4.1 Epithelial Tissue

Question 1

Epithelial Tissue:
Location
Uses
Characteristics

Answer 1

• Covers surfaces and lines cavities
• Externally: protects body from drying out, injury, bacterial invasion
• Internally: protects, cilia sweep impurities, secretes mucus, absorption
• divides rapidly
• gets nutrients from underlying connective tissue
• free surface and basement membrane
• avascular - no blood vessels
• Classified by shape and layers (squamous; cuboidal; columnar - simple; stratified)

Question 2

Simple Squamous Epithelium

Answer 2

Flattened cells
Diffusion of substances (not protection)
Found in: blood capillaries; air sacs (alveoli)

Question 3

Stratified Squamous Epithelium

Answer 3

• protection; avoiding drying out
• found in skin, entrances to structures open to the outside
  -Keratinized or non keratinized

Question 4

Keratinized Stratified Squamous Epithelium

Answer 4

• superficial portion of skin
  Cells produces at the basal of skin move outward, getting more and more keratin until they die

Question 5

Non-Keratinized stratified squamous epithelium

Answer 5

• lining of moist surfaces near entrances to the body (mouth, vagina, anus)
• protects against abrasion and drying out

Question 6

Cuboidal Epithelium

Answer 6

• Stratified is usually 2 layers, found in linings of larger ducts (mammary and salivary)
• Cube shaped cells with basement layer
• found in glands: salivary, thyroid, pancreas… also in ovaries and lines kidney tubules
• Secretion; absorption

Question 7

Columnar Epithelium

Answer 7

• long cells
• modified to perform particular functions - many are goblet cells which secrete mucus onto the surface
• lines digestive organs; uterine tubes
• protections; secretion; digestion
• stratified is uncommon: pharynx (back of throat); male urethra

Question 8

Pseudostratified Columnar Epithelium

Answer 8

• Looks layered but isn’t, each cell touches basement layer, caused by varying nucleus placement
• tapers and narrow at one end, wider end has nucleus
• Ciliated “” lines reproductive tract, air passages (nasal cavities and trachea)
• goblet cells scattered among ciliated “” - capture particles and ciliary motion moves them up
• protection; secretion; movement of mucus and sex cells

Question 9

Transitional Epithelium

Answer 9

• changes in response to tension
• changes between squamous and cuboidal
• lining of urinary bladder, ureters, urethra
• allows bladder to expand and contract