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11
Blood
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The Composition and Functions of Blood
Functions of Blood1. Transport
• Carries oxygen to tissues• Carries carbon dioxide and other wastes away from tissues• Hormones
2. Defense• Defends body against pathogens• Removes dead and dying cells
3. Regulation• Body temperature• Water-salt balance• Body pH
Blood is a fluid tissue (“fluid connective tissue”)
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Composition of Blood• Includes liquid plasma + formed elements:
– Erythrocytes - red blood cells (RBCs)– Leukocytes - white blood cells (WBCs)– Platelets – involved in blood clotting– Plasma – non-living fluid
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Liquid portion of blood~ 92% is water~ 8% is composed various salts and organic molecules:
Plasma
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Erythrocytes, Leukocytes, PlateletsFormed Elements
• Skull• Ribs• Vertebrae• Pelvis• Ends of femurs and humerus’
distribution of red bone marrow (red)
Produced continuously in the red bone marrow of the:
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Erythrocytes (RBCs)
Hemoglobin binds with oxygen on red blood cells
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•Stem cells differentiate (turn into) into “committed cell” (to be a RBC)•Erythropoietin (EPO) stimulates production and maturation of RBCs
Production of Red Blood Cells
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Hemoglobin (Hb) Oxygen loading – occurs in lungsO2 diffuses from lung air sacs to blood, then through RBC to bind w/ HbWhen O2 binds to iron, Hb becomes oxyhemoglobin
changes 3-d shape → becomes ruby redWhen O2 detaches from iron, Hb becomes deoxyhemoglobin
color changes to deep dark red
Which one is Oxygenated? Deoxygenated?
Oxygen Loading StepsOxygen Loading:Step 1: Oxygen moves from the lung air sacs into the bloodStep 2: Oxygen moves through the red blood cells, to the hemoglobin that is on the red blood cellsStep 3: Oxygen binds to hemoglobin and then to iron. Step 4: Blood turn bright red and leaves the heart to go into the body - this is when the hemoglobin becomes oxyhemoglobin.
Unloading: Step 1: Blood arrives where oxygen is needed Step 2: Oxygen detaches from the iron and moves into the body Step 3: Blood is now considered deoxyhemoglobin and turns dark, deep, violet-ish red.
Oxy = Oxygen De= Without Hemo= Blood 9
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Erythrocyte Disorders
Anemia – blood has abnormally low oxygen-carrying capacity• Blood oxygen levels cannot support normal metabolism• Signs/symptoms include fatigue, paleness, shortness of breath, and chills
Polycythemia – excess RBCs that increase blood viscosity
• from cancer, decreased oxygen or excess EPO
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Differ from RBCs:• larger• have a nucleus• do not contain hemoglobin
White Blood Cells (Leukocytes)
• fighting infection• destroying dead or dying body cells• recognizing and killing cancerous cells
• derived from stem cells in the red bone marrow• able to leave the bloodstream
Functions include:
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Platelets
Function in clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels
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Hemostasis
Series of reactions for stoppage of bleeding
Three steps:
1. Vascular spasms – immediate vasoconstriction in response to injury
2. Platelet plug formation
3. Coagulation (blood clotting)
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Hemophilia – inherited clotting disorders caused by lack of plateletsThrombus – stationary blood clotEmbolus – dislodged blood clotIf dislodged clot blocks a blood vessel:
Platelet Homeostasis
Pulmonary embolismCerebrovascular accident or stroke