physio- block I

Question 1

different types of microscope

Answer 1

• electron microscope
• dark field microscope
• laser microscope
• polarizing microscope
• scanning electron microscope

notes say to know at least 4

Question 2

What is a microscope? Why different objectives are used?

Answer 2

Instrument that enlarges image of object that is not visible by the naked eye

• different objectives are used to see different things since all of them have diff magnifications

Question 3

When is oil immersion lens used? What is the use of cedar wood oil in microscopy?

Answer 3

oil immersion lens: for very high magnification (1000x)

cedar wood oil: used to create a clearer image, since it prevents light from being scattered as it passes from the slide to the objective lens

Question 4

Why field diaphragm is used? When different intensities of light are used?

Answer 4

field diagram: controls amount of light that reaches specimen

• different intensities of light are used depending on the specimen being viewed since some require more light & some require less light

Question 5

What magnification is obtained with the high-power objective? And the other lens?

Answer 5

magnification of high power objective lens is 40x so **total magnification is 400x

low power (10x) so total magnification 100x

oil immersion lens (100x) so total magnification 1000x

Question 6

what is the use of condenser in microscope?

Answer 6

focuses light from illuminator onto stage

Question 7

RBC count in normal adults

Answer 7

males: 5.2 +/- 0.3 million/microliter

females: 4.7 +/- 0.3 million/microliter

Question 8

Heyem’s solution (constituents & functions)

Answer 8

Heyem’s solution: RBC diluting fluid, greenish bottle

NaCl → maintains osmolarity

Na2SO4 → prevents aggregation of RBCs

HgCl2 (mercuric chloride) → anti fungal & anti-bacterial agent (preservative)

H2O (distilled) → solvent

Question 9

where are the WBC and RBC counting areas in a neubars chamber?

Answer 9

neubar chamber is a 3 x 3 grid

corners are the WBC areas (are 4x4 inside)

middle piece is the RBC counting area (5x5 grid)
- RBC area is also bounded by triple lines on all sides

Question 10

What are the identification points of a hemocytometer (improved Neubauer chamber)?

Answer 10

+ sign in the H area

RBC region is triple bounded on all side and narrower

while WBC region is wide, double bounded

Question 11

What precautions are observed while handling a hemocytometer?

Answer 11

handle with care & prevent it from dropping

dont rub the surface while cleaning

use only distilled water to clean

Question 12

What is the qualitative difference between the metallized and ordinary glass Neubauer chamber?

Answer 12

difference is the + sign

the metal one is coated with rhodium

Question 13

Thomas rule

Answer 13

when counting neubars chamber, count cells that touch left & top lines but not ones that touch the right & bottom lines of each square (so go in an S figure)

to prevent double counting

Question 14

why is the blood diluted before counting?

Answer 14

cell density of blood is extremely high so it would be difficult to count without diluting first

• heyem’s fluid can also prevent blood clotting since it is isotonic

Question 15

What is the use of graduations on the stem of the RBC’s pipette?

Answer 15

used for dilution purposes

graduation at 0.5 - allows to take half of blood sample

graduation at 1 - allows to take full sample of blood

mark at 101- where dilution is drawn up to create the correct dilution

Question 16

What is polycythemia? What clinical picture would you expect in an individual suffering from polycythemia?

Answer 16

abnormal increase in RBC count or conc. of hemoglobin in the blood

clinical features: shortness of breath, fatigue, dizziness

Question 17

What is anemia? What clinical picture would you expect in an individual suffering from anemia?

Answer 17

insufficient supply of blood to body tissues bc of lack of adequate healthy red blood cells or hemoglobin

• lower RBC count expected in these individuals

Question 18

What precautions will be observed while determining RBC count using hemocytometer?

Answer 18

• no blood from patients suffering from blood-clotting disorders or on anti-coagulants
• all materials should be clean and dry
• first drop of blood discarded
• tip of pipette should constantly be in blood to avoid air bubbles
• do not milk finger
• reduce light intensity to enhance contrast

Question 19

What factors affect the RBC count?

Answer 19

• genetic factors like inherited diseases
• environmental factors like malnutrition & smoking
• errors in calculation like incorrect dilution

Question 20

dilution factor for RBC’s & platelets

for WBCs?

Answer 20

RBC’s/platelets: 200

WBC’s: 20

Question 21

counting magnification for WBC, RBC, platelets

Answer 21

WBC: 10x

RBC: 40x

platelets: 100x

Question 22

WBC count range in men & women

Answer 22

same range in both

4000-11,000 cells/microliter

Question 23

Turk’s solution (components + uses)

Answer 23

light blue solution- pretty color used for WBC count

glacial acetic acid → hemolysis of RBC’s without affecting WBC’s (kills off the RBC’s)

gentian violet (1% solution) → staining! stains nuclei of WBC’s

distilled water → acts as solvent

Question 24

Rees-Ecker’s solution (components + uses)

Answer 24

pink color
for platelet count

brilliant cresyl blue → stains platelets

sodium citrate → prevents clotting & makes fluid isotonic

formalin → prevents fungal growth & lyses of RBC’s

distilled water (H2O) → solvent

Question 25

diff b/w tubes for RBC & WBC counts

Answer 25

**RBCs**: has a red bead inside, ticker bulb, and the mouthpiece is red **WBCs**: has a white tube and thinner bulb

Question 26

when charging a hemocytometer, why do you discard the first drop of blood?

Answer 26

because the stem of the pipette is typically filled with only diluting fluid, not a mixture of blood and diluting fluid

Question 27

how to charge hemocytometer for WBC count

Answer 27

fill blood up until 0.5 then fill up the rest with turk's solution then mix using figure 8 symbol then discard the first drop and place the second drop slightly lower than the coverslip

Question 28

What factors affect the WBC count?

Answer 28

- infections - stress (exercise makes your WBC levels go up) - medications - diseases

Question 29

Why the blood dilution of 1 in 20 is obtained for WBC counting instead of 1 in 200 as in RBC and platelet counts?

Answer 29

the dilution factor is lower bc WBC's are also lower in number than RBC's

Question 30

What is **leukocytosis**? What does it indicate? What is **leukopenia**? What are its causes?

Answer 30

**leukocytosis**: when WBC count exceeds 11,000 cells/microliter - *shows in infections, burns, hemorrhage* - *mostly favorable sign showing body is defending against foreign material* **leukopenia**: when WBC count goes below 4000 cells/microliter - *caused by immune disorders like infections, viruses, malnutrition or depression of bone marrow (due to radiation, poisoning, or alcoholism*

Question 31

What is the normal platelet count?

Answer 31

150,000-130,000 platelets per microliter

Question 32

Which hormone stimulates thrombopoiesis?

Answer 32

thrombopoietin (TPO)

Question 33

What functions are performed by the platelets?

Answer 33

- blood clotting - release clotting factors - heal wounds

Question 34

Why is blood diluted before counting?

Answer 34

to reduce concentration of cells per microliter making it easier to count with more accuracy

Question 35

What is thrombocytopenia? What clinical picture would you expect in an individual suffering from thrombocytopenia?

Answer 35

**thrombocytopenia**: condition where platelet count is too low (deficient) *clinical picture: bruising, bleeding that doesnt stop, nosebleeds*

Question 36

conduction velocity calculation in power lab

Answer 36

**conduction velocity = distance/latency** *distance* = b/w the 2 points of stimulation *latency*= proximal latency - distal latency

Question 37

speed for simple muscle twitch & effect of temp graph speed for

Answer 37

**SMT & temp graph**: 625 mm/s **tetanization graph**: 2.5 mm/s

Question 38

frog saline and human saline diff

Answer 38

**frog saline**: 0.65% **human saline**: 0.9%