Epithelial Tissues And Exocrine Glands

Question 1

What is a mucous membrane?

Answer 1

They line internal tubes which open to the exterior. They bear mucus secreting cells to some degree.

Question 2

What is a serous membrane?

Answer 2

Thin, two part membranes which line certain closed body cavities. The secrete a lubricating fluid which promotes friction free movement.

Question 3

Give some examples of where you will find mucous membranes:

Answer 3

Alimentary tract, urinary tract, respiratory tract

Question 4

Give some examples of where you will find serous membranes:

Answer 4

The viscera, peritoneum, pleural sacs, pericardial sac.

Question 5

Describe a mucous membrane histologically:

Answer 5

An epithelium and adjacent layer of connective tissue (lamina propria).

A layer of smooth muscle also in the alimentary tract.

Question 6

Describe a serous membrane histologically:

Answer 6

Simple squamous epithelium which secretes a lubricating fluid and a thin layer of connective tissue.

Question 7

Define epithelia:

Answer 7

Sheets of contiguous cells, of varied embryonic origin, that cover the external surface of the body and line internal surfaces.

Question 8

Describe simple epithelia:

Answer 8

One cell layer thick

Question 9

Describe cuboidal epithelia:

Answer 9

Appear square in section perpendicular to the basement membrane

Question 10

Describe squamous epithelia:

Answer 10

Flattened, irregularly shaped cells

Question 11

Describe columnar epithelia:

Answer 11

Taller than cuboidal, appear columnar at right angles to the basement membrane.

Question 12

Describe pseudostratified epithelia:

Answer 12

Columnar epithelia with nuclei disposed at different levels.

Question 13

Describe transitional epithelia:

Answer 13

Stratifies epithelium that is specialised to stretch. Appears 4-5 cells when relaxed, 2-3 when stretched.

Question 14

Describe stratified epithelia:

Answer 14

More than one cell layer thick

Question 15

Describe the epidermis:

Answer 15

Stratifies squamous keratinised epithelium made if keratinocytes and their products.

Question 16

What are the four layers of the epidermis?

Answer 16

Stratum corneum (horny layer)

Stratum granulosum (granular layer)

Stratum spinosum (prickle cell layer)

Stratum basale (basal layer)

Question 17

What is the basal layer/surface?

Answer 17

The interface between epithelia and underlying supporting tissues. Marked by the basement membrane.

Question 18

What makes up the granular layer?

Answer 18

Keratinocyte granules

Other fibrous proteins

Enzymes which degrade the phospholipid bilayer

Cross linking proteins (fillagrin)

Question 19

What is the horny layer made of?

Answer 19

Flattened corneocytes

Question 20

What makes up the prickle cell layer?

Answer 20

Daughter keratinocytes. Terminal differentiation begins here and keratinocytes lose their ability to divide.

Question 21

How long does it take a keratinocyte to move from the basal layer to the stratum corneum?

Answer 21

28-40 days.

Question 22

What are melanocytes?

Answer 22

Dendritic cells of neural crest origin

Found at basal layers

Produce melanocytes

Question 23

What are langerhans cells?

Answer 23

Dendritic cells of bone marrow origin

Scattered throughout the prickle cell layer

Present antigens to T lymphocytes

Question 24

What is a gland?

Answer 24

An epithelial cell or collection of cells specialised for secretion

Question 25

Exocrine glands are…

Answer 25

Glands with ducts

Question 26

Endocrine glands are …

Answer 26

Ductless glands which secrete into the bloodstream

Question 27

Possibilities of exocrine gland structure:

Answer 27

Duct system may be branched or unbranched

The secretory component can be tubular or acinar

Both types of secretory component may be coiled or branched

Question 28

What is merocrine secretion?

Answer 28

Process is exocytosis

Question 29

What is apocrine secretion?

Answer 29

Discharge of free, unbroken, membrane bound vesicles containing secretory product.

E.g. Fat droplets in milk

Question 30

What is holocrine secretion?

Answer 30

The whole cell breaks down to release the product.

E.g. The sebaceous gland of skin

Question 31

What makes the pancreas both endocrine and exocrine?

Answer 31

It contains nests of endocrine cells (islets of langerhans) embedded in a large exocrine gland.

Question 32

How is secretion of hormones by endocrine glands controlled?

Answer 32

By metabolic factors, other hormones and the nervous system.