Xanthelasma

xanthelasma Deposits of fatty plaque that form blisterlike lesions on the eyelids, usually the upper eyelids near the corner of the NOSE. The lesions are yellowish in color and often indicate HYPERLIPI-DEMIA (elevated BLOOD levels of cholesterol and triglycerides). Though harmless, the lesions can cause the eyelid to droop, obscuring vision when an upper lid and interfering with lid closure when a lower lid. A plastic surgeon can remove the lesions in a simple outpatient OPERATION, though the lesions tend to recur, particularly when blood lipid levels remain high.

See also BLEPHAROPLASTY; CHOLESTEROL BLOOD LEVELS; LESION; SURGERY BENEFIT AND RISK ASSESSMENT; TRIGLYCERIDE BLOOD LEVEL.

The integumentary system encloses the body, protecting it from, as well as allowing its interactions with, the external environment. Physician specialists who treat conditions of the SKIN, HAIR, and NAILS are dermatologists. This section, "The Integumentary System," presents an overview of the structures and functions of the integumentary system, a discussion of dermatological health and disorders, and entries about the health conditions that can affect the skin, hair, and nails.

Structures of the Integumentary System

SKIN                                                      SEBACEOUS GLANDS

epidermis

sebaceous

dermis

ducts

subcutaneous layer

NAILS

WEAT GLANDS

cuticle

eccrine sweat glands

nail

apocrine sweat glands

nail bed

AIR

matrix

llicle

(nail root)

Functions of the Integumentary System

The integument, from the Latin word for "cloak," covers the body. Its structures-the SKIN, HAIR, and NAILS-form the image the body presents to the outside world. Its functions-protective barrier, tactile perception, temperature regulation, IMMUNE RESPONSE-enable the body to survive in that outside world.

The foundation of the integumentary system is the skin, which, as the body's largest organ, accounts for 15 percent of the body's weight. It sheaths the body in protective insulation from scalp to sole, coating every stretch and fold between. The skin's three layers-epidermis, der-mis, and subcutaneous layer-form the interface between the body's internal and external environments. The endless exchange of information is so wearing that the skin completely replaces its outermost layer, the epidermis (about 36,000 square inches of surface area), every three to four weeks.

What looks remarkably the same from day to day is, in reality, always changing.

In the beginning Attesting to the skin's importance for survival and function, the skin and the BRAIN are the first two distinctive organs to emerge during embryonic development. The cells of each arise from the primitive neural crest, also called the neuroectoderm. By three weeks of ges-tational age the neural crest differentiates. The cells that migrate inward become NERVE cells, forming the brain and SPINAL CORD. The cells that migrate outward become the two major cell types of cells that form the skin: keratinocytes and melanocytes.

By seven weeks gestational age the skin develops hair follicles that, six weeks later, begin to cover the head with hair. At 20 weeks gestational age that hair coat, called lanugo, has spread to cover the entire body. Some babies, especially those born prematurely, still sport this coat at birth, which is often disconcerting to anxious parents but quickly falls away. The formation and function of the sebaceous glands parallels that of the hair follicles. As hair begins to sprout, the sebaceous glands secrete a thick, ointmentlike precursor to sebum, called vernix, that covers the skin's surface. Vernix establishes a waterproof barrier that protects the skin as the FETUS floats in AMNIOTIC FLUID. Also by 20 weeks the skin contains SWEAT GLANDS, eyelashes and eyebrows, fingernails and toenails, and the unique surface ridges on the fingertips that will become fingerprints.

Xanthelasma (Dermatology)

Xanthelasma teaches you the details you ought to understand regarding this skin condition that will also be associated with the development of serious cardiovascul

Disorders Of Eyelid, Lacrimal System And Orbit, including: Blepharitis, Chalazion, Stye, Dacryoadenitis, Trichiasis, Xanthelasma, Xerophthalmia, … Ptosis (eyelid), Orbital Cellulitis

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