Tissue Types/Cell Coordination Flashcards
Tissue
group of similar cells with common function + nonliving macromoles and fluid
Basic types of tissues
epithelial
muscle
nervous
connective
Epithelial
function
secretion
absorption
lining
covering
protection
connective
function
connection
integration
support
exchange
store
defense
Muscle
function
contraction
movement
Nervous
recieve/transmit/integrate info
goals of tissues
communication
physical support
cohesiveness and exclusivity
cell junctions
definition
specializations of cell surface that connect adjacent cells to each other or part of ECM
cell junctions
function
tissue continuity
cohesion
cell junctions
components
transmembrane protein (TMP)
connect to attachment protein
connect to cytoskeletal filament
attachment proteins are peripheral
cytoskeletal is actin or intermed
Types of Cell Junctions
occluding/tight
anchoring/adhering
communicating/gap
Occluding Junctions
seal that encircles a cell/stitches
band of interlocking branching/reticulating sealing strands
only in epithelial cells at luminal end of lateral domain
shows as fusion of adjacent cells TEM
Occluding Junctions
functions
regulate paracellular permeability
reg which lumen contents get b/t cells
block pathogens
signaling
Occluding Junctions
structure
TMP: claudins (required for correct formation, water) and occludins (stability)
AP: ZO proteins
CC: actin filaments
AP= attachment protein
CC= cytoskeletal component
hereditary claudin-14
mutation that inc permeability of water in hearing receptors (organ of corti) so no action potentials = deafness
Anchoring Junctions
@ lateral or basal domain
Anchoring Junction
functions
link cytoskeletons of adjacent cells
connect cytoskeleton to ECM fibers
mechanotransduction for morphogenesis/cell differentiation
Subtypes of anchoring junctions
adhesion belt
desmosomes
hemidesmosomes
focal adhesions
Adhesion belts
@ lateral domain
function: lateral adhesion to adj cells, resist mechanical stress
Adhesion belt
structure
TMP: cadherins
AP: catenins, vinculin, alpha-actinin
CC: actin filaments
Desmosomes
@ random on lateral domain
basal to adhesion belts
Desmosomes
function
lateral adhesion to adj cells
resist mechanical stress
tissue morphogenesis/cell differentiation
Desmosomes
structure
TMP: cadherins
AP: desmoplakin, catenin
CC: intermediate filaments
Hemidesmosomes
@ basal domain
esp epithelia of cornea, oral mucosa, esophagus, vagina
Hemidesmosomes
functions
anchor basal domain to ECM
resist abrasion or shearing
Hemidesmosomes
structures
TMP: integrins, type XVII collagen (within cell)
»laminins, type IV collagen (ECM/basement)
AP: desmoplakin-like proteins
CC: intermediate filaments
TMP no counterpart so half desmosome
Focal adhesions
@ basal domain
Focal adhesions
functions
anchor basal domain to basement membrane and ECM
sense/transmit signal from ECM into cell
regulate cell migration
Focal adhesions
structure
TMP: integrins (in cell)»_space; fibronectin, laminins (in ECM)
AP: talin, vinculin, alpha-actinin
CC: actin filaments
Pemphigus vulgaris
clinical relevance of anchoring junctions
antibodies vs desmoglein 1 and 3 (TMP desmo)»_space; connections disrupted = severe blistering of skin and mucous membranes
basal domain stays attached, fluid b/t basal and apical
Bullous pemphigoid
Clinical for anchoring junctions
autoimmune disease antibodies vs type XVII collagen (TMP hemi)»_space; disrupt connections to basement membrane = large blisters under epidermis
cell stays together but separates from basement membrane
Communicating Junctions
broad pores/channels align to form conduits spanning cell membranes
@ lateral domain (embryos, muscle, neurons esp)
Communicating Junctions
functions
form channels b/t cytoplasm of adj cells
direct exchange fluids/metabolites/signals
coordinate activity across entire tissue
Communicating Junctions
structure
TMP: 6 connexins in circle = connexon
AP: none
CC: none
Junction complexes
@ simple epithelial
function: triple barrier
Junction complex
structure
apical»basal
1.occulding tight junction
2.adhesion belt
3.ring of small desmosomes “belt”
ducts and capillaries are one cell layer thick “simple” so need extra pr
domains w/ cell junctions
lateral bc cell to cell
basal bc cell to basement mem
apical domain none
Structure of Gap/Comm Junctions
simplified
only transmembrane proteins
Structure of occluding and anchoring junctions
simplified
All 3 components
TMP + AP + CC
junctions with ‘adhesion’
anchoring
connect to actin filaments
AP: alpha actin, vinculin
junctions with ‘desmo’
anchoring
connect with intermediate filaments
AP: desmoplakin
lateral junctions
anchoring
cadherin TMP
catenin AP
basal junction
anchoring
integrin TMP
plus type XVII collagen in hemidesmosomes
TMPs in basal domain
connect to laminins + fiber
hemidesmosomes fiber = type IV collagen
focal fiber = fibronectin
