Epithelial Tissue Flashcards
Where: Simple Squamous
Pericardium, peritoneum, pleural membrane (mesothelium)
Endothelium.
Capillary/lymphatic vessel walls. Alveoli. Generally anywhere diffusion is required to occur quickly.
Function:Simple Squamous
Provides serous membrane around organs.
Filtration. Minimising diffusion distance.
Where: Simple cuboidal
Ovary surface.
Anterior surface of lens, pigmented epithelium on retina.
Lining of kidney tubule and glandular ducts
Secretory portion of glands.
Function: Simple cuboidal
Secretion and absorption
Where: Simple Non-ciliated Columnar Epithelium
Lines gastrointestinal tract, ducts of glands and gallbladder.
Function: Simple Non-ciliated Columnar Epithelium
Secretory and absorption.
Goblet cells produce mucus in the GI tract to protect against acidic gastric juices.
Villi increase surface area to allow more absorption.
Where: Simple Ciliated Columnar Epithelium
Lining of bronchioles and sinuses.
Uterine tubes and uterus
Central canal of spinal cord
Brain ventricles
Function: Simple ciliated epithelium.
Cilia beat to move substances such as mucus along the GE tract, or the oocyte along the uterine tubes, or the spinal fluid along the canal and ventricle.
Mucus produced by goblet cells to trap protein.
Where: Pseudostratified Columnar Epithelium
Ciliated: Upper respiratory tract
Non ciliated: Larger ducts of glands, epididymis, urethra.
Function: Pseudostratified Columnar Epithelium
Ciliated: Produces mucus to trap pathogens and cilia removes them.
Nonciliated: Absoprtion and protection
Where/Function: Stratified Squamous Epithelium
Keratinised: Superficial layer of skin-waterproof and protection against abrasion.
Nonkeratinised: Lines wet surfaces (mouth, tongue, esophagus, vagina, epiglottis and pharynx)
Protection
Where: Stratified Cuboidal Epithelium
Sweat gland ducts
Esophagal glands
Male Urethra
Function: Stratified Cuboidal Epithelium
Protection
Secretion and absorption to a lesser extent
Where: Stratified Columnar Epithelium
Urethra
Large glandular ducts
Anal mucus membrane
Conjunctiva
Function: Stratified Columnar Epithelium
Protection and Secretion
Where : Transitional Epithelium
Bladder
Ureter and urethra
Function: Transitional Epithelium
Allows organs and lining to stretch without rupturing.
Example :Simple tubular
Intestinal glands
Example: Simple branched tubular
Gastric glands.
Mucous glands of the oesophagus, tongue and duodenum.
Example: Simple coiled tubular
Sweat glands
Example: Simple acinar
Glands of penile urethra
Example: Compound tubular
Bulbourethral glands (gland under the prostate-involved in semen production)
Seminiferous tubules
Mucous glands in mouth.
Example: Compound acinar
Mammary glands
Example: Compound tubuloacinar
Acinar glands of pancreas (digestive enzymes)
Salivary glands
Glands of respiratory tract.
Tight Junction
Occludins and claudins attach to cytoskeleton of neighbouring cell. Creates seal to prevent diffusion of material through interstitial space, maintains polarity of cell.
Adherens Junction
Cadherins span interstitial space and bind to cadherins from the neighbouring cell. Cadherins bind to catenins within the cell, which connect them to actin microfilaments which form a protein plaque.
Desmosomes/Hemidesmosomes
Cadherins still bind to each other in the interstitial space but they are bound to desmoplakin within the cell, which are attached to keratin intermediate filaments by integrins. Hemidesmosomes are the same but integrins instead of cadherens bind to other integrins, which attach to laminin intermediate fibres in the basement membrane.
Gap Junction
6 connexins arranged in a ring to for a connexon/hemichannel-joins with hemichannels on opposite membrane.
Allows 1000AU mass of molecules to pass through- such as neurotransmitters.
Basement Membrane
Basal and reticular lamina.
Basal: Secreted by the epithelial tissue. Made of laminins, collagen, proteoglycans and glycoproteins AMONG OTHERS. Acts as selectively permeable filter.
Reticular: Produced by fibroblasts in the connective tissue. Made of fibronectin and collagen. Adhesive purposes.
Holocrine Secretion
Stores secretions in cytosol. When secretion occurs the cell ruptures and secretes cell contents (such as a lot of phospholipid) along w product. High rate of mitosis to replace ruptured cells
Sebaceous glands.
Apocrine Secretion.
Stores product near the apical membrane, which can pinch off to form a large secretory vesicle. Cells repairs itself after.
Mammary glands
Merocrine
Secretes product normally by synthesising secretory vesicles at the Golgi apparatus and secreted by exocytosis.
Most exocrine glands: Salivary and Pancreas.
