Lecture 27 Flashcards
How many grams of plasma protein circulate in the blood per liter of plasma?
60-80g of plasma proteins / 1L of plasma
What are 4 common characteristics among plasma proteins?
1) Concentration of plasma proteins in the plasma is greater than their concentration in the extracellular fluid
2) Plasma proteins are synthesized in the liver or in the reticuloendothelial system (spleen, bone marrow & lymph)
3) Plasma proteins are not present in the blood due to tissue damage, rather they are always circulating (no tissue injury for PP)
4) Function is mediated through the plasma itself (do not have to travel to a certain tissue site to be functional)
What are the classifications of plasma proteins?
Albumin (large peak), alpha 1, alpha 2, beta, & gamma
What are examples of plasma protein biomarkers for disease?
1) Liver cirrosis - decreased levels of albumin
2) Rheumatoid Arthritis - increased levels of gamma proteins
3) Multiple Myeloma - Increased levels of M protein indicated by a sharp gamma peak
What are the functions of functional groups attached to plasma proteins?
1) Transport of small molecules + ions
2) Maintain osmotic pressure
3) Transport iron + partake in iron oxidation
4) Hemoglobin metabolism
5) Protease inhibitors
6) Immune response
7) Coagulation
How many amino acids are found in albumin?
580 amino acids in length
What is the molecular weight of albumin?
66,000 g/mol
What does albumin help transport?
1) Calcium 2+ ions
2) bilirubin
3) fatty acids
4) common drugs (such as aspirin, penicillin, etc.)
What are two major functions of albumin?
1) Major protein that maintains colloid osmotic pressure (maintains 80% of osmotic pressure)
2) Albumin can be broken down into amino acids for nutritional needs (amino acids can be taken up by tissue that need to synthesize proteins)
What is hyperalbuminemia?
It is a very rare condition that only occurs in cases of severe dehydration (the concentration of albumin becomes too high in relation to plasma levels, due to water loss)
What is hypoalbuminemia?
A more common condition that occurs when albumin is lost due to:
1) a lack of synthesis
2) higher excretion rates
(it is found in kidney disease and liver dysfunction)
What transports iron in the plasma?
Transferrin transports iron in the Fe3+ state
What transports copper in the plasma?
Ceruloplasmin carries copper in the Cu2+ state through the blood and to copper requiring enzymes
What is a similar function of transferrin and ceruloplasmin?
In levels of excess iron or copper, transferrin and ceruloplasmin respectively will prevent toxicity by binding excess ions in the plasma
How do transferrin and ceruloplasmin assist each other in carrying the correct form of iron and copper respectively?
Ceruloplasmin carries Cu2+, which takes an electron from Fe2+ to make Cu+ and Fe3+ (transferrin can then carry Fe3+):
Cu2+ + Fe2+ –> Cu+ + Fe3+
What is Wilson’s Disease caused by?
Very low levels of ceruloplasmin
What occurs in patients with Wilson’s Disease?
1) Copper toxicity due to elevated levels of copper
2) Copper accumulates in the brain and liver causing dysfunction of both
What causes Atransferrinemia?
Low levels of transferrin in the plasma
How can Atransferrinemia be mediated?
Requires frequent blood transfusions
What must be conserved when RBCs are lysed?
Iron (need to prevent the urinary excretion of it)
What binds to free hemoglobin when RBCs are lysed?
Haptoglobin
What binds to free heme when hemoglobin is further lysed?
Hemopexin
What is the function of haptoglobin and hemopexin?
They are two transport proteins that will take their respectively bound components to the liver, where iron can be stored
What will be excreted once RBCs have been lysed properly?
1) Heme without Fe2+
2) Globin molecules
What are examples of protease inhibitors?
1) alpha 1 antitrypsin
2) alpha 1 antichymotrypsin
3) alpha 2 macroglobulin
What does alpha 1 antitrypsin do?
It inhibits elastase (elastase prevents further tissue breakdown)
What does alpha 2 macroglobulin do?
It inhibits certain enzymes in the blood clotting cascade
What are other examples of transport plasma proteins?
1) LDL and HDL
2) Retinol binding protein (binds and transports retinol - prevents night blindness)
3) Thyroxine (binds prealbumin + globulin)
4) Steroid binding globulins
What do gamma globulins do?
They assist in forming antibodies, which are necessary to fight off and eliminate foreign antigens from the body
What is fibrinogen?
The precursor of fibrin, which is the main substance of a clot
