Lecture 5 - Epithelial Tissue Flashcards
Germ layers of epithelial tissue
All three layers. Ectoderm –> epidermis, endoderm –> lining of GI tract and respiratory tract, mesoderm –> endothelium, mesothelium
Two types of epithelial tissue
Membranous epithelia, glandular epithelia
Five functions
protection/containment, absorption, secretion, sensation, contractility
apical vs. basal
apical –> uptake, secretion, protection; basal –> cell-substrate contact
Simple Epithelial Tissue
Just one layer of cells
Simple squamous tissue
Flat tissue; Found in lungs, blood vessels, cavities; serves as site of diffusion of fluids and gasses.
Simple Cuboidal Epithelium
cube-ish cells, centrally located nucleus; Found in ducts of the kidney, thyroid glands, salivary glands; serves as site of excretion, secretion, absorption (good surface:volume ratio)
Simple columnar epithelium
height>width, nucleus basal; found in intestine; good for absorption
Simple columnar ciliated epithelium
Columnar with cilia; oviduct/respiratory tract; propel ovum over cell surface, towards uterus
Pseudo-stratified columnar ciliated epithelium
Ciliated columnar cells w/ nuclei at different heights; Trachea; propel mucus and trapped particles
Stratified epithelial tissue
2 or more layers; serves as protection
Stratified squamous epithelium
many layers, top one squamous, lower ones more cuboidal; oral cavity, esophagus, cervix, vagina; serves to withstand chronic abrasion
Stratified Squamous keratinized epithelium
like stratified squamous with surface layer of keratin (dark pink H&E); epithelial surface of the skin; also withstands chronic abrasion
Stratified cuboidal epithelium
1-2 layers cuboidal cells; larger excretory ducts of exocrine glands (salivary glands); provide thicker lining
transitional epithelium
many layers of cells, surface layer large, round pillow shaped; urinary tract; withstands toxicity and accommodates stretch
types of glandular epithelia
- Exocrine, stays connected to surface epithelia during development, when epithelial cells invade connective tissue
- Endocrine, after epithelia cells invade connective tissue the duct cells break down and the gland is surrounded by connective tissue. Two types
2a. Endocrine glands that secrete into capillaries
2b. Follicular endocrine glands, secrete into interior lumen
Types of exocrine glands
Merocrine –> No loss of membrane so glands not exposed to lumen (goblet cell)
apocrine –> secretory product in vesicles
Holocrine –> whole cell broken for discharge of products (sebaceous glands)
Synthesis of mucigen
Protein component made in RER, carb. part attached in Golgi
Goblet cell function
Upper GI –> protective coat
Lower GI –> lubrication
Respiratory –> prevent drying, humidifies air, act as a sticky surface to trap potential irritants
