Chapter 4: Tissues Flashcards
Tissue
group of cells that have similar embryological origin and are specialized for a particular function
Histology
study of tissues
4 types of tissue
- connective
- epithelial
- nervous
- muscle
cell junctions
points of physical contact btwn adjacent cells
functions of cell junctions
- support
- sealing
- communication
- interaction
Types of cell junctions
- tight junctions
- adherens junctions
- desmoosomes
- hemidesmosomes
- gap junctions
Tight junctions
function & location
- fluid tight seals
- found in stomach, intestines, bladder
Adherens junction
function
- made of actin filaments + plaques of protein that anchor cells together or to ECF
Desmosomes
aka anchoring junctions
- bond cytoskeletons of adjacent cells
- linked by transmembrane glycoproteins that extend across cell proteins to create strong bond
hemidesmosomes
- integrin family of protein that connect cells to extracellular material (i.e. basement membrane)
- 1/2 of a desmosome
gap junctions
- allow cells in tissue to communicate quick through connexins
- connexins=channels that flow ions from other cells cytoplasm
- i.e. heart tissue
characteristics of epithelial tissue
- arranged in sheets that cover body (internal & external)
- closely packed
- many cell junctions
- apical (free) surface + basal surface (basement membrane)
- avascular (frequently replaced, mitotic)
- no nerve supply
apical (free) surface
faces a lumin
basal surface
- sits on basal lamina (top layer or basement membrane)
- NOT reticular lamina (below basement)
functions of epithelial tissue
- protection
- absorption
- gas exchange
- secretion
- transpo
- lubrication
- repair
how are epithelium covering and lining classified?
- cell arrangement
- cell shape
types of cell arrangement
- simple
- stratified
- pseudo-stratified
Simple cells
- single layer
- sits on basement membrane
stratified
multiple layers of cells
pseudo-stratified
appears multi-layered but all sit on basement membrane
types of cell shapes
- squamous
- cuboidal
- columnar
- transitional
squamous cell
flat with central nucleus
cuboidal
cube shape with single nucleus
columnar cell
tall, long with nucleus twd bottom
simple columnar epithelium
descrption, function, types
- single layer of column shape cells
- lines GI, respiratory tracts, glands
- increase surfacearea for absorption, movement
- goblet type: produces premucin
- non-ciliated type: microvolli at apical border
stratified epithelium
- stratified squamous epithelium
- stratified cuboidal epithelium
- stratified columnar epithelium
- transitional epithelium
stratified squamous epithelium
descrition, function, location
- several layers, top=squamous
- lines mouth, esophagus, vagina, anus
- softens apical surface, protects, repels water/bacteria
- keratinized type: skin, top layer has keratin
- non-keratinized: no keratin
stratified cuboidal epithelium
description, function, location
- several layers, top=cuboidal
- lines ducts of glands. surrounds developing egg cells and testes
- protection