Blood Lecture 1: Biochemical Composition of Blood PDF

Blood Lecture 1 Biochemical composition of blood Prof Ash Toye [email protected] Biomedical Sciences Building A100f School of Biochemistry Learning Objectives: Lecture 1: Biochemical Composition of Blood List the main components of blood, Describe serum proteins and their functions, Describe...

Blood Lecture 1 Biochemical composition of blood Prof Ash Toye [email protected] Biomedical Sciences Building A100f School of Biochemistry Learning Objectives: Lecture 1: Biochemical Composition of Blood List the main components of blood, Describe serum proteins and their functions, Describe the importance of serum protein electrophoresis, Describe the use of serum enzymes for diagnosis. How much blood? Blood volume depends on size! Animal Approx blood volume (mL)* Mouse 1.5 Rat 25 Rabbit 300 Dog (beagle) 1000 Cat 200 Sheep 4,500 Human 5,000 Pig (large white) 14,000 Cow 30,000 Horse 40,000 *You don’t have to learn these values! Function of blood Delivery: nutrients to tissue Waste collection: removes waste products Communication route: e.g. hormones from manufacturing site to target tissues Defence: External insult Wound healing Tissue repair Composition of whole blood Cell free 55% of blood volume 1% of blood volume plasma White blood cells Platelets, Buffy coat Haematocrit, packed cell volume PCV Erythrocytes (red blood cells) Make up about 45% of blood volume Plasma constituents Plasma is made up of: Proteins Anions (Cl-, HCO3-, PO43- ) and Cations (Na+, K+, Ca2+, Mg2+) Small molecules: e.g. glucose, amino acids (Gln, Ala), lactate, glycerol, urea, ketones 6-8% of plasma Plasma v Serum Serum is the liquid component of blood when blood is allowed to clot Plasma contains clotting factors, serum does not (Tube show here includes anti-coagulants). Function of plasma proteins plasma proteins transport albumin, proteins which transport iron, copper, hormones, lipids, etc inflammatory response and immunity haemostasis oncotic pressure immunoglobulins, complement proteins, acute phase proteins clotting factors all proteins NB: Oncotic pressure is only due to protein. Osmotic pressure results from all protein and other molecules dissolved in blood Oncotic pressure is exerted by protein in plasma Oncotic pressure: water moves in Arterial end Plasma proteins Venous end Hydrostatic pressure: water moves out Hydrostatic pressure mmHg Oncotic pressure Blood vessel length Function of plasma proteins plasma proteins transport albumin, proteins which transport iron, copper, hormones, lipids, etc inflammatory response and immunity haemostasis oncotic pressure immunoglobulins, complement proteins, acute phase proteins clotting factors all proteins, especially albumin The Functions of Albumin Most abundant protein in plasma and is synthesized by liver Oncontic pressure Transport protein Albumin is: Negatively charged at physiological pH Highly polar It has a large capacity to non-specifically bind ligands e.g. fatty acids, steroid hormones, drugs. Albumin bound molecules are: solubilised retained in blood stream Regulated (biological activity) to a degree due to competition for binding sites They may be neutralised- antioxidant function of albumin Low Levels of Albumin Condition: Hypoalbuminaemia reduces the oncotic pressure and leads to oedema Lower oncotic pressure Causes of hypoalbuminaemia: chronic liver disease malnutrition chronic renal disease Other proteins involved in transport Substance Transport Protein Iron Transferrin* Copper Caeruloplasmin* Hormones Thyroid hormone binding globulin Cortisol binding globulin Sex hormone binding globulin Haemoglobin Haptoglobulin Lipids Apolipoproteins Globulin is a generic term given to many plasma proteins * Rare conditions exist where they are depleted Using plasma proteins as diagnostic tools What determines the concentration of proteins in the plasma? Blood volume Hydration Rate of synthesis by: Liver Cells of the immune system Rate of breakdown and loss: Breakdown: uptake and degradation of proteins by cells Loss via kidney and/or gut What measurements can be made? Total protein concentration of limited clinical use Serum electrophoretic pattern allows separation and semi-quantitative assessment of individual proteins Enzyme measurements used to detect cell damage Serum protein electrophoresis (SPE) Inexpensive and easy-to-perform screening procedure Agarose gel electrophoresis separates proteins on the basis of charge anode cathode Serum electrophoretic pattern Constant experimental conditions result in a highly reproducible pattern transferrin complement C3* albumin b1 b2 - + α1 α2 α1-antitrypsin α1-acid glycoprotein* g IgG IgA IgM IgD IgE Haptoglobulin* α2-macroglobulin* caeruloplasmin * Acute phase proteins SPE: data presentation Graph Gel albumin b1 b2 Band density albumin b α 1 α 2 1 b2 - + g Position on gel α1 α2 Table g sample Reference range Species specific characteristic SPE patterns albumin albumin Normal canine SPE globulins Normal feline SPE globulins albumin Normal equine SPE globulins Serum protein electrophoresis in veterinary diagnosis 1 Albumin: decreases in prolonged malnutrition, chronic liver or renal disease increases in dehydration (fast, short term change). Increased alpha-globulins: acute inflammatory diseases (bands include acute phase proteins) Increased beta-globulins: indicative of liver disease Acute phase proteins The concentration of acute phase proteins increases in response to inflammation and they are an important part of the innate immune response. These non-specific markers of inflammation are useful diagnostic tools and can be identified via SPE as increases in the alpha and beta bands. Also: e.g. a1-acid glycoprotein (alpha-1) Complement (C3 and C4) (beta-band) Acute phase reaction C-reactive protein (CRP) Serum amyloid protein (SAA) Haptoglobulin (alpha-2) a2-macroglobulin (alpha-2) Low levels, other tests NB indicators of inflammation and overtraining Serum protein electrophoresis in veterinary diagnosis 2 Decreased gamma-globulins: immune suppression or immune deficiency conditions aka hypogammaglobulinaemia Normal Hypogammaglobulinaemia Increased gamma-globulins: An overall increase in the broad g band indicates a polyclonal immune response which can be indicative of chronic infection Chronic infection A sharp, distinct increase in one area of the g band is seen in multiple myeloma, a cancer caused by the monoclonal expansion of a single type of antibody producing cell and hence a single antibody Paraproteinaemia Limitations of SPE Important (e.g. some acute phase) proteins produced in quantities too low to detect. Changes in band density can be ‘missed’. It takes a 30% change in albumin levels to show on the SPE. Serum enzymes in diagnosis Concentration of cellular enzymes in serum is normally LOW Enzyme activity in serum may be increased by cell proliferation or damage, e.g. cancer, cell death, trauma Analysis of serum enzymes can provide useful information about which tissue has been damaged, e.g. Enzyme Indicative of… ALT (alanine aminotransferase) Liver damage ALP (alkaline phosphatase) Bone deposition, liver damage, hyperthyroidism, biliary disease, increased steroid levels GDH (glutamate dehydrogenase) Liver disease g GT (g glutamyl transferase) Liver disease CK (creatine kinase) Muscle damage AST (aspartate aminotransferase) Muscle and liver damage