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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.
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Layers
Epidermis This is the top layer of the skin made up of epithelial cells. Its main job is protection. Structurally it consists of a keratinized stratified squamous epithelium which is comprised of four types of cells: keratinocytes, melanocytes, Merkel cells, and Langerhans' cells. The majority of the epidermis is the keratinocyte which produces keratin. Keratin is a fibrous protein that aid in protection. Millions of dead keratinocytes rub off everyday. A totally new epidermis is present every 25 to 45 days. Melanocytes create melanin, the substance that gives our skin color. These cells are found deep in the epidermis layer. Accumulations of melanin are packaged in melanosomes (membrane-bound granules). These granules form a pigment shield against UV radiation for the keratinocyte nuclei.
Dermis (Cutis)
The dermis is the mid layer of skin, thick inner layer of skin, which comprises blood vessels, connective tissue, nerves, lymph vessels, sweat glands and hair shafts. It has two main layers:
- The upper layer for touch, pain and heat, which communicate with the central nervous system and is responsible for the folds of the fingerprints.
- 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:
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
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
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Wikipedia content modification information:
- This page was last modified on 10 October 2008, at 18:09.
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