Module 4: Epithelial Tissue Flashcards
What are the 2 types of Epithelial Tissue?
- Covering/Lining Epithelium
- Glandular Epithelium
Covering/Lining Epithelium:
Forms outer layer of skin and
internal structures
Glandular Epithelium
Forms glands of body
6 Functions of Epithelia:
- Protection
- Absorption
- Filtration
- Excretion
- Secretion
- Sensory reception
Apical Surface
- Free surface exposed to exterior environment or cavity
of organ (essentially just the top surface of skin) - Often have microvilli or cilia
Basal Surface
Inside/bottom layer than anchors the skin
Basal Lamina
- Adhesive sheet beneath Basal Surface
- Joins epithelial
tissue to connective tissue
Fun Facts about Epithelial Tissue!
- Avascular, but are innervated
- High regenerative capacity…paper cut heals fast
CLASSIFICATION: Simple
- One layer of cells
↓ Therefore, it’s a thin sheet
↓ Good for diffusion - Absorption, Secretion, Filtration
CLASSIFICATION: Stratified
- Multiple stacked layers… LIKE BRICKS!
- Good for protection
- Regenerate from basal surface
CLASSIFICATION: Pseudostratified
- MOSTLY one layer
- Cells of different sizes/shapes
NUCLEI SHAPE: Squamous
- Disc shaped central Nuclei
NUCLEI SHAPE: Cuboidal
- Large spherical (round) central Nuclei
NUCLEI SHAPE: Columnar
- Round-Oval Nuclei
Simple Squamous Epithelium:
Description:
Function:
Location:
(D, L, F:)
D: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm. Simplest of the epithelia
F: Allows materials to pass by diffusion and filtration in sites where protection is not important. Secretes lubricating substances in serosae
L: Air sacs of lungs
Simple Cuboidal Epithelia:
D, F, L:
D: Single layer of cubelike cells with large, spherical central nuclei
F: Secretion and Absorption
L: Kidney tubules
Simple Columnar Epithelia
D, F, L:
D: Single layer of tall cells with round/oval nuclei.
-Many cells bear microvilli, some bear cilia
-Layer may contain mucus-secreting unicellular glands (GOBLET CELLS)
F: Absorption, secretion of mucus (bc of goblet cells), enzymes, and other substances.
- Ciliated typed propels mucus (or reproductive cells by ciliary action)
L: NONCILIATED TYPE lines most of the digestive tract.
Ciliated type lines small bronchi
Pseudostratified Columnar Epithelium
D, F, L:
D: Single layer of cells of differing heights, some no reaching the free surface. May contain mucus-secreting cells (goblet cells) and bear cilia
F: Secrete substances, particularly mucus…propulsion of mucus by ciliary action
L: Nonciliated type in male sperm carrying ducts
CILIATED TYPE lines the trachea
Stratified Squamous Epithelium
D, F, L:
D: Thick membrane (many layers). Basal cells are cuboidal/columnar and metabolically active. SURFACE CELLS ARE SQUAMOUS. In the keratinized type, the SURFACE cells are full of keratin and therefore dead (NAILS). Basal cells are active in mitosis and produce the cells of the more superficial layers
F: Protects underlying tissues in areas subjected to abrasion
L: Nonkeratinized type forms the moist lining of the esophagus
Keratinized type forms the epidermis of the skin
Transitional Epithelium
D, F, L:
D: Resembles both STRATIFIED squamous and STRATIFIED cuboidal.
Basal cells are cuboidal or columnar.
Surface cells dome shaped or squamous-like, depending on degree of ORGAN STRETCH
F: Stretches readily, permits stored urine to expand urinary organ
L: Lines the ureters/bladder
How many cells do glands consist of?
One or more cells
What do glands do?
They make or secrete a particular substance
What are the 2 types of Glandular Epithelium?
- Unicellular Glandular Epithelium
- Multicellular Glandular Epithelium
Unicellular Glandular Epithelium is:
Scattered within epithelial sheets (e.g Mucous and goblet cells)
