Integumentary System (skin)

Consists of one organ: Skin
Its functions include: Protection, Homeostasis (temperature, water), storage of energy in the form of fat, sensory reception (touch, pain, heat and cold).

The General Anatomy of the Skin

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The General Functions of the Skin
Epidermis: Protects from UV radiation coming in. Stops foreign pathogens (bacteria, viruses, parasites) from entering.Helps make vitamin D.
Dermis: Contains blood flow that allows hair to grow, exocrine glands function inside of the dermis, sensory functions.
Hypodermis (also known as: subcutaneous): Contains energy reserves in the form of fat (adipose tissue).

Skin Color


Albinism is known as being albino. The inherited condition is caused by the melanin pigment not being produced by the melanocytes. The cells are still distributed normally. Peolple with this condition have light colored skin and hair. Their eyes are usually red. They hve different levels of melanin production.

Colors of the epidermis is caused by the interaction between pigment composition and concentration and the dermal blood supply.
Carotene and melanin are the two variable quantities of pigments in the epidermis.
Carotene is an orange-yellow pigment that normally accumulates inside epidermal cells. In orange vegetables.
Melanin is a brown, yellow or black pigment produced by melanocytes. Melanocytes manufacture and store melanin and inject that pigment into the epithelial cells. Melanin helps prevent skin damge by absorbing uv radiation before it reaches the deep layers of the dermis and epidermis.'
Blood vessesls in the dermis normally give the skin a reddish tint that is common in lightly pigmented individuals.
UV Rays are beneficial in small amounts but produce harmful and serious results in long term exposure.

Anatomy: Hair projects out of the skin almost everywhere. Exceptions are the sides and soles of the feet, palms of the hands, sides of the fingers and toes, lips, and portions of the external genital organs. Hair forms in hair follicles. Hair follicles lie in the dermis and extend to the subcutaneous layer. The walls of each follicle contain all the cells found in the epidermis.

Physiology: Hair provides sensation and protection for the head. Your head secretes oil to lubricate hair. Hair protects the scalp from UV rays, it also cushions from light hits to the head. Hair also provides insulation. Hairs in the nose and hte ear as well as the eyelashes prevents things from entering the body.

Hair Color: Hair color reflects differences in the type and amount of pigment produced by melanocytes at the papilla. The condition of your hair is influenced by hormonal; and environmental factors. Pigment production decreases with age and the color of your hair lightens toward gray. White hair results from having air bubbles within your hair shaft.

Hair Loss: As a hair grows in the scalp for 2 to 5 years, it rests at for a period of time. Once another growth period begins, the follicle makes a new hair and the elder hair gets pushed to the front to be shed. On average, about 50 hairs are lost each day. Over 100 hairs usually show that something is wrong. This rate of hair loss can increase with factors such as pregnancy, high fever, stress, and drugs. In males, sex hormones that circulate through the body effect the scalp, and cause what we call and see as "peach fuzz".

Sebaceous Glands

Physiology: Glands that secrete sebum (oil), usually associated with hair follicles.
Sebum is a waxy secretion that coats the surfaces of hairs.
Several sebaceous glands may communicate with a single follicle by means of short ducts. Glands cells make large amounts of lipids as they mature and their death releases the lipids into the passageway of the gland. Contraction of the arrector pilli muscle elevates the hair and squeezes the sebaceous gland. This forces sebum onto the surface of the skin where the sebum prevents drying and breaking of the hair and skin.

Sebaceous glands are sensitive to changes in the concentrations of sex hormones and their secretory activities can accelerate during puberty. Because of this, a person with large sebaceous glands may be prone to develop acne during this time. Acne occurs when the sebaceous ducts become blocked and secretions accumulate, which causes the inflammation and provides a fertile environment for bacteria.

Sweat Glands
Anatomy: Sweat is 99% water and the other 1% consists of salt, anti-bacterial fluid and waste products such as urea.

Physiology Merocrine Sweat Glands: Far more numerous and widely spread than apocrine glands. Palms and soles of the feet have the highest number of merocrine glands. Merocrine glands are coiled tubular glands that discharge their secretions directly onto the surface of the skin. The purpose of this is to keep the skin cool and body temperature down. this entire process is called perspiration.

Physiology apocrine Sweat Glands: Located in the groin, armpit and nipples. The gland is stimulated by hormonal changes in the body, and is controlled by the body's temperature. The apocrine gland releases the product when part of the secretory cell in the gland breaks off. external image apocri6.jpg

Nail bed: Beneath nail plate, moves forward with nail plate.
Free edge: Anterior margin of nail plate, corresponding to cutting edge
Cuticle: Protects matrix from possible infections, connects nail plate to epidermis
Lunula: Visible part of matrix, whitish crescent shaped base
Nail root: Part of nail embedded underneath skin
Nail body: Actual nail, several layers of dead, flattened cells. Pink appearance due to underlying capillaries.

Physiology: Nails are formed at the phalanges (fingers and toes) of the human body. Nails protect the exposed tip and help limit their distortion when you apply pressure in any way.

Aging and the Integumentary

  • Skin injuries and infections increase due to thinning epidermis and slowing immune system.
  • Vitamin D production decreases. Muscle and bone strength decrease due to their reliance on vitamin D.
  • Melanocyte activity decreases. Skin becomes paler and is more sensitive to sun damage.
  • Skin becomes scaly and dry due to decreases in oil production (sebaceous glands).
  • Hair thins and changes color due to slower growth and less melanocyte activity.
  • Skin gets saggy and wrinkly due to the breakdown of the connective fibers under the skin.
  • The ability to sweat decreases due to decreased sweat gland activity. This reduces the skin's ability to lose heat.
  • Skin repairs more slowly due to slower stem cell activity in the skin.
  • Secondary sex characteristics of the skin fade (body hair location, fat deposit location). This is due to less sex hormone circulating in the body.