A CH 3 Tissues Flashcards
Connective tissue
Highly variable
Most abundant tissue type
Epithelial tissues
Covering and lining
Glandular
Muscular tissue
3 major types (smooth, muscle, cardiac)
Produce force through contraction
Nervous tissue
Generate electrical signals
Coordinate body activities
Tight Junctions
Fluid tight seals
Consists of weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells
Found in cells of epithelial tissue that line the stomach, intestines, and urinary bladder
they inhibit the passageway of substances leaking across cells, blood, or surrounding tissues
Anchoring junctions
plaque proteins
adherins
Desmosomes
Hemidesmosomes
Adherens junction
contain plaque a dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and microfilaments of the cytoskeleton. Transmembrane glycoproteins called cadherins join the cells
Each cadherin inserts into the plaque from the opposite side, partially crosses the intracellular space and connects to the adherin of an adjacent cell
often form extensive zones in epithelial cells called adhesion belts
they help epithelial surfaces resist separation during various contractile activates as when food moves through the intestines,
Desmosomes
Contain plaque and have transmembrane glycoproteins (caherins) that extend into intracellular space between adjacent cell membranes and attach to another one
However unlike adherens the plaque does not attach to microfilaments instead it attaches to elements of the cytoskeleton known as intermediate filaments consisting of keratin
common among cells of the epidermis ad among cardiac muscle cells
prevent epidermal cells from separating under tension and contraction
Hemidesmosomes
Do not link adjacent cells
they look like half of a desmosomes
the transmembrane glycoproteins are called integrins rather than cadherins
on the inside of the plasma membrane integrins attach to intermediate filaments made of the protein keratin
On the outside of the plasma membrane the integrins attach to the protein laminin which is present in the basement membrane
therefore they anchor cells not to each other but to the basement membrane
Gap Junctions
Membrane proteins called connexins from tiny fluid filled membrane tunnels called connexons that connect neighboring cells
separated by very narrow intercellular gap
through the connexons, ions and small molecules can diffuse from the cytosol of one cell to another, but not the passage of large molecules
allow cells to communicate with one another
Found in lens and cornea of eye, developing embryo and heart, gastrointestinal tract and uterus
Enable nerve or muscle impulses to spread rapidly among cells
Epithelial Tissue General Features
Closely packed cells Continuous sheets Apical and Basal surfaces Many cell junctions Avascular Basement membrane Good nerve supply Regenerates easily and faster than any other tissue
Simple Squamous Epithelial
Single layer of cells, centrally located nucleus that is flattened
Found in cardiovascular and lymphatic systems, heart, blood vessels, lymphatic vessels, (this is known as endothelium)
Serous membrane, such as peritoneum, pleura, or pericardium is known as mesothelium
It is also found in the air sacs of lungs and capsule of kidneys
Function filtration, diffusion and secretion
not found where we have mechanical stress
Simple cuboidal epithelial
Location: covers the surface of ovary, lines the anterior surface of capsule if the lens of the eye, lines kidney tubules and smaller ducts of many glands
Function is secretion and absorption
Nonciliated simple columnar epithelial
Has microvilli and goblet cells
Location: lines the gastrointestinal tract, ducts of many glands, and gallbladder
Function: secretion and absorption at a higher level than cuboidal
Secretes a lot of mucus
Ciliated simple columnar epithelium
Location: lines some bronchioles of respiratory tract, uterine tubes, uterus
Function: the cilia moves in unison to move things towards the throat where they can be coughed out or spit out
Pseudostratified columnar epithelium
Can either be ciliated or not
Location: ciliated lines the airways of most the upper respiratory tract
Nonciliated lines larger ducts of many glands, epidermis and part of the male urethra
Function: ciliated secretes mucus that traps foreign particles
Nonciliated absorption and secretion
Stratified squamous epithelium
Keratinized or nonkeratinized
Location: keratinized forms superficial layer of the skin
Nonkeratinized lines wet surfaces such as the lining of the mouth esophagus part of the epiglottis part of he pharynx vagina and overs the tongue
Function first line of defense, protection against abrasion, water loss, ultra violet radiation and foreign invaders
Stratified cuboidal epithelium
Location: ducts of adult sweat glands and esophageal glands and part of the urethra
Function: protection and limited secretion and absorption
Stratified columnar epithelium
.
Transitional epithelium
Location: lines urinary bladder and portions of ureters and urethra
Function: it allows the urinary organs to stretch to hold a variable amount of fluid without rupturing, while still serving as a protective lining
Unicellular glands
Example is a goblet cell
They secrete mucus directly onto the apical surface of a lining epithelium
