A&P Chapter 5

subcutaneous tissue

not part of the skin; loose connective tissue with abundant deposits of adipose tissue. Attaches the dermis to underlying structures; adipose tissue provides energy storage, insulation, and padding; blood vessels and nerves from the subcutaneous tissue supply the dermis

Papillary layer

papillae project towards the epidermis; loose connective tissue. brings blood vessels close to the epidermis; dermal papillae from fingerprints and footprints.

langerhans cells

part of the immune system

Functions of the integumentary system

1. protection. against abrasion and harmful effects of ultraviolet light. keeps microorganisms from entering the body and prevents dehydration by reducing later loss from the body 2. sensation. sensory receptors that can detect heat, cold,touch, pressure, and pain. 3. temperature regulation. blood floe through the skin and activity of sweat glands regulate body temperature. 4. Vitamin D production. skin produces a molecule that can be transformed into vitamin D, and important regulator of calcium. 5. Excretion. small amount of waste products are excreted through the skin and glands

Stratum Corneum

Most superficial layer of the epidermis. composed of 25 or more layers of dead, squamous cells joined by desmosomes. When desmosomes break apart the cells shed from the surface of the skin. Cornified Cells which are dead cell, are hard protein envelope, filled with protein keratin. the envelope and the keratin are responsible for several structural strength of the stratum corneum known as soft keratin. Lipids are released from lamellar bodies surrounding the skin cells, the lipids are responsible for many of skins permeability characteristics.

Stratum spinosum

Superficial to the stratum basal, consisting of 8-10 layers, when the stratum I pushed to the surface, it flatten, Desmosomes break apart, new ones form. cell usually shirk from one another, expects where they are attached, calls appear spiny-hence.

Stratum Lucidum

Thin, clear zone above the stratum granulosum. Several layers of dead cells with indistinct boundaries. keratin fibers are present but not keratohyalin, making the cell appear somewhat transparent.

melanin

a group of pigments primarily responsible for skin, hair, and eye color. provides protection against ultraviolet light for the sun.

Dermis

a layer of connective tissue. responsible for most of the structural strength of the skin. strength of the dermis is seen in leather

subcutaneous tissue (hypodermis)

a layer of loose connective tissue, not part of the skin or the integumentary system. does connect the skin to underlying muscle or bone.

Dermis

connective tissue containing fibroblasts, a few adipocytes and macrophages. Collagen is the main connective tissue fiber, but elastic and reticular fibers are also present. adipocytes and blood vessels are scare in the dermis compared with the subcutaneous tissue. the dermis contains nerve endings, hair follicles, smooth muscles, glands, and lymphatic vessel.

Stratum granulosum

consists of five layers of flattened, diamond-shaped cells with long axes oriented parallel to the surface of the skin. presence of non membrane- bound proteins granules of keratohyalin, accumulate in cytoplasm, of the cell and are proteins that give structural support of the epidermis . In the most superficial layers of the stratum granulosum, the nucleus and other organelles degenerate, the cell dies. keratin fibers and keratohyalin granules within the cytoplasm do not degenerate.

Integumentary system

consists of the skin and accessory structures, such as hair, glands, and nails

Melanocytes

contribute to skin color.

thin skin

covers the rest of the body, is flexible than thick skin. hair is only in thin skin. thin and thick skin, is referred to only to epidermis only.

Stratum Basale

deepest portion of the epidermis, is a single layer of cuboidal or columnar cells. Strength is provided by hemidesmosomes, anchor the epidermis to the basement membrane, the desmosomes hold the keratinocytes together. Keratinocyte stem cells of the, other daughter cells is pushed towards the surface and becomes keratinized. Keratinocytes are made here.

Strata

epidermis is divided into regions. From deepest to most superficial: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

thick skin

has all five epithelial strata, the stratum corneum has many layers of cells. Found in areas subjects to pressure or friction, like soles of feet and fingertips.

erythema

inflammatory response stimulated by infection, sunburn, allergic reactions, insect bites, or even blushing

melanocytes

irregularly shaped cells with many long processes that extend between the keratinocytes of the stratum basale and the stratum spinosum.

albinism

is usually a recessive genetic trait that results from an inability to produce tyrosinase. the result is a deficiency or an absence of pigment in the skin, the hair, and the irises of the eye. exposure to ultraviolet light darkens the melanin already present in the skin and stimulates melanin production, resulting in tanning.

lamellar bodies

keratin fiber, lipid-filled, membrane-bound organelles, form inside the keratinocytes.

carotene

lipid-soluble and, when large amounts of carotene are consumed, the excess accumulates in the stratum corneum and in adipocytes of the dermis and subcutaneous tissue. causing the skin to develop a yellowish tint.

reticular layer

mat of collagen and elastic fibers; dense irregular connective tissue. is the main fibrous layer of the dermis; strong in many directions, forms cleavage lines.

Keratinocytes

most abundant cell of the epidermis, they produce a protein mixture called keratin, makes cells more durable. the ability to resist abrasion and reduce water lose. Produced when keratinocyte stem cells undergo mitosis in the deepest layer of the epidermis.

melanosomes

move into the cells processes of the melanocytes. melanocytes produce melanin. all races have the same number of melanocytes, racial variations in skin color are determined by the amount and types of melanin produced by the melanocytes, as well as by the size, number, and distribution of the melanosomes.

merkel cells

specialized epidermal cells associated with the nerve endings responsible for detecting light touch and superficial pressure.

corn (cornified)

the skin over boy prominences may develop a cone-shaped structure. cells are dead, have a hard protein envelope. are filled with keratin.

Epidermis

upon the dermis. is the superficial layer of the skin, consisting of epithelial tissue. stratified squamous epithelium, separated from the underlying dermis by a basement membrane.

keratinization

where cells accumulate keratin. cells eventually die and produce an outer layer of dead, hard cells that resists abrasion and forms a permeability barrier.

callus

with skin subjected to friction or pressure, the number of layers in the stratum corneum greatly increase to produce a thickened area.