Skin Integumentary System

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Skin and the Integumentary System A. Skin is composed of 2 main layers 1. Epidermis is made of keratinized stratified squamous epithelial tissue, is superficial to the dermis, and is avascular. 2. Dermis is mainly connective tissue, is deep to the epidermis, and is vascular * The skin contains collagen (for strength) and elastic (for stretch) fibers. * The skin is thicker on the posterior than the anterior parts of the body; thicker on lateral parts of limbs than medial parts. —Subcutaneous layer (or hypodermis) is deep to dermis, but is not part of skin. It is mainly adipose tissue B. Layers of epidermis (from deepest to superficial) 1. Stratum Basale (= base) a. has stem cells that continuously divide by mitosis…show more content…
The pattern of this residue forms fingerprints. 2. The Reticular Layer a. This layer is deeper to the papillary layer. b. Has collagen and elastic fibers, but not reticular like name suggests. c. Skin Color is determined by 3 pigments: melanin, carotene, and hemoglobin. 1) All races have about the same number of melanocytes, but produce different quantities of melanin in the melanocytes. Melanin is brownish-black 2) Carotene is yellow-orange 3) Hemoglobin is a red pigment found in the red blood cells of the blood. 4) Low levels of melanin and carotene make the epidermis somewhat clear, which means the blood colors the skin. Caucasian people have skin color ranging from pink to red, depending on the amount of O2 in their blood. People of color have more melanin and carotene. d. Many nervous accessory structures are found here: 1) Cold Receptors are sensitive to cold. 2) End Organ of Ruffini is also sensitive to pressure. 3) The Hair Root Plexus is a nerve that wraps around the hair follicle and is stimulated by movement of the follicle (considered to be touch). D. Epidermal derivatives 1. Sebaceous (oil) glands are found here connected to hair…show more content…
b. Apocrine glands are primarily found in the axillary region, the pubic region, and the areolae (pigmented area around the nipple). 1) Their ducts empty into hair follicles. 2) Begin to function at puberty 3. Ceruminous glands (a modified sweat gland) located in the outer ear canal. —Produce cerumen (ear wax). The function is to trap foreign substances. 4. Hair a. A hair is keratinized cells welded together. b. It is present on almost all skin surfaces, as well as inside the nose and the ear canal. Its function is protection. c. A hair is made up of the root (part below the surface of the epidermis) and grows upward to become the shaft (part above the surface of the epidermis). d. The hair follicle is epidermal cells that are found around the root, but it’s still part of the dermis. e. Melanocytes are also found in the hair bulb, and give hair its color 5. Nails are plates of tightly packed, hard, keratinized cells of epidermis. a. The nail body is the part that is visible up to the part that extends past the end of the digit (this is called the free edge). b. The white area at the proximal end of the body is called the
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