Chapter 4: Tissues Flashcards
Where are epithelial tissues located?
Covers body surfaces
Lines body cavities
Hollow organs and ducts
Forms glands
What does connective tissue do?
This protects and supports the body and its organs
Binds organs together
Stores energy reserves as fat
Provides immunity
What does muscular tissue do?
This generates physical force needed to make body structures move
What does nervous tissue do?
This detects changes inside and outside the body and initiates and transmits nerve impulses that coordinate body activities to help maintain homeostasis
What are cell junctions?
These are the points of contact between most epithelial cells and some muscle and nerve cells, tightly joining them into functional units
What are the two main types of epithelial tissue?
Surface epithelium (aka covering and lining epithelium)
Glandular epithelium
Where is surface epithelium located?
Outer covering of the skin and some internal organs
Lines body cavities, blood vessels, ducts, and interiors of the respiratory, digestive, urinary, and reproductive systems
Makes up parts of the organs for hearing, vision, and touch.
Where is glandular epithelium located?
Makes up secreting portion of glands like sweat, thyroid, adrenal, and digestive glands
What are the general features of epithelium?
Mostly or entirely made up of closely packed cells with little extracellular material between them
Arranged in continuous sheets
Have an apical (free) surface, lateral surface, and basal surface
Avascular
Has a nerve supply
High capacity for renewal by cell division
What is the apical surface of epithelium?
This is the surface exposed to a body cavity, lining of an internal organ, or the exterior of the body.
For epithelia with multiple layers, this is the most superficial layer
What is the lateral surface of epithelium?
This is the surface that faces adjacent cells
What is the basal surface of epithelium?
This is the surface that attaches to a basement membrane. For epithelia with multiple layers, this is the deepest layer
What is a basement membrane?
This is a thin extracellular structure made mostly of protein fibers. It acts as an anchor between epithelial tissue and its underlying connective tissue
How are basement membranes affected in diabetes mellitus?
In untreated cases, basement membranes of capillaries can thicken especially in the eyes and kidneys, leading to blindness and kidney failure
What are the 3 different arrangements of epithelial cells layers?
Simple
Pseudostratified
Stratified
What are simple epithelium layers, and what are they for?
These are a single layer of cells
They are for diffusion & osmosis, filtration, secretion, and absorption
What are pseudostratified epithelium, and what are they for?
These appear to have multiple layers because the cell nuclei lie at different levels, and not all cells reach the apical surface. These are actually a type of simple epithelium since all of the cells rest on the basement membrane.
Cells that reach the apical surface may contain cilia and others can secrete mucous
Which pseudostratified epithelium secretes mucous?
Goblet cells
What are stratified epithelium, and what is it for?
This is a type of epithelium that is made up of two or more layers of cells.
It protects underlying tissues in locations with wear and tear
What are the 4 cell shapes of epithelia?
Squamous cells
Cuboidal cells
Columnar cells
Transitional cells
What are squamous cells and what are they for?
These are thin epithelial cells and allow for rapid passage of substances through them
What are cuboidal cells and what are they for?
These are equivalently tall and wide epithelial cells shaped like cubes or hexagons. They may have microvilli at their apical surface and function in either secretion or absorption
What are columnar cells and what are they for?
These are tall epithelial cells like columns that protect underlying tissues. Their apical surfaces may have cilia or microvilli, and usually specialize in secretion and absorption
What are transitional cells and what are they for?
These change shape from flat to cuboidal and back in organs that stretch to a larger size and then collapse to a smaller size like in the urinary bladder