Epithelia Flashcards
Recall info about epithelia
-covers the internal and external surfaces
-found in various organs
-tightly packed : minimum extracellular space
-two surfaces; apical (free) and basal ( attached) surfaces
-avascular: nourishment by diffusion
-have a basement membrane
What are the functions of epithelia
-Protection and barrier function
-Absorption and secretion
-Sensory perception
-Transport
-Filtration and excretion
-Diffusion of gasses
What is the classification based on the number of cell layers
Simple
What is the classification based on the number of cell layers
Stratified
What is the classification based on the cell shape
Squamous
What is the classification based on the cell shape
Cuboidal
What is the classification based on the cell shape
Columnar
What is the function of junctional complexes ?
-assist epithelial cells to adhere to each other
-control/restrict the moment of materials between adjacent cells
Name 3 cell junctions
Tight junctions, desmosomes, gap junctions
What are tight junctions ?
-impermeable junctions
- form continuous seals around the cells -> prevents molecules from molecules passing through the intermolecular space
Which cell junction is this ?
Tight junctions
What are desmosomes?
-anchoring junctions
- bind adjacent cells together
-acts like a molecular Velcro
-helps form an internal tension reducing network of fibres
Which cell junction is this?
Desmosomes
What are gap junctions:?
-communicating junctions
-allow ions and small molecules to pass
-are particularly important for communication in heart cells and embryonic cells
What are the 6 epitheliums ?
-simple squamous
-simple cuboidal
-simple columnar
-pseudo-stratified columnar
-stratified squamous
-transitional
Which epithelium is this based on the pic and give its description, function and location
-simple squamous
DESCRIPTION:
Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia.
FUNCTION:
Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae (linings of ventral body cavity).
LOCATION:
Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; serosae.
Which epithelium is this based on the microscopic image?
Simple squamous
Which epithelium is this based on the pic and give its description, function and location
-simple cuboidal
DESCRIPTION:
Single layer of cubelike cells with large, spherical central nuclei.
FUNCTION:
Secretion and absorption.
LOCATION:
Kidney tubules; ducts and secretory portions of small glands; ovary surface.
Which epithelium is this based on the microscopic image?
Simple cuboidal
Which epithelium is this based on the pic and give its description, function and location
-simple columnar
DESCRIPTION:
Single layer of tall cells with round to oval nuclei; many cells bear microvilli, some bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells).
FUNCTION:
Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action.
LOCATION:
Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.
Which epithelium is this based on the microscopic image?
Simple columnar
Which epithelium is this based on the pic and give its description, function and location
-pseudostratified columnar
DESCRIPTION:
Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia.
FUNCTION:
Secrete substances, particularly mucus; propulsion of mucus by ciliary action.
LOCATION:
Ciliated variety lines the trachea and most of the upper respiratory tract; nonciliated type in males’ sperm-carrying ducts and ducts of large glands.
Which epithelium is this based on the microscopic image?
Pseudostratified columnar
Which epithelium is this based on the pic and give its description, function and location
-stratified squamous
DESCRIPTION:
Thick epithelium composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers.
FUNCTION:
Protects underlying tissues in areas subjected to abrasion.
LOCATION:
Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry epithelium.
Which epithelium is this based on the microscopic image?
Stratified squamous
Which epithelium is this based on the pic and give its description, function and location
-transitional
DESCRIPTION:
Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch.
FUNCTION:
Stretches readily, permits stored urine to distend urinary organ.
LOCATION:
Lines the ureters, bladder, and part of the urethra.
Which epithelium is this based on the microscopic image?
Transitional
What are the two exocrine secretions and how do they differ?
Which secretion is this ?
Endocrine secretion
Compare exocrine secretion with endocrine secretion
What is meant by apocrine ?
-pinched off portion of the cell
-secrete fat droplets into breast milk
Which junction is this ?
Gap junction
