510-01 Intro to Histology Flashcards
A __ consists of two or more different types of cells that function together
tissue
What are the 4 primary tissue classes?
- epithelial 2. connective 3. muscular 4. nervous
An ____ is a structure w/ discrete boundaries that is composed of 2 or more tissue types
organ
epidermis is ____ (tissue/organ). Skin is an ____ (tissue/organ).
tissue, organ
____ is the science of preparing tissues for microscopic study
Histotechnology
7 steps of histotechnology for routine, clinical light microscopy: mnemonic?
- Grossing and Fixation 2. Processing 3. embedding 4. sectioning 5. staining 6. coverslipping 7. diagnosis GooFy People Enjoy Saving Sick Cats + Dogs
In gross processing of fresh specimens, why are the specimens cut into small pieces?
to facilitate penetration of fixatives
During gross processing, the specimen can be marked with ink for ____ or to specify a ____
orientation, margin
During gross processing + fixation, specimens are preserved in what fixatives? Why?
- buffered solutions of FORMALDEHYDE or GLUTERALDEHYDE
- to prevent decay
Aldehydes react with ___ in proteins and form stable bridges between adjacent proteins which leaves them unaffected by ____ or other degrading agents
nitrogen, enzymes
2 ways that aldehydes fix proteins:
1) stabilize bonds so that they don’t break down from bacteria
2) stiffens bonds so that tissue gets harder
Processing:
1) During the processing stage of histotechnology, ___ is removed from the tissue and is gradually replaced with ___
2) During processing, alcohol is removed with solvents like ___ or less toxic solvents like ___
3) Solvents are then replaced with mixtures of heated ___ and other ___
1) water, alcohol
2) xylene, limolene
3) paraffin, waxes
During Embedding, processed specimens are oriented in molds filled with ___ ____. After this cools, the embedded specimens are removed from the molds
liquid wax
During sectioning, specimens embedded in paraffin wax blocks are cut on a ___ into thin section, normal ___ microns thick. These sections form a ___ as they are cut from the block.
microtome, 4-5, ribbon
What is the diameter of a red blood cell? Why is that useful?
~8 microns. Most specimens have blood cells, can be used to compare to size of specimen
During sectioning, the ribbon that is formed is then transferred to a __ water bath and floated to remove ___
warm, wrinkles
Why must waxes be removed before staining? How is this done?
Wax must be removed because the stains that are to be used are water-based. Slide is microwaved until proteins stick, then wax is removed with solvents
What is the standard reference stain?
Hematoxylin + Eosin (H&E)
What part of cell does hematoxylin stain and what color? Eosin?
Hematoxylin stains cell nuclei blue/purple Eosin stains cytoplasm and connective tissues pink/orange and erythrocytes bright red
Why are coverslips glued onto the microscope slides over the stained samples?
to protect and preserve the sections
What is the difference between a pathologist and a histologist?
pathologist can diagnose diseases
(T/F) electron microscopes produce images in color
False, only light microscopes produce images in color
Specimens processed for electron microscopes are embedded in hard ___ and cut into sections only ___ microns or less thick, and stained with metals like ___.
plastic, 0.01, lead
Visible light is focused with __ __. Electrons are focused with ___.
glass lenses, magnets
Raw electron microscope images are in what color?
they are grey scale
Do electron or light microscopes have a greater resolution?
electron
What are the two type of electron microscopes? What is the difference?
Transmission- beam goes through sample, gives 2d image Scanning- beam bounces back from sample, gives 3d image
What are the 3 planes of section?
Longitudinal- cut along the longest direction of a structure
Cross- cut perpendicular to the length of a structure
Oblique- cut at an angle b/w cross section and longitudinal section
What are the distinguishing features of the 4 tissue classes?
- types of cells (shapes and functions)
- arrangements of cells
- Characteristics of the ECM (proportion of water, types of fibrous proteins, composition of ground substance)
- proportion of the volume of the cells to the volume of the ECM.
What is ground substance? What is it a part of? How can the consistency differ?
ground substance is the material between cells in addition to water and fibrous protein. It is part of the ECM. It can be liquid (plasma), rubbery (cartilage), stony (bone) or elastic (tendon).
How does the proportion of the volume of cells to volume of ECM differ between tissue classes?
Connective tissue cells are separated by a large volume of matrix. Epithelial, nerve, and muscle tissues have very little matrix between cells.
What 3 things are epithelia named for?
- number of layers of cells
- shape of cells
- surface modifications
Which type of epithelium has one layer of cells? More than one layer?
simple, stratified
Is pseudostratified epithelium simple or stratified?
Simple, but look stratified
What shapes can epithelial tissue assume?
squamous, cuboidal, columnar, transitional
Why do different parts of the tongue and mouth feel different?
They are all keratinized to a various degrees
(T/F) In connective tissue, the volume of ECM is significantly less than the volume of cells.
False
Muscle cells respond to stimuli by ___
contracting
3 types of muscles tissue:
Which ones are striated?
smooth, skeletal, cardiac
-skeletal and cardiac are striated
Nerve tissue is composed of __ and ___ cells.
neurons and glial cells
Differentiation
unspecialized tissues, as in an embryo, change into specialized mature types
Metaplasia
A normal or abnormal change in type of tissue.
Examples:
normal- calcification of cartilage during endochondral ossification
abnormal- tracheal epithelium in smokers transforms from pseudostratified, ciliated epithelium into stratified, non-ciliated epithelium.
Can abnormal metaplasia be reversed?
yes
Hypertrophy
enlargement of pre-existing cells (ex: muscle growth form exercise
Hyperplasia
an abnormal increase in the number of cells in an organ or tissue, causes tissue or organ to enlarge
NOT TUMOR
Neoplasia
growth of abnormal tissue into a tumor
can be benign or malignant
There are approximately 200 different types of ___ in the human body
cells
