Exam 1 Flashcards
What is histology?
A branch of anatomy that deals with the minute structure of animal + plant tissues as discernible with the microscope
Fixation
Tissue samples placed in solutions of chemicals that will preserve the cell and tissue structure
Dehydration
Tissue is placed in a cassette, transferred through a series of concentrated alcohol to remove the water from the specimen
Clearing
An organic solution, that is miscible w/alcohol + paraffin, is used to remove the alcohol from the dehydrating step
Infiltration
Sample + cassette are placed in paraffin wax until it becomes infiltrated with the substance
Embedding
Sample is placed into a mold containing melted paraffin and cooled so it can harden
Trimming
Paraffin block is trimmed to expose the tissue for sectioning utilizing an instrument (microtome) to shave off thin sheets to be placed on a slide
Mounting
Slide is stained and the preserved by adding a glass coverslip
Hematoxylin
Basic dye that binds to acidic components. Has a positive charge. Stains negative structures blue
Eosin
Acidic dye, binds to basic components. Has a negative charge. Stains positive structures pink to red
Collagen stains ____ color with the eosin dye
Pink
Cell nuclei stain _______ with hematoxylin
Purple
Giemsa-Wright Stain
Stains red blood cells red. Stains white blood cells purple
Silver stain
Stains fungi + reticular fibers of the lymph nodes
Periodic acid schiff (PAS) stains
Stain carbohydrates, glycogen, and mucus deep red
Toluidine blue
Stains mast cells purple and everything else blue
Tissue composition
Cells and extracellular matrix
Organ composition
Parenchyma and stroma
Parenchyma
Cells that perform the function of the organ
Stroma
Supporting tissue
Functions of epithelium
Covering of external surfaces, lining of internal surfaces, protection, absorption, secretion, sensation, and contraction
Two kinds of epithelium
Cover + lining epithelium and glandular epithelium
Epithelium structure consists of?
Basement membrane, connections between cells, and specialized apical structures
Basement membrane
Consists of the basal laminate and the reticular lamina
Basal lamina
Connects directly to the epithelial tissues. Lamina lucida (loose) layer. Lamina densa (dense) layer
What is the protein in the lamina lucida?
Laminin
What is the protein in the lamina densa?
Type IV collagen + perlecan
Reticular lamina
Connects the basal lamina to the underlying connective tissue
What is the reticular lamina made up of?
Reticular fibers, anchoring fibrils, and anchoring plaques
Functions of the basal lamina
Structure, organization, and filtration
Intercellular junctions
Present in most tissues but more prominent in epithelial tissue
What are the intercellular junctions?
Tight junctions, adherens junction, desmosomes, gap junctions, and hemidesosomes
Tight junctions (zonula occludens)
Most apical junction. Forms bands that completely encircle each cell. Zonula occludens will fuse the membranes of adjacent cells to seal off the intercellular space.
What are the proteins in tight junctions?
Claudins and occludins
Belt desmosomes (zona adherens)
Forms a band that encircles each cell. A thick filament in the cytoplasm insert into attachment plaques
What are the proteins in belt desmosomes?
Cadherin and catenin
Spot desmosomes (macula adherens)
Spot adhesion between cells. Cytokeratin filaments insert into plaques in cell membrane. Provide strong attachment point between cells
What is the protein in spot desmosomes?
Cadherins
What are the proteins in the attachment plaques of the spot desmosomes?
Desmoplakin + plakoglobin
Hemidesmosome
Uses integrins to attache to the epithelial cells to basal lamina
Gap junctions (communicating junctions)
Occur anywhere along lateral surface of cells. Allows ions + other small molecules to pass through to facilitate cellular communication
What is the protein in gap junctions?
Connexons
Tight junction major functions
Seals adjacent cells to one another, controlling passage of molecules between them, separates apical and basolateral membrane domains
Adherens junction major function
Provide points linking the cytoskeletons of adjacent cells, strengthens + stabilizes nearby tight junctions
Desmosomes major functions
Provides points of strong intermediate filament coupling between adjacent cells, strengthening the tissue
Hemidesmosome major functions
Anchors cytoskeleton to the basal lamina
Gap junction major functions
Allows direct transfer of small molecules and ions from one cell to another
Microvilli
Have a central core of actin filaments. Uniform in length and densely packed. Also called brush border
What is the purpose of microvilli?
Increase the surface area for absorption or secretion
Stereocilia
Long, non-motile projections that are similar to microvilli in structure. Found in parts of the male reproductive system + inner ear
What is the function of stereocilia?
Assist with absorption
Cilia
Long and wide projections. Perform a rapid beating pattern that moves fluid + suspended matter in one direction along epithelium
Squamous cells
Flat. Width > height
Cubodial cells
Square, round. Width = height
Columnar cells
Tall and slender. Width < height
Endothelium
A layer of simple squamous epithelia that lines the blood vessels, lymph vessels, the inner surface of the cornea, heart, lungs, nerves and muscles
Mesothelium
Layer of simple squamous epithelia that lines large body cavities and secretes a lubricant film called serous fluid
Simple squamous
Lining of vessels (endothelium), serous lining of cavities, pericardium, pleura, peritoneum (mesothelium)
Simple squamous function
Facilitates the movement of visceral, active transport by pinocytosis, secretion of biologically active molecules
Simple cubodial
Covering the ovary and thyroid
Simple cuboidal function
Covering and secretion
Simple columnar
Lining of the intestine + gallbladder
Simple columnar function
Protection, lubrication, absorption, and secretion
Stratified squamous keratinized
Epidermis
Stratified squamous keratinized function
Protection and prevents water loss
Stratified squamous nonkeratinized
Found in mouth, esophagus, larynx, vagina, and anal canal
Stratified squamous nonkeratinized functions
Protection, secretion, and prevents water loss
Stratified cuboidal
Sweat glands and developing ovarian follicles
Stratified cuboidal functions
Protection and secretion
Stratified transitional
Bladder, ureters, and renal calyces
Stratified transitional functions
Protection and distensibility
Stratified columnar
Makes up the conjuctiva
Stratified columnar function
Protection
Pseudostratified
Layers of cells with nuclei at different levels. Not all cells reach the apical surface but all cells adhere to basal surface
Pseudostratified cells
Line the trachea, bronchi, and nasal cavity
Pseudostratified cell function
Protection, secretion, cilia-mediated transport of particles trapped in mucus out of the air passages
Unicellular glands
Found in simple columnar, simple cubodial, and Pseudostratified epithelia. Most commonly goblet cells
Goblet cells
Secrete lubricating mucus and aids in the function of the organs they are found in
Exocrine glands
Remain connected with the surface epithelium forming tubular ducts that lead to another organ/body surface, where secretion is used
Endocrine glands
Lose the connection to their original epithelium and lack ducts