The Integumentary System

1. List the various functions of the integumentary system

Protection, thermoregulation, sensation, excretion, defense, water retention, blood reservoir, absorption, social/nonverbal communication

a.     Superficial epidermis

The outermost layer. Has no blood vessels. Made of layered cells that produce keratin, die, and shed. Main job is protection.

b.     Underlying dermis

The layer beneath the epidermis. Contains blood vessels, nerves, hair follicles, and glands. Provides strength, sensation, and temperature regulation.

3. Describe the hypodermis structure and function (superficial fascia or subcutaneous layer)

The hypodermis is a layer of loose connective tissue and fat beneath the dermis that stores energy, insulates, cushions, and anchors the skin to underlying muscle and bone.

a.     What tissue types is it made up of?
b.     Is it part of the skin?

It is made up of loose connective tissue and adipose tissue (fat). No.

Keratinocytes

The most abundant cell in the epidermis. They produce keratin

Melanocytes

Cells that produce melanin, the pigment responsible for skin, hair, and eye color

 Dendritic (Langerhans) cells

Immune cells that patrol the epidermis and detect foreign invaders

Tactile discs (Merkel cells)

Sensory cells found in the deepest layer of the epidermis. Light pressure and temperature

 

Tactile corpuscle

Light pressure and temperature

Lamellar corpuscles

Deep pressure

Identify the 4-5 distinct layers of the epidermis and name their characteristic features (note that the stratum lucidum is found only in thick skin and that the tissue type of the epidermis is keratinized stratified squamous epithelium)

a.     Stratum basale

b.     Stratum spinosumm

c.     Stratum granulosum

d.     Stratum lucidum

e.     Stratum corneum

Papillary layer:

has dermal papillae, Meissner’s corpuscles, etc.

Reticular layer

has sweat and sebaceous glands, Pacinian corpuscles, hair follicle, etc.

a.     Sebaceous sweat gland and duct

Location: Found in the dermis, attached to hair follicles 

Mode of secretion: Holocrine 

Function: Produces sebum (oil) to lubricate and waterproof the skin and hair, and inhibits bacterial growth

b.     Eccrine sweat gland and duct

Location: Found in the dermis throughout almost the entire body surface, most abundant on palms, soles, and forehead. Duct opens directly onto the skin surface as a pore

Mode of secretion: Merocrine 

Function: Produces watery sweat to cool the body through evaporation

dermis with hair follicles

papillary layer

eccrine sweat

layers of epidermis and papillary layer of dermis

Hair papilla

skin layers

sebaceous

stratum basale

stratum granulosum