Chapter 5: Integumentary System

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Test 1: Chapter 5,6,7

Integumentary System

forms the external body covering and protects deeper tissues from injury. Synthesize vitamin D and houses cutaneous (pain, pressure) receptors and sweat/oil glands.

Layers of the integumentary system

Epidemis and dermis

Epidermis

superficial region; epithelial cells; nonvascularized; 4 cell types and 4 or 5 layers

What are the cells of the epidermis

keratinocytes, melanocytes, epidermal dendritic cells, and tactile cells

Keratinocytes

produce fibrous protein keratin; arise in stratum basale; these cells undergo continuous mitosis

Composition and function of Keratinocytes

Which cells are tightly connected to one another by desmosomes. Arise in the stratum basale and undergo constant mitosis for epidermal growth. They are dead by the time they reach the surface of the skin.

Keratin

fibrous protein that helps give the epidermis its protective properties.

Melanocytes

epithelial cells that synthesize the pigment melanin. Found in the stratum basale.

Epidermal dendritic (Langerhans) cells

macrophages that help activate the immune system; first line of defense against pathogens

Tactile (Merkel) cells

touch receptors that expand into the epidermis. Associated with sensory nerve endings.

What are the 5 layers of the epidermis ?

(1) stratum corneum (2) structum lucideum (3) Stratum granulosum (4) stratum spinosum (5) Stratum Basale

Thick skin

covers the palms, fingertips, and soles of the feet

Thin skin

What kind of skin covers the rest of the body

Stratum Corneum

(horny layer) 20 to30 cell layers thick that accounts for up to ¾ of the epidermal thickness. Keratin and thickened plasma membranes of cells protect the skin against abrasion and penetration and glycolipids b/w its cells waterproofs this layer. Barrier against biological, chemical, and physical assaults.

Statum Lucidum

thin translucent band, consists of rows of clear, flat, dead kertinocytes. Visible only in thick skin.

Stratum Granulosum

consists of 3-5 layers in which the cells flatten. Keratinization begins. Cells flatten, nuclei and organelles begin to disintegrate and begin to accumulate 2 types of granules: keratohyaline granules and the lamellated granules.

Keratohyaline granules

What granules help to form keratin in the upper layers

Lamellated granules

granules that contain water resitant glycolipid that is spews into the extracellular space and is a major factor in slowing water loss across the epidermis.

Stratum Spinosum

Which stratum is several cell layers thick; Contain intermediate filaments mainly pre-keratin filaments that attaches to the desosomes. Abundant melanin granules and dendritic cells.

Stratum Basale

deepest epidermal layer, contain single row of stem cells, youngest keratinocytes, 10-25% of cells are the melanocytes. Also called, germinativum: cells that undergo rapid division

Dermis

Middle region, vascularized, bulk of the integumentary system; fibrous connective tissue.

Dermis

strong flexible connective tissue. Cells include: fibroblasts, macrophages, mast cells and white blood cells. Supplied with nerve fibers, lood vessels, and lymphatic vessels.

What are the 2 layers of the dermis?

Papillary and Reticular

Papillary layer

What layer forms the thin superficial, areolar connective tissue in which collagen and elastic fibers form woven mat with small blood vessels.

Dermal papillae

superior surface of papillary layer contain capillary loops, non encapuslated free nerve endings (pain receptors) and ecapsulated touch receptors (meissner's corpuscles)

Reticular Layer

makes up 80%of the thickness of dermis. Dense fibrous connective tissue, elastic fibers provide stretch-recoil properties.

Hypodermis

deepest region; anchors to muscles; subcutaneous deep into skin in various regions. Shock absorber and insulator

Cutaneous Plexus

network of blood vessels that nourishes the hypodermis it also contains collagen fibers that forms cleavage of tension lines.

Collagen Fibers

single most abundant protein in the body

Adipose tissue

fat storage, oils having unsaturated bonds (c=c; carbon-carbon double bonds) found in the hypodermis layer.

What are the 3 pigments that contribute to skin color?

Melanin, carotene and hemoglobin

Melanin

produced in melanocytes; migrates to keratinocytes where it forms "pigment shields" for nuclei (protects DNA from UV light damage); concentrated amounts found in freckles and pigmented moles

Carotene

yellow to orange, mostly in the palms and soles; Vitamin A precursor (necessary for normal vision); acquired from diet

Hemoglobin

oxygen carrying pigment of red blood cells. Produce pink or red color skin when concentrated in surface capillaries.

What are the appendages of the skin?

sweat glands, oil glands, hairs and hair follicles, nails

Sweat (Sudoriferous) glands

Eccrine and Apocrine sweat glands

Eccrine sweat glands

(merocrine exocytosis secretion) abundant on palms, soles, and forehead; 99% water, NaCl, vitamin C, antibodies, and metabolic wastes; ducts connect to pores; body temperature regulation by cooling as the water of sweat evaporation

Apocrine sweat glands

(merocrine exocytosis glands) approx. 2000 of the; largely confined to axillary and anogenital areas. produce during puberty. Larger than eccrine glands and lie deeper in the dermis. Ducts connect to hair follicles.

Ceruminous glands

Modified apocrine glands in external ear canal; secrete cerumen (wax); mammary glands

Mammary glands

specialized sweat glands, secrete milk

Sebaceous (oil) glands

develop from hair follicles; become active at puberty; create sebum (oily substance)

Sebum

oily holocrine secretion (secretion by cell rupture) softens and lubricates the hair and skin, prevents hair from becoming brittle and slows water loss from the skin; has bactericidal action

Hair Functions

guarding the scalp against physical trauma; helps prevent heat loss; protects from sunlight (UV rays)

Hair

consists of dead keratinized cells; contains hard keratin; more durable than soft keratin of skin

melanin (yellow, rust brown, black)

hair pigments

gray/white hair

decreases melanin production, increased air bubbles in shaft.

Hair follicle

extends from the epidermal surfaced into dermis; two-layered wall: outer connective tissue root sheath, inner epithelial root sheath

Hair bulb

expanded deep end of the hair

Root hair plexus

Hair follicle receptor; sensory nerve ending around each hair bulb

Arrector Pilli

smooth muscle attached to follicle; responsible for goose bumps.

Vellus

pale, fine body hair of children and adult females

Terminal

coarse, long hair of eyebrows, scalp, axillary, and pubic regions (and face and neck of males)

Alopecia

hair thinning in both sexes after age 40

True baldness

genetically determined; sex-linked trait (male pattern baldness)

Structure of a nail

scale-like modifications of the epidermis on fingers and toes. Hard keratin composition

Functions of the integumentary system

1) protection 2) body temperature regulation 3) cutaneous sensations 4)metabolic function 5) blood reservoir 6) excretion

What are the 3 types of barriers used for Protection

(1) chemical, (2) physical/mechanical, and (3) biological.

Chemical barrier

which barrier has low pH secretion (acids) and defensins (antimicrobial proteins) retard bacterial activity.

Physical/Mechanical barrier

keratin and glycolipids block most water and water-soluable substances; limit penetration of skin by lipid-soluble substances (poison ivy)

Biological barrier

macrophage and macrophage-like cells; dendritic (taking up the bacteria and activate immune system) cells of the epidermis

Cutaneous sensation

temperature, touch, and pain; exteroceptors-- respond to stimuli arising outside the body

Metabolic function

nutrients reach the surface of the skin by diffusion; synthesis of Vitamin D precursor (UV light converts precursor to Vitamin D); what function of the integumentary system is this?

Blood Reservoir

What integumentary system function holds up to 5% of body's blood volume (not in epidermis)

Excretion

what integumenatary system function has nitrogenous wastes and salt in sweat (ammonia urea, uric acid)

Skin Cancer

most skin tumors (undifferentiated cells) are benign; primary risk factor is overexposure to UV radiation.

Liposomes

enzymes in skin lotions that can fix damage DNA

3 Major types of skin cancer

1) Basal Cell Carcinoma 2) Squamous cell carcinoma 3) Melanoma

Basal Cell Carcinoma

least malignant, most common; stratum basale cells (undifferentiated) proliferate and slowly invade dermis and hypodermis. Cured by surgical removal.

Squamous Cell Carcinoma

second most commom; involves keratinocytes of stratum spinosum; most common on scalp, ears, lower lip, and hands; grow rapidly and metasize. Treated by radiation therapy and surgically removed.

Melanoma

Most dangerous; involves melanocytes; highly metastatic and resistant to chemotherapy; treated by wide surgical excision accompanied by immunotherapy

ABCD rule of Melanoma

Asymmetry, Border, Color, and Diameter

Burns

heat, electricity, radiation, certain chemicals; causes tissue damage, denatured cell protein and cell death

Immediate threat of burns

dehydration and electrolyte imbalance leading to renal shutdown and circulatory shock.

First Degree

epidermal damage ONLY. localized redness, edema (swelling), and pain

Second Degree

epidermal and upper dermal damage; blisters appear

Third Degree

entire thickness of skin damaged; gray-white, cherry red, or black; no initial edema or pain (nerve endings destroyed) skin grafting usually necessary

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