Microanatomy Flashcards
Histology
Science concerned with the microscopic structure of cells, tissues, organs and their function.
a.k.a. microanatomy
Tissue
Cellular and fibrous elements in which one particular type of cell or fiber usually predominates.
Organized to form the material basis of one of the functional systems of the body.
Cell
The smallest unit of an organism which can carry out self-sustaining functions
Tissue preparation
4 Steps
- Stop biological activity and degradation
- Tissues are decalcified, dehydrated, and perfused into an embedding medium (paraffin or resin)
- Tissues are stained
- Sliced into very thin sections
Fixation
Cause linkage of macromolecules.
Increases effectiveness of staining.
Shrinkage is a frequent byproduct.
Some degree of distortion occurs to cells
Staining
Facilitates microscopic observations dependent on the intrinsic characteristics of the cell.
Acidic dyes
Carry a negative charge
React with ionic + cell structures:
Ionized amino groups or proteins
Basic dyes
Carry a positive charge
React with anionic - cell structures:
Phosphate groups of nucleic acids, sulfate groups of glycosaminoglycans, and carboxyl groups of proteins
Basophilic
Refers to cellular/extracellular elements
Include portions of chromatin, nucleoli, ergatosplams, and carbohydrate groups of cartilage matrix.
Acidophilic
Eosinophilic
Include most cytoplasmic filaments, most intracellular structures, and most unspecialized cystoplasm, and most extracellular fibers (ionized amino groups).
Ergastoplasm
Portion of cytoplasm that stains with basic dyes to phosphate groups of RNA
H & E
Hematoxylin & Eosin
Hematoxlyin = behaves like basic dye
Eosin = an acid dye
Light microscopy
LM
Examination of stained sections by transillumination
Use 3 types of lenses:
Electron microscopy
EM
Small blocks of fresh tissue are rapidly fixed
A beam of electrons are sent through tissue, they can’t penetrate through glass, so specimen is mounted on metal grids.
Plasma membrane
Plasmalemma
The selective barrier, acts as the “skin”.
Protects, communicates and has specific receptors for outer boundary of the cell.
Has a trilaminar appearance (ectoderm, mesoderm, endoderm) layers.
Tight junctions
Protein molecules of adjacent cells fuse together like a zipper
Ex: GI Tract
Desmosomes
Raised thickenings on cell walls.
Send keratin filaments to attach to desmosomes of adjacent cells
Gap junctions
Hollow protein cylinders “connexons”
Has protonatious ring
Ex: Skin
Protonatious ring
Creates a pore to allow certain molecules through based on size
Cell-to-cell junctions
3 Types:
Tight junctions
Desmosomes
Gap junctions
Determine how cells are linked to each other and interact
Glycocalyx
Like the fingerprint of a cell.
Immune cells read this to identify cells
Plasma membrane structure
Has two layers of phospholipid molecules
Hydrophilic faces water
Water is outside and inside every cell - super important to send/recieve messages and transact nutrients
Hydrophobic faces inward on both sides of phospholipid layers
Cytoplasm
Cytoplasmic matrix
Combo of cytosol and organelles.
More organelles = more function
*think jello mold with its contents
Organelles
Operate within cytosol and inclusions are suspended within it.
Mitochondria
Eosinophilia when present in great quantities.
ATP occurs here.
Very reliant on the presence of Type I muscle fibers (slow twitch).
Ribosomes
Basophilic.
Produced dark regions of cytoplasm
Nissl bodies (via E.R. of neurons), or
Basophilic bodies (most other cells).
Rough endoplasmic reticulum
Basophilic structures
High RNA presence
A system of tubes within:
Ribosomes externally
Cysternae internally
Microtrabecullae of the matrix
Cross sectional structural network of the cytoplasmic matrix
Smooth endoplasmic reticulum
Eosinophilic cytoplasm if plentiful.
A highly membranous structure.
Cysternae
Fluid filled sites
Protein modification inside R.E.R.
Oxidative phosphorylation
Mitochondria are efficient at ATP generation
Golgi apparatus
Storage & protein synthesis
Lysosomes
Membrane sacs of digestive enzymes for intracellular digestion.
Degradation of worn out organelles.
Function: Removes waste, garbage
Cytoskeleton
Elements include:
Microfilament
Microtubules
Microtrabeculae
Microfilament
Act in cell structure, movement, contraction and division.
Have network like appearance
Microtubules
Act as conveyer belts inside cells
Microtrabeculae
Helps suspend and organize components of cytoplasm and organelles
Nucleus
Negatively charged
Basophilic
Intensity depends on concentration of DNA /RNA
Nuclear membrane
Appears as two layered phospholipid barrier.
Has pores present for movement of RNA molecules out and protein molecules in.
Chromatin & Activity
Thread like structures made of DNA and “histone proteins”
High synthetic activity is a reflection of dispersed chromatin large nuclei
Low synthetic activity is a clumping of chromatin and poorly visible nucleoli.
Nucleoli
Darkly stained bodies with no membranes
High synthetic activity is a reflection of rRNA synthesis.
Muscle Tissue
Uniquely excitable
Soft tissue that gives rise to muscles’ ability to contract.
Nervous Tissue
Uniquely excitable
Makes up the CNS & PNS
Function: integration and communication
Epithelial Tissue
Very flexible in activity.
The go-to for barrier membranes.
Function: Line the outer surfaces of organs and blood vessels
Connective Tissue
“Catch all”
If not muscle, nervous, or epithelial then it’s connective!
Ex: blood, bone, cartilage, ligaments, tendons, etc…
Very plastic in appearance and have many functions.
