Integumentary system facts for kids
Quick facts for kids Integumentary system |
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| Cross-section of all skin layers |
The integumentary system is the set of organs forming the outside of an animal's body.
The integumentary system includes skin, hair, scales, feathers, hooves, and nails. The name comes from the Latin integumentum, which means 'a covering'.
The integumentary system acts as a physical barrier and serves to protect and maintain the body of the animal.
Structure
Skin
The skin is one of the largest organs of the body. In humans, it accounts for about 12 to 15 percent of total body weight and covers 1.5 to 2 m2 of surface area.
The skin (integument) is a composite organ. It is made up of at least two major layers of tissue: the epidermis and the dermis.
Epidermis
The epidermis is the outermost layer. It is very strong. It serves as the first line of protection against the outer environment.
The epidermis is separated from the dermis by the basement membrane (basal lamina and reticular lamina). The epidermis contains melanocytes and gives color to the skin. The deepest layer of the epidermis also contains nerve endings.
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.
Between the integument and the deep body musculature there is the hypodermis. Substantial collagen bundles anchor the dermis to the hypodermis. That permits most areas of the skin to move freely over the deeper tissue layers.
The epidermis cells contain keratin.
Dermis
The dermis is the second layer that supports the epidermis. It is composed of tissues such as collagen with elastin arranged in a diffusely bundled and woven pattern.
The dermis has two layers: the papillary dermis and the reticular layer. These layers serve to give elasticity to the integument. They allow stretching and, while also resisting distortions, wrinkling, and sagging. Blood vessels and nerves end in the dermal layer. Many chromatophores are also stored in this layer, as are the bases of integumental structures such as hair, feathers, and glands.
Hypodermis
The hypodermis (the subcutaneous layer) is a layer beneath the skin. It is immediately above the dermis and is attached to it by collagen and elastin fibers. It is composed of adipocytes - cells which accumulate and store fats.
The hypodermis acts as an energy reserve. The fats contained in the adipocytes can be put back into circulation or transformed into energy. The hypodermis participates in thermoregulation since fat is a heat insulator.
Functions
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 the body's equilibrium.
Its main 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, vitamin D
- Maintenance of the body form
- Formation of new cells from stratum germinativum to repair minor injuries
- Protect from UV rays.
- Regulates body temperature
- It distinguishes, separates, and protects the organism from its surroundings.
It also has sensory receptors which detect pain, sensation, pressure, and temperature.
Clinical significance
Possible diseases and injuries to the human integumentary system include:
See also
In Spanish: Sistema tegumentario para niños
