Epithelial Tissues Flashcards
Apical Specializations
Microvilli
Stereocilia/stereovilli
Cilia
Flagella
Characteristics of epithelia
Cellularity Polarity Attachment A vascular Innervation Regeneration
Epithelial Polarity
Basal domain: rests on basal lamina, anchors cells to underlying CT
Apical domain: directed toward the exterior surface/lumen
Lateral domain: communicates with adjacent cells
Apical specializations-functions
Increase surface area
Move substances along the epithelia
Microvilli
Cytoplasmic processes containing an actin core
Specialized for absorption and increase surface area
Stereovilli
Actin core provides rigidity
Microvilli of unusual length, long and immotile
Increase SA
Only in epididymis and sensory cells of inner ear
Cilia
Hair-like extension containing an axoneme
Microtubule based structure
Motile: propel substances by beating in wave-like fashion
Primary: immotile, sensors in cell
Nodal: embryonic, L/R axis determination
Flagella
Modified, motile cilia
Forward movement of sperm
Intercellular junctions
Occluding Junctions (Zonula occludens) Anchoring junctions Gap junctions Focal adhesions Hemidesmosomes
Occluding Junctions (zonula occludens)
Impermeable, allows cells to function as a barrier
Encircle cells near their most apical surface
Increase in these decreases permeability
Occludins, claudins
Anchoring junctions
Lateral adhesions that link into the cytoskeleton of adjacent cells
Zonula adherens: actin filaments
Macula adherentes (desmosomes): intermediate filaments
Cadherins
Gap Jnctions
Fluid-filled channels that connect approved cells
Communication
Connexin aggregates
Focal Adhesions
Anchor actin filaments to basement membrane
Integrins
Hemidesmosomes
Anchor intermediate filaments to basement membrane
Integrins
Simple Squamous Epithelia
Location: lining of blood and lymphatic vessels (endothelium) lining of serous membranes (mesothelium) lining alveoli in lungs loop of Henle in kidney various ducts
Function: exchange, barrier, and lubrication
Simple Cuboidal
Location: kidney tubules
glands and associated ducts
Terminal bronchioles
Covering of ovary
Function: absorption, barrier, secretion
Simple columnar
Location: auditory tubes Uterus Oviducts (ciliated) Stomach SI/LI Gallbladder
Function: absorption and secretion
Pseudostratified Columnar Ciliated
Location: lining of nasal cavity
Pharynx
Trachea
Bronchi
Function: absorption and secretion, debris and particulate movement
Urothelium
Transitional Epithelium
Location: urinary bladder
Ureters
Urethra
Function: barrier, distensible property
Nonkeratinized stratified squamous
Location: oral cavity Portions of the pharynx Esophagus Anus Vagina Urethra Cornea
Function: barrier and protection
Apical. Layer of cells retain nuclei
Keratinized stratified squamous
Location: epidermis of skin
Function: barrier and protection
Apical layer of cells do not have nuclei
Stratified cuboidal
Location: sweat glands and ducts
Ovarian follicles
Salivary gland ducts
Function: barrier and passageway
Basement membrane
Located adjacent to basal domain
Selective barrier between tissues permits diffusion of nutrients
Mucous membrane
ET that secretes mucus
Serous membrane
ET that lines specific internal cavities of the body
Fluid derived from serum
Peritoneum, pericardium and pleura
Mesothelium: simple squamous ET that comprises part of a serous membrane
Gland types
Exocrine
Endocrine
Secrete mucus, hormones, enzymes, and wastes
Exocrine glands
Merocrine
Apocrine
Holocrine
Merocrine glands
Salivary glands; secretion is delivered in membrane-bound vesicles to apical surface and undergo exocytosis
Holocrine glands
Sebaceous glands
Secretion accumulates within a cell—> apoptosis
Secretion and cell debris are released
Apocrine glands
Sweat/mammary
Release of the apical portion of the cell, surrounded by cytoplasm within a plasma membrane
Unicellular gland
Single, secretory cells distributed among non-secretory cells
Goblet Cell: mucus-secreting cell fond lining the intestines and respiratory tract
Multicellular Glands
Classified by arrangement and shape of secretory cells and Ductal elements
Secretory cells are either mucous or serous cells
Serous cells take up dye
Mucous cells do not take up dye
Simple tubular
Secretory cells from straight tube
Simple coiled tubular
Coiled tubular secretory portion located deep in tissue
Simple branched tubular
Branched tubular gland with wide secretory portion
Simple actin are
Single layer of secretory cells
Simple branched acinar
Secretory portion opens directly into the lumen
Compound tubular
Coiled secretory portion located deep in tissue
Compound acinar
Alveolar-shaped secretory unity’s, pyramid shaped secretory cells
Compound tubuloacinar
Tubular and acinar secretory units; will have demilunes
