Histotechnology Exam 1 Questions
(chapter 1) | Questions with
Solutions
What method is used to stabilize proteins making it resistant to further
damage? - -Fixation
- Name two methods of fixation? - -Chemical reaction (formaldehyde) and
physical (heat or dessication)
- What are two causes of Post mortem putrefaction if the tissue is not fixed?
***** - -bacteria or mold
- What factor causes autolysis if tissue is not fixed? **** - -enzyme attack
- What are four functions of fixatives? - -1. kills tissue to prevent
putrefaction and autolysis
2. maintains proper relationship between intracellular and extracellular
substances
3. preserves refractive indexes
4. enhances stains
- What three organs contain the highest levels of enzymes? - -liver, kidney,
and brain
- True or False. You can over fix tissue? - -True. Over fixation dries out the
tissue and limits the quality. Can attempt steaming the sections to remedy
over fixation.
- If you receive a breast sample on a Friday night, what method must be
performed to prevent exceeding the allowed formalin fixation time to
perform the Her2 test? - -Must place the tissue in 70% alcohol for one day
and then place in formalin the following day.
- How quickly does formalin penetrate tissue? - -1 mm per hour
- True or False. When fixing a liver specimen, the fixation time should be
doubled? - -True. The enzymes found in the cytoplasm need to be fixed well.
- What is the name of a fixative that is combined with the protein molecule?
Give an example. - -additive fixative
Ex. formaldehyde
, - What is the name of a fixative that removes water from tissue? Give two
examples - -nonadditive fixative.
Ex. alcohol or acetone
- At what pH does formaldehyde cross-link the amino groups? - -7.0
- Name three factors that influence fixation? - -temperature, size, and time
- At what temperature are most fixatives performed at? - -room
temperature (20°C) up to 45°C
- What size should sections of tissue be sampled that are being processed
for routine processing (10-12 hours)? - -3mm thick (thinner for shorter
processing times)
- What size should sections of tissue be sampled that are being processed
for whole mounts (36 hour processing)? - -8mm thick
- What event must occur for penetration of fixative to occur? - -Blood supply
must stop
- What will be present in the center of tissue that has a lego appearance?
What stage was interrupted to cause this to happen? - -water will be present
and the center will not be properly fixed. Alcohol was not able to properly
penetrate the tissue. Alcohol removes water from tissue.
- What is commonly the pH of fixatives? - -7.2-7.4
- What is commonly the osmolarity of fixatives? - -340mOsm (salty)
- What molar value is common in fixatives? - -0.1 molar with pH 7.4
- What simple aqueous fixative is used for fixing nuclei-proteins, fast acting,
is added to other fixatives to counteract shrinkage, and lyses red blood cells?
Does not fix carbs or lipids. - -acetic acid (5% acetic acid = vinegar)
- What simple aqueous fixative is considered a additive fixative, fixes lipids
but doesn't make them insoluble, and associated with an increased loss of
lipids the longer the fixation time, rapid fixation time, hardens tissue, can
cause pigment if the pH drops below 6.0? **** - -formaldehyde
- Formaldehyde comes as a liquid that is _____% to _____%, which is
considered 100% formalin. - -37-40%
(chapter 1) | Questions with
Solutions
What method is used to stabilize proteins making it resistant to further
damage? - -Fixation
- Name two methods of fixation? - -Chemical reaction (formaldehyde) and
physical (heat or dessication)
- What are two causes of Post mortem putrefaction if the tissue is not fixed?
***** - -bacteria or mold
- What factor causes autolysis if tissue is not fixed? **** - -enzyme attack
- What are four functions of fixatives? - -1. kills tissue to prevent
putrefaction and autolysis
2. maintains proper relationship between intracellular and extracellular
substances
3. preserves refractive indexes
4. enhances stains
- What three organs contain the highest levels of enzymes? - -liver, kidney,
and brain
- True or False. You can over fix tissue? - -True. Over fixation dries out the
tissue and limits the quality. Can attempt steaming the sections to remedy
over fixation.
- If you receive a breast sample on a Friday night, what method must be
performed to prevent exceeding the allowed formalin fixation time to
perform the Her2 test? - -Must place the tissue in 70% alcohol for one day
and then place in formalin the following day.
- How quickly does formalin penetrate tissue? - -1 mm per hour
- True or False. When fixing a liver specimen, the fixation time should be
doubled? - -True. The enzymes found in the cytoplasm need to be fixed well.
- What is the name of a fixative that is combined with the protein molecule?
Give an example. - -additive fixative
Ex. formaldehyde
, - What is the name of a fixative that removes water from tissue? Give two
examples - -nonadditive fixative.
Ex. alcohol or acetone
- At what pH does formaldehyde cross-link the amino groups? - -7.0
- Name three factors that influence fixation? - -temperature, size, and time
- At what temperature are most fixatives performed at? - -room
temperature (20°C) up to 45°C
- What size should sections of tissue be sampled that are being processed
for routine processing (10-12 hours)? - -3mm thick (thinner for shorter
processing times)
- What size should sections of tissue be sampled that are being processed
for whole mounts (36 hour processing)? - -8mm thick
- What event must occur for penetration of fixative to occur? - -Blood supply
must stop
- What will be present in the center of tissue that has a lego appearance?
What stage was interrupted to cause this to happen? - -water will be present
and the center will not be properly fixed. Alcohol was not able to properly
penetrate the tissue. Alcohol removes water from tissue.
- What is commonly the pH of fixatives? - -7.2-7.4
- What is commonly the osmolarity of fixatives? - -340mOsm (salty)
- What molar value is common in fixatives? - -0.1 molar with pH 7.4
- What simple aqueous fixative is used for fixing nuclei-proteins, fast acting,
is added to other fixatives to counteract shrinkage, and lyses red blood cells?
Does not fix carbs or lipids. - -acetic acid (5% acetic acid = vinegar)
- What simple aqueous fixative is considered a additive fixative, fixes lipids
but doesn't make them insoluble, and associated with an increased loss of
lipids the longer the fixation time, rapid fixation time, hardens tissue, can
cause pigment if the pH drops below 6.0? **** - -formaldehyde
- Formaldehyde comes as a liquid that is _____% to _____%, which is
considered 100% formalin. - -37-40%
