Haematology Flashcards
what are the two main fluid compartments?
1) intracellular (28L)
2) extracellular (14)
what are the components of extracellular fluid compartments?
- 11L in interstitial fluid
- 3L in plasma
- small compartments
what are small fluid compartments?
-cerebrospinal fluid
-intraocular fluid
-fluids of the GI tract
-fluid compartment of the lung
etc.
interstitial fluid
fluid occupying the space between the cells, derived from filtration from the capillaries, same constituents as plasma except for large proteins which are present at lower concentration
what are the 3 major types of proteins in the plasma?
1) albumin
2) globulin
3) fibrinogen
albumin
most abundant plasma protein, provides colloid osmotic pressure in the plasma, acts as nonspecific carrier protein
globulin
proteins with specificity (e.g. specific carrier proteins, enzymes, immunoglobulins)
fibrinogen
key factor in blood clotting, polymerizes into long fibrin threads during blood coagulation
colloid osmotic pressure
the osmotic pressure caused by protein presence, colloid osmotic pressure increases when protein concentration increases
outward pressure =
Pc (capillary pressure) + interstitial fluid colloid osmotic pressure
inward pressure=
Pif (interstitial fluid pressure) + plasma colloid osmotic pressure
edema
swelling due to accumulation of excessive fluid in interstitial compartment, may result from changes in osmotic colloid pressure
presence of proteoglycan, gel formation, and collagen support in interstitial compartment ensures:
- uniform distribution of fluid compartments
- prevents fluid accumulation due to gravity
- maintenance of optimal intracellular distance
- mechanical support
lymph system
an accessory route for transport of fluid and macromolecules from interstitial space to veins
lymph flow is a function of:
interstitial fluid pressure
cytokines
control proliferation and differentiation of blood cells
what are cells called once differentiation starts (stimulation by differentiation factors)
committed progenitor cells (destined to become a specific group of blood cells)
interleukins and stem cell factor
increase production of all haemopoietic stem cells
erythropoietin
differentiation factor; stimulate differentiation to erythrocytes
thrombopoietin
differentiation factor; stimulate differentiation to megakaryocytes
granulocytes-monocytes colony-stimulating factors
differentiation factor; stimulate differentiation to granulocytes and monocytes
polymorphonuclear cells
aka granulocytes (neutrophils, eosinophils, basophils)
hematocrit
a measure of the proportion of volume that is occupied by red blood cells, determined by centrifugation
main functions of erythrocytes
1) transport of Hb (oxygen carrier molecule)
2) Hb acts as an acid-base buffer for blood
3) RBC contains carbonic anhydrase which catalyzes production of bicarbonate
colony-forming unit erythrocyte (CFU-E)
committed cells that become erythrocytes
what is the molecular basis of sickle-cell anemia
Glu to Val on codon 6
megaloblastic anemia
caused by lack of either vitamin B12 or follic acid, results in diminished DNA synthesis and failure of nuclear maturation of RBC
pernicious anemia
a form of megaloblastic anemia caused by impaired absorption of vitamin B12 due to lack of an intrinsic factor that mediates vitamin B12 absorption
15-30% of iron is stored as:
ferritin (mostly stored in the liver)
transferrin (beta globulin)
plasma protein that binds iron
- transferrin-iron complex can bind to specific receptors on the erythroblasts in the bone marrow for synthesis of heme molecule
- abnormalities in transferrin cause anemia
platelets
-contain surface glycoprotein that recognizes collagen and damaged endothelial tissue
platelets do not have a nucleus but contain:
- actin, myosin, thrombosthenin (cause platelets to contract)
- residuals of endoplasmic reticulum and Golgi (can make some enzymes and store calcium)
- mitochondria and enzymes to produce ATP and ADO
- enzyme system to produce eicosanoids (thromboxane A2)
- fibrin-stabilizing factor (+ growth factors used for injury-damaged tissue growth)
haemostasis (prevention of blood loss) can be achieved by:
1) vascular spasm and constriction
2) formation of platelet plug
3) blood coagulation
4) growth of tissue to repair the injury
vascular constriction resulting from a cut or rupture of a blood vessel
- local myogenic spasm (result of vasoconstrictor thromboxane A2 released by platelet cells)
- nervous reflex (initiated by activation of pain receptors)
platelet plug
sufficient to stop blood loss for small ruptures, in most cases, blood coagulation occurs
blood coagulation
in severe trauma, blood clot beings to develop in 20 seconds. minor trauma = 1-2 minutes. activation of extrinsic and intrinsic factors that lead to activation of thrombin
thrombin
an enzyme that is the proteolytic product of prothrombin (alpha-globulin), produced in the liver due to action of vitamin K
prothrombin activator
produced following vascular trauma, involves complex interactions between a number of clotting factors
factor III
tissue thromboplastin: initiates extrinsic pathway (lipoprotein & phospholipid). released from tissue following trauma
factor XII
Hagemen factor: initiates intrinsic pathway following blood trauma. contact of this factor with platelet and collagen or wettable surface results in configuration change and activation, which in turn activates other factors to lead to clotting
factor I
fibrinogen
factor II
prothrombin
factor III
tissue factor, tissue thromboplastin
factor IV
calcium
factor V
proaccelerin; labile factor; Ac-globulin (Ac-G)
factor VII
serum prothrombin conversion accelerator (SPCA); proconvertin; stable factor
factor VIII
antihemophilic factor (AHF); antihemophilic globulin (AHG); antihemophilic factor A
factor IX
plasma thromboplastin component (PTC); Christmas factor; antihemophilic factor B
factor X
Stuart factor; Stuart-Prower factor
factor XI
plasma thromboplastin antecedent (PTA); antihemophilic factor C
factor XII
Hageman factor
factor XIII
fibrin-stabilizing factor
absence of factor VIII
hemophilia A (85% of cases), an X-linked recessive trait
what are natural anticoagulants contained in the blood?
- glycocalyx
- thrombomodulin
- heparin
glycocalyx
mucopolysaccharide adsorbed to inner surface of endothelium, repels the clotting factors and platelets
thrombomodulin (alpha 2-macroglobulin, 360 000D)
binds with thrombin and prevents coagulation
heparin
activate other factors that remove thrombin, also increases activity of antithrombin-III by 100-1000 fold
