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Blood: Cells and Plasma Proteins Beth A. Bouchard BIOC 212: Biochemistry of Human Disease Spring 2005. I. Major functions of blood and its components: transport and distribution of essential nutrients to tissues removal of waste products defense against internal insult - PowerPoint PPT Presentation
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Blood: Cells and Plasma Proteins
Beth A. BouchardBIOC 212: Biochemistry of Human Disease
Spring 2005
I. Major functions of blood and its components: transport and distribution of essential nutrients to
tissues removal of waste products defense against internal insult repair of damaged tissues
II. Two major components of blood: liquid phase and formed elements
Plasma - blood treated with anticoagulants to prevent clot formation then centrifuged to remove the cells
Serum - blood that is allowed to form a fibrin clot then centrifuged to remove the cells and the clot
Plasma
“Buffy coat”
Red blood cells
Plasma
Buffy coat
Red blood cells
Red Blood Cells(Erythrocytes)
1011 produced per day
Anucleate
Lack intracellular organelles (incapable of protein synthesis and repair)
Contain specific proteins and ions
Transport oxygen, and remove CO2 and H+
Finite life span of 60-120 days beforebeing destroyed in the spleen
2-3 m in diameter
150-400 x 106/mL blood
Normal subcellular structures except they lack a nucleus
Capable of mitochondrial protein synthesis
Platelet function is dependent upon their activation
Involved in blood clotting
Contain secretory organelles called alpha-granules, which contain proteins important in blood clotting
Circulate for 10 days before being destroyed
Platelets
Plasma proteins
Synthesized by liver or produced by plasma (B) cells
A. AlbuminB. TransferrinC. CeruloplasminD. Enzymes – coagulation enzymes, complement factorsE. C-reactive protein – acute phase reactantF. Immunoglobulins – humoral immunity
Transport proteins
66 kDa
ALBUMIN
Accounts for ~50% of the total plasma protein and ~ 50% of the total liver protein production
Half-life ~ 20 days
Highly polar
At pH 7.4 it is anionic with 20 negative charges per molecule
Transport of long chain fatty acids & sterols Transport of bilirubin Binding and solubilization of drugs
Functions of Albumin
Regulation of colloidal pressure
Decreases in albumin concentration cause edema
Gaw: Clinical Biochemistry; Churchill Livingstone (1999), p. 44.
Causes of decreased plasma albumin:I. Decreased synthesis
A. malnutrtionB. malabsorptionC. advanced chronic liver disease
II. Abnormal distribution or dilutionA. overhydrationB. increased capillary permeability like in septicemia
III. Abnormal excretion or degradationA. nephrotic syndromeB. burnsC. hemorrhageD. certain catabolic statesE. protein losing enteropathies
IV. Rare congenital defects A. hypoalbuminemia B. analbuminemia
TRANSFERRIN
Transports iron in plasma as ferric ions (Fe3+) – each transferrin molecule binds 2 Fe3+
Protects the body against the toxic effects of free iron
Normally 30% saturated with Fe3+ - increased or decreased saturation is indicative of iron overload or deficiency, respectively
Decreased in inflammatory states due to excessive degradation of transferrin- Fe3+ complexes
CERULOPLASMIN
Major copper transport protein
Regulates oxidation-reduction, transport and utilization of iron
Increased concentrations are found in active liver disease or tissue damage
Decreases are sometimes observed in individuals with Wilson’s disease
ENZYMES
Enzymes of the coagulation and complement cascade have a defined function in blood
Others reside elsewhere in the body and appear incidentally in the blood – their measurement is of diagnostic value
Acid phosphatase Amylase
Creatine kinaseAlanine
aminotransferase
C-REACTIVE PROTEIN (CRP)
Major component of the acute phase response and a marker of bacterial infection
Mediates the binding of foreign polysaccharides, phospholipids and complex polyanions, as well as the activation of complement
<1 mg/mL in normal plasma
Slightly elevated levels of CRP are indicative of chronic, low-grade inflammation and have been correlated with an increased risk of cardiovascular disease
IMMUNOGLOBULINS
Proteins produced and secreted by B cells specific for the foreign particle that stimulated their synthesis
Five classes of Ig
Multiple myeloma: arises from the aberrant proliferation of a single B cell. Light chains of Igs are produced in excess of heavy chains = paraproteins.
Elevated serum protein levels are usually due to an increase in the Ig fraction and may indicate the presence of a paraprotein.
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