plasma Flashcards
what are the 4 main fluid compartments and what percentage do they make up?
intracellular (55%)
(extracellular) interstitial fluid (36%)
plasma (7%)
transcellular fluid (2%)
describe interstitial fluid’s role.
found between cells
carries oxygen and nutrients to cells
acts as a vehicle for the removal of cellular waste products
what is the relationship between interstitial fluid and lymph?
interstitial fluid is drained from the tissues by lymphatic vessels
known as lymph when collected by these vessels
lymph drains to secondary lymphoid organs (e.g lymph nodes) and is a component of adaptive immune response
what is plasma?
liquid component of blood
how does plasma’s composition differ from that of interstitial fluid?
very similar
plasma contains much more protein
give 2 examples of transcellular fluid.
ocular fluids
cerebrospinal fluid
describe the composition of blood.
plasma (55%)
red cells (45%)
buffy coat (leukocytes and platelets) (<1%)
what is apherisis and why is it useful?
technique in which a donor’s blood is collected and centrifuged to separate a specific component
remaining components returned to the donor
therefore different cell fractions can be purified for further use
what is serum?
not the same as plasma
generated by letting blood clot for several minutes
this depletes the plasma of coagulation factors and traps cells and platelets within the clot
produces serum
why are plasma and serum useful in diagnostics?
easy to obtain clinical specimen
elevated levels of some molecules can provide biomarkers of disease
e.g unique proteins secreted by cells or released during cell death
what are the respective advantages of serum and plasma in diagnostics?
plasma - quicker to prepare
serum - generates cleaner sample (fewer cells)
what percentage of plasma is made up by proteins?
7%
how can the proteins in plasma be assayed?
electrophoresis
serum albumin (most abundant, therefore the largest peak) - closest to the cathode
subsequent components are globulins (closest to furthest from cathode)
- alpha 1
- alpha 2
- beta 1
- beta 2
- gamma
what are the 2 major types of protein in plasma?
serum albumin
globulins
what percentage of the total plasma proteins is made up by serum albumin?
55%
where is serum albumin produced?
liver
what are the key functions of serum albumin?
transport of lipids
transport of hormones
transport of ions
maintain osmotic pressure of plasma
what is the role of serum albumin specifically in relation to transport of lipids?
lipolysis from breakdown of triglycerides in adipose tissue produces fatty acids
albumin transports fatty acids around the body for use by other tissue in β-oxidation
what percentage of the total plasma proteins is made up by globulins?
35%
divided into 3 groups
what protein are serum alpha 1 globulins typified by?
alpha 1 antitrypsin (A1AT)
where is A1AT produced?
liver
what does A1AT do?
inhibits proteases
why is A1AT’s role important? give a specific example.
helps protect tissues from many enzymes
e. g neutrophil elastase
- released by neutrophils during inflammation
- defective/deficient A1AT can lead to degradation of lung tissue - loss of elasticity and respiratory problems
what 2 proteins are serum alpha 2 globulins typified by?
haptoglobin
α2 macroglobulin
what does haptoglobin do? why is this relevant in diagnostics?
binds to haemoglobin released from erythrocytes
resulting complex removed by the spleen
measuring levels of haptoglobin can help diagnose haemolytic anaemia in combination with other parameters
what is α2 macroglobulin and what is its role?
broad action protease inhibitor
can inactivate fibrinolysis (breakdown of fibrin involved in blood clotting)
give 3 examples of beta globulins.
complement protein C3 and C4
transferrin
where is transferrin produced and what is its role?
beta globulin
generated by the liver
helps transport dietary iron and iron released from ferritin stores
what 2 types of protein make up a large proportion of the gamma globulins?
immunoglobulins (antibodies)
C-reactive protein (acute phase protein)
what can an increase of the gamma proportion of the globulins reflect?
increased immune system activity; can indicate infection
why are electrolytes important even though they only make up ~1% of the plasma?
major contributors to osmolarity
describe the relative concentration of Na⁺ in the plasma and in the blood cells.
30 times higher in the plasma than in the blood cell
describe the relative concentration of K⁺ in the plasma and in the blood cells.
30 times higher in the blood cell than in the plasma
how and why is the positive charge from intracellular K⁺ ions balanced?
balancing required otherwise differences in charge would tear cells apart
mainly balanced by extracellular Cl⁻ ions
many anions inside cell also neutralise high concentration of potassium inside the cell
- e.g proteins, nucleic acids, phosphorylated proteins
describe the relative concentration of Ca²⁺ in the plasma and in the blood cells.
several thousand times higher in the plasma than in the blood cell
what can an increase in intracellular calcium be associated with and what can it be due to?
associated with signalling events
due to either:
- opening calcium channels allowing influx from the exterior
- release of intracellular stores
why is intracellular magnesium important?
important co factor for many enzymes
what are the 5 key ions found in plasma and in blood cells?
K⁺
Na⁺
Ca²⁺
Mg²⁺
Cl⁻
how is the electrolyte gradient between the inside and outside of the cell maintained?
active transport of ions
notably by protein pumps such as Na⁺-K⁺ pumps (also known as Na⁺-K⁺ ATPase)
why are Na⁺-K⁺ pumps also known as Na⁺-K⁺ ATPase?
hydrolysis of ATP is needed to provide energy for transportation
what is the ratio between Na⁺ ions actively transported out of the cell by Na⁺-K⁺ pumps and K⁺ ions that move into the cell?
3:2
3 Na⁺ pumped out, 2 K⁺ enter
why is the maintenance of the Na⁺-K⁺ gradient across the plasma membrane important?
important for function of electrically excitable cells
e.g muscle fibres, neurones
maintenance of cell volume
how can you tell that the active transport of Na⁺ and K⁺ is significantly important, referring to the resources it uses?
more than a third of ATP consumed during rest is to power the Na⁺-K⁺ pumps
when ATP levels are depleted, what happens to the shape of the cell and why, referring to the movement of ions?
inward movement of Na⁺ and water
cells become more spherical
