sistem integument

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SISTEM INTEGUMENT

"Integumentary " redirects here; in botany, an integument refers to an outer membrane of an ovule,

which later develops into the testa, the seed coat

Integumentary system

The integumentary system is the organ system that protects the body from damage, comprising 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, wheregases 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


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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. The Papillary layer which is the superficial layer and consists of the areolar

connective tissue and 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 stretchingand 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


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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 bodys first line of defense against

infection, temperature change, and other challenges to homeostasis. Functions include:

Protect the bodys internal living tissues and organsProtect 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

Cold SoresMosquito bites

Impetigo

Rubella

STD

Cancer

Psoriasis

References

^ Integumentary+System at the US National Library of Medicine Medical Subject Headings (MeSH)

^ Marieb, Elaine; Katja Hoehn (2007). Human Anatomy & Physiology (7th ed.). Pearson BenjaminCummings. p. 142.

^ 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.

sistem integument

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