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MLS 222/L MIDTERMS > DEHYDRATION > Flashcards

DEHYDRATION Flashcards

1
Q

This is done in preparation for impregnation

A

dehydration

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2
Q

This process of removing intercellular and extracellular water from the tissue following fixation and prior to wax impregnation is known as

A

dehydration

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3
Q

the solution utilized for dehydration

A

dehydrating agents

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4
Q

many of the dehydrating agents are alcohols of various types that are used in _________ strengths

A

increasing

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5
Q

why are dehydrating agents used in increasing strengths

A

to remove aqueous tissue fluids with little disruption

to the tissue caused by diffusion currents.

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6
Q

the removal of water by evaporation from a solid, semi-solid or liquid.

A

drying

Note: SOLID TISSUES should NEVER be allowed to AIR DRY

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7
Q

involves slow substitution of the water in the tissue with an organic solvent

A

Dehydration

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8
Q

Most dehydrating agents are strong ____________ that bring about some ___________ and ________ of cell components.

A

organic solvents; shrinkage; extraction

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9
Q

how to counter the shrinkage and extraction of cell components when using dehydrating agents

A

To minimize these effects:

  • dehydrating agents are used in a GRADED SERIES for SHORT PERIODS OF TIME
  • water is GRADUALLY replaced so that violent osmotic changes do not produce distortions
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10
Q

an ideal dehydrating solution should dehydrate gradually without producing considerable shrinkage or distortion of tissues.

A

False. an ideal dehydrating solution should dehydrate RAPIDLY without producing considerable shrinkage or distortion of tissues

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11
Q

an ideal dehydrating solution should not evaporate very fast

A

True

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12
Q

an ideal dehydrating solution should be able to dehydrate even fatty tissues

A

True

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13
Q

an ideal dehydrating solution should harden tissues excessively

A

False. SHOULD NOT harden tissues excessively

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14
Q

an ideal dehydrating solution should be able to remove stains

A

False. should NOT remove stains

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15
Q

an ideal dehydrating solution should not be toxic to the body

A

True

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15
Q

an ideal dehydrating solution should not be toxic to the body

A

True

16
Q

an ideal dehydrating solution should not be a fire hazard

A

True

17
Q

whatever dehydrating agent is used, the amount in each step should not be less than 10 times the volume of the tissue in order to ensure
complete penetration of the tissue by the dehydrating solution.

A

True

18
Q

Dehydration time must be as brief as possible to

A

minimize the risk of extracting cellular constituents

19
Q

any water-miscible, anhydrous fluid can be used as a dehydrating agent providing that it

A
  • does NOT damage the tissue PROTEINS

- is MISCIBLE with the fluids to be used subsequently

20
Q

commonly used dehydrating agents

A
  • alcohol (most common)
  • Acetone
  • Dioxane
  • Cellosolve
  • triethyl phosphate
  • tetrahydrofuran
21
Q

this is an alcohol recommended for routine dehydration

A

ethyl alcohol

22
Q

the best dehydrating agent because it is fast-acting, it mixes with water and many organic solvents, and it penetrates tissues easily

A

ethanol

23
Q

advantages of ethanol as a dehydrating agent

A
  • fast-acting
  • mixes with water and many organic solvents
  • penetrates tissue easily
  • not poisonous
  • not very expensive
24
Q

an alcohol dehydrating agent which is primarily employed for blood
and tissue films and for smear preparations

A

methyl alcohol

25
Q

disadvantage of methyl alcohol

A

it is a toxic dehydrating agent

26
Q

an alcohol dehydrating agent utilized in plant and animal micro-techniques

A

butyl alcohol

27
Q

butyl alcohol is also a fast-acting dehydrating agent

A

False. butyl alcohol is a slow dehydrating agent

28
Q

butyl alcohol produce less shrinkage and hardening than ethyl alcohol

A

true

29
Q

this dehydrating agent is recommended for tissues which do not require rapid processing

A

butyl alcohol

30
Q

why is it not advisable to transfer fixed tissues directly from water or aqueous fixative directly into absolute ethanol.

A

causes a rapid removal of water
which can distort the appearance of more delicate cells and structures
Hence:
-It is advisable to remove water gently and allow the tissue to slowly adjust to its removal.
-The more delicate the tissue, the more gently this should be done, but
there is no hard and fast rule

31
Q

dehydration process

A
  • 70% ethyl alcohol
  • 95% ethyl alcohol
  • 100% ethyl alcohol

MLS 222/L MIDTERMS (2 decks)

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