Histology Flashcards
Describe epithelium.
Cellular and avascular. Tends to line and cover, or form glands.
Describe connective tissue. What are the four types?
Is derived from mesenchyme, is the most abundant tissue, is defined by its matrix, and tends to be supportive.
4 types: connective tissue proper, cartilage, bone, and blood.
Describe muscle tissue. What are the three types?
Cellular, well vascularized, and contracts, causing movement.
3 types: skeletal, cardiac, and smooth.
Describe nervous tissue.
Composed of neurons and glial cells. Generates and conducts electrical impulses.
What are the epithelial functions?
- Mechanical protection of underlying tissue.
- Protection against dehydration
- Selective absorption
- Secretion and lubrication
- Digestion
- Transport
- Excretion
- Reproduction
What are the three types of epithelium?
- Lining (Surface) Epithelia
- Glandular Epithelia
- Special Epithelia
What are the features of lining (surface) epithelia?
- Continuous sheets of cells held together by cell junctions.
- Serve as a barrier membrane
- Avascular
- Rest on a basement membrane
- Most are mitotically active
What are the names for the lining (surface) epithelia based on?
- Number of cell layers
- Height and shape of cells at the free/apical surface
What are the different numbers of cell layers that can be seen in the lining (surface) epithelia? Describe them.
- Simple – 1 cell layer (function tends to be exchange)
- Stratified – 2 or more cell layers (function is protective)
- Pseudostratified – 1 layer with all cells lying on the basement membrane, but appears to be several cell layers (often has an apical surface modification)
Describe the height and shape of cells that can be seen at the free/apical surface of the lining (surface) epithelia.
- Squamous- flat cells with bulging nuclei
- Cuboidal – a box like cell with round, central nuclei
- Columnar – cells that are taller than they are wide
- Transitional – Cells at apical surface change shape when the lumen is full or empty, only in parts of the urinary system. Function is to stretch without tearing when full, and to prevent passage of anything into or out of the urine
Where are microvilli seen? What is its function? What are stereocilia?
Striated border of the intestines, brush border of the kidney, and the stereocilia of the epididymis.
Function is usually to increase the surface area for exchange
stereocilia - really long microvilli
Where are cilia located? Describe them.
Cilia are located on the apical surface of the cells which line the trachea and the fallopian tubes.
- A membrane covering with a “9 +2” arrangement of microtubules.
- Motile
Where is ciliated pseudostratefied columnar epithelium found?
respiratory tract
When observing the transitional epithelium, how can you tell if the lumen is full of urine or empty?
full - epithelium stretches and distends, so cells flatten
empty - cells become cuboidal or balloon shaped
Which would show thicker epithelial lining and why: teat sinus or teat canal?
teat canal - prevents leakage of milk
What is the urachus?
functional remnant of part of the duct of allantois
What makes up pseudostratified columnar epithelium? What gives it its name?
consists of basal cells and columnar cells
nuclei of these two cell types are at different levels so they appear layered
How many lumens are in the endothelium? What are the ones referenced?
5 lumens; urachus, umbilical arteries and veins
Describe the lumenal or apical side of the epithelium.
striated border formed by microvilli
Where is pseudostratified columnar epithelium with stereocilia found?
epididymis
What attaches the stratified squamous epithelium?
intercellular bridges
What are papillae?
finger-like projections of pale pink loose connective tissue; can be isolated pieces scattered through the epithelium
Where is stratified columnar epithelium commonly found?
larynx, pharynx, ducts of large glands
What type of epithelium lines the mammary gland?
bistratified cuboidal epithelium
What are the qualities of skeletal muscle?
- banding pattern
- multinucleate
- myofibrils
What are the qualities of cardiac muscle?
- branching of cells
- single centrally located nucleus
- striated
- intercalated disks
What are the qualities of smooth muscle cells?
- spindle shaped
- one centrally located nucleus
What forms the outermost wrapping of the nerve?
epineurium
What is mesothelium?
single layer of squamous or cuboidal cells that line the mesentery
What is the superficial layer of the dermis? What makes it up?
Papillary layer; areolar CT
What are the layers of the mucosa?
- epithelium
- lamina propria (areolar CT)
- muscularis mucosae
What cell types are common in areolar CT?
- fibroblasts
- eosinophils
- lymphocytes
- plasma cells
What makes up the submucosa?
dense irregular connective tissue
Where can elastic fibers be found?
- walls of arteries
- pulmonary alveolar septa
- vocal cords
Why are reticular fibers PAS-positive?
PAS = periodic acid-schiff
staining method used to detect fibers with a high proportion of glycogen or carbohydrate macromolecules
What are adipocytes?
accumulate large deposits of lipids that are dissolved and extracted during preparation of slide, leaving a large empty vacuole with a thin rim of cytoplasm
What are chromophils? What are chromophobes?
Chromophils - possess an affinity for certain dyes
Chromophobes - lack an affinity for dyes
What color do acidophils and basophils stain?
acidophils - light orange
basophils - blue or red
Where is the Rathke’s pouch located?
between the pars distalis and pars intermedia
What are the zones of the adrenal gland?
- zona multiformis (outermost)
- zona fascuculata
- zona reticularis (innermost)
How would you determine if you were looking at a slide of an adrenal gland of a chicken?
would have a gross lack of organization when compared to mammalian adrenal
