Unit 4.1 - Integumentary System

Epidermis

Made of epithelial tissue.

Consists of multiple cell layers.

Contains no blood vessels.

Keratinocytes

Majority of the epidermal cells.

Produces keratin and lamellar granules that release lipid rich secretion that serve as a water repellent sealant to prevent entry of foreign materials.

Melanocytes

Found in the basal section of the epidermis.

Produces melanin that absorb harmful UV radiation and DNA damage.

Intraepidermal Macophages

Function as immune cells in the epidermis.

Tactile Epithelial Cells

Detects touch sensations on the epidermis.

Dermis

Thicker than epidermis which connective tissues containing collagen and elastic fibres.

Hypodermis (Subcutaneous Layer)

Loose connective tissue with collagen and elastin fibres.

Not part of the skin.

Papillary Region

Just beneath the epidermis.

Contains free nerve endings that give rise to sensations of temperature, pain, tickling, and itching.

Reticular Region

Located between the papillary region and subcutaneous layer.

Contains blood vessels, nerves, hair follicles, and glands.

Sweat (Sudoriferous) Gland

Secretes a dilute salt fluid to cool the body.

Sebaceous Gland

Secretes a lipid mixture (sebum) to keep skin moist.

Apocrine Gland

Secretes in response to fear or excitement (body odour)

Ceruminous Glands

Modified sweat glands in the external ear.