Blood

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Blood

• Transport- gases, nutrients, waste
• Transport- processed molecules
• Transport- regulatory molecules
• Regulation- pH, osmosis
• Maintenance- body temp
• Protection- foreign substances
• Clot formation

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Hematopoiesis

• Process of blood cell formation
• Fetus- liver, thymus gland, spleen, lymph
  nodes, red bone marrow
• After birth- red bone marrow, lymph tissues
• All formed elements derived from stem cell
• Stem cells give rise to cell lines
• Development of cell lines regulated by growth
  factors

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Fig. 11.2
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Red Blood Cells

• Disk-shaped
• Bi-concave- greater surface area
• Bendable- easy to get through small capillaries
• No nuclei- lost during development
• Hemoglobin- main component- responsible for red
  color

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Fig. 11.3
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RBC Function

• Transport oxygen and carbon dioxide
• Hemoglobin- 4 protein chains, 4 heme groups
• Heme- has an iron molecule
• Oxygen binds to iron
• Bright red blood- oxygenated
• Dark blood- deoxygenated
• 98.5 oxygen transported by Hb

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http//www.bio.davidson.edu/Courses/Molbio/MolStud
ents/spring2005/Heiner/hemoglobin.html
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RBC Function

• Two thirds of iron are found in blood
• Women need to replace more iron due to
  menstruation
• Carbon dioxide transport- hemoglobin,
  bicarbonate, plasma
• 23 attached to Hb
• 7 dissolved in plasma

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Bicarbonate

• 70 bound to bicarbonate
• Carbonic anhydrase coverts water and carbon
  dioxide to H and bicarbonate
• CO2 H2O ? H HCO3-

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Life History of RBC

• 2.5 million destroyed per second
• 2.5 million made per second
• Stem cells form proerythroblasts which give rise
  to cell line
• Each step in transformation brings cell closer to
  a mature blood cell
• Stimulated by low blood oxygen
• Increase erythropoietin production by kidneys

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Fig. 11.4
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Life History of RBC

• Removed by macrophages in spleen and liver
• Globin broken down to amino acids
• Iron transported to red bone marrow
• Heme- bilirubin and taken up by liver
• Bilirubin- yellow pigment, normal part of bile,
  malfunction results in jaundice
• Bilirubin converted in intestine, gives feces its
  brown color

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Fig. 11.5
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White Blood Cells

• Leukocytes- spherical, lack Hb, large, nucleated
• Blood is used to transport leukocytes
• Leukocytes can move by ameboid movement
• 2 functions
• Protect
• Remove dead cells, debris

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White Blood Cells

• Named according to their appearance
• Granulocytes- large cytoplasmic granules
• Neutrophils - most abundant, phagocytize
• Basophils - least common, increase inflammation
  and reduce blood clotting
• Eosinophils reduce inflammation, attack worms
• Agranulocytes- small granules
• Lymphocytes immune system, produce antibodies
• Monocytes one of the largest, macrophages,
  activate lymphocyctes

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Platelets

• Thrombocytes
• Cell fragments- membrane w/ cytoplasm
• Produced in red bone marrow by megakaryocytes
• Prevent blood loss 2 ways
• Formation of plugs
• Formation of clots

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Preventing Blood Loss

• Too much blood loss death
• 3 ways to prevent
• Vascular spasm
• Platelet plugs
• Blood clot

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Vascular Spasm

• Immediate, temporary constriction of blood vessel
• Closes vessel, prevents blood flow
• Produced via nervous system reflexes and chemicals

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Platelet Plugs

• Accumulation of platelets seal small break in
  vessel
• Small tears occur daily- maintain integrity of
  circulatory system
• Series of steps- happens at same time

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Platelet Plugs

• Platelet adhesion- platelets stick to exposed
  collagen
• - von Willebrands factor- protein released
  by blood vessel, bonds platelets to collagen
• Platelet release reaction- activated platelets
  change shape, release chem.
• - chem. activate other platelets which
  express fibrinogen receptors
• Platelet aggregation- fibrinogen forms bridges
  between fibrinogen receptors of other platelets

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Blood Clotting

• Clot- network of fibrin, which traps blood cells,
  platelets and fluid
• Formation depends upon clotting factors
• Normally they are inactive
• 3 steps to clot formation

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Clot Formation

• Two ways to start- clotting factor contacts
  connective tissue
• Thromboplastin- released from injured cells
• Series of clotting factors until prothrombinase
  is formed
• Prothrombinase converts prothrombin to thrombin
• Thrombin converts fibrinogen to fibrin
• Fibrin CLOT

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Fig. 11.9
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Control of clots

• No control 1 big clot
• Anticoagulants- prevent clotting factors from
  forming clots
• Antithrombin and heparin- inactivate thrombin
• Away from injury site, anticoagulants prevent
  spread of clot

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Clot retraction

• Condensing of clot into smaller structure
• Platelets contain ACTIN and MYOSIN
• Platelets form small extensions that attach to
  fibrin
• Contraction of extensions contracts clot
• Serum (plasma w/ no clotting factors) is squeezed
  out
• Reduces flow of blood to area

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Fibrinolysis

• Dissolving of clots
• Plasminogen is converted to plasmin
• Stimulated by thrombin, other clotting factors
  and tissue plasminogen activator (t-PA)
• Plasmin dissolves fibrin over a few days

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Fig. 11.10