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Integumentary System
Anatomy
Question | Answer |
---|---|
integumentary system | consists of the skin and its derivatives (nails, hair, sweat glands, and sebaceous glands) |
integument | the skin covering the body (is the body's largest organ and accounts for 7-8% of body weight), |
cutaneous membrane | another word for integument |
dermatology | the scientific study and treatment of the integument |
main function of the integument | acts as a barrier to the outside world and protects internal body structures |
all the functions of the integument | protection, prevention of water loss, metabolic regulation, secretion and absorption, immune function, regulation of body temperature, sensory reception |
how the integument acts as protection | cushions organs and protects from bumps, chemicals, UV radiation |
how the integument prevents water loss | water is unable to exit the skin unless it is secreted by sweat glands |
how the integument acts in metabolic regulation | produces vitamin D for calcium absorption |
how the integument acts in immune function | initiates immune response against pathogens |
how the integument regulates body temperature | body temperature is influenced by capillaries and sweat glands |
how the integument acts in sensory reception | keeps us aware of conditions at the body's surface, detects heat, cold, touch, pressure and vibration |
three major regions of the integument | epidermis, dermis, and hypodermis |
epidermis | the superficial region of the integument (keratinized, stratified squamous epithelium) (aka the epithelium of the integument, consists of strata) |
dermis | middle region of the integument (primarily dense irregular connective tissue) |
hypodermis | deepest region of the integument (subcutaneous layer and is mostly adipose tissue) (closely involved with structure and function of the skin) |
composition of the epithelium of the integument (epidermis) | (from deep to superficial) stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum |
stratum corneum (details) | first three layers with living keratinocytes and the most superficial two layers have dead keratinocytes |
stratum basale (aka basal layer) | deepest epidermal layer, separates the epidermis from the dermis, and is occupied by three cell types (keratinocytes, melanocytes, tactile cells) |
keratinocytes | most abundant cells in epidermis and regenerate new cells to replace old cells shed at the surface (name derived from the synthesis of keratin) |
keratin | protein that strengthens the epidermis |
melanocytes | produce and store pigment (melanin) |
melanin | responsible for the darker tones of skin |
tactile cells (aka Merkel cells) | sensitive to touch (nerve endings are stimulated) |
stratum spinosum (aka spiny layer) | several layers of polygonal keratinocytes that begin to develop into specialized, non-dividing keratinocytes (named for spiny appearance under microscrope) |
epidermal dendritic cells (Langerhans cells) | immune cells that help initiate immune response and are responsive to pathogens and epidermal cancer cells, often present in stratum spinosum and stratum granulosum |
stratum granulosum (granular layer) | three to five layers of keratinocytes, first layer of keratinization |
keratinization | process where keratinocytes fill with keratin, fully keratinized cell dead but structurally sound, and process not complete until more superficial layers |
stratum lucidum (transulent layer/ clear layer) | two to three layers of keratinocytes found only on thick skin within the palms and soles |
stratum corneum (hornlike layer) | 20 to 30 layers of dead, interlocking keratinized cells, most superficial layer of epidermis, surface unsuitable for the growth of microorganisms |
migration of keratinocytes | originate in the stratum basale, migrate through strata to stratum corneum over two weeks (undergoing structural changes), remain in stratum corneum another 2 weeks and then are shed |
variations in the epidermis occur because of... | variations between the different body regions, variations between individuals, and variations in thickness, color and skin markings |
freckles and nevus (mole) | concentrations of melanocytes (mutations can affect that skin and indicate cancer) |
thick skin | on the palms of hands, soles of feet, and surfaces of fingers and toes, has all five layers of epidermal strata (includes stratum lucidum), has sweat glands, has no hair follicles or sebaceous glands |
thin skin | covers most of the body, lacks a stratum lucidum (only four layers), has sweat glands, hair follicles, and sebaceous glands |
coloration from hemoglobin | hemoglobin is bright red upon binding oxygen and gives blood vessels in dermis a reddish tint that is seen more easily in fair skinned individual or if blood vessels dilate |
hemoglobin | an oxygen binding compound present in red blood cells |
coloration from melanin | occurs in black, brown, tan, yellow-brown shades of skin, although all people have the same number of melanocytes, the amount of melanin in skin varies according to heredity and light exposure (UV light stimulates melanin production), |
melanin | pigment produced and stored in melanocytes (activity and color produced by melanocytes varies among individuals - darker skinned people produce more and darker colored melanin) |
nevus | mole, harmless overgrowth of melanin forming cells (rarely may become malignant - monitor for changes suggesting malignancy) |
ridge patterns of the skin | complex arches and whorls on fingers, palms, soles and toes (formed from large folds and valleys of dermis and epidermis) that help increase friction in contact (each individual has a unique pattern of friction ridges - allows for personal identification) |
dermis | second major layer of the skin and is composed of strong, flexible connective tissue (dense irregular) that is richly supplied with blood vessels and nerves |
two layers of the dermis | papillary layer and reticular layer |
components of the dermis | primarily collage with elastic and reticular fibers, cells serving an immune function, blood vessels, sweat glands, subcutaneous glands, hair follicles, nail roots, and sensory nerve endings |
papillary layer of the dermis | superficial region of the dermis that is directly adjacent to the epidermis, has dermal papillae (give it its name) that connect with epidermal ridges to interlock and increase the area of contact between layers |
epidermal ridges | projections of the epidermis |
dermal papillae | projections of the dermis that contain capillaries and sensory nerve endings |
reticular layer of the dermis | deeper, major portion of the dermis that extends from papillary layer to hypodermis (subcutaneous) layer and consists primarily of dense irregular connective tissue |
dermal nerve fibers | sensory nerve fibers and motor nerve fibers |
sensory nerve fibers | detect pressure, vibration and cold |
motor nerve fibers | control blood flow and gland secretions |
innervation | to supply (an organ, body part) with nerves, or to stimulate (nerve, muscle, organ) to action |
dermal blood vessels | supply nutrients to epidermis and dermis and play an important role in body temperature and blood pressure regulation (vasoconstriction, vasodilation) |
vasoconstriction | blood vessel diameters narrowed, occur when trying to conserve heat, and look pale when exposed to cold |
vasodilation | blood vessel diameter increased, occurs when needing to loose heat, why nipple may become flushed during exercise |
hypodermis (subcutaneous) layer | not considered part of the integument, consists of areolar and adipose connective tissue, pads and protects the body, acts as energy reservoir, and provides thermal insulation |
derivatives of the epidermis | nails, hair and hair follicles, sweat glands, and sebaceous glands |
nails | scalelike modification of the epidermis that is made of hard, dead keratinized cells and is equivalent to the hooves or claws of other mammals (used as tools) |
hair is found almost everywhere on the body except | the hands and palmar surface of the fingers, the sides and soles of the feet and toes, the lips |
hair composition | composed of keratinized cells growing from hair follices |
pilus | a single hair (shape of a slender filament) |
types of hair | velus and terminal |
velus (fine hair) | primary human hair, found on upper and lower limbs and female faces |
terminal hair (coarse, pigmented, longer) | on scalp, eyebrows, eyelashes, men's beards, and during puberty replaces velus hair in axillary and pubic regions |
three zones along the length of a hair | hair bulb, root, and shaft |
hair bulb | swelling at the base where hair originates in the dermis (consist of dead epithelial cells) |
root | potion of hair deep in skin surface and both root (consist of dead epithelial cells) |
shaft | portion of hair beyond skin surface, and is the only region containing living epithelial cells |
functions of hair | protection, heat retention, sensory reception, and chemical signal dispersal |
hair as protection | protects scalp from sunburn and injury, hair within nostrils traps particles, and eyelashes protect eyes |
hair as heat retention | prevents loss of heat from scalp to air |
hair as sensory reception | has associated tactile receptors |
hair as disperser of chemical signal | secrete pheromones by specific sweat glands onto hairs in axillary and pubic regions |
pheromones | chemical signals involved in attracting sexual partners |
alopecia | thinning of hair |
hair loss | may be normal scalp loss of 10 to 100 hairs a day, but could be a result of drugs, dietary factors, radiation, high fever, stress or aging |
male pattern baldness | loss of hair from only some regions of the scalp and is the result of a combination of genetic and hormonal factors (baldness allele is dominant in males and recessive in females) |
two types of sweat glands | merocrine glands and apocrine glands |
merocrine gland | most numerous, discharges their secretions onto skin surface (i.e. sweat), and are a major function of thermoregulation |
thermoregulation | regulation of body temperature by fluid evaporation |
sweat | composed of 99% water and 1% other chemicals and includes electrolytes, metabolites and waste products |
apocrine gland | discharge their secretion into hair follicles, confined to axillary, anal, and genital area, and produce a special kind of sweat (murky odor - attracts a mate, and fatty substance in the sweat) |
sebaceous glands (oil glands) | produce oily secretions called sebum, occur over entire body (except palms and soles), and are activated during puberty |
sebum | acts as a lubricant for skin and hair, has bactericidal properties, and discharge into a hair follicle |