Tissue Epithelia Flashcards
What is the function of epithelial tissue?
Physical protection, permeability, secretion and sensation
Epithelial tissue characteristics
Cellularity, polarity, avascular, regeneration, attachment and innervation
What does epithelial tissue rest on?
Basement membrane (thin extracellular sheet)
Epithelium that is primarily involved in secretion?
Arranged into glands
What surface of the epithelial is free?
Apical; opposite of the basement membrane
Describe a tight junction
IMPERMEABLE, cells function as a barrier
Encircle cells at most apical surface
2 types of bacteria that impairs tight junctions and increases permeability
Bacteria with food poisoning binds in intestines = loss of tissue fluid
Helicobacter Pylori binds in stomach = gastric ulcers
Describe a gap/communicating junction
Fluid filled channels that allow cell to cell communication
3 types of anchoring junctions
Adherens, desosomes, hemidesosomes
Adherens
Lateral adhesion; cadherin:actin interactions
Desosomes
Lateral adhesion; cadherin:intermediate filament interactions
Hemidesosomes
Basal adhesion; integrin:intermediate filament interactions
Describe the action of pemphigus vulgaris
Impaired desosome function; reduces cell to cell adhesion and results in oral mucosa blisters
Function of apical microvilli
Absorption; made of an actin core
Found in intestines
Apical stereocilia
Abnormally long microvilli; made of actin core
Found in epididymis and hair cells of inner ear
Apical cilia
Long and motile; made of microtubules
Propel substance across tissue, work as sense, have role in L/R axis determination
Simple squamous function
Exchange, barrier, lubrication
2 types of simple squamous
Endothelium (lining of blood and lymphatic vessels) and mesothelium (lining serous membranes; pericardium, pleura, peritoneum)
Simple cuboidal function
Absorption, barrier, secretion
Simple columnar function
Absorption, secretiton
Simple columnar nucleus shape
Either circle or egg shaped, can orient more towards basal surface
Pseudostratified columnar ciliated
Falsely stratified; located in the airways for debris movement, absorption, secretion; Has goblet (mucus secreting) cells
Urothelium – psuedostratified
ONLY in urinary system (bladder, ureters, urethra)
Has a distensible property – cells extend when bladder is empty and contract/widen when bladder is full
Nonkeratinized stratified squamous
Barrier and protection - located in many openings such as oral cavity, anus, vagina, urethra, cornea
Keratinized stratified squamous
Barrier and protection - has wispy things – located in epidermis of skin
Stratified cuboidal-columnar
Function as passageways; located in sweat glands, ducts, ovarian follicles, salivary glands
Unicellular glands
Single, secretory cells amongst non-secreting cells
Goblet cell- mucus secreting cell in intestines and airways
Exocrine glands
Secrete products into ducts; secretory cells grouped as acinus
Parenchyma definition
Functional tissue
Stroma
Connective tissue support
Endocrine glands
Secrete products directly into the blood
Apocrine glands
Exocrine; release apical portion of cell; mammary glands
Holocrine glands
Exocrine; secretion builds up inside cell which causes apoptosis – all cell contents/debris is released
Merocrine glands
Exocrine; secretion released via membrane bound vesicles that will undergo exocytosis; salivary glands
