19) Skin Structure And Function

Question 1

What are the five layers of epidermis? (Including other names for them)
Which one is only present in some areas of skin? (Eg palmar and plantar surfaces, tends to be hairless)

Answer 1

From surface to deeper:
Stratum Corneum (horny or corny cell layer)
Stratum Lucidum (transparent layer) — only found in some areas!
Stratum Granulosum (granular layer)
Stratum Spinosum (spinous/prickle cell layer)
Stratum Basale(basal cell layer)

Question 2

What is psoriasis
What is the mechanism of psoriasis?
How does it present?
What are the treatment options?

Answer 2

Psoriasis is an autoimmune disease, it is the most common inflammatory dermatosis
In psoriasis keratinocytes take only 2-3 days to migrate from basale to corneum (severe psoriasis) instead of 28-40 days normally. (In less severe disease it takes 7-8 days)
It presents with Acanthosis which is where you have dark patches in creases of skin.
Silvery skin.
Systemic treatments- immunosuppressants, antihistamines; topical treatments- topical steroids (hydrocortisone), topical immunosuppressants, emollients (moisturiser)

Question 3

What is another name for the dermis?
What is the name for the epidermis and dermis together?
What are the three parts of the Dermis?
Functions of the Dermis?

Answer 3

Dermis is also called the cerium, and with epidermis they’re called the cutis
Papillary Dermis, (upper layer, loose connective tissue)
Dermal papillae
Reticular Dermis (lower layer, dense irregular connective tissue)
Functions of the dermis are:
Thermoregulation (Hairs, arrector pili muscle, and sweat glands)
Sensing (touch vibration pain etc)
Structure to skin, body shape.

Question 4

What is the hypodermis?
What are the functions of the hypodermis?

Answer 4

Also known as subcutaneous layer or superficial fascia layer. It is the lowest layer of skin, loose connective tissue containing mainly adipose tissue. (Some neurovascular bundles/ lymphatics)
The functions are: Providing an energy store- generate heat
Insulation, underlying muscle thermogenesis.
Shock Absorber -cushions impacts, protecting underlying structures
Connects skin to underlying muscle and bones.
Makes hormones, eg leptin.

Question 5

Mechanoreceptors (7 types)

Answer 5

Root hair plexus - hair moves
Pacinian Corpsule - deeper vibrations
Nocioreceptors or nerve endings - pain
Ruffinis corpuscle - stretch and torque thermoreceptor
Tactile corpsule of meissner - light vibration and touch
Tactile disks of merkel - light touch
krause’s end bulbs - cold temperature