Introduction To Microscopy🔬 Flashcards
True or False
for an image to be seen by the eye, the image must be presented to the eye in colors of the visible spectrum and/or varying degrees of light intensity.
True
What are the eye receptors of the retina for sensing color?
Cone cells
What are the cells for distinguishing levels of brightness, NOT IN COLOR?
Rod cells
Where is the location of cone cells and rod cells?
On the retina, at the back of the inside of the eye.
What are the mechanisms for admitting light and focusing it on the retina?
1- The front of the eye
2- the iris
3- the curved cornea
4- and the lens
The “message” is sent to the brain via what?
The optic nerve.
How the image must be spread to be seen clearly?
The image must be spread on the retina at a sufficient VISUAL ANGLE.
What happens if the light falls on non-adjacent rows of retinal cells (a function of magnification and the spreading of the image) ?
We will be unable to distinguish closely details as being separate (resolution).
Or
We wouldn’t see the details clearly.
How to see the details as being separate?
There must be sufficient contrast between adjacent details and/or the background to render the magnified, resolved image visible.
What are the tasks of the microscope?
Three tasks;
1- magnification: produce a magnified image of the specimen.
2- resolution: separate the details in the image.
3- contrast: render the details visible to the eye, camera, or other imaging device.
What are the five types of microscopies?
- Simplemicroscope.
- Compound
microscope. - Electron
microscope. - Stereomicroscope.
- Scanningprobe
microscope.
When using simple microscope the objects brought very close to the eye cannot have their images brought to focus on the retina?
Because of the limited ability of the eye’s lens to change its shape in simple microscopes.
What are the convex lenses?
Lenses that are thicker in the center than the periphery.
How the object can be focused while using simple microscopes?
The object could be focused by use of the magnifier placed between the object and the eye.
How can simple microscopes, cornea, and eye lenses spread the image on the retina?
By magnification through increasing the visual angle on the retina.
True or False
When you look into a compound microscope, you are not looking at the specimen, you are looking at an ACTUAL of the specimen?
FALSE
I’m actually looking at the IMAGE of the specimen.
When you should use an electron microscope?
- When I need to see the image in HIGH RESOLUTION as the image can be magnified in manometers.
- to see the very fine details of the specimen.
What are the types of electron microscope?
- The transmission electron
microscope (TEM)
-the beam is not scattered - The scanning electron microscope (SEM)
-scattered beam of electrons
What is the metal used in electron microscope ?
Tungsten
What type of lenses used in electron microscope?
Magnetic coils
Why magnetic coils are used in electron microscopes?
- magnetic coils are capable of focusing the electron beam on the sample.