Chapter 4 Flashcards
Epithelial tissue
Covers body surfaces and lines hollow organs, body cavities, and ducts; it also forms glands
This tissue allows the body to interact with both its internal and external environments
Connective tissue
Protects and supports the body and it’s organs. Various types of connective tissues hind of and together, store energy reserves as fat, and help provide the body with immunity to disease-causing organisms
Muscular tissue
Is composed of cells specialized for contraction and generation of force. Muscular tissue generates heat that warms the body
Nervous tissue
Detects changes in a variety conditions inside and outside the body and responds by generating electrical signals called verve action potential (nerve impulse) that activate muscular contractions and glandular secretions
Tight junctions
Consist of weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways
Epithelial tissues that lines the stomach, intestines, and urinary bladder have many tight junctions
Inhibit passage of substances between cells and prevent the contents of these organs from leaking into the blood or surrounding tissue
Adherens junctions
A dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments of the cytoskeleton
Contains plaque that is attached to microfilaments
Transmembrane glycoproteins called Cadherins join the cells.
In Epithelial cells, adherens junctions often form extensive zones called adhesion belts because they encircle the cell similar to the way a belt encircles your waist.
Desmosomes
Like adherens, desmosomes contain plaque and have transmembrane glycoproteins (cadherens) that extends into the intercellular space between adjacent cell membranes and attach cells to one another.
Plaque of desmosomes does not attach to microfilaments, instead a desmosomes plaque attaches to elements of the cytoskeleton known as intermediate filaments, which consist of the protein keratin
These spot wed-like junctions are common among the cells that make up the epidermis (outermost layer of the skin) and among cardiac muscle cells in the heart. Desmosomes prevent epidermal cells from separating under tension and cardiac muscle cells from pulling apart during contraction
Hemidesmosomes
Do not link adjacent cells
Transmembrane glycoproteins are integrins
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. Thus hemidesmosomes anchor cells not to each other but to the basement membrane
Gap junctions
Membrane proteins called connexins form tiny fluid filled tunnels called connexons that connect neighboring cells.
They are not fuse together as in tight junctions but are separated by a very narrow intercellular gap.
The transfer of nutrients, and perhaps wastes takes place through gap junctions in avascular tissues suck as the lens and cornea of the eye
Gap junctions allow the cells in a tissue to communicate with one another.
Gap junctions also enable nerve or muscle impulses to spread rapidly among cells, a process that is crucial for the normal operation of some parts of the nervous system and for the contraction of the muscle in the heart, gastrointestinal Tracy, and uterus.
How are epithelial classified?
Epithelial tissues are identified by both the number of pages and the shape of the cells in the upper layers
What are the classification base on the # of cell layers
Simple epithelial- single layer
Stratified epithelial-2 or more layers
What are the types of epithelial tissues base on the shape?
Squamous epithelial tissue- extremely thin cells (resemble the scales of fish)
Cuboidal epithelial tissue- cells that are square/cube like, marginally longer than they are wide
Columnar epithelial tissue- elongated cell involves in absorption of materials
What are the eight different types of epithelial tissue?
Simple squamous epithelial Simple cuboidal epithelial Simple columnar epithelial Stratified squamous epithelial Stratified cuboidal epithelial Stratified columnar epithelial
Pseudostratified columnar epithelial
Transitional epithelial
Simple squamous epithelial
Single layer of cells (thin sheets)
Located in the alveoli of lungs, important for the exchanges of gases between the blood and lungs
Simple cuboidal epithelial
Single layer of cells ( cube/square like shape)
Location- line the Lumen (space inside the tubular) of collecting ducts in the kidney and are present in the thyroid.
