Ch. 5 Integumentary System

What are the 6 functions of Integumentary System?

1. Protection

2. Body temperature regulation

3. Cutaneous sensation

4. Metabolic functions

5. Blood reservoir

6. Excretion

What are the three types of barrier for protection in the integumentary system?

1. Chemical barriers: Low pH secretion (acid mantle)and defenses retard bacterial activity

2. Biological barriers: Dendritic cells and macrophages

3. Physical/mechanical barriers

   1. Keratin and glycolipids block most water and water-soluble substsances

   2. Limited penetration of skin by lipid-soluble substances, plant oleoresins (e.g., poison ivy), organic solvents, salts of heavy metals, some drugs

How is body temperature regulation function for the integumentary system?

~500 ml/day of routine insensible perspiration (at normal body temperature)

At elevated temperature, dilation of dermal vessels and increased sweat gland activity (sensible perspiration) cool the body

**Vasconstriction (cold outside), Vasodilation (hot outside, to cool down)

What is Cutaneous sensation?

Temperature, touch and pain sensation by the skin

What is metabolic functions of the integumentary system?

Synthesis of vitamin D precursor and collagenase

Chemical conversion of carcinogens and some hormones

What is the function of blood reservoir for integumentary system?

up to 5% of body’s blood volume

What is excretion by integumentary system?

Nitorgenous waste and salt in sweat is excreted by the skin

What is the cutaneous membrane and accessory structures of integumentary system?

Cutaneous membrane (skin)

Accessory structure (hair, glands, nails)

What are the three major regions of skin

1. Epidermis: superficial region

2. Dermis: middle region

3. Hypodermis: (superficial fascia, subcutaneous tissue) - deepest region

   1. Subcutaneous layer deep to skin (not technically part of skin)

   2. Mostly adipose tissue

What is the Epidermis made up of?

1. Keratinized stratified squamous epithelium

2. Cells of epidermis

   1. Keratinocytes: produce fibrous protein keratin

   2. Melanocytes: 10-25% of cells in lower epidermis; produce pigment melanin

3. Epidermal dendritic (Langerhans) cells: macrophages that help activate immune system

4. Tactile (merkel) cells: touch receptors

What are the 5 layers of the epidermis

C(ome) L(ets) G(et) S(un) B(urnt)

1. Stratum Corneum: Most superficial layer; 20-30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space

2. Stratum Lucidum: Only found in thick skin (palm and sole)

3. Stratum granulosum: Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (released glycolipids) and keratohyaline granules.

4. Stratum spinosum: Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin

5. Stratum basale: Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layer. See occasional melanocytes and epidermal dendritic cells

What is the dermis layer made up of?

Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells.

Strong, flexible connective tissue

What are the two layers of the Dermis?

Papillary & Reticular

What is found in the Papillary Layer?

Areolar connective tissue with collagen and elastic fibers and blood vessels

Dermal papillae contain: Capillary loops, Meissner’s corpuscles, free nerve endings

What is found in the reticular layer of the dermis?

~80% of the thickness of dermis

Dense irregular connective tissue

Collagen fibers provide strength and resiliency

Elastic fibers provide stretch-recoil properties

What are friction ridges?

Epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints

What are Cleavage Lines?

Collagen fibers arranged in bundles from cleavage (tension) lines

Incisions made parallel to cleavage lines heal more readily

How do we have skin color?

Melanin, Carotene and Hemoglobin

1. Produced in melanocytes; migrates to keratinocytes where it forms “pigment shields” for nuclei

2. Two melanin forms: Eumelanin (black or brown pigment) and Pheomelanin (red or yellow pigment)

3. Darkening of skin occurs when melanin accumulates

Freckles and pigmented moles

1. Local accumulations of melanin

What are the four derivatives/appendages of the skin?

1. Sweat glands

2. Oil glands

3. Hair and hair follicles

4. Nails

What are the two types of sweat (sudoriferous) glands and what are their function?

1. Eccrine (merocrine) sweat glands: abundant on palms, soles, and forhead

   1. Sweat: 99% water, NaCl, vitamin C, antibodies, dermcidin, metabolic wastes

   2. Ducts connect to pores

   3. Function in thermoregulation

2. Apocrine sweat glands: confined to axillary and anogenital areas

   1. Sebum: sweat + fatty substances and proteins

   2. Ducts connect to hair follicles

   3. Functional from puberty onward (as sexual scent glands)

3. Specialized apocrine glands

   1. Ceruminous gland: in eternal ear canal; secrete cerumen

   2. Mammary glands

What is the sebaceous (oil) glands, where is it found and what is its function?

1. Most develop from hair follicles

2. Become active at puberty

3. Widely distributed

4. Sebum

   1. Oily holocrine secretion

   2. Bactericidial

   3. Softens hair and skin

What is hair made up of?

1. Consists of dead keratinized cells

2. Contains hard keratin; more durable than soft keratin of the skin

3. Hair pigments: melanins (yellow, rust brown, black)

   1. gray/white hair: decreased melanin production, increased air bubbles in shaft

What is in the hair structure?

1. Hair shaft

2. Arrector pili

3. Sebaceous gland

4. Hair root

5. Hair bulb

Where is the hair follicle found and what is the structure?

Extends from the epidermal surface into dermis

Two-layered wall: outer connective tissue root sheath, inner epithelial root sheeth

What is the arrector pili?

Smooth muscle attached to follicle

Responsible for “goose bumps”

What are the two types of hair?

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)

What is the hair growth phase?

Growth phase followed by regressive stage and resting phase

Growth phase varies (3-10 years in scalp, 3-4 months in eyebrows)

What is Alopecia

Hair thinning in both sexes after age 40

What is true (frank) baldness?

Genetically determined and sex-influenced condition

Male pattern baldness is caused by follicular response to DHT (dihydrotestosterone)

What is the structure of the nail?

Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes

Nail biting - onychophagia

**look at notes

What is skin cancer? what are the risk factors to getting skin cancer?

Most skin tumors are benign (do not metastasize)

Risk Factor

1. Overexposure to UV radiation

2. Frequent irritation of the skin

What are the three major types of skin cancer?

Basal cell carcinoma: least malignant, most common

Squamous cell carcinoma: Second most common

Melanoma: most dangerous

Where is basal cell carcinoma found and how is it cured?

Stratum basale cells proliferate and slowly invade dermis and hypodermis

Cured by surgical excision in 99% of cases

Where is squamous cell carcinoma found and how is it treated?

1. involves keratinocytes of stratum spinosum

2. Most common on scalp, ears, lower lip, and hands

3. Good prognosis if treated by radiation therapy or removed surgically

Why is melanoma the most dangerous and how is it treated?

Involves melanocytes

Highly metastatic and resistant to chemotherapy

Treated by wide surgical excision accompanied by immunotherapy

What is the ABCDE rule for melanoma?

A: Asymmetry; the two sides of the pigmented area do not match

B. Border exhibits indentations

C: Color is black, brown, tan, and sometimes red or blue

D: Diameter is larger than 6mm (size of a pencil eraser)

E: Evolve

What is four types of burn and what is skin burn?

Heat, electricity, radiation, certain chemicals

Burn: tissue damage, denature proteins, cell death

Why can burn be an immediate threat?

Dehydration and electrolyte imbalance, leading to renal shutdown and circulatory shock

Hypovolemic shock

What is the rule of nines?

Used to estimate the volume of fluid loss from burns

Adult patient who have burns that cover about 15-25% or more of their body need fluid resuscitation

What is the rule of 9 total?

1. Anterior and posterior head and neck 9% (4.5% each)

2. Anterior and posterior upper limbs 18% (9% each or 4.5% for each limbs anterior or posterior)

3. Anterior and posterior trunk (36%) (9% for anterior torso, 9% for posterior torso, 9% for anterior abdomen, 9% for posterior lumbar)

4. Anterior and posterior lower limbs (36%) (9% for each limbs anterior and posterior)

5. Perineum (1%)

What are the three types of burns? What is partial-thickness burn and full-thickness burns?

Partial-thickness: First degree, Second degree

Full-Thickness burns: Third degree

What is first degree burn damage?

Epidermal damage only

Localized redness, edema (swelling), and pain

What is second degree burn damage?

Epidermal and upper dermal damage

Blisters appear

What is third degree burn damage?

Entire thickness of skin damaged

Gray-white, cherry red, or black

No initial edema or pain (nerve ending destroyed)

Skin grafting usually necessary

What is the difference in skin comparing young to old age?

1. Epidermal replacement slows, skin becomes thin, dry and itchy

2. Subcutaneous fat and elasticity decrease, leading to cold intolerance and wrinkles

3. Wrinkles develops due to loss of elastic and collagen filaments in the dermis

4. Increased risk of cancer due to decreased numbers of melanocytes and dendritic cells

What is bedsores (decubitis ulcers)?

Caused by excessive pressure

Common in elderly patients

Can become infected and fatal