Integumentary system

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In zootomy, the integumentary system is the external covering of the body, comprised of the skin, hair, feathers, scales, nails, sweat glands and their products (sweat and mucus).

The name derives from the Latin integumentum, which means 'a covering'.

1 As an organ system
2 In botany
3 Anatomy
4 Layers
- 4.1 Epidermis
  - 4.1.1 Sublayers
5 Functions
6 Diseases and injuries
7 See also
8 Sources

[edit] As an organ system

The integumentary system is often the largest organ system of an animal by surface area. It distinguishes, separates, protects and informs the animal with regard to its surroundings. Small-bodied invertebrates of aquatic or continually moist habitats respire using the outer layer (integument). This gas exchange system, where gasses simply diffuse into and out of the interstitial fluid, is called integumentary exchange.

[edit] In botany

In botany, the integument refers to the envelope of an ovule.

[edit] Anatomy

The cutaneous membrane (skin) and its accessory structures (hair, scales, feathers, nails, exocrine glands) make up the integumentary system.

There are three layers of skin:

Below the dermis, the subcutis acts to protect underlying muscles, tissues, and other organs. Hair on the surface of the skin helps maintain body temperature and filter out harmful particles.

Cutaneous glands include:

Sweat glands (also known as sudoriferous glands) - excrete sweat to regulate temperature
Sebaceous glands - oil-producing glands that keep skin and hair moist and soft
Ceruminous glands - glands of the ear canal that produce earwax
Mammary glands - milk-producing glands located in the breasts.

[edit] Layers

[edit] Epidermis

The epidermis is the thin outer layer of skin that contains melanin which gives skin its color and allows for the skin to tan. The epidermis also encompasses the protein keratin which stiffens epidermal tissue to form finger nails. The outermost layer consists of 25-30 layers of dead cells. Further levels include:

Scaly Cells form the surface of the skin
Melanocytes give the skin color
Langerhans cells are formed in the bone marrow and work to fight infection

It is divided into the following sub-layers:

[edit] Sublayers

Epidermis is divided into the following 5 sublayers or strata:

Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum germinativum (also called "stratum basale")

Dermis: (Thick inner layer of skin) This consists of blood vessels, connective tissue, nerves (provides senses such as touch and heat), lymph vessels, sweat glands, receptors, and hair shafts. It has two main layers: a. Upper Papillary: Causes finger prints, it contains receptors which communicate with the Central Nervous System (touch, pressure, hot, cold, and pain receptors) b. Lower Reticular: Made of dense elastic fibers that house the hair follicles, nerves, and glands

[edit] Functions

The integumentary system has multiple roles in homeostasis, including protection, temperature regulation, sensory reception, biochemical synthesis, and absorption. All body systems work in an interconnected manner to maintain the internal conditions essential to the function of the body. The skin has an important job of protecting the body and acts somewhat as the body’s first line of defense against infection, temperature change or other challenges to homeostasis.

The intergumentary system has numerous functions:

Protects the body’s internal living tissues and organs
Protects against invasion by infectious organisms
Protects the body from dehydration
Protects the body against abrupt changes in temperature
Helps excrete waste materials through perspiration
Acts as a receptor for touch, pressure, pain, heat, and cold (see Somatosensory system)
Protects the body against sunburns
Generates vitamin D through exposure to ultraviolet light
Stores water, fat, and vitamin D