Background & History, Microscopy, Tissue Prep & Staining, Epi. Characteristics 1 Flashcards
What are the characteristics of a virtual image?
-Real -Upright -inside focal point -Can be magnified
What is Histopathology?
The study of diseased tissue
What is refractive power?
A measure of how much a lens bends light waves. Measured in diopters
What are the four basic tissue types?
Epithelial tissue Connective Tissue Muscular Tissue Nervous Tissue
What type of epithelial are kidneys?
Simple cuboidal
What is refraction of light?
The bending of light as it passes through a medium. When traveling through a vacuum, velocity is fixed.
What type of epithelial is the ileum?
Simple columnar
What are 4 examples of connective tissue?
Dense Bone Cancellous bone Adipose Tissue Hyaline Cartilage
What is resolution?
The ability of a microscope to distinguish two lines as separate entities. Diameter of diffraction lines around the points must be reduced.
What are 3 examples of muscular tissue?
Smooth muscle Cardiac muscle Skeletal muscle
What are 2 types of nervous tissue?
Purjinke cells Cerebral Cortex
What is the equation for refractive index?
RI = velocity of light/velocity in medium
What is a focal point?
The point at which all lines converge after passing through a lens.
Indicate which major tissue group these each belong: a) ducts of glands b) skin c) lining of blood and lymphatic vessels d) fat e) red and white blood cells f) kidney tubules g) cartilage h) tendons and ligaments
a) epithelial b) epithelial and CT c) epithelial d) CT e) CT f) epithelial g) CT h) CT
What two histologists shared a Noble Peace Prize in Physiology/Medicine?
John O’Keefe and Edward I. Moser
What is the highest resolution for a TEM?
0.5-10 angstroms
What is the equation for resolution?
d = (0.61)wavelength/n sin alpha (want a small d)
What is the concept of humoral pathology?
That diseases are due to an imbalance of 4 fluid humors: blood, phlegm, yellow bile and black bile
Who found out that it wasn’t due to humoral imbalances but based on organ level in pathology?
Giovanni Battista Morgagni
What role did Bichat play in histology?
Frenchman; described 21 membranes “father of modern histology” via tissue level and didn’t use a microscope; organic life
What role did Virchow place in histology?
German; cellular level; used the cell theory that all life forms contain cells from existing cells
What does the degree of bending depend upon? (2)
The angle at which the light strikes the surface and the refractive index (n)
What are the characteristics of a real image?
Located outside of the focal point Inverted Can be projected into a screen A short focal point indicates greatest magnification
What is the max value for n (refractive index)?
1.4 (oil)
What is the max value for sin alpha?
180
What values can be changed to improve resolution? (2)
Shorter wavelength Larger n (refractive index)
What is the highest resolution of a light microscope?
0.5 micrometers
What are the components of a light/bright field microscope? (4)
Condensor Objective lens Ocular lens Stage Light source
What are the pros and cons of light microscope?
Pros: ability to magnify and resolve structural detail Cons: specimen must be thin, little contrast in unstained specimen
How does Phase Contrast Microscope work, what is examined with them?
Views living cells, unstained cells and tissues. Converts phase shifts (invisible to eye) in light passing through a transparent specimen to brightness changes (visible) in the image. Light passing thru cell regions become deflected and out of phase with main stream light waves which are matched with other induced out of phase wavelengths which cancels their amplitude and creates light waves that can be seen.
How does a fluorescence microscope work and what do they detect?
Detects molecules that emit light of wavelengths within the visible range when exposed to a UV light source. Used to detect induced fluorescence (such as Ag, Ab, injected fluorescent tracers)
How does a confocal scanning microscope work and what is visualized?
A pinhole is added to eliminate out-of-focus light to increase optical resolution and contrast. Used to view 3D images. This type uses a mixture of fluorescent and light microscopes with a scanning system that employs a laser beam that produces a scanning spot that utilizes a mirror system that moves across a specimen and data from each spot on the specimen is recorded and stored into a computer, which then creates a visual image.
What are the advantages of a confocal scanning microscope (3)?
Very thin optical images of specimen can be created (1um thick) Out-of-focus images are subtracted by the computer Computer can make 3D reconstructions of specimens by stacking individual images.
What are the components of TEM microscope?
Cathode Heated tungsten filament (electron source) Anode; drives electrons thru the column Series of electromagnets; condenser lens, objective lens, and projection lens. Specimen holder Viewing screen and photographic film
What does TEM microscope utilize rather than light?
A beam of electrons rather than light?
What does a fluorescence microscope detect and what is its most widespread application?
Detects molecules that emit light of wavelengths in the visible range when exposed to a UV light source Detects naturally occurring fluorescent (autofluorescent) molecules i.e. Vitamin A Widespread use of visualization of induced fluorescence: Ag or Ab in immunochemical staining procedures and fluorescent tracers injectoed into animals or cells
What are the 4 steps in tissue fixation and embedding?
Fixation Dehydration Removal of alcohol Embedding
What are the characteristics of fixation, why is it used?
Prevents further deterioration and hardens tissue prior to embedding and sectioning. Any fixative radically distorts a specimen Ideal fixatives give greater optical contrast (w/ staining) with the least amount of distortion