6.1, 6.2 Epithelium, Exocrine Gland And Dermatology

Question 1

What is the function of the skin? (8)

Answer 1

1) Protection
2) Temperature Regulation and Insulation
3) Sensation
4) Immunity - langherhans cell (type of dendritic cell in prickle layer) of epidermis interact with T cells to protect from foreign material
5) Endocrine
6) Electrolyte balance - water, waste products; urea, salt
7) Growth
8) Cosmetic

Question 2

Effects of Inflammation? (6)

Answer 2

Redness, Heat, Swelling (inc. vessel permeability), Pain, Loss of function, itching

Question 3

Compare normal and psoriasis skin

Answer 3

Normal

• normal stratum corneum
• quiescent epidermis

Psoriasis

• desquamating (comes off in flakes) stratum corneum
• highly proliferative epidermis

Question 4

What is Toxic Epidermal Necrolysis? (3)

Answer 4

1) caused by allergy to drug
2) epidermis detaches from dermis
3) body susceptible to infection so life threatening

Question 5

What is lichenification? (3)

Answer 5

1) hardening of skin
2) due to atopic eczema (most common type)
3) usually in flexural areas

Question 6

What is a mucous membrane?

Answer 6

1) Line internal tubes open to exterior e.g. Alimentary, respiratory, urinary
2) epithelial tissue which secretes mucous
3) structure - epithelium, CT (lamina propria), muscularis mucosae (smooth muscle)

Question 7

What is a serous membrane? What are the two layers called?

Answer 7

1) line certain closed body cavities eg. Peritoneum, pleura, pericardium
2) simple squamous epithelium secreting watery fluid to lubricate
3) simple squamous, thin CT carrying blood vessels and nerves

1) visceral and parietal

Question 8

What is the basement membrane?

Answer 8

1) thin, flexible layer lying between epithelial cells and CT
2) basal lamina secreted by epithelial cells is on top of it
3) holds cells on top of it together

Question 9

Describe simple squamous cells and example of where they can be found?

Answer 9

1. 1 layer
2. Thin, flat cells
3. Lubrication - gas exchange
4. Peritoneum, pleura, lining of body cavities basically

Question 10

Describe simple cuboidal cells and where they can be found?

Answer 10

1) 1 layer
2) Cuboidal cells
3) exocrine glands, absorption, secretion
4) (thick so protective) - kidney tubules, ovary surface, hormone synthesis - thyroid

Question 11

Simple columnar and example

Answer 11

1. 1 layer
2. Column like
3. Surface area increased (can inc. microvilli)
4. So oviducts for transport, line most of lower GI tract (small intestine and colon), stomach, gastric glands

Question 12

Pseudostratified and example

Answer 12

1. 1 layer but looks like a few but all attached to basement membrane
2. Secretion and conduit, absorption, mucus -particle trapping and removal
3. Lining of nasal cavity, trachea, bronchi

Question 13

Stratified squamous - keratinised and non-keratinised

Answer 13

Non-keratinised

• few layers, nucleus in all cells
• protection against abrasion
• reduces water loss but remains moist
• oral cavity, vagina, inner surface of eye

Keratinised

• few layers, no nucleus on top layers of cells
• protection against abrasion, microbes, UV light damage
• prevents water loss
• our surface of skin!

Question 14

Transitional epithelium

Answer 14

1. Go from columnar to cuboidal

2. Bladder - relaxed ==> distended, ureters, urethra

Question 15

4 layers of epidermis starting from top

Answer 15

1) stratum corneum - horny layer
2) stratum granulosum - granular layer
3) stratum spinosum - prickle layer
4) stratum basal - basal layer

CRYING GIRLS SPRAY BOOGERS

Question 16

Name two other cells of the epidermis and their functions.

Answer 16

1) langerhans - macrophage like dendritic cells in prickle layer that interact with T cells protecting against foreign material
2) melanocytes - dendritic cells that produce melanin, sits superior to nucleus, prevents UV damage

Question 17

Describe the stages of epidermis development?

Answer 17

28-40 days

1) Basal layer - has epidermal stem cells called keratinocytes
2) Prickle Layer - keratinocytes lose ability to divide, Terminal differentiation begin, keratinocytes synthesise keratin for strength.
3) Granular Layer - Keratinocytes lose plasma membrane, differentiate into corneocytes, layer contains keratohyalin granules (keratin, other fibrous proteins and enzymes that degrade bilayer).
4) Horny layer - flattened corneocytes, skin barrier.

Question 18

What is an exocrine gland?

Answer 18

An epithelial cell/collection of cells specialised for secretion

Question 19

How is cystic fibrosis caused?

Answer 19

Autosomal recessive
CFTR - Cystic Fibrosis Transmembrane Regulator - not present in apical membrane
Deletion of 3 nucleotides - loss of AA phenylalanine at position 508

Question 20

What parts of the body does CF affect?

Answer 20

Lungs, pancreas, liver, kidneys, intestine, vas deferens.

Question 21

How can you classify glands?

Answer 21

Destination - exo(ducts), endo(ductless - to blood)
Structure - unicellular/multicellular, acinar/tubular, coiled/branched
Secretion - merocrine (exocytosis), apocrine (membrane bound droplets), Holocrine (membrane rupture)

Question 22

Describe CF

Answer 22

CFTR absent
Chloride ion transport affected - Cl- ions don’t leave, water does not follow to hydrate mucus - viscous mucous
Serious pulmonary infection

Poor reabsorption of Cl- so sweat rich in Cl- and Na+

Pancreas - exocrine part affected - too little water so thickened causing blocked ducts to gut - gut gets insufficient pancreatic digestive enzyme

Vas deferens often absent

Question 23

Describe the function of the pancreas

Answer 23

Exocrine and endocrine

Exocrine

• pancreatic acini
• synthesis, stores, secretes digestive enzymes

Endocrine

• islets of langerhans
• hormones insulin and glucagon
• insulin released when blood sugar too high
• glucagon released when blood sugar too low

Question 24

Describe function of sweat gland, sebaceous glands

Answer 24

Sweat - merocrine (exocytosis) glands in dermis of skin

Sebaceous - holocrine (membrane rupture) filling hair follicles with sebum