Quiz: Epithelium

Simple squamous epithelium

• Made up of cells having the appearance of thin, flat plates

• The cells fit closely together providing smooth, low-friction surface over which fluids can move easily

• Found lining surfaces utilizing simple passive diffusion such as alveolar epithelium in lungs

  • Also found in the lining of cavities such as blood vessels (endothelium) and heart (mesothelium) 

Simple cuboidal epithelium

• Made up of cells which are roughly cuboidal in shape, appearing square in cross section

  • Each cell has a spherical nucleus in the center

• Commonly found in the secretive or absorptive tissue like exocrine gland of pancreas and lining of kidney tubules as well as ducts of the glands

  • Also constitute the germinal epithelium, which produces the egg cells in the female ovary and the sperm cell in the male testes

Simple columnar epithelium

• Made up of columnar cells which are elongated and column shaped

  • The nuclei are elongated and are usually located near the based of the cells

• Forms the lining of the stomach and intestines

  • Some are specialized for sensory reception

• Goblet cells are found in between the cells of the duodenum which secrete mucin

Pseudostratified epithelium

• Made up of simple columnar cells whose nuclei appear at different heights

• Can possess fine hair-like extensions of their apical membrane called cilia

• Found in the airways, uterus, and fallopian tubes

Lungs (Alveoli)

• Simple squamous epithelium

• Thin, flat cells with flattened nuclei

• Gas exchange between air and blood

Stomach (Pyloric region)

• Simple columnar epithelium

• Tall, column-shaped cells

• Secretes mucus and gastric juice; protects stomach lining

Small intestine (Villi of Jejunum)

• Simple columnar epithelium

• Tall, column-shaped cells with microvilli

• Absorption of nutrients and secretion of mucus

Kidney (Glomerulus)

• Simple squamous epithelium

• Thin, flat cells

• Filtration of blood to form urine

Epididymis

• Pseudostratified columnar epithelium

• Tall, columnar cells with stereocilia

• Absorption of excess fluid, storage and maturation of sperm

Trachea

• Pseudostratified columnar epithelium

• Tall, columnar cells with cilia

• Traps and removes small foreign objects from airway

Stratified lining epithelia

• Multilayered

• Lies in the inner superficial surfaces that are exposed to considerable wear and tear such as esophagus, vagina, conjunctiva, and epidermis

Stratified squamous epithelium

• Thick membrane composed of several cell layers

  • Basal cells are cuboidal or columnar and metabolically active

  • Polygonal layer lies next to it

  • Surface cells are flattened (squamous)

• Protects underlying tissues in areas subjected to abrasion

Stratified squamous keratinized epithelium

• Basal cells are active in mitosis and produce the cells of the more superficial layers

• Most apical layers of cells are dead and loose their nucleus and cytoplasm, instead contain a tough, resistant protein called “keratin”

  • Makes the epithelium waterproof

• Found in mammalian skin

Stratified squamous non-keratinized epithelium

• “Moist” stratified epithelium

• Living cells that protect inner cavities from friction

• Found in the esophagus

Transitional epithelium

• Many layers

• Cells at the base are cuboidal or columnar, and on the surface, large dome-shaped cells

• Found in tissues that stretch

  • It can appear to be stratified cuboidal when the tissue is not stretched

  • Appears stratified squamous when the organ is distended and the tissue is stretched

• Sometimes called “uroepithelium”

• Found in the urinary bladder, ureter, and urethra

Skin epidermis

• Stratified squamous keratinized epithelium

• Columnar, rounded

• Protection

Esophagus

• Stratified squamous non-keratinized epithelium

• Columnar, squamous

• Protection and covering of passageway for food

Ureter

• Transitional epithelium

• Columnar, squamous and dome-shaped

• Transport and storage

Urinary bladder

• Transitional epithelium

• Columnar, rounded and dome-shaped

• Storage and control of urine

Urethra

• Transitional epithelium

• Flat for female; Columnar for male

• Transport and protection

Stratified columnar epithelium

• Composed of multiple layers of cells

• Basal cells are cuboidal

• Surface cells are columnar

• Largest ducts of exocrine glands

• Barrier and conduit

Stratified cuboidal epithelium

• Ducts of salivary glands, sweat glands

Sweat gland ducts in scalp