Epithelial Cell Tissue Flashcards
Epithelial Tissue
- Single or multi layered sheet covering every free surface in the body
- Cells are joined by protein junctions which are anchored to a basement membrane
- Polarized: apical and basal surfaces
- where most cancer comes from
Connective tissue
Defined by the cell type (which are separated from one another) and the extracellular matrix of which they secrete
ex) Loose/Dense/Blood/Bone
Muscle Tissue
ex) Skeletal, smooth, and cardiac
- characterized by abundance of contractile elements
- cellular or functional syntitium
Nervous Tissue
Highly excitable cells specialized for transmitting electrical impulses
- neuron: dendrite, cell body, axon, and synapse
- myelin: increases speed of conduction - appears in most tissue preps, with a central dark axon
- Neuroglia - supports cells of the nervous system
Epithelial Tissue
Lines all surfaces of the body: external, internal (closed and open)
Polarized:
- apical domain: faces the exterior world lumen or body cavity
- lateral domain: cell junctions, vary for each tissue type
- basal domain: anchored to the basement membrane
- Secretory glands and specialize receptors: smell, taste, hearing, and vision
Epitheloid Tissue
Anchored together on a basement membrane but lacks a free surface
ex) Endocrine cells - leydig cells of the testes, beta cells, and alpha cells of the pancreas
Function of epithelial tissue
- Protection: stratified squamous
- Absorption: blood passes through the lumen and are absorbed by microvilli (columnar and cuboidal)
- Secretion: all types
- Transport: through cell and surface (lungs, fallopian tubes: cilia moves egg, and pharynx: cilia moves mucous)
- receptors
Simple Squamous Epithelium
- One flat layer
- Location: air sacs of lungs and the lining of the heart, blood vessels, and lymphatic vessels
Function: Allows material to pass through by diffusion and filtration, and secretes lubricating substance
ex) mesothelium - covers internal organs (has adipocytes - large white outlined by purplish-pink)
other ex) / endo and pericardium (makes pericardial fluid) / endothelium (signals to blood for clots) / mesothelium (covers entire female-reproductive tract) / outer layer of Bowman’s capsule
Simple Cuboidal Epithelium
- One cubed layer
- Location: in ducts and secretory portions of small glands and in kidney tubules
- Function: secretes and absorbs
- Found in: pancreatic ducts and have spherical nuclei/apical surfaces faces the lumen of the duct
Found in: bronchioles (controlling the conduction of air
Found in: Liver (hepatocytes): high livers of absorption and secretes hormones/bile salts
Simple Columnar Epithelium (ciliated and smooth)
Ciliated Location: Ciliated tissues are in bronchi, uterine tubes, and uterus
Smooth Location: digestive tract and bladder
Function: absorbs and secretes mucous/enzymes
- has goblet cells
- Note: intestines are tubes can be scrunched in pictures
- Cilia help things move
Stratified Squamous Epithelium
Location: lining of esophagus, mouth, and vagina
Function: protects against abrasion
Non-keratinized: Vaginal wall, esophagus
Keratinized: skin (thick-no hair and thin - hair)
Simple columnar to stratified squamous
- anus to rectum
- stomach to esophagus
- uterus to vaginal wall
Stratified cuboidal Epithelium
Location: sweat glands, salivary glands, and mammary glands
Function: protective tissue
- typically two layers
Stratified Columnar Epithelium
Location: male urethra and the ducts of some glands
Function: secretes and protects
Transitional Epithelium
Location: lines bladder, urethra, and uterus
Function: allows the urinary organs to expand and stretch
- multi-layered
- surface cells are large and dome shaped and will flatten when there is a distention of bladder
Pseudo-stratified Epithelium
Location: ciliated tissues lines the trachea and much of the upper respiratory tract
Function: secretes mucous and ciliated tissue moves mucous
- all cells are attached to basement membrane
- goblet cells
ex) epididymis
Apical Modifications
Cilia: larger
Microvilli: hazy/disorganized (can only be seen in small intestine/neprons)
Microvilli
Location: uterine gland/placenta: for trans epithelial transport // enterocyte (small intestine): taking macronutrients from GI tract
Function: Increase surface area for transport
- typically found on apical side of cuboidal or columnar epithelia
- not on squamous
- core of actin filaments
Microvilli structure
Core of actin filaments cross-linked by actin-bundling proteins
- stabilized by spectrin
- contractile properties: myosin II, and tropomyosin are linked to the terminal web
- villin tip
Stereocilia
Location: Limited to epididymis and vas deferens (sperm movement)
- inner ear - hair cells
- thinner than microvilli
- internal actin filaments - cross linked by fimbrin
- lack villin tip
Cilia
Location: nearly every cell in the body
- axoneme: microtubule-based internal structure
1) motile cilia: contain motor proteins for force production
2) primary cilia: solitary projections function as receptors
3) found only in the embryo - allow for rotational movement (gastrulation)
Cilia Structure
Axoneme (Ax): microtubule core of cilia
Basal bodies (BB): microtubule organizing center, continuous with 9 outer triplets
- inner two start at transitional zone (TZ)
- alar sheets: anchors basal body to apical membrane
- basal foot (BF): thought to adjust basal bodies, rotation
- striated rootlet (SR): anchored the cilum into the cytoplasm
Primary cilium
Sense fluid flow: receives mechanical, osmotic, chemical or light info and has specialized receptors
Cell-Cell junctions
Occluding zone
Adhering Junctions - zonula adherens
Adhering Junctions - macula adherens
