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

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 and its appendages(including hair
Hair

Hair is a protein filament that epidermal growth from hair follicle deep within the dermis. The fine, soft hair found on many nonhuman mammals is typically called fur; wool is the characteristically curly hair found on sheep and goats....
, scales
Scale (zoology)

In most biology nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration....
, and nails
Nail (anatomy)

A nail is a horn -like structure at the end of an animal's finger or toe. See also claw....
). The integumentary system has a variety of functions; it may serve to waterproof, cushion and protect the deeper tissues, excrete wastes, regulate temperature and is the location of receptors for pain, sensation, pressure and temperature. In humans the integumentary system additionally provides vitamin D synthesis.

The integumentary system is the largest organ system
Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
.






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

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 and its appendages(including hair
Hair

Hair is a protein filament that epidermal growth from hair follicle deep within the dermis. The fine, soft hair found on many nonhuman mammals is typically called fur; wool is the characteristically curly hair found on sheep and goats....
, scales
Scale (zoology)

In most biology nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration....
, and nails
Nail (anatomy)

A nail is a horn -like structure at the end of an animal's finger or toe. See also claw....
). The integumentary system has a variety of functions; it may serve to waterproof, cushion and protect the deeper tissues, excrete wastes, regulate temperature and is the location of receptors for pain, sensation, pressure and temperature. In humans the integumentary system additionally provides vitamin D synthesis.

The integumentary system is the largest organ system
Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
. It distinguishes, separates, protects and informs the animal with regard to its surroundings. Small-bodied invertebrates of aquatic or continually moist habitats respire
Respiration (physiology)

In animal physiology, respiration is the transport of Oxygen from the outside air to the cells within Tissue s and the transport of carbon dioxide in the opposite direction....
 using the outer layer (integument). This gas exchange system, where gases simply diffuse into and out of the interstitial fluid
Interstitial fluid

Interstitial fluid is a solution which bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes Blood plasma and transcellular fluid....
, is called integumentary exchange.

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 comprising 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.

The Epidermis itself is made up of four to five layers. The stratum basale is the only layer capable of cell division 'pushing up' cells to replenish the outer layer which is constantly shedding dead cells. The Epidermis does not contain blood vessels (non vascular). It contains the pigment melanin
Melanin

Melanin is a class of compounds found in the plant, animal, and protista kingdom , where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine....
 which gives skin colour and allows the skin to tan, uneven distribution of melanin causes freckles. From the dermis to the epidermis the layers are named, stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (the extra layer that occurs in places such as palms and soles of the feet), and the stratum corneum (the most superficial layer, made up of all dead cells, proteins, and glycolipids which keep the body waterproof)

The protein keratin
Keratin

Keratins are a family of fibrous protein; tough and insoluble, they form the hard but mineral structures found in reptiles, birds, amphibians and mammals....
 stiffens epidermal tissue to form fingernails. Nails grows from thin area called the nail matrix
Matrix (nail)

The formative layer of cells at the base of the fingernail or toenail. Also called the keratogenous membrane, matrix unguis....
, growth of nails is 1 mm per week on average. The lunula
Lunula

The word lunula means moon-like and commonly refers to:* Lunula * The openings in the test of sand dollars* Two round brackets and the text between them...
 is the crescent shaped area at the base of the nail, this is a lighter colour as it mixes with the matrix cells.

The epidermis contains different types of cells, the most common are: squamous cells which are flat, scaly cells on the surface of the skin, basal cells which are round cells, and melanocyte
Melanocyte

Melanocytes are cell located in the bottom layer of the skin's epidermis , the middle layer of the eye , the inner ear, meninges, bones and heart....
s which give the skin its colour. The epidermis also contains Langerhan's cells
Langerhans cell

Langerhans cells are dendritic cells in the Epidermis , containing large granules called Birbeck granules. They are normally present in lymph nodes and other organs, including the stratum spinosum layer of the epidermis....
, which are formed in the bone marrow and then migrate to the epidermis. They work in conjunction with other cells to fight foreign bodies as part of the body's immune defence system. Granstein cells play a similar role.

Dermis (Cutis)

The dermis is the mid layer of skin, thick inner layer of skin, which comprises blood vessel
Blood vessel

The blood vessels are the part of the circulatory system that transport blood throughout the body. There are three major types of blood vessels: the artery, which carry the blood away from the heart, the capillary, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from...
s, connective tissue
Connective tissue

Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
, nerve
Nerve

A nerve is an enclosed, cable-like bundle of Peripheral nervous system axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons....
s, lymph vessel
Lymph vessel

In anatomy, lymph vessels are thin walled, valved structures that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the vascular system....
s, sweat gland
Sweat gland

The skin contains two different groups of sweat glands: apocrine sweat glands and merocrine sweat glands. Both gland types contain myoepithelial cells , specialized epithelial cells located between the gland cells and the underlying basal lamina....
s and hair shafts. It has two main layers:
  1. Composed of two layers- papillary and reticular
  2. The upper layer for touch, pain
    Nociceptor

    A nociceptor is a sensory receptor that reacts to potentially damaging stimuli by sending nerve signals to the spinal cord and brain. This process, called nociception, usually causes the perception of pain....
     and heat, which communicate with the central nervous system and is responsible for the folds (called dermal papillae) of the fingerprint
    Fingerprint

    A fingerprint is an impression of the friction ridges of all part of the finger. A friction ridge is a raised portion of the epidermis on the palmar or digits or plantar skin, consisting of one or more connected ridge units of friction ridge skin....
    s. The light touch sensors which are in the papillary section of the dermis are called Meissner's corpuscles.
  3. The lower layer made of dense elastic fibers that house the hair follicle
    Hair follicle

    A hair follicle is part of the skin that grows hair by packing old Cell s together. Attached to the follicle is a sebaceous gland, a tiny sebum-producing gland found everywhere except on the hands, lips and soles of the feet....
    s, nerves, gland
    Gland

    A gland is an Organ in an animal's body that synthesizes a substance for release such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface ....
    , and gives the skin most of its stretchiness and strength. In this layer there are also touch receptors, these however are for sensing pressure, these sensors are called Pacinian Corpuscles


Subdermis (Hypodermis/Superficial Fascia)

The subdermis is the layer of tissue directly underneath the dermis. It is mainly composed of areolar connective tissue and adipose tissue
Adipose tissue

In histology, adipose tissue or fat is loose connective tissue composed of adipocytes. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and Thermal insulation the body....
. Its physiological functions include insulation, the storage of energy and aiding in the anchoring of the skin. It also cushions the underlying body for extra protection against trauma.

Functions

The integumentary system has multiple roles in homeostasis
Homeostasis

Homeostasis is the property of a system, either open system or closed system, that regulates its internal environment and tends to maintain a stable, constant condition....
. 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
    Infection

    An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host resources to multiply ....
     organisms
  • Protects the body from dehydration
    Dehydration

    Dehydration is the removal of water from an object. In Physiology terms, it entails a relative deficiency of water molecules in relation to other dissolved solutes....
  • Protects the body against abrupt changes
    Weather

    Weather is a set of all the Phenomenon occurring in a given atmosphere at a given time. Weather phenomena lie in the hydrosphere and troposphere....
     in temperature
    Temperature

    In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
  • Helps excrete
    Excretion

    Excretion is the process of eliminating waste products of metabolism and other non-useful materials. It is an essential process in all forms of life....
     waste materials through perspiration
  • Acts as a receptor for touch, pressure, pain, heat, and cold (see Somatosensory system
    Somatosensory system

    The somatosensory system is a diverse sensory system comprising the receptors and processing centres to produce the sensory modality such as touch, temperature perception, proprioception , and nociception ....
    )
  • Protects the body against sunburn
    SunBurn

    SunBurn is a regional event held in Florida. Although SunBurn has its roots in the annual Burning Man festival in Nevada, it is not an official Burning Man event, because the organizers of SunBurn do not condone the direction that the Burning Man Organization has taken over the years....
    s
  • Generates vitamin D
    Vitamin D

    Vitamin D is a group of fat-soluble prohormones, the two major forms of which are vitamin D2 and vitamin D3 . The term vitamin D also refers to metabolites and other analogues of these substances....
     through exposure to ultraviolet
    Ultraviolet

    Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 400 nanometer to 10 nm, and energies from 3 Electron volt to 124 eV....
     light
    Light

    Light, or visible light, is electromagnetic radiation of a wavelength that is Visible spectrum to the human eye , or up to 380?750 nm. In the broader field of physics, light is sometimes used to refer to electromagnetic radiation of all wavelengths, whether visible or not....
  • Stores water
    Water

    Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
    , fat
    Fat

    Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemistry, fats are generally ester of glycerol and fatty acids....
    , and vitamin D
    Vitamin D

    Vitamin D is a group of fat-soluble prohormones, the two major forms of which are vitamin D2 and vitamin D3 . The term vitamin D also refers to metabolites and other analogues of these substances....


Diseases and injuries

Possible diseases and injuries to the human integumentary system include:
  • Rash
    Rash

    A rash is a change of the skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin....
  • Blister
    Blister

    A blister is a small pocket of fluid within the upper layers of the skin, typically caused by forceful rubbing , burning, freezing, chemical exposure or infection....
  • Athlete's foot
    Athlete's foot

    Athlete's foot is a fungal infection of the skin that causes scaling, flaking, and itching of affected areas. It is typically transmitted in moist areas where people walk barefoot, such as showers or bathhouses....
  • Infection
    Infection

    An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host resources to multiply ....
  • Sunburn
    SunBurn

    SunBurn is a regional event held in Florida. Although SunBurn has its roots in the annual Burning Man festival in Nevada, it is not an official Burning Man event, because the organizers of SunBurn do not condone the direction that the Burning Man Organization has taken over the years....
  • Skin cancer
    Skin cancer

    Skin cancer is a malignant growth on the skin which can have many causes. The most common skin cancers are basal cell cancer, squamous cell cancer, and melanoma....
  • Albinism
    Albinism

    Albinism is a form of hypopigmentation congenital disorder, characterized by a partial or total lack of melanin Biological pigment in the eyes, skin and hair ....
  • Acne
    Acne vulgaris

    Acne vulgaris is a skin condition caused by changes in the pilosebaceous units . Severe acne is inflammation, but acne can also manifest in noninflammatory forms....


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