Lecture 15 - Epithelial Tissues

Question 1

What are tissues?

Answer 1

Groups of cells similar in structure and perform a common or related function

Question 2

Histology

Answer 2

The study of tissues.

Question 3

What are the four basic tissue types?

Answer 3

Connective, epithelial, nervous and muscle

Question 4

Epithelium

Answer 4

Sheet of cells that covers body surfaces or cavities
Ex. Skin

Or as glandular epithelium that secretes substances
Ex. Salivary glands

Question 5

Functions of epithelial tissue

Answer 5

Protection, absorption, filtration, excretion, secretion and sensory reception

Question 6

Apical surface

Answer 6

The exposed, upper side of the epithelial tissue

Question 7

Basal surface

Answer 7

Lower attached side that faces inwards toward the body and sits on a basal lamina

Question 8

What is a basal lamina?

Answer 8

A non cellular adhesive sheet that attaches the epithelial cells to the rest of the body

Question 9

Epithelial tissue characteristics

Answer 9

make continuous sheets that have little space between cells.
They form tight junctions and desmosomes with neighbouring cells
supported by a basement membrane
composed of the basal lamina and the reticular lamina.

Epithelial tissues are innervated (supplied by nerve fibres), but avascular (no blood vessels).
Epithelial tissue has a high regeneration capacity to repair damage due to friction or hostile substances

Question 10

What is the reticular lamina?

Answer 10

a layer of extra- cellular material made of collagen fibres that is deep to the basal lamina

Question 11

Simple epithelia (first part of name)

Answer 11

A single layer thick

functions in absorption, secretion, and filtration.

Question 12

Stratified epithelia (first part of name)

Answer 12

Two or more layers thick and involve din protection
Ex. Skin

Question 13

Squamous epithelia (second part of name)

Answer 13

Flattened and scale like

Question 14

Cubodial epithelia (second part of name)

Answer 14

Box like or cube shaped

Question 15

Columnar epithelia (second part of name)

Answer 15

Tall and column like

Question 16

Where is Simple squamous epithelium located?

Answer 16

located where filtration or exchange of substances occurs.
Ex. In lungs

Question 17

Where is Simple cubodial epithelium located?

Answer 17

forms the smallest ducts of glands or kidney tubules (found lining ducts of glands)

Question 18

Where is simple columnar epithelium located?

Answer 18

lines the digestive tract. These cells in the intestines can have microvilli. (found lining intestinal tract)

Question 19

Pseudostratified columnar epithelium

Answer 19

contains cells of varying heights that all sit on the basement membrane, giving the appearance of many layer (NOT STRATIFIED)
Found in trachea

Question 20

What does Stratified squamous epithelium make up?

Answer 20

the external part of the skin, and extends into every body opening

Question 21

Where is stratified cubodial epithelium found?

Answer 21

mostly in the ducts of some of the larger glands

Question 22

Where is stratified columnar epithelium found?

Answer 22

in the pharynx, in the male urethra, and lining some glandular ducts.

Question 23

Transitional epithelium

Answer 23

forms the lining of the urinary bladder and is specialized to allow cells to change shape and stretch.

Question 24

Endocrine glands

Answer 24

Ductless glands that secrete hormones directly into the blood or lymph.
They secrete hormones, chemical messengers that bind to receptors in specific target organs to generate some response

Ex. Pituitary gland, adrenal glands

Question 25

Exocrine glands

Answer 25

have ducts and secrete their products through an epithelial surface.
They are more numerous than endocrine glands.
Ex of secretions: mucous, sweat, oil, and salivary glands.

Even though your stomach is inside your body, it lined with epithelial tissue and is exposed to the outside world every time you eat and drink. Stomach acid and other gastrointestinal secretions are produced by exocrine glands.

Question 26

Unicellular exocrine glands

Answer 26

most common unicellular glands are goblet cells.
They are found in epithelial linings of intestinal and respiratory tracts.

These cells produce mucin, a sugar-protein that can dissolve in water to form mucus, a slimy protective, lubricating coating.

Question 27

Multicellular exocrine glands

Answer 27

consist of a duct and a group of secretory cells.
They are usually surrounded by supportive connective tissue that supplies blood and nerve fibers to the gland.

Classified by structure:
Simple vs. compound, tubular vs. alveolar
And By mode of secretion:
• Merocrine, holocrine or apocrine

Question 28

Simple glands

Answer 28

Simple glands have an unbranched duct.

In tubular glands, secretory cells form long ducts that can be straight or coiled.
In alveolar or acinar glands, secretory cells form pockets or sacs Simple glands have an unbranched duct.

SEE SLIDE FOR PICTURES

Question 29

Compound glands

Answer 29

In a compound gland, the duct branches to more than one group of secretory cells.

Tubuloalveolar glands have both tubular ducts and alveolar pockets or sacs

SEE SLIDE FOR PICTURES

Question 30

Merocrine glands

Answer 30

Merocrine glands secrete products by Exocytosis as secretions are produced.
Ex. sweat, saliva, pancreatic juices

SEE SLIDE FOR PICTURES

Question 31

Holocrine glands

Answer 31

Holocrine glands accumulate products within the cell and then rupture.
Ex. sebaceous oil glands

SEE SLIDE FOR PICTURES

Question 32

Aprocrine glands

Answer 32

Apocrine glands release their secretions by budding off a portion of the cytoplasm. Ex. lactating mammary glands

SEE SLIDE FOR PICTURES