Integument
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In biology, The Integumentary System is an organ system that protects the body from damage, comprising the skin, hair, scales, nails, sweat glands and their products (sweat and mucus). The integumentary system has a variety of functions; in animals, it may serve to waterproof, cushion and protect the deeper tissues, excrete wastes, regulate temperature and is the location of sensory receptors for pain, pressure and temperature. The name derives from the Latin integumentum, which means 'a covering'.

The integumentary system is the largest organ system. 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 gases simply diffuse into and out of the interstitial fluid, is called integumentary exchange.

Layers

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 gives the protein keratin which stiffens epidermal tissue to form finger nails. The outermost layer consists of 25-30 layers of dead cells.

Dermis (Cutis)

The dermis is the bottom-most, thick inner layer of skin, which comprises blood vessels, connective tissue, nerves, lymph vessels, sweat glands and hair shafts. It has two main layers:

1. The upper layer for touch, pain and heat, which communicate with the central nervous system and is responsible for the folds of the fingerprints.
2. The lower layer made of dense elastic fibers that house the hair follicles, nerves, gland, and gives the skin most of its stretchiness and strength.

=Subdermis (Hypodermis)

The subcutaneous tissue or subcutis is the layer of tissue directly underlying the cutis. It is mainly composed of adipose tissue. Its physiological function includes insulation and storage of nutrients. It also cushions the body for extra protection.

Functions

The integumentary system has multiple roles in homeostasis. 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. Functions include:

• 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

Diseases and injuries

Possible diseases and injuries to the human integumentary system include:

• Rash
• Blister
• Athlete's foot
• Infection
• Sunburn
• Skin Cancer

Australian Institute of Health and Welfare National Perinatal Statistics Unit, UNSW published congenital malformation rate 1981-92 / 10,000, shows that only a 0.5% of birth defects are in the integumentary system.

See also

• Exoskeleton and shell
• Major systems of the human body

In botany

In botany, the integument refers to the envelope of an ovule. It is made up of maternal tissue that will eventually develop into the seed coat.

References

• Kardong, Kenneth V. (1998). Vertebrates: Comparative Anatomy, Function, Evolution, second edition, USA: McGraw-Hill, 747 pp.. ISBN 0-07-115356-X/0-697-28654-1. 

External links

• Aquatic Path Details of the integumentary system of the fathead minnow
• biology4kids