood Cells-Platelets
Term | Definition |
---|---|
Plasma | Liquid portion of the blood.H2O,electrolytes,hormones,metabolisms,proteins |
Plasma Proteins | Albumin:highest amount-draws fluid into capillary-binds hydrophobic hormones. Globulins: many sub-groups-gamma globulins are anitbodies. Fibrinogen:final protein for blood clot formation |
Erythrocytes-RBC's | Carry oxygen and CO2. NO organelles, only hemoglobin-Hb |
Production | In bone marrow from stem cells. ~ 20mL of RBC per day (~50mL of blood/day). Low blood oxygen causes release of EPO from kidneys. |
Shape | Biconcave disks-8 microns across. Spectrin net under membrane helps maintain shape. Fluidity of membrane allow squeeze through capillary. Membrane-membrane squeeze goes inc. transport. |
Destruction | RBC membranes lose cholesterol over time. Rupture in spleeen capillaries at 120 days. If spleen lost, liver ruptures RBC's. |
Hemoglobin | Adult:2 alpha+beta chainsEach subunit has a protein(globin)w/heme group in centerEach heme has iron atom at centerOxy binds at lungs + release at tissuesFetal:2 alpha + 2 gamma chains.Higher affinity for oxy than adult hemo. Draws oxy from maternal blood. |
Anemias | Lack of oxygen (altitude). Reduced RBC's (bleeding), no anemia w/ menses(50mL/5 days). REduced delivery (circulatory). Reduced use (cyanide). |
Sickle Cell | Single Hb mutation. Low oxygen to Hb forms stacks, changes cell shape. Sickled cells hang up on branch pts. Survival value: proteciton from malaria: parasites lay eggs in RBC's growing malarial parasites rupture weakened RBC membranes before maturity. |
Iron Deficiency | Lack of iron, dec. amount of Hb. NOT from using non-iron cookware (wrong form of iron in cookware). |
Platelets | Pinched off parts of megakaryocytes in bone marrow |
Production | Megakaryocytes stay in bone marrow. Platelets pinch off and enter circulaiton. Spleen, kidneys, and liver make thrombopoletin. Thrp stimulates platelet formation. Thrp binds to platelets in blood, when platelets low increase free. |
Activation | Activated by collagen and other proteins in connective tissue of blood vessels. Platelets adhere, inc ADP release, more p's come and stick. Makes platelet plug. |
Hemostasis | Stoppage of bleeding |
Vasoconstriction | Dec. BP at site of cut, tone constricts small vessels. |
Platelet Plug | Exposure of collagen, leads to platelet sticking, leads to ADP positive feedback. Prostacyclin from healthy blood vessels blocks platelet adherence |
Coagulation | Blood clotting-2 systems. Both lead to fibronogen (soluble) leads to fibrin (self-adhering). Forms mesh that traps RBC's etc. |
Intrinsic System | Inside plasma-collagen activate. Cascade needs Ca2+ and all factors in pathway. |
Extrinsic System | Thromoplastin from damaged tissue starts cascade. Merges w/ IS halfway down |
Clot Removal | Plasminogen trapped in clot leads to cascades started by collagen leads to plasmin. Plasmin is an enzyme that slowly dissolves a clot over ~ 2 weeks. |