Skin

Question 1

Largest organ of the body?

Answer 1

Skin

Question 2

Function of skin:

Answer 2

• regulates body temp
• stores blood
• synthesises vitamin D
• excretes and absorbs substances
• protection

Question 3

What is the difference between thick and thin skin?

Answer 3

Thick skin - hairless
Thicker epidermis and no hair follicles

Thin skin - hairy

Question 4

Layers of keratinised epidermis from the top layer: (5)

Answer 4

1- stratum basale

2 - stratum spinosum

3 - stratum granulosum

4 - stratum lucidum

5 - stratum corneum

Question 5

Describe the first layer of epidermis

Stratum basale

Answer 5

contains the basal keratinocytes that form the basal lamina and attach to the dermis.

These keratinocytes proliferate and regenerate the epidermis.

Question 6

Describe the second layer of epidermis

Stratum spinous

Answer 6

contains the super basal keratinocytes that differentiate and start to produce different types of keratin molecules

Presence of desmosomes

Question 7

Describe the third layer of epidermis

Stratum granulosum

Answer 7

Keratinocytes start losing their nuclei and the cytoplasm appears granular.

Lipids are released from the cells

Question 8

Describe the fourth layer of epidermis

Stratum Lucidum

Answer 8

Clear or translucent layer only found in palms and soles

Question 9

Describe the final layer of epidermis

Stratum corneum

Answer 9

10-30 flattened cells without a nucleus or other organelles.

Cells surrounded by keratin, lipids and other cross linked proteins forming a barrier named the cornfield envelop.e

Constant regeneration as dead cells are exfoliated- 4 weeks.

Question 10

3 major types of glands:

Answer 10

Holocrine gland

Merocrine gland

Apocrine gland

Question 11

What does holocrine gland do?

Example

Answer 11

released by the rupture of the plasma membranes.

Destroys the cells and results on the secretion of the product and cell remnants into the lumen. e.g. sebaceous glands.

Question 12

What does merocrine gland do?

Example

Answer 12

released by exocytosis (fusion of secretory vesicles with cell membrane and release of product to outside of the cell)

Thus, the gland is not damaged - ‘eccrine’ term specifically used for sweat glands.

Question 13

What does apocrine gland do?

Example

Answer 13

Secretions are released by budding of the apical portion of cells including the secreted product.

No damage but cytoplasm and cell membrane material is lost as part of this process e.g. mammary glands.