HIstology Chapter 1 Flashcards
Chemical level of organization goes to what higher level of organization?
Cellular level
The cellular level of organization goes to what higher level of organization?
Tissue level
The tissue level of organization goes to what higher level of organization?
Organ level
The organ level of organization goes to what higher level of organization?
Organ system level
The organ system level of organization goes to what higher level of organization?
Organismal level
Are the heart and the blood vessels the same organ?
No, they are separate.
How does light microscopy work?
Specimens are examined via transillumination (i.e. light passing through the specimen to facilitate observation).
What are the two types of electron microscopy?
Scanning and Transmission
What kind of pseudo images does a SEM create?
Three dimensional
What kind of things can atomic force microscopy view?
Molecular structures like DNA
What is resolving power/resolution?
Defined as how far two objects must be separated from one another so that they can be distinguished as two distinct objects.
What is the resolving power of the human eye?
0.2mm
What is the resolving power of a light microscope?
0.2 micrometers
What is the resolving power of SEM
2.5nm
What is the resolving power of TEM?
0.05nm (theoretical)/ 1.0nm (tissue section)
What is the resolving power of atomic force microscopy?
50.0 pm
What are five things resolution is dependent upon?
1.optical system, 2.wavelength of light source, 3.specimen, 4.quality of fixation, 5.staining intensity
What does a TEM micrograph typically look like in terms of its color?
Black and white
What is a structure found in micrographs that can be used for size reference as it is typically one size?
A red blood cell
How large is a red blood cell?
7.8 micrometers
What are the six steps involved in making a slide for light microscopy?
1.acquisition of cells or tissue, 2.fixation, 3.processing, 4.embedding, 5.sectioning, 6.staining
What does “fixation” do when creating a light microscopy slide?
This stops metabolism, kills bacteria and viruses, and helps harden the tissue.
What are three examples of chemicals used to “fix” tissues used in light microscopy?
Formalin, formaldehyde, glutaraldehyde
What do the fixing chemicals do to preserve the tissues?
They cause cross-linking among the proteins which halts their activity.
What are the three steps involved during the processing step of tissue to be used in light microscopy?
1.dehydration, 2.clearing, 3.infiltration
Explain the dehydration process of tissue used in microscopy slide preparation.
The tissue will be submerged in a graded series of alcohol that removes water and replaces it with alcohol.
Explain the clearing process of tissue used in microscopy slide preparation. Also what was the chemical discussed in class?
This is a substance that makes the tissue sample more clear and also is miscible with the paraffin wax used later. The chemical discussed in class was xylene.
Explain the embedding process used in microscopy slide preparation.
The tissue is placed into a container that then has hot paraffin wax poured over it.
What part of the specimen embedded in paraffin, will eventually be cut and put onto a slide?
The surface of the tissue that is facing down.
What is the machine used for sectioning and embedded specimen?
a microtome
What is still left on the specimen that will need to be removed before staining can occur?
The remaining paraffin wax.
How is the tissue prepared for staining?
The tissue is moved from one organic solvent to the next until a stain can be added.
Does the sample have to be prepared so that a cover slip can be glued to the slide?
Yes
What are the three problems with the typical histological technique used to prepare tissues to be observed with a light microscope examination?
1.time consuming, 2.the solvents used dissolve lipids, 3.shrinkage of tissues
What can be used to reduce the time needed to prepare a light microscopy slide?
Use a cryostat.
How does a cryostat work?
Liquid nitrogen is used in a process that freezes a sample so that it can be cut right away.
Does fixing happen when a cryostat is used?
No, proteins can still function.
What is a solution to the issue of solvents dissolving lipids in tissue samples?
Double fixation
What is double fixation and what are the chemicals used?
First, fixation with glutaraldehyde and then a second fixation with osmium tetroxide.
What is osmium tetroxide?
A heavy metal used in fixing tissue.
What is a solution to hot paraffin wax shrinking tissue that it prepared for light microscopy slides?
Embedding the tissue in resin/liquid plastic.
What does osmium tetroxide stain and make visible?
Plasma membranes
What charge does an acidic dye have?
Net negative charge
What kind of charged tissue does an acidic dye bind to?
Cationic cell/tissue components. These are acidophilus or eosinophilic.
What are three examples of acidic dyes?
Eosin, orange G, and acid fuchsin
What are some examples of tissue that acidic dyes will stain?
MItochondria, secretory granules, collagen fibers (as well as other secretory fibers), general cytoplasm, basement membrane
Are more cellular tissues acidophilic or basophilic?
Acidophilic, it is a less specific dye.
What charge does a basic dye carry?
A net positive charge, the bind to anionic tissues with a net negative charge.
What are some examples of basic dyes?
Toluidine blue, alacian, and methylene blue; hematoxylin, although not a basic dye acts like one.
What are some examples of tissue that basic dyes will bind to?
The negative phosphate group on DNA and RNA (cell nucleus, nucleoli, RNA-rich portions of the cytoplasm); the carboxyl groups of proteins; sulfate groups of cartilage matrix (GAGs)
What color does hematoxylin dye tissue?
Blue
What color does eosin dye tissue?
Pink
What color does hematoxylin and eosin (H&E) dye tissue?
Purple
Hematoxylin has an affinity to what organelle?
The nuclei
Eosin has an affinity to what part of the cell?
The cytoplasm
What binds to molecules for use in fluorescence microscopy?
DAPI binds to DNA and actin filaments and illuminates tissue.
What are phase contrast microscopes good for viewing?
Cell cultures
Why would you want to use phase contrast microscopy over bright field microscopy?
If we do not want to kill the specimen..
What are the five steps involved in histochemistry and cytochemistry?
1.section immersed in a solution of enzyme’s substrate, 2.enzyme acts on substrate, 3.section put in contrast with a marker compound, 4.marker compound reacts with molecule produced by enzymatic action on substrate, 5.final product (insoluble and visible by light or electron microscopy) precipitates over site
What fixing process must be used in histochemistry and cytochemistry to that enzymes are still functional?
Cryostat
What is immunohistochemistry used to view?
Specific macromolecules with tagged compound
Approximately how many different types of cells are there in the human body?
200
What is the plasma membrane composed of?
Phospholipids, cholesterol, proteins, and chains of oligosaccharides