Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Stack #96661
Microscopy complete
| Question | Answer |
|---|---|
| Key characteristics of a reliable microscope are: | Magnification – ability to enlarge objects and (Resolving) Power - ability to show detail |
| Magnification in most microscopes results from interaction between | visible light waves and curvature of the lens |
| the image appears enlarged | Depending on the size and curvature of the lens |
| extent of enlargement | magnification |
| refraction | angle of light passing through convex surface of glass changes |
| power of objective X power of ocular = | total magnification |
| 3 Types of Light Microscopes | Bright-field, Dark-field, Phase-contrast |
| most widely used microscope; specimen is darker than surrounding field; live and preserved stained specimens | Bright-field |
| Microscope that uses brightly illuminated specimens surrounded by dark field; live and unstained specimens | Dark-field |
| Microscope that transforms subtle changes in light waves passing through the specimen into differences in light intensity, best for observing intracellular structures | Phase-contrast |
| Microscope useful in diagnosing infections | Fluorescence Microscope |
| Fluorescence Microscope | Modified compound microscope with an ultraviolet radiation source and a filter that protects the viewer’s eye; Uses dyes that emit visible light when bombarded with shorter UV rays - fluorescence |
| Forms an image with a beam of electrons that can be made to travel in wavelike patterns when accelerated to high speeds | Electron Microscopy |
| Electron Microscopy | Magnification between 5,000X and 1,000,000X; Electrons have tremendous power to resolve minute structures because resolving power is a function of wavelength. |
| 2 Types of Electron Microscopes | Scanning electron microscopes (SEM) and (TEM) Transmission electron microscopes |
| Transmission electron microscopes (TEM) | transmit electrons through the specimen. Darker areas represent thicker, denser parts and lighter areas indicate more transparent, less dense parts. |
| Scanning electron microscopes (SEM) | provide detailed three-dimensional view. SEM bombards surface of a whole, METAL-COATED SPECIMEN with electrons while scanning back and forth over it. |
| Two types of Specimen Preparation techniques | Wet mounts and Fixed mounts |
| Wet mounts | allow examination of characteristics of live cells: motility, shape, and arrangement |
| Fixed mounts | are made by drying and heating a film of specimen. This smear is stained using dyes to permit visualization of cells or cell parts. |
| Staining Dyes create contrast by | imparting a color to cells or cell parts. |
| Positive staining | surfaces of microbes are negatively charged and attract basic dyes |
| Negative staining | microbe repels dye, the dye stains the background |
| Simple stains | one dye is used; reveals shape, size, and arrangement |
| Differential stains | use a primary stain and a counterstain to distinguish cell types or parts (examples: gram stain, acid-fast stain and endospore stain) |
| Special stains | reveal certain cell parts not revealed by conventional methods: capsule and flagellar stains |
Created by:
tamiboren
Popular Nursing sets