Integumentary System

The skin is the largest organ in the body: 12-15% of body weight, with a surface area of 1-2 meters. Skin is continuous with, but structurally distinct from mucous membranes that line the mouth, anus, urethra, and vagina. Two distinct layers occur in the skin: the dermis and epidermis. The basic cell type of the epidermis is the keratinocyte, which contain keratin, a fibrous protein. Basal cells are the innermost layer of the epidermis. Melanocytes produce the pigment melanin, and are also in the inner layer of the epidermis. The dermis is a connective tissue layer under the epidermis, and contains nerve endings, sensory receptors, capillaries, and elastic fibers.

The integumentary system has multiple roles in homeostasis, including protection, temperature regulation, sensory reception, biochemical synthesis, and absorption. All body systems work in an interconnected manner to maintain the internal conditions essential to the function of the body.

Follicles and Glands

Hair follicles are lined with cells that synthesize the proteins that form hair. A sebaceous gland (that secretes the oily coating of the hair shaft), capillary bed, nerve ending, and small muscle are associated with each hair follicle. If the sebaceous glands becomes plugged and infected, it becomes a skin blemish (or pimple). The sweat glands open to the surface through the skin pores. Eccrine glands are a type of sweat gland linked to the sympathetic nervous system; they occur all over the body. Apocrine glands are the other type of sweat gland, and are larger and occur in the armpits and groin areas; these produce a solution that bacteria act upon to produce "body odor".
 

Hair and Nails

Hair, scales, feathers, claws, horns, and nails are animal structures derived from skin. The hair shaft extends above the skin surface, the hair root extends from the surface to the base or hair bulb. Genetics controls several features of hair: baldness, color, texture.

Nails consist of highly keratinized, modified epidermal cells. The nail arises from the nail bed, which is thickened to form a lunula (or little moon). Cells forming the nail bed are linked together to form the nail.

The part growing into the body is called the root, the exposed part of the nail is called the body, and the part that extends from the skin is called the free border (the part you have to clip).

The condition and color of the nails and nail beds are often useful as an early-warning system to self-diagnose underlying or sub-clinical health conditions. The nails and nail beds are found at the ends of our arms and legs- the last areas of the body to receive oxygen and nutrients carried in the blood, and will often show signs of deficiencies sooner than tissues receiving sufficient nutrients. The skin of the body provides a protective barrier to outside environmental substances, but the nails are porous (have small channels and holes) and allow substances and chemicals (especially chemicals such as acetone used in nail polish and remover) to travel directly into the highly vascular (lots of blood supply) nail beds.
 

Many women have reported to us that their fingertips become numb after “doing their nails”. Repeated exposure to toxic chemicals in this manner is very dangerous. Exposure to acetone can cause nerve damage, contribute to diabetes and other metabolic disorders, and can create such symptoms in the body as blood poisoning; dizziness; drowsiness; gastritis; headaches; increased heart rate; impaired reflexes; incoordination; inflammation of stomach; liver injury; loss of sensation; nausea; pneumonia; respiratory failure; restlessness; shock; slurred speech; stupor; vomiting; weakness. Over-exposure to acetone has also been related to low birth rate; coma and death. We recommend that you look at and try the non-chemical products and cosmetics, including nail polish and remover offered by the following companies: Aveda, Ecobella, Earth Science, Paul Pender’s, and Real Purity.

Biotin, a member of the B vitamin family, nourishes and promotes the growth of strong nails, healthy hair and skin. It aids specifically in the treatment of seborrheic dermatitis. Biotin deficiencies cause dry, scaly skin and seborrhea (excessive secretions of sebum, an oily substance made from fat and cellular debris). Biotin deficiencies in children under 6 months old cause “cradle cap” or hair loss (alopecia) and infantile seborrheic dermatitis. Folic acid, pantothenic acid (B5), para amino benzoic acid (PABA), and copper are all known to diminish the graying of hair. Copper is also necessary for the formation of the stretchable connective tissue elastin, which helps keep the skin firm, supple, and pliable (less wrinkles). L-cysteine, an amino acid, supplies the sulfur which is essential for healthy, strong hair and nails. Inositol and zinc both function to regulate the oil content in hair and are both essential to maintain good hair growth.

For fungal nail infections we recommend the topical application of Tea tree oil (melaleuka). This oil works very well with even the most stubborn fungal infections. We have seen this product work for patients who swore they “had tried everything, without success”.

Nutrients which are important to hair growth and the maintenance of hair color and thickness include folic acid, pantothenic acid (B5), PABA, inositol, silica, and biotin. If a person’ hair is becoming coarse, dry and brittle, or if their nails are becoming thin and brittle, often with grooves going sideways across the nails, then these could be signs of hypothyroidism. This is treatable by nutritionally supporting the thyroid gland with kelp products or thyroid glandular products. Kelp is a good source of the trace minerals needed for human metabolism (including iodine for the thyroid gland) and to support the growth and maintenance of hair, nails and skin. Essential fatty acids are important for maintaining the oils and moisture in the skin and hair. Antioxidants such as vitamin A, C, E, with zinc and copper help maintain the oxygen supply to the hair follicles and outer layers of the skin.

Skin and Homeostasis

Skin functions in homeostasis include protection, regulation of body temperature, sensory reception, water balance, synthesis of vitamins and hormones, and absorption of materials. The skin's primary functions are to serve as a barrier to the entry of microbes and viruses, and to prevent water and extracellular fluid loss. Acidic secretions from skin glands also retard the growth of fungi. Melanocytes form a second barrier: protection from the damaging effects of ultraviolet radiation. When a microbe penetrates the skin (or when the skin is breached by a cut) the inflammatory response occurs.

Heat and cold receptors are located in the skin. When the body temperature rises, the hypothalamus sends a nerve signal to the sweat-producing skin glands, causing them to release about 1-2 liters of water per hour, cooling the body. The hypothalamus also causes dilation of the blood vessels of the skin, allowing more blood to flow into those areas, causing heat to be convected away from the skin surface. When body temperature falls, the sweat glands constrict and sweat production decreases. If the body temperature continues to fall, the body will engage in thermiogenesis, or heat generation, by raising the body's metabolic rate and by shivering.

Water loss occurs in the skin by two routes:

• evaporation
• sweating

In hot weather up to 4 liters per hour can be lost by these mechanisms. Skin damaged by burns is less effective at preventing fluid loss, often resulting in a possibly life threatening problem if not treated.

Skin and Sensory Reception

Sensory receptors in the skin include those for pain, pressure (touch), and temperature. Deeper within the skin are Meissner's corpuscles, which are especially common in the tips of the fingers and lips, and are very sensitive to touch. Pacinian corpuscles respond to pressure. Temperature receptors: more cold ones than hot ones.

Skin and Synthesis

Skin cells synthesize melanin and carotenes, which give the skin its color. The skin also assists in the synthesis of vitamin D. Children lacking sufficient vitamin D develop bone abnormalities known as rickets.

Skin Is Selectively Permeable

The skin is selectively soluble to fat-soluble substances such as vitamins A, D, E, and K, as well as steroid hormones such as estrogen. These substances enter the bloodstream through the capillary networks in the skin. Patches have been used to deliver a number of therapeutic drugs in this manner. These include estrogen, scopolamine (motion sickness), nitroglycerin (heart problems), and nicotine (for those trying to quit smoking).

Additional information regarding conditions of the special senses can be found here.

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