BL - Epithelial Tissues And Exocrine Glands

Question 1

What do mucous membranes line?

Answer 1

Certain internal tubes which open to the interior, e.g. alimentary, respiratory, urinary

Question 2

What does a mucous membrane consist of?

Answer 2

EPITHELIUM lining the lumen of a tube, layer of connective tissue called LAMINA PROPRIA, third layer of smooth muscle cells (only in alimentary tract) called MUSCULARIS MUCOSAE

Question 3

What are serous membranes?

Answer 3

Thin, two-part membranes which line certain closed body cavities and envelope the viscera.

Question 4

Why do serous membranes secrete fluid?

Answer 4

It promotes friction free movement of the structures the membrane surrounds.

Question 5

What does the serous membrane consist of?

Answer 5

A SIMPLE SQUAMOUS EPITHELIUM which secretes fluid and a THIN LAYER OF CONNECTIVE TISSUE which attaches the epithelium to adjacent tissues.

Question 6

Do serous membranes completely enclose the organs?

Answer 6

No - the organs are surrounded by the membrane but not completely enveloped.

Question 7

Which is the outer side of the serosa - visceral or parietal?

Answer 7

Parietal is outside, visceral is inside.

Question 8

What are epithelia?

Answer 8

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

Question 9

Give an example of an exterior surface with an epithelial lining.

Answer 9

Skin

Question 10

Give an example of an interior space that opens to the exterior which has an epithelial lining.

Answer 10

Gastrointestinal tract, respiratory tract, genitourinary tract.

Question 11

Give an example of an interior space which does not open to the exterior which has an epithelial lining.

Answer 11

Pericardial sac, pleural sacs, peritoneum, blood vessels, lymphatic vessels

Question 12

What is the basement membrane?

Answer 12

Thin, flexible, acellular layer which lies between epithelial cells and connective tissue.

Question 13

What does the basement membrane do?

Answer 13

It serves as a strong, flexible layer to which epithelial cells adhere, and a cellular/molecular filter.

Question 14

What does the basement membrane consist of?

Answer 14

Basal lamina laid down by epithelial cells, which is augmented by a variably thick layer of reticular fibrils.

Question 15

Give a location where a simple squamous epithelium could be found.

Answer 15

Lining of blood and lymph vessels, lining of body cavities, gas exchange epithelium

Question 16

Give some functions of the simple squamous epithelium.

Answer 16

Lubrication, gas exchange, barrier, active transport

Question 17

Give some locations of the simple cuboidal epithelium.

Answer 17

Thyroid follicles, small ducts of exocrine glands,

Question 18

Give some functions of the simple cuboidal epithelium.

Answer 18

Absorption and conduit, secretion

Question 19

Give some locations of the simple columnar epithelium.

Answer 19

Stomach lining and gastric gland, small intestine and colon.

Question 20

Give some functions of the simple columnar epithelium.

Answer 20

Absorption, secretion, lubrication, transport.

Question 21

What is the difference between simple and stratified epithelia?

Answer 21

Simple has one layer of cells while stratified has many layers. Pseudostratified has one layer but appears to have many.

Question 22

Give a location of pseudostratified epithelia.

Answer 22

Lining of nasal cavity, trachea and bronchi.

Question 23

Give a function of pseudostratified epithelia.

Answer 23

Secretion and conduit, absorption

Question 24

Give a location of a stratified squamous non-keratinised epithelium.

Answer 24

Oral cavity, oesophagus, larynx.

Question 25

Give a function of stratified squamous non-keratinised epithelia.

Answer 25

Protection against abrasion, reduced water loss while remaining moist.

Question 26

Why does the epidermis of the skin have no blood supply?

Answer 26

Nutrients can diffuse directly into it.

Question 27

What are the four layers of the epidermis?

Answer 27

Horny layer, granular layer, prickle cell layer, basal layer.

Question 28

Which layer of the epithelium does keratinocyte mitosis occur in?

Answer 28

The basal layer.

Question 29

How is the keratin found in the epidermis formed?

Answer 29

Keratinocytes are formed in the basal layer, then move upwards to form the prickle cell layer. They lose the ability to divide here. Keratinocytes synthesise keratins (fibrous proteins).

Question 30

What happens to keratinocytes in the granular layer?

Answer 30

They lose their plasma membrane and begin differentiating into corneocytes (main cells of stratum corneum).

Question 31

What are keratohyalin granules made of?

Answer 31

Keratins, other fibrous proteins, enzymes

Question 32

Give two examples of cross-link proteins found in the granular layer.

Answer 32

Fillaggrin (aggregates keratins), involucrin (corneocyte envelope).

Question 33

What is the stratum corneum (horny layer) made up of?

Answer 33

Layers of flattened corneocytes. It has a major role in skin barrier function.

Question 34

What is the transit time of a keratinocyte from the basal layer to the stratum corneum?

Answer 34

28-40 days.

Question 35

What are melanocytes?

Answer 35

Dendritic cells of neural crest origin which occur at intervals along the basal layer of the epidermis.

Question 36

What do melanocytes do?

Answer 36

They produce melanin, the main main pigment that gives the skin its colour.

Question 37

What are Langerhans cells?

Answer 37

Dendritic cells of bone marrow origin scattered throughout the prickle cell layer.

Question 38

What do Langerhans cells do?

Answer 38

They have a highly specialised capacity to present antigens to T lymphocytes. They also mediate immune reactions.

Question 39

Give some examples of where you would find stratified squamous keratinised epithelium?

Answer 39

Surface of skin and some in oral cavity.

Question 40

What are the functions of stratified squamous epithelia?

Answer 40

Protection against abrasion and physical trauma, prevention of water loss and microbial invasion, shields against UV light damage.

Question 41

What shape are cells in the transitional epithelium?

Answer 41

They vary in shape from columnar/cuboidal to flattened.

Question 42

Give some locations of transitional epithelium.

Answer 42

Renal calyces, ureters, bladder, urethra.

Question 43

Give some functions of transitional epithelium.

Answer 43

Distensibility, protection of underlying tissues from toxic chemicals.

Question 44

What is a gland?

Answer 44

An epithelial cell or collection of cells specialised for secretion.

Question 45

What is the difference between an endocrine and exocrine gland?

Answer 45

``` Exocrine = a gland with ducts. Endocrine = a gland which secretes directly into the bloodstream ("ductless") ```

Question 46

Give an example of a unicellular exocrine gland.

Answer 46

A goblet cell.

Question 47

What is meconium ileus?

Answer 47

An inability to pass the first faeces, often occurs in newborns with CF.

Question 48

What is an acinus?

Answer 48

The secretory unit of many exocrine glands.

Question 49

Name the five different structures of simple glands.

Answer 49

Simple tubular, simple coiled tubular, simple branched tubular, simple alveolar, simple branched alveolar.

Question 50

What is merocrine secretion?

Answer 50

Exocytosis - the vast majority of glands function this way.

Question 51

What is apocrine synthesis?

Answer 51

Secreted droplets covered by plasmalemma, eg fat droplets in milk.

Question 52

What is holocrine secretion?

Answer 52

The whole cell breaks down, eg sebaceous gland of skin.

Question 53

Why does the exocrine pancreas often become inflamed in people with cystic fibrosis?

Answer 53

The secretions contain too little water and become thickened, resulting in the ducts becoming blocked.