Integumentary system: Difference between revisions
No edit summary |
No edit summary |
||
| Line 18: | Line 18: | ||
Code = [[Terminologia Histologica|TH]] H3.12.00.0.00001 | |
Code = [[Terminologia Histologica|TH]] H3.12.00.0.00001 | |
||
}} |
}} |
||
The ''' |
The '''SCRUB''' is the [[organ system]] that protects the body from various kinds of damage, such as loss of water or abrasion from outside. The system comprises the [[skin]] and its appendages<ref>{{MeshName|Integumentary+System}}</ref><ref>{{cite book |
||
| last=Marieb | first=Elaine | coauthors=Katja Hoehn |
| last=Marieb | first=Elaine | coauthors=Katja Hoehn |
||
| title=Human Anatomy & Physiology |
| title=Human Anatomy & Physiology |
||
Revision as of 15:02, 26 February 2013
| Integumentary system | |
|---|---|
| Identifiers | |
| MeSH | D034582 |
| TA98 | A16.0.00.001 |
| TA2 | 7040 |
| TH | H3.12.00.0.00001 |
| FMA | 72979 |
| Anatomical terminology | |
The SCRUB is the organ system that protects the body from various kinds of damage, such as loss of water or abrasion from outside. The system comprises the skin and its appendages[1][2] (including hair, scales, feathers, hoofs, and nails). The integumentary system has a variety of functions; it may serve to waterproof, cushion, and protect the deeper tissues, excrete wastes, and regulate temperature, and is the attachment site for sensory receptors to detect pain, sensation, pressure, and temperature. In most terrestrial vertebrates with significant exposure to sunlight, the integumentary system also provides for vitamin D synthesis.
Layers of the skin
The integumentary system is the largest of the body's organ systems. In humans, this system accounts for about 12 to 15 percent of total body weight and covers 1.5-2m2 of surface area.[3] It distinguishes, separates, and protects the organism from 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.
The human skin (integument) is composed of a minimum of 3 major layers of tissue: the epidermis; dermis; and hypodermis. The epidermis forms the outermost layer, providing the initial barrier to the external environment. Beneath this, the dermis comprises two sections, the papillary and reticular layers, and contains connective tissues, vessels, glands, follicles, hair roots, sensory nerve endings, and muscular tissue.[4] The deepest layer is the hypodermis, which is primarily made up of adipose tissue. Substantial collagen bundles anchor the dermis to the hypodermis in a way that permits most areas of the skin to move freely over the deeper tissue layers.[5]
Epidermis
This is the top layer of skin made up of epithelial cells. It does not contain blood vessels. Its main function is protection, absorption of nutrients, and homeostasis. In structure, it consists of a keratinized stratified squamous epithelium comprising four types of cells: keratinocytes, melanocytes, Merkel cells, and Langerhans' cells. The major cell of the epidermis is the keratinocyte, which produces keratin. Keratin is a fibrous protein that aids in protection. Keratin is also a water-proofing protein. Millions of dead keratinocytes rub off daily. The majority of the skin on the body is keratinized, meaning waterproofed. The only skin on the body that is non-keratinized is the lining of skin on the inside of the mouth. Non-keratinized cells allow water to "stay" atop the structure.
The protein keratin stiffens epidermal tissue to form fingernails. Nails grow from thin area called the nail matrix; growth of nails is 1 mm per week on average. The lunula is the crescent-shape area at the base of the nail, this is a lighter color as it mixes with the matrix cells.
Dermis
The dermis is the middle layer of skin, composed of dense irregular connective tissue and areolar connective tissue such as collagen with elastin arranged in a diffusely bundled and woven pattern. The dermis has two layers. One is the papillary layer which is the superficial layer and consists of the areolar connective tissue. The other is the reticular layer which is the deep layer of the dermis and consists of the dense irregular connective tissue. These layers serve to give elasticity to the integument, allowing stretching and conferring flexibility, while also resisting distortions, wrinkling, and sagging.[4] The dermal layer provides a site for the endings of blood vessels and nerves. Many chromatophores are also stored in this layer, as are the bases of integumental structures such as hair, feathers, and glands.
Hypodermis
Also called the hypoderm, subcutaneous tissue, or superficial fascia and the bottom layer of the integumentary system in vertebrates (hypoderm and subcutaneous are from Greek and Latin words, respectively, for "beneath the skin"). Types of cells that are found in the hypodermis are fibroblasts, adipose cells, and macrophages. It is derived from the mesoderm, but unlike the dermis, it is not derived from the dermatome region of the mesoderm. In arthropods, the hypodermis is an epidermal layer of cells that secretes the chitinous cuticle.
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 as the body’s first line of defense against infection, temperature change, and other challenges to homeostasis. Functions include:
- Protect the body’s internal living tissues and organs
- Protect against invasion by infectious organisms
- Protect the body from dehydration
- Protect the body against abrupt changes in temperature, maintain homeostasis
- Help excrete waste materials through perspiration
- Act as a receptor for touch, pressure, pain, heat, and cold (see Somatosensory system)
- Protect the body against sunburns by secreting melanin
- Generate vitamin D through exposure to ultraviolet light
- Store water, fat, glucose, and vitamin D
- Maintenance of the body form
- Formation of new cells from stratum germinativum to repair minor injuries
Diseases and injuries
Possible diseases and injuries to the human integumentary system include:
- Rash
- Blister
- Athlete's foot
- Infection
- Sunburn
- Skin cancer
- Albinism
- Acne
- Herpes
- Herpes labialis, commonly called a cold sore
- Mosquito bites
- Impetigo
- Rubella
- STD
- Cancer
- Psoriasis
References
- ^ Integumentary+System at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- ^ Marieb, Elaine (2007). Human Anatomy & Physiology (7th ed.). Pearson Benjamin Cummings. p. 142.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Martini & Nath: "Fundamentals of Anatomy & Physiology" 8th Edition, pp.158,Pearson Education, 2009
- ^ a b The Ageing Skin - Structure of Skin
- ^ Pratt, Rebecca. "Integument". AnatomyOne. Amirsys, Inc. Retrieved 2012-09-28.
The integumentary system consists of the largest organ in the body, the skin. This extraordinary organ system protects the internal structures of the body from damage, prevents dehydration, stores fat and produces vitamins and hormones. It also helps to maintain homeostasis within the body by assisting in the regulation of body temperature and water balance. The integumentary system is the body's first line of defense against bacteria, viruses and other microbes. It also helps to provide protection from harmful ultraviolet radiation. The skin is a sensory organ in that it has receptors for detecting heat and cold, touch, pressure and pain. Components of the skin include hair, nails, sweat glands, oil glands, blood vessels, lymph vessels, nerves and muscles. Concerning integumentary system anatomy, the skin is composed of a layer of epithelial tissue (epidermis) that is supported by a layer of connective tissue (dermis) and an underlying subcutaneous layer (hypodermis or subcutis).