Exam 2 Review:  Chapter 5:  General Terms

organ system - A group of interacting, interrelated, or interdependent organs forming a complex functional whole; the set of organs of the body regarded as a functional physiological unit.

skin - The membranous tissue forming the external covering or integument of a human and consisting of the epidermis (stratified squamous epithelium and epidermal derivatives) and the dermis (dense irregular connective tissue; the functions of the skin include protection and immune defense, thermoregulation, sensation,  communication, vitamin D synthesis, etc.

dermatology - The branch of medicine that is concerned with the physiology and pathology of the skin.

excretion - The physiological processes of discharging waste molecules/matter (e.g., respiration, urine, sweat, particularly feces) from individual cells and from the body.

subcutaneous - Located or placed just beneath the skin, usually within the dermis.

hypodermis - The subcutaneous layer of loose connective tissue containing a varying number of fat cells found below the dermis in many regions of the body.

elasticity - The property of returning to an initial form or state following deformation; flexibility.

superficial fascia - A sheet or band of irregular dense fibrous connective tissue separating the dermis from underlying muscles, tendons, ligaments or bones.

vitamin D - A fat-soluble vitamin occurring in several forms, especially vitamin D₂ or vitamin D₃; required for proper calcium absorption and metabolism and therefore for normal growth of teeth and bones; produced in the skin by ultraviolet irradiation of sterols found in milk, fish, and eggs.

callus

1. A localized thickening and enlargement of the horny layer (stratum corneum) of the skin. Also called a callosity.
2. The hard mineralized tissue which develops around the ends of a fractured bone during healing.

epidermal derivative - Any specialized structure derived from the germinal epithelium of the epidermis including hair and hair follicles, nails, sweat glands and sebaceous glands.

epidermal ridges - The series of unique genetically determined patterns of narrow, raised strips of epidermis which are located on the palms of the hands and soles of the feet which increase friction and, therefore, traction of the foot and gripping ability of the hand; skin gland pores open on the crests which leave a pattern of oil and sweat on touched surfaces which permit the identification of fingerprints, palm prints, etc.; the pattern of these ridges is regulated by heredity.

thermoregulation - The maintenance of a constant internal body temperature independent from the environmental temperature; the skin (radiates heat even when dry), sweat glands (evaporative cooling), subcutaneous adipose tissue (thermal insulation), and dermal capillary beds (adjusts blood flow to encourage or discourage radiant heat loss) play important roles in thermoregulation.

primary germ layers - The first three tissue types to differentiate in an early stage of embryonic development and from which all other more specialized tissues are later derived; specifically, ectoderm, mesoderm, and endoderm.

ectoderm - The outermost of the three primary germ layers of an embryo, from which the epidermis, nervous tissue, and, in vertebrates, sense organs develop.

mesoderm - The middle embryonic germ layer, lying between the ectoderm and the endoderm, from which the connective tissues, including muscle and bone, and the urogenital and circulatory systems develop.

endoderm - The innermost of the three primary germ layers of an animal embryo, developing into the epithelial linings of the gastrointestinal tract, the lungs, and associated structures.

List:

 1. the two basic layers of the skin and the tissue layer immediately deep to these; ID the tissue type of each of these layers.

                 superficial layer = epidermis - a keratinized stratified squamous epithelium
                 next layer = dermis - a dense fibrous connective tissue
                 deeper layer = hypodermis - a loose fibrous connective tissue

 2. nine physiological functions of the skin.

                 physical barrier, chemical barrier, uv radiation barrier, biological barrier (antimicrobial protection),
                 thermoregulation, cutaneous sensations (sensory), communication, excretion (minor),
                 blood reservoir, Vitamin D synthesis and other metabolic functions

 5. four epidermal derivatives and describe the function of each.