Skin & Sensory Receptors

Question 1

What are the functions of the skin?

Answer 1

• Protection
• Sensation
• Regulation

Question 2

What are the 2-3 main layers of skin called and what are they comprised of?

Answer 2

• Outer Epidermis (epithelial cells)
• Underlying Dermis (connective tissue)
• Superficial fascia/hypodermis/subcutis (deep to dermis, loose connective tissue with varying amount of fat)

Question 3

What type of epithelium is the epidermis made of?

Answer 3

Stratified squamous

Question 4

What are the 5 layers in thick skin? Describe them

Answer 4

From deep to superficial:

1. Stratum Basale= Small portion of Merkel cells & melaninocytes, single row of renewing keratinocytes
2. Stratum Spinosum= Langerhan cells, Keratinocytes w/spiny appearance, filaments in cells resist tension
3. Strarum Granulosum= Keratohyaline granules, lamellated granules, keratinocytes flatterned out
4. Stratum Lucidium= very thin
5. Stratum Corneum= 20-30 cell layers

Question 5

Which layer is very thin/absent in thin skin?

Answer 5

Stratum Lucidum

Question 6

What are the 3 types of non-epithelial cells present in the epidermis?

Answer 6

• Melanocytes= pigment cells
• Langerhans cells= immunological role
• Merkel cells= Act as mechanoreceptors

Question 7

What are warts?

Answer 7

Small, hard, benign growth of the skin caused by a virus

Question 8

Where are arrector pili muscles located? What is their function?

Answer 8

• Attached to base of hair follicle at one end and derma tissue at the other
• Generate/retain heat when the body is cold

Question 9

What is the dermis made up of?

Answer 9

• Connective tissue containing irregular bundles of collagen fibres & networks of elastic fibres
• Contains the blood & nerve supply of the skin

Question 10

What are the 2 layers of the dermis?

Answer 10

• Papillary layer= superficial loosely woven
• Reticular layer= deep, thick, dense

Question 11

What happens to the skin layers in areas prone to friction and shearing forces?

Answer 11

• Thick skin
• Epidermis & dermis interdigitate forming series of epidermal downgrowths= rete ridges
• Also upward projecting dermal papillae
• This arrangement gives rise to fingerprints

Question 12

What is a blister?

Answer 12

Small bubble of the skin filled with serum caused by friction/burning/damage

Question 13

How are burns classified?

Answer 13

• First degree= Superficial, epidermis only
• Second degree= Partial thickness, epidermis & superficial layer of dermis
• Third degree= Full thickness, epidermis & dermis may include subcutaneous tissue, loss of fluid

Question 14

What are cutaneous sensory receptors classified into?

Answer 14

• Free nerve endings/simple receptors/ unencapsulated nerve endings
• Encapsulated nerve endings/ compound receptors

Question 15

Describe free nerve endings

Answer 15

• Branching axons devoid of surrounding schwann cells
• Some function as nociceptors/ thermoreceptors
• Others associated with shaft of hair follicle where they become rapidly adapting mechanoreceptors
• Some Merkel cell-neurite complexes act as mechanoreceptors to pressure

Question 16

Describe encapsulated nerve endings

Answer 16

• Function as mechanoreceptors
• Meissner’s corpuscle= rapidly adapting, in glabrous skin within epidermal papillae, respond to light touch
• Ruffini endings= in cutaneous tissue, slow adapting, respond to stretching & shearing
• Pacinian corpuscle= interosseous membrane, rapidly adapting, respond to vibration & pressure
• Merkel cell-neurite complex= in dermal erpidermal junction, slow adapting, respond to pressure