chapter 5 test the skin

Stratum granulosm has four to six layers

Cells appearances flat nuclei n organelles disintegrate n keratinzation begin

Apocrine sweat glands. Confined to axillary and angential areas sweat n fatty substance plus protein

Viscous milky yellow thicker like. Syrup high viscously orderless until bacteria interaction body order ducts empty into hair follicle

I. Appendages of the Skin b. A hair has three layers of keratinized cells: the inner core is the medulla, the middle layer is the cortex, and the outer layer is the cuticle.

c. Hair pigments (melanins of different colors) are made by melanocytes at the base of the hair follicle.

b. Melanocytes are epithelial cells that synthesize the pigment melanin. c. Dendritic cells, or Langerhans cells, are macrophages that help activate the immune system.

d. Tactile, or Merkel, cells are associated with sensory nerve endings.

Sebaceous oil glands widely distributed n thick skin of palms n soles develop from hair follicle secrete into hair follicle

Secrete sebum bactericidal softens hair n skin help reduce water loss can affect skin

Nails are scale like modifications of epidermis protective cover for distal dorsal surface of fingers n toes hard keratin

Bone in nails is phalanx sweat glands all skin surface except nipples parts of external growth

Function of integumentary system 1. Protection has 3 types of barriers chemical skin secretion n melanin

Physical barrier flat dead cells stratum defense against radiation damage biological barrier dendritic of skin cells epidermis

- structure of a Hair Follicle d. The hair matrix within the hair bulb is a group of actively dividing cells that produce the hair.

e. Associated with each hair follicle is a bundle of smooth muscle cells called an arrector pili muscle which, when contraction occurs, causes the hair to stand upright.

3. Layers of the Epidermis d. The stratum lucidum (clear layer) is found only in thick skin and is composed of dead keratinocytes

e. The stratum corneum (horny layer) is the outermost protective layer of the epidermis composed of a thick layer of dead keratinocytes.

C. Epidermis 1. The epidermis is a keratinized stratified squamous epithelium that consists of four cell types, arranged in four to five layers.

2. Cells of the Epidermis a. The majority of epidermal cells are keratinocytes that produce a fibrous protective protein called keratin.

Modified glands 1. Ceruminous gland ear canal secret cerurum earwax water resistant

2. Mammary gland secrete milk lactation milk production

Four cell types 1. keratinocytes protein is found, biotin most cells of epidermis is tightly connected by demoses

2. Melanocytes is pigmentation packed into melanosomes protect apical surface is skin hair eyes

B. Nails 1. A nail is a scalelike modification of the epidermis that forms a protective covering on the dorsal side of the distal finger or toe

2. Nails are made up of hard keratin and have a free edge, a nail plate attached to the skin, and a root embedded in the skin. 3. The nail matrix, located within the proximal part of the nail bed, is responsible for nail growth.

III. Functions of the Integumentary System A. Protection 1. Chemical barriers include skin secretions that inhibit bacterial growth and melanin that protects skin from UV damage.

2. Physical or mechanical barriers are provided by the continuity of the skin and the hardness of the keratinized cells. 3. Biological barriers include the dendritic cells and the macrophages of the dermis, while DNA helps convert UV radiation to dissipated heat

B. Burns 1. A burn is tissue damage resulting from intense heat, electricity, radiation, or certain chemicals, all of which denature cell proteins and cause cell death to affected areas.

2. Risks to a burn patient include dehydration and electrolyte imbalance due to fluid loss, as well as infection of burned areas. 3. The rule of nines divides the body surface into 11 areas of 9% each, plus 1% for genitalia, and is used to evaluate fluid loss through burns.

Homeostatic Imbalances of Skin A. Skin Cancer 1. Basal cell carcinoma results from invasive proliferation of cells of the stratum basale and is the least malignant and the most common skin cancer.

2. Squamous cell carcinoma derives from the keratinocytes of the stratum spinosum and tends to grow rapidly and metastasize if not removed.

D. Dermis 1. The dermis is composed of strong, flexible connective tissue and is well supplied with blood vessels, nerves, and lymphatic vessels

2. The dermis is made up of two layers: the thin, superficial papillary layer that forms dermal papillae that give rise to fingerprints; and the reticular layer, accounting for 80% of the thickness of the dermis, which forms cleavage and flexure lines. E. Skin color is determined by three pigments: melanin, carotenes, and haemoglobin

D. Sebaceous (Oil) Glands 1. Sebaceous glands secrete sebum, an oily secretion, and are found all over the body, except the palms of the hands and soles of the feet.

2. The sebaceous glands function as holocrine glands, secreting their product into a hair follicle or to a pore on the surface of the skin. 3. Secretion by sebaceous glands is stimulated by hormones

Skin marking 1. Dermal folds at or near joints dermis tightly secured to deeper structure joint movement cause creases

... visible on hands, elbow, toes where ever flexing n binding happens

2. Apocrine sweat glands are confined to the axillary and anogenital areas and produce a fat and protein-rich true sweat

3. Ceruminous glands are modified apocrine glands found lining the ear canal that secrete earwax, or cerumen. 4. Mammary glands are modified sweat glands that secrete milk.

2 body temp regulation maintain homeostasis body to hot it sweat to cool sensible perspiration

3. Cutaneous part of nervous system detects temp touch pain

3. Dendritic cells is sensory response macrophages key activation of immune response

4. Tactile cells through touch when body responds to stimuli lots of receptors

3. Melanoma is a cancer of the melanocytes and is the most dangerous of the skin cancers because it is highly metastatic and resistant to chemotherapy.

4. The ABCD rule is used to evaluate moles or pigmented spots for cancer and corresponds to Asymmetry, Border irregularity, Color, and Diameter

Metabolic function synthesis of vitamin d precursor n collagenous

5 blood reservoir up to 5℅ of body blood volume 6. Excretion limited nitrogen containing waste ammonia urea

The Skin A. The skin consists of two regions: the outermost epidermis, an epithelial tissue; and the inner dermis, a connective tissue.

B. The hypodermis, also called the superficial fascia, is subcutaneous tissue beneath the skin consisting mostly of adipose tissue that anchors the skin to underlying muscle, allows skin to slide over muscle, and acts as a shock absorber and insulator

B. The skin plays an important role in body temperature regulation by using the sweat glands of the skin to cool the body and constriction of dermal capillaries to prevent heat loss.

C. Cutaneous sensation is made possible by cutaneous sensory receptors, which are part of the nervous system, in the layers of the skin.

V. Developmental Aspects of the Integumentary System A. The epidermis develops from the embryonic ectoderm, and the dermis and the hypodermis develop from the mesoderm. B. By the end of the fourth month of development the skin is fairly well formed.

C. During infancy and childhood, the skin thickens and more subcutaneous fat is deposited. D. During adolescence, the skin and hair become oilier as sebaceous glands are activated

Cells accumulate lamellar grantes are water resistant glycolipids slow water loss

Cell differentiation cells change from stratum basale to stratum corneum accomplish by apoptosis nucleus break down plasma m thicken

2. Recticular layer most of dermis thickness dense fiber connective tissue elastic fiber provide stretch recoil properties

Collagen fibers provide strength n resiliency bind water. Recticular are clevage like

Dermis has 1. papillary layer it's areolar connective tissue with collagen n elastic fiber's n blood vessels loose tissue phagocytes can patrol for micro

Contain capillary loops excess to blood supply n exchange. Meissner's corpsule r touch receptors

Dermis is strong flexible n connective tissue masts cell n white blood cells, fibers in matrix bind body together

Contain nerve fibers blood n lymphatic vessels body control epidermal n hair follicles oil n sweat glands elastic

D. The skin provides the metabolic function of making vitamin D, which is important for calcium absorption, when it is exposed to sunlight.

E. The skin may act as a blood reservoir by holding up to 5% of the body's blood supply, which may be diverted to other areas of the body should the need arise. F. Limited amounts of nitrogenous wastes are excreted through the skin.

Apocrine sweat glands contain myoephitheialcells contract upon nerve system

Eccrine sympathetic nervous system abandont n palms

E. The skin reaches its optimal appearance when we reach our 20s and 30s; after that time, the skin starts to show the effects of cumulative environmental exposure.

F. As we age, the rate of epidermal cell replacement slows and the skin thins, becoming more prone to bruising and other types of injuries.

Hair follicles extends from epidermal surface to dermis two layered part dermis

Hair bulb expand deep end hair follicle receptor root hair plexus hair matrix actively dividing area

Arrector Lilli smooth muscle attached to follicle responsible for goose bumps

Hair papilla closer to tissue excess to nutrients

Layers of epidermis the stratum basale is the deepest attached to dermis

Stratum bpinosum layer gas several layers is thick attached to desmomes

C. Sweat (Sudoriferous) Glands 1. Eccrine, or merocrine, sweat glands produce true sweat and are abundant on the palms of the hands, soles of the feet, and forehead.

a. Secretion of eccrine glands is regulated by the sympathetic nervous system and is used to prevent the body from overheating.

II. Appendages of the Skin A. Hairs and Hair Follicles 1. Hairs, or pili, are flexible strands produced by hair follicles that consist of dead, keratinized cells.

a. The main regions of a hair are the shaft, which projects from the skin, and the root, which embeds in the skin.

3. Types and Growth of Hair a. Hairs can be classified as pale, fine vellus hairs, or longer, more coarse terminal hairs.

b. Hair growth and density are influenced by many factors, such as nutrition and hormones. c. The rate of hair growth varies from one body region to another and with sex and age.

4. Hair Thinning and Baldness a. After age 40, hair is not replaced as quickly as it is lost, which leads to hair thinning and some degree of balding, or alopecia, in both sexes

b. Male pattern baldness is a genetically determined, sex-influenced condition caused by a gene that changes the hair follicle response to DHT

4. Burns are classified according to their severity. a. First-degree burns involve damage only to the epidermis.

b. Second-degree burns injure the epidermis and the upper region of the dermis. c. Third-degree burns involve the entire thickness of the skin

3. Layers of the Epidermis a. The stratum basale (basal layer) is the deepest epidermal layer and is the site of mitosis. b. The stratum spinosum (prickly layer) is several cell layers thick and contains keratinocytes, melanin granules, and the highest concentration of dendritic cells.

c. The stratum granulosum (granular layer) contains keratinocytes that are undergoing a great deal of physical changes, turning them into the tough outer cells of the epidermis.

2. Structure of a Hair Follicle a. Hair follicles fold down from the epidermis into the dermis and occasionally into the hypodermis. b. The deep end of a hair follicle is expanded, forming a hair bulb, which is sur-rounded by sensory nerve endings called a hair follicle receptor, or root hair plexus.

c. The wall of a hair follicle is composed of a peripheral connective tissue sheath, a thickened basement membrane, and an inner epithelial root sheath.