Plasma Flashcards
Percentage Components of fluid in body
- 55% Intracellular, 45% Extracellular Within extracellular: - 36% Interstitial fluid (IF) - 7% Plasma - 2% Transcellular fluid
Features of Interstitial Fluid
- Between cells
- Cells take up O2 and nutrients from it and release metabolic waste into it
- Drains from tissues via lymphatic vessels, then called lymph
What is Plasma?
Liquid part of blood i.e. blood with the cells removed
Plasma vs IF composition
Similar in composition, although plasma has much more protein
How do you divide up the different components of a blood sample?
Apply anticoagulant to prevent clotting factors from being used, then centrifuge
What is the percentage composition of the different components of a blood sample after centrifugation?
- Red cells 45%
- Plasma 55%
- Buffy coat <1% (leukocytes and platelets)
What is the appearance of a blood sample after centrifugation?
Yellow plasma on top, Red blood cells on bottom, thin white buffy coat in between
What is Apherisis?
Donor blood is centrifuged to separate the components, can return the rest to the donor
Plasma vs Serum
Serum is what you get if you let the plasma clot i.e. use up the coagulation factors. Plasma is easier to get than serum for lab tests, serum takes longer but is ‘cleaner’ (less cells). Plasma contains clotting factors, serum does not.
What percentage of plasma is proteins?
7%
Types of plasma proteins and their percentage weight
- Serum Albumin (biggest and most common - 55% of plasma proteins)
- Globulins (Alpha1, Alpha2, Beta, Gamma) (35% of plasma proteins)
What are Globulins?
Chains of haemoglobin - Each globulin is therefore attached to haem, 4 of these couples in each haemoglobin molecule
Features of Serum Albumin
- Made by liver
- Transport of lipids, hormones and ions
- Maintains osmotic pressure of plasma
Features of Alpha1 Globulins
- Alpha-1 antitrypsin (A1AT) is the main A1 globulin.
- This inhibits proteases, hence protecting tissues from them
Features of Alpha2 Globulins
- Include haptoglobulin and Alpha2-macroglobulin
- Haptoglobulin: binds to haemoglobin released from RBCs, this complex is then removed by the spleen. Measuring haptoglobulin levels helps with diagnosis of haemolytic anaemia.
- A2-macroglobulin - protease inhibitor - one of the proteins it inhibits is plasmin (haemostasis lecture)
Features of Beta Globulins
Includes proteins such as transferrin, which is made in the liver and carries iron in blood.
Features of Gamma Globulins
- Main ones are immunoglobulins/antibodies and C-reactive protein (an acute phase protein i.e. goes up in inflammation)
What happens to globulin levels during an infection?
Increases as more antibodies (gamma globulins) released
What is the NA+-K+-ATPase?
- 3 Sodium ions moved out of cell for every 2 potassium ions moved in.
- Needs energy from ATP as ions are moving against their conc. grad.
- This transporter explains why sodium and potassium are high and low extracellularly respectively
Why does the ratio of sodium and potassium inside and outside of cells need to be maintained?
So that cells can be depolarised/electrically excited when needed i.e. muscle contraction, neurone excitation. They also help maintain cell volume by regulating osmosis.
What happens to cells when ATP is used up with regards to the NA+-K+-ATPase?
Would swell and become spherical, as sodium ions and subsequently water (osmosis) would move in
Most common ions in plasma vs cells
Na+ in plasma, K+ in cells (due toNa+-K+-ATPase)
Main functions of plasma
The main functions of plasma include clotting, immune defence, transport of hormones, nutrients, and waste products and the maintenance of osmotic pressure.
Uses of plasma
/Biomarkers - lab tests for diagnostic purposes
/Passive immunotherapy - E.g. intravenous immunoglobulin G (IVIG): protects against common pathogens donors are exposed to
/Passive immunity - vaccines
/Hyperimmune globulin - ELISA test
