Practical Flashcards
what device is used to determine hb?
Sahli’s haemoglobinometer
different methods of hb calculation
Indirect colorimetric methods
• tallquist’s method - hb is converted into oxyhb
• haldene’s method - hb is converted into deoxyhb
• cyanmeth method - hb is converted into cyanmeth
Direct methods
• Van Slyke’s method for oxygen carrying capacity
• iron estimation
• spectrophotometery
direct all good. of indirect cyanmeth is the best
advantages and disadvantages of sahli’s haemoglobinometer and errors
advantages: easy to use, affordable (inexpensive) and fairly accurate
disadvantages : time consuming as the colour has to be matched with the standard
and day time is required
errors :
personal
instrumental : fading of colour strips (standard) in comparator
pipette error : formation of air bubbles while sucking the blood
can we use h2so4 and hno3 instead of hcl
no
h2so4 - formation of unstable compound
hno3 - causes precipitation
why glass distilled water and not copper distilled water
because cu2+ ions will interfere with colour matching and therefore lead to error.
and tap water because impurities
can u use more or less of n/10 hcl than upto 10 mark. why do you have to wait for 10 minutes?
as the instrument is standardised for adding n/10 hcl upto 10 mark and it is also the minimum essential amount required for the formation of acid haematin from 20 mm3 of blood.
most (95%) of haemoglobin is converted to acid haematin within 10 minutes
physiological variations
- age - children > adults
- sex - men > women
- diurnal - evening > morning
functions of hb in blood
- transport of o2 from lungs to various tissues
- transport of co2 from tiisues to lungs
- maintains the acid base balance by acting as a buffer
stage where hb synthesis starts
proerythroblast
calculations of white blood cell count
• dilution factor
volume of bulb = 11-1 = 10 (2 drops from stem are discarded)
10 volume of diluted blood contains 0.5 volume of blood.
therefore, 20 volume of blood will contain 1 volume of blood
so, dilution factor = 20
Area of one square = 1 x 1 mm2
Area of four squares= 4 x 1 x 1 mm2
Depth of each square = 1/10 mm
therefore volume of all four squares = 4/10 mm3
let the total number of white blood cells present in all four squares be x
therefore, x = x1+x2+x3+x4
now since 4/10 mm3 volume contains x number of cells,
so 1mm3 of volume will contain = x x 10/4
now after multiplying the dilution factor,
total white blood cells = x x 10/4 x 20
= x x 50 /mm3 of blood
normal wbc
4000-11000 /mm3 of blood
above 50,000 - leukemia
below 4000 - leukocytopenia
above 11,000 - leukocytosis
wbc dilating fluid
turk’s fluid
• glacial acetic acid - for rbc lysis
• gentian blue / methylene blue - for staining the nucleus of wbcs
• distilled water - for dilution
physiological leucocytosis and leucocytopenia
- in females in menstruation, pregnancy and lactation
- after severe exercise
- after cold bath
- stress
- diurnal variations - evening > morning low
leucocytopenia
- starvation
pathological - leucocytosis and leucocytopenia
leucocytosis -
• acute and chronic infection
• allergic disorders
• leukemia
leucocytopenia
• typhoid fever
• bone marrow depression
• viral or protozoan infection
where are wbcs produced?
monocytes + granulocytes - bone marrow
lymphocytes - bone marrow and lymphoid tissues
errors of wbc
• pipette errors
- if pipette is wet hemolysis occurs
- blood drawn beyond the 0.5 mark
- less blood drawn due to air bubbles
- sedimentation of wbcs in the bulb
- initial drops are not discarded rbc count decreases
• chamber errors
- air bubble in chamber
- overflowing of fluid into the trenches therefore wbc count decreases
• field errors
- uneven distribution of cells
- not following the L rule and counting along all the four borders of the squares leading to repeated counting
hayem’s fluid
Hayem’s fluid:
a. nacl - provides isotonicity
b. na2so4 - anticoagulant
c. hgcl2 - antimicrobial and preservative
d. Distilled water – solvent medium and dilution
what happens to wbc in rbc count
the wbcs remain as they are. very less in number so does not interfere in rbc count
counting of rbcs
• dilution factor
volume of bulb = 101-1 = 100 (2 drops from stem are discarded)
100 volume of diluted blood contains 0.5 volume of blood.
therefore, 200 volume of blood will contain 1 volume of blood
so, dilution factor = 200
Area of one square = 1/5 x 1/5 mm2
Area of five squares= 5 x 1/5 x 1/5 mm2
Depth of each square = 1/10 mm
therefore volume of all five squares = 5/250 mm3
let the total number of red blood cells present in all five squares be N
therefore, N = N1+N2+N3+N4+N5
now since 5/250 mm3 volume contains x number of cells,
so 1mm3 of volume will contain = x x 250/5 = 50x
now after multiplying the dilution factor,
total white blood cells = 50x x 200
= 10000x /mm3 of blood
what is anemia
anemia is defined as the deficiency of hemoglobin in the blood which can be caused by either too few red blood cells or too little hemoglobin in the cells.
pathological variation anemia polycythemia
anemia
- Pernicious Anemia
- aplastic anemia
- iron deficiency
polycythaemia - primary - polycythemia vera (cancerous production of rbcs) - secondary polycythemia • chronic respiratory diseases • congenital heart disease
what is the imp of keeping a control in the blood group experiment
- to compare and to look for the presence or absence of agglutination
- also helps to rule out pseudo agglutination
what prevents the coagulation of blood in this experiment
sodium citrate in saline prevents the coagulation
mechanism of hemostasis
- vascular spasm
- platelet plug formation
- blood coagulation
- clot retraction
bleeding time prolonged in
idiopathic thrombocytopenic purpura
clotting time is prolonged in
classical hemophilia and Christmas disease, vitamin k deficiency and liver diseases - hepatitis, cirrhosis
why clotting time more than bleeding time
because clotting time is a biochemical process wherein there is an interaction between various clotting factors and this requires more time than a mechanical process like vascular spasm
different laboratory anticoagulants
• edta (Ethylenediamine tetra acetic Acid)
• oxalates and citrates
combine with ca2+ and decreases theur concentration and therefore prevents process of coagulation
• heparin inhibits thrombin formation.
platelet count is increased and decreased in (pathologically)
inc • trauma • infections • bone marrow malignancy • splenectomy • iron deficiency anemia
dec • idiopathic thrombocytopenic purpura • infections (like dengue) • splenomegaly • aplastic anemia
functions of platelets
- vascular spasm
- platelet plug formation
- blood coagulation
- stabilizing the clot
- clot retraction
- mild phagocytosis
- repair of ruptured blood vessel (PDGF)
thrombocytopenic purpura
clinical condition in which there is a decrease in platelet count below 50,000 per mm3 characterized by multiple subcutaneous hemorrhage and prolonged bleeding and clotting retraction time
clinical significance of reticulocyte
to see observe the effect of hematinic drugs on erythropoiesis during recovery from anemia
normal : adult and Children - 0.2 -2%
infant and cord blood - 2-6%
wintrobe and westergrens normal values
males :
wintrobe - 0-9mm at the end of 1st hour
westergrens - 3-5 mm at the end of 1st hour
females
wintrobe - 0-20 mm
westergrens - 5-7 mm
wintrobes tube advantage
quantity of blood needed is small
same can be used for pcv
normal values of pcv
- males - 40-47
- females - 37% to 45%
pcv
height of rbc coloumn/ total height of blood coloumn x 100
mcv mch mchc
mcv - average volume of a red blood cell
- pcv/red cell count x 10
- 78-94 umm3
mch - represents average weight of hemoglobin in one red cell
- hb gm% / rbc count x 10
- 27-32 pg
mchc - represents the amount of hb per 100 ml of red cells
- hb gm % / pcv x 100
- 32-38%
normal fragility
0.46-0.34 % of nacl
osmotic fragility imp
- no direct clinical significance but additional investigation to detect intrinsic defects of rbcs in diff types of anemia like hemolytic anemia, sickle cell anemia and hereditary spherocytosis
fragility is altered in
increased - venous blood stored blood hereditary or acquired spherocytosis sickle cell anemia
decreased -
thalassemia
iron deficiency anemia
due to mismatching
acute or first degree - chills, rigor, fever, pain in loin
second degree - hemolysis or jaundice
delayed third degree - acute renal shutdown.
spirometry
fev fev1 fev2 - obstructive jaundice dec
fev1 and fev2 normal and vc is decreased
dyspnoeic index
mvv - rmv / mvv x 100
normal - 90 and reduced below 60-70
hb normal values
men - 15 -17 gm /100 ml.
In Females:13 - 14.5 gm/100ml.
newborn:23 gm/100ml. of blood
