General information and the epidermis for chapter 5

The other functions of the skin

• Production of melanin

• production of keratin

• Synthesis of vitamin D3

• Storage of lipids

the two parts of this system

• Cutaneous mebrane

• Accesory structures

The two layers of the cutaneous membrane

Outer epidermis and inner dermis

What does the outher epidermis have

stratified keratinized squamos epithelial tissues and melanocytes

What does the dermis have

A thicker layer of connective tissues

What do the accessory structures have

• Hair

• Nails

• Multicelular exocrine glands

The structure of the dermis:

• Collagen

• Elastin

• Nerves

• Capillaries

Structure of the epidermal appendages or the accesory structures

• Hair follicles

• sweat glands

• sebaceus glands

Function of sebaceus glands:

• Produce sebum

• Maintains hair and skin conditions and PH

• antimicrobial

Structure of the hypodermis or subcutaneous tissue

• Fat

• connective tissues

Location of thin skin

Every part of the body except palms, palmar digits, soles

Location of thick skin

Palms, palmar digits, soles

What layer does thin skin lack in contrast to thick skin?

stratum lucidum

Epidermal ridges in thin skin

lacking since there is fewer dermal papillae

epidermal ridges in thick skin?

present since there is numerous dermal paillae

what is present in thin skin but absent in thick skin?

• Hair follecules

• Arrector pilli muscle

• sebacous glands

Which type of skin has more sudoriferous glands?

Thick skin

which skin has sparser density receptors?

thin skin

which skin has denser density receptors?

thick skin

Is the epidermis avascular?

Yes

How does the epidermis gain nutrients?

Through diffusion from the connective tissue of the dermis

The cells of the epidermis:

• Keratinocytes

• Melanocytes

• Merkel Cells

• Dendritic cells

Most common cell in the epidermis

Keratinocytes

Function of a keratinocyte

• They produce and acumulate keratin in thier cytoplasm

• this makes the epidermis waterproof and resistant to mechanical stress

• Protects the epidermis from everything

What joins the keratinocytes together

desmosomes

In what layers/strata are the keratinocytes found in?

All of them

Where are the melanocytes located in the epidermal?

Stratum basale

What do the Merkel cells have?

sensory receptors that are associated with neurons in the dermis

Functions of Merkel cells

Can detect stimulus

What layer is the Merkel cell located in?

Stratum basale

Another name for dendritic cells

Langerhans cells

Functions of dendritic cells

• Arises to the bone marrow and migrates to skin

• phagocytes of the immune system

• protects skin from pathogens

The layers of skin from deepest to most superficial

basale, spinosum, granulosum , lucidum , corneum

What happens in the stratum basale?

Cells frequently divide by mitosis and some become cells of a higher strata

What does the corneum have?

A bunch of dead cells