microlab microscopy

what is the most commonly used microscopy technique

light microscopy

light microscopy often requires

staining of the specimen to be able to visualize the structures of interest

light microscopy is limited to a minimal resoluton of

approximately 200 nanometers (nm)

define minimal resolution

the distance between two points that are still distinguishable as two separate entities

the resolution is limited by physical properties of

light and the lens of the microscope

the shorter the wavelength the (anti limit)

better the resolution

what value of the objective lens limits the resolution

aperture

what can you place between the coverslip of slide and objective lens to tune the aperture value

immersion oil

describe fixation

chemical fixatives preserve tissue by preventing degradation, and help to maintain the structure of the cell and of sub-cellular components.

describe dehydration

water is removed from the sample as it does not mix with embedding media

describe embedding

the same is embedded in a solid external matrix to facilitate sectioning

describe sectioning

the specimen is cut into thin sections. routine histology —> slices are 2-5 micrometers thick

describe mounting

attaching samples to the microscopy slide

describe staining

sample is stained to add contrast and label structures of interest

what are fluorescent dyes

fluorophores that bind to specific cellular structures

fluorescent molecules are linked to

another molecule that specifically binds to the cellular component to visualize

how does fluorescent microscope work

shines a specific wavelength on the sample using excitation filter or with lasers

describe excitation filter

filter that only allows light of the specific wavelength that excites the fluorophore to pass through

describe emission filter

filter between the dichroic mirror and camera that filters out all other (background) wavelengths

describe transmission electron microscopy (TEM)

use a high voltage electron beam to produce an image, and the electrons that pass through the sample are detected

describe scanning electron microscopes (SEM)

produce an image by probing the surface of a specimen

reflection electron microscopes (REM)

use an electron beam that is pointed at a thin specimen to detect the scattered electrons that are reflected by the specimen

TEM images are always

black and white

which tube-like organ completes digestion of proteins, fats, and carbohydrates

small intestine

what percent of nutrients and water does the small intestine absorb

90%

what inside the small intestine increases the surface area and absorption efficiency of the nutrients

intestinal epithelium

describe cell junctions & function

are molecular structures between cells that stabilize the tissue, form barriers and allow for transport of molecules between two cells

what is the largest cell junction

desmosomes

desmosomes functions

connect keratin fibers of two cells like a hook-and loop fastener

tight junctions function

seals the intestinal epithelium and prevents liquid from escaping within the individual cells tightly connecting them

describe villi

intestinal epithelium folded into a finger-like projections

describe lamina propria

loose web of connective tissue, predominately consisting of extracellular macromolecules

villi function

increase the surface area of the small intestine which is essential for effcient nutrient uptake

what can inflammation of the small intestine be caused by

food borne pathogens or autoimmune disease

example food borne pathogens

salmonella

example of autoimmune disease

coeliac disease

coeliac is triggered by

gluten

describe gluten

protein found in grains (wheat, barley, and rye)

in genetically predisposed individuals gluten is recognized as an

antigen and triggers immune response

patients with coeliac disease suffer from

chronic constipation, diarrhea, anemia, fatigue, and children die

malabsorption syndrome is also known as

runting - stunting disease

malabsorption syndrome occurs in

young chickens

malabsorption leads to

delay in growth of the affected individuals and an overall reduced productivity of the chicken farm

infected chickens of malabsorption syndrome develop

enteric lesions, intestinal inflammation, and dilation