BIOL 10: Skin

Question 1

What are the major layers of the skin?

Answer 1

Going from most outer to least.

1) epidermis
2) dermis
3) hypodermis

Question 2

What are the epidermal strata (5)?

Answer 2

Going from deepest to most outer:

1) stratum basale: contains melanocytes and keratinocytes (where keratinocytes proliferate); separated from the dermis through the basement membrane
2) stratum spinosum: squamous cell layer where Langerhans cells reside and keratinocytes connect
3) stratum granulosum: where keratinocytes die
4) stratum lucidum: only found in thick hairless skin (palms and soles), clear layer
5) stratum corneum: contains several layers of flattened keratinocytes (forming a “horny” boundary between outside environment and body)

Question 3

Basal lamina

Answer 3

The basement membrane of the dermis, connected to the stratum basale (epidermis) through hemidesmosomes

Question 4

Keratinocytes

Answer 4

The most predominant cells of the skin and produce keratin

Question 5

Melanocytes

Answer 5

Produce melanin, contained in the stratum basale of the epidermis

Question 6

Where are melanocytes derived from?

Answer 6

Neural crest cells

Question 7

Langerhans cells

Answer 7

Special macrophages that are capable of presenting antigens to T-cells to activate the immune system; they are contained in the stratum spinosum

Question 8

What are the layers of the dermis?

Answer 8

The papillary layer and the reticular layer

Question 9

Papillary layer of the dermis

Answer 9

Consists of loose connective tissue

Question 10

Reticular layer of the dermis

Answer 10

Lies below the papillary layer of the dermis and is more dense

Question 11

Where do sweat glands, sensory receptors, hair follicles, and blood vessels reside in the skin?

Answer 11

In the dermis

Question 12

List and describe the different tactile sensory receptors (5).

Answer 12

• Merkel cells: within the epidermal-dermal junction; sense deep pressure and texture
• Meissner’s corpuscles: sense light pressure
• Pacinian corpuscles: sense deep pressure and vibration
• Ruffini endings: sense stretching
• free nerve endings: sense pain through nociceptors

Question 13

What are some integumentary mechanisms involved in thermoregulation?

Answer 13

Sweating, piloerection, vasodilation, vasoconstriction, insulation

Question 14

Arrector pili muscles

Answer 14

Muscles that erect hairs on the skin

Question 15

How is brown fat beneficial in thermoregulation?

Answer 15

Brown fat has less efficient electron-transport chain during cellular respiration and releases more energy as heat during ATP production as a result.