Epithelial Tissue Flashcards
Epithelial tissue cells
Aggregated polyhedral cells
Small amount of extracellular matrix
Connective tissue cells
Several types of fixed and wandering cells
Abundant amount of extracellular matrix
Muscle tissue cells
Elongated contractile cells
Moderate amount of extracellular matrix
Nervous tissue cells
Elongated cells with extremely fine processes
Very small amount of extracellular matrix
Epithelial tissue function
Lining of surface or body cavities; glandular secretion
Connective tissue function
Support and protection of tissues/organs
Muscle tissue function
Strong contraction; body movements
Nervous tissue function
Transmission of nerve impulses
General Function of Cytoskeleton
Structural: Structural support to cell; stabilizes junctions between cells
Movement: Assists in cytosol streaming and cell motility
Tight Junction
Cytoskeletal components: Actin filaments encircling the entire cell
Functions: Seals adjacent cells to one another, controlling passage of molecules between them; separates apical and basolateral membrane domains
(6-pack rings)
Adherent Junction
Cytoskeletal components: Actin filaments located right beneath tight junction
Functions: Provides points linking the cytoskeletons of adjacent cells; strengthens and stabilizes nearby tight junctions
(6-pack rings)
Desmosome
Cytoskeletal components: Intermediate filaments
Functions: Provides points of strong intermediate filament coupling between adjacent cells, strengthening their tissue
(Spot weld)
Hemidesmosome
Cytoskeletal components: Intermediate filaments
Functions: Anchors cytoskeleton to the basal lamina (basement membrane)
(Spot weld)
Gap Junction
Cytoskeletal components: None
Functions: Allows direct transfer of small molecules and ions from one cell to another as a way to communicate
Simple Squamous
Function: Facilitates the movement of the viscera (mesothelium), active transport by pinocytosis, secretion of biologically active molecules
Examples: Lining of vessels (endothelium); Serous lining of cavities: pericardium, pleura, peritoneum (mesothelium)
Simple Cuboidal
Function: Covering and secretion
Example: Covering the ovary, thyroid
Simple Columnar
Function: Protection, lubrication, absorption, secretion
Example: Lining of intestine, gallbladder
Stratified Squamous keratinized (dry)
Function: Protection; prevents water loss
Example: Epidermis
Stratified Squamous nonkeratinized (moist)
Function: Protection; secretion; prevents water loss
Example: Mouth, esophagus, larynx, vagina, anal canal
Stratified Cuboidal
Function: Protection; secretion
Example: Sweat glands, developing ovarian follicles
Stratified Transitional
Function: Protection, distensibility (the capacity to swell as a result of pressure from inside)
Example: Bladder, uterus, renal calyces
Stratified Columnar
Function: Protection
Example: Conjunctiva
Pseudostratified
Function: Protection, secretion; cilia-mediated transport of particles trapped in mucus out of the air passages
Examples: Lining of trachea, bronchi, nasal cavity
Goblet cells
unicellular glands that are simply scattered secretory cells.
Simple Glands
Exocrine glands with ducts that do not branch
Simple Tubular, Branched Tubular, Coiled Tubular, Acinar (or Alveolar), Branched Acinar
Compound Glands
Exocrine glands with ducts from several secretory units that converge into larger ducts
Tubular, Acinar, Tubuloacinar
Simple Tubular
A class of simple exocrine glands with elongated secretory portion; duct usually short or absent
Examples: Mucous glands of colon, intestinal glands or crypts
Branched Tubular
A class of simple exocrine glands with several long secretory parts joining to drain into one duct.
Coiled Tubular
A class of simple exocrine glands where the secretory portion is very long and coiled
Example: Sweat glands
Acinar or Alveolar (Simple)
A class of simple exocrine glands that have a rounded, saclike secretory portion
Branched Acinar
A class of simple exocrine glands with multiple saclike secretory parts entering the same duct
Example: Sebaceous glands of the skin
Tubular
A class of compound exocrine glands with several elongated coiled secretory units and their ducts converge to form larger ducts
Acinar or Alveolar (Compound)
A class of compound exocrine glands that have several saclike secretory units with small ducts converging at a larger duct
Example: Exocrine pancreas
Tubuloacinar
A class of compound exocrine glands that have ducts of both tubular and acinar secretory units that converge at larger ducts
Example: Salivary glands
Mechanisms of exocrine gland secretion
Merocrine, Holocrine, and Apocrine
Holocrine glands
Exocrine glands where cells disintegrate and the contents become secretion; involves cell disruption; involved in common form of acne
Example: Sebaceous gland of hair follicle
Apocrine glands
Exocrine glands where the apical portion of secretory cell is pinched off and secreted
Example: Mammary gland
Merocrine glands
Most common exocrine glands secretion where secretory vessels release contents by exocytosis; exocrine glands with merocrine secretion are either serous or mucous according to their secretory products, which give distinct staining to the cells.
Example: Salivary glands
Serous cells
synthesize proteins such as digestive enzymes, that are not glycosylated proteins
Filled apically with secretory granules
Well-developed RER and Golgi complexes.
Mucous cells (e.g., goblet cells)
Glycosylated proteins* (=glycoproteins) called
mucins.
Well-developed RER and Golgi complexes.
Lots of secretory granules
Absorption
the process of transport from an organ or duct’s lumen to capillaries near the epithelial basement membrane.