Epithelial tissue and skin

Question 1

Epithelia definition

Answer 1

Sheets of contiguous cells, of varied embryonic origin, covering the external surface of the body and lining many internal surfaces

Question 2

How do epithelia have their embryonic origins?

Answer 2

All from germ layers
Ectoderm (epidermis)
Endoderm (GI tract)
Mesoderm (inner body cavities lining)

Question 3

How are epithelia classified

Answer 3

Into simple (one cell layer thick), and stratified/compound (more than 1 cell layer thick)

Simple can be squamous, cuboidal, columnar or pseudostratified
Stratified can be squamous, cuboidal, columnar or transitional

Question 4

Mucous membranes vs serous membranes

Answer 4

Mucos; lining internal tubes that open to the exterior (eg GI tract, respiratory tract, urinary tract)3 layers include epithelium lining lumen, lamina propria (connective), muscularis mucosal (smooth)

Serous; line closed body cavities and envelope the viscera. (Eg peritoneum, pleural sacs, pericardial sacs) layers include mesothelium, connective tissue. Function to exclude a lubricating fluid and allow friction free movement of structures.

Question 5

Goblet cells

Answer 5

Mucus, moistens, lubricates

Question 6

Club cells

Answer 6

Secretion for protection of bronchioles, act as stem cells, detoxification

Question 7

Microfold cells

Answer 7

Only in small intestine

Question 8

Stereocillia

Answer 8

Inner ear, respond to fluid motion for hearing and balance

Question 9

Explain the position, structure and function of the basement membrane

Answer 9

.

Question 10

Simple squamous location and functions

Importance of layer in location

Answer 10

Bowmans capsule, endothelial lining of blood/lymph vessels, mesothelium of pleural and peritoneal cavities

Fast material exchange and barrier (vascular and lymphatics)
Barrier in brain and CNS

Mesothelium: exchange and tissue lubrication, barrier in bowmans capsule, lubrication in serosa of lungs, heart and viscera

Question 11

Simple cuboidal location and functions

Importance of layer in location

Answer 11

Thyroid, certain glandular ducts, proximal kidney tubules

Absorption and conduit. (Exocrine glands)
Absorption and secretion (kidney tubules)
Barrier/covering (ovary)
Hormone syntheis/storage/mobilisation (thyroid)

Question 12

Simple columnar location

Importance of layer in location

Answer 12

Jejunum and much of GI tract

Question 13

Pseudostratified location

Importance of layer in location

Answer 13

Upper respiratory tract

Question 14

Stratified squamous non-keratinised epithelium

Importance of layer in location

Answer 14

Eg in oesophagus, vagina etc

Question 15

Stratified squamous keratinised epithelium

Importance of layer in location

Answer 15

Eg in skin

Question 16

(Importance of layer in location)

Transitional epithelium

Answer 16

Eg in urinary tract

Question 17

Stratified cuboidal epithelium

Importance of layer in location

Answer 17

Eg in glandular ducts

Question 18

(Importance of layer in location)

Stratified columnar epithelium

Answer 18

Eg in male urethra

Question 19

What makes up the Basement membrane and what is in contact with it

Answer 19

Basal lamina
Reticular lamina

Only the basal layer of cells in a compound epithelium is in contact with the basement membrane

Holds cells to connective tissue and guide for cell migration during development

Question 20

What happens in the early and chronic stags of smoking and what can this later cause?

Answer 20

Smoking overview:
• Mucocillirary escalator stops functioning
• Early stage: thickening of mucus layer, cilia die off, cilliagenesis is 2 to 4 days

• Chronic stages: goblet and basal cells rapidly increase in number, club cells metaplasia (tumour) or die, carnigens increase mutation frequency, pneumocytes in alveoli die - type 2 cells become type 1 and 2. Fibroblasts lay down scar tissue
• can cause acute bronchitis, chronic bronchitis, emphysema, COPD or asthma