Lecture 12: Epithelial Tissue Flashcards
Epithelial Tissue Characteristics
- cellularity, polarity, attachment, avascular, innervation, regeneration
- rests on basement membrane
- physical protection, permeability ,secretion, sensation
Epithelial Polarity
- Apical Surface - face lumen/surface
- Basal Surface - on basement membrane, anchors to CT
- Lateral Surface - attaches to adjacent cells
Tight/Occluding Junction
- impermeable, allows cell to act as BARRIER (belt-like)
- increasing junctions = decreasing permeablity
Gap/Communication Junction
- fluid-filled channels connection cells
- mediates communication (CONNEXIN)
Anchoring Junctions (3 types)
- Adherens - lateral adhesion (actin); belt-like
- Desmosome - lateral adhesion (intermediate filaments), spot-like; involve cadherins
- Hemidesmosomes - basal adhesion (intermediate filaments), spot-like; involve integrins
H. pylori and Tight Junctions
- bacteria bind tight junctions, increasing permeability
- loss of tissue fluid into intestinal lumen
gastric ulcers in stomach
Pemphigus vulgaris and Desmosomes
- abnormal desmosome function = dec. cell-to-cell adhesion
blisters of oral mucosa
Microvilli characteristics and Celiacs disease
- contain actin core
- nutrient absorption, inc. surface area by 20-30x
Celiacs = loss of microvilli on absorptive cells in small intestine
Sterocilla characteristics
- microvilli of unusual length; long and less mobile
- actin core
restricted location = epididymis and hair cells of inner ear
Cilia characteristics and 3 types (motile, primary, nodal)
- long, highly motile, internal microtubule arrays (longer than microvilli)
Motile: beat in wave-like fashion (keep airway clean)
Primary: immotile, chemo/osmo/mechanoreceptors
Nodal: embryonic –> left/right axis determination
Simple Squamous (Location and Function)
Location: alveoli, loop of Henle, ducts
- endothelium: line blood/lymphatic vessels
- mesothelium: line serous membranes
Function: exchange, barrier, lubrication
Simple Cuboidal (Location and Function)
Location: Kidneys, ovary covering, terminal bronchioles
Function: absorption, barrier, secretion
Simple Columnar (Location and Function)
Location: auditory tubes, uterus, oviducts, stomach, gallbladder, SI/LI
Function: absorption, secretion
Pseudostratified Columnar Ciliated (Location and Function)
Location: nasal cavity, pharynx, bronchi
Function: absorption, secretion, movement of debris
Urothelium (Location and Function)
Location: urinary bladder, ureters, urethra
Function: barrier, distensible
Nonkeratinized Stratified Squamous (Location and Function)
Location: oral cavity, pharynx, esophagus, anus, vagina, urethra, cornea
Function: barrier, protection
Keratinized Stratified Squamous (Location and Function)
Location: epidermis of skin
Function: barrier, protection
Stratified Cuboidal (Location and Function)
Location: sweat glands/ducts, ovarian follicles, salivary gland ducts
Function: barrier, passageway
Mucous vs Serous membranes
Mucous: secretes mucus. lines body cavity and tubular organs
Serous: smooth, transparent, two-layered membrane (fluid derived from serum)
Unicellular Glands (and Goblet Cells)
- simplest in structure
Goblet: mucous secreting cell lining intestines and respiratory tract
What is parenchyma and stroma?
parenchyma: functional tissue of an organ, does not include CT or other supporting tissue
stroma: connective tissue that separate gland into lobules
Which acini (mucous or acini) is more prominent in:
- parotid gland?
- sublingual gland?
- submandibular gland?
- serous acini
- mucous acini
- mucous and serous acini
Merocrine, Holocrine, and Apocrine glands
Merocrine: membrane-bound vesicles (salivary gland)
Holocrine: apoptosis, secretion and cell debris (sweat)
Apocrine: release apical portion of cell in plasma membrane (mammary glands)
Simple vs Compound glands and tubular vs acinar
Simple (unbranched ducts)
Compound (2+ branches) –> can have tubular and acinar for tubuloacinar
Tubular (straight tube)
Acinar (saclike structure)
