Tissues and Skin Flashcards
(15 cards)
What is Histology
the study of cells
What are Tissues?
groups of cells that are similar in function and structure
Name the four primary tissue types and their function.
Epithelia- coverings and linings
Connective- protection, insulation, transport, & attachment
Muscle- generate movement
Nervous- internal communication that controls body structures
What is Epithelium or Epithelial Tissue?
a sheet of cells that cover a body surface or line a body cavity
Name and Define Functions of Epithelia.
Protection: physical barrier,
Absorption: movement of materials into cells,
Sensory reception: gathers input from receptors,
Secretion/Excretion; movement of materials out of cells (glandular epithelia),
Diffusion: exchange
Filtration: forcing fluid through membranes
Name and Define Characteristics of Epithelia.
Polarity: having upper and lower surfaces. Upper are termed Apical having a free-surface & may include cilia and microvilli; and lower are basal that are attached to the surface.
Avascular: have no blood vessels, blood supply is found in the underlying connective tissue
Regeneration: cell replacement from cell division (mitosis).
Tight Junctions: proteins that hold epithelial cells tightly together to form a sheet of cells
Connective Tissue Support: all epithelia sit upon connective tissues. The two tissues are connected by a Basement Membrane; composed of proteins and collagen fiber. EXTRA** They include the Basal Lamina: secreted by ET, made up of collagen fibers & glycoproteins, and Reticual Lamina: secreted by CT, made up of reticular fibers & glycoproteins
How do you classify Epithelia?
By number of cell layers;
*simple::have a single cell layer
*stratified::have two or more cell layers
By cell shape;
*Squamous::flattened cells
*Cuboidal:: cube-like/shaped cells
*Columnar:: tall cells, (nuclei are elongated)
Simple Squamous Epithelial Tissue
Is a single layer of flat cells.
Functions: Diffusion, Filtration, some perform Secretion
Locations: linings of Heart, Blood Vessels, Body Cavities, Kidney Capsules, & Air Sacs of Lungs
Special Names to Know: Mesothelium: simple squamous epithelium of serous membrane (or serosa) and cover internal cavities in bodies AND Endothelium: simple squamous epithelium that lines the entire circulatory system
Simple Cuboidal Epithelial Tissue
Is a single layer of cubelike cells. (resemble donuts)
Functions:Absorption and Secretion
Locations: Kidney tubules & Ducts of Glands (Gland Ducts)
Simple Columnar Epithelial Tissue
Is a single layer of tall cells (with basally located nuclei)
Functions: Absorption and Secretion
Location: lining Digestive Tract, Uterine Tubes, some Gland Ducts, small Bronchi, regions of Uterus, and Gallbladder.
(EXTRA**NONCILIATED include digestive tract, gallbladder, and some Gland Ducts. CILIATED include uterine tubes, regions of Uterus, and small Bronchi.)
Specializations include:
*Cilia-hairlike processes that have a sweeping motion, made of microtubules.
*Goblet Cells-mucus secreting unicellular gland
Pseudostratified Columnar Epithelial Tissue
Is a single cell layer of cells that vary in height. Not all reach the apical surface but all cells touch the basal surface.
Functions: Sweeping of Mucus and Secretion
Locations: depend if they are Ciliated or Nonciliated.
Pseudostratified Ciliated Columnar Epithelial Tissue is located in Respiratory Tract and Trachea
Pseudostratified Nonciliated Columnar Epithelial Tissue is located in male sperm-carrying ducts & ducts of large glands
Stratified Squamous Epithelial Tissue
many cell layers where those at the apical surface are flattened
Function: Protection of underlying tissues from abrasion
Locations: depend if they are
NONKERATINIZED (moist, living) line the mouth, esophagus and vagina
KERATINIZED (cells containing keratin proteins) builds the epidermis of the skin
Stratified Cuboidal Epitherlial Tissue
two or more layers of cube-like cells (resemble donuts)
Function: Protection
Location: Largest ducts of Sweat Glands, Mammary glands & Salivary glands
Stratified Columnar Epithelial Tissue
two or more layers of tall cells; usually APICAL elongated and columnar & BASAL cuboidal
Function: Protection, Secretion
Location: rare in body- small amounts in male urethra and in large ducts of some glands
Transitional Epithelial Tissue
many cell layers whole apical cells change between squamous and cuboidal depending on the stretch of the organ/tissue
Function: Absorption, Secretion, Stretches to allow distension of the structures they line
Locations: lining Urinary Bladder, Ureters
