the integumentary system. skin (integument ) overview of the skin largest organ of the body (15% of...

35
The Integumentary System

Upload: daniel-brown

Post on 31-Dec-2015

216 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

The Integumentary System

Page 2: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Skin (Integument)

Page 3: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Overview of the Skin• Largest organ of the body (15% of body weight)• Skin thickness variable, normally 1-2 mm• Protection

– chemical barrier (waterproof)– physical barrier (tough)– immune system activator

• Body temperature regulation – blood flow through the skin– sweat glands– hairs

• Sensation– sense touch, temperature and pain

• provides information outside of the body

Page 4: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Functions of the Integumentary System

• Largest organ of the body • Protection – chemical, physical, and mechanical barrier:

Stratified layers of keratinized cells create a tough barrier impermeable to most foreign invaders.

• Body temperature regulation is accomplished by:– Regulation of blood flow to skin: dilation (cooling) and

constriction (warming) of dermal vessels– Increasing sweat gland secretions to cool the body

Page 5: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Functions of the Integumentary System

• Metabolic functions – synthesis of vitamin D in dermal blood vessels

• Blood reservoir – skin blood vessels store up to 5% of the body’s blood volume

• Excretion – limited amounts of nitrogenous wastes are eliminated from the body in sweat

Page 6: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Skin (Integument)

• Consists of three major regions– Epidermis – outermost superficial region– Dermis – middle region– Hypodermis (superficial fascia) – deepest

region• Deep Fascia: lies under the hypodermis.

– Lines the muscles arteries and nerves

Page 7: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Epidermis

• Outer portion of the skin is exposed to the external environment and functions in protection.

• Composed of keratinized stratified squamous epithelium, consisting of four distinct cell types and four or five layers (strata).

• Cell types include keratinocytes, melanocytes, Merkel cells, and Langerhans cells.

Page 8: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Cell and Layers of the Epidermis

Page 9: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

• Deepest epidermal layer firmly attached to the dermis.• Consists of a single row of the youngest keratinocytes

melanocytes and merkel cells.– Keratinocytes – produce the fibrous protein keratin which

makes the cells more resistant to punctures and abrasions.

– Melanocytes – produce the brown pigment melanin. The darker your skin the greater the concentration of these cells. Protects against UV radiation (sunlight) damage.

– Merkel cells – function as touch receptors in association with sensory nerve endings.

• Cells undergo rapid division, hence its alternate name, stratum germinativum.

Layers of the Epidermis: Stratum Basale (Basal Layer)

Page 10: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

• Keratinocytes form desmosomes which hold the cells together. • The spiny appearance is the result of the forces that

pull these cells apart.

• Langerhans( dendritic) cells: macrophages from bone marrow that migrate to the epidermis.

– Capture foreign material and present it to the immune system are abundant in this layer.

Stratum Spinosum (Prickly Layer)

Page 11: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

• 3-5 cell layers thick made of keratinocytes.• Keratinocytes undergo apoptosis

– (programmed cell death).– Keratinocytes produce keratin

• A tough protein that makes the skin resistant to abrasions.

– Exocytose glycolipids accumulate in between the cells of this layer.

• Providing the waterproofing property to skin– This will also cut off nutrients for the more

superficial layers of the epidermis

Stratum Granulosum (Granular Layer)

Page 12: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Stratum Lucidum

• Thin translucent zone seen only in thick skin( Lips, palms of hands and soles of feet.

• Keratinocytes have no nucleus or organelles – dead cells since they no longer have a blood

supply.– does not stain well which give a clear appearance.

Page 13: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

• Outermost layer of keratinized cells

• Accounts for three quarters of the epidermal thickness– ( approximately 30 layers thick)

• Functions include:– Waterproofing and preventing water loss.– Protection from abrasion and penetration.

Stratum Corneum (Horny Layer)

Page 14: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2
Page 15: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Dermis

Papillary layer

Reticular layer

Page 16: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Layers of the Dermis

• Papillary layer– Its superior surface contains finger like projections called dermal

papillae which adhere to the basal layer of the epidermis.– Dermal papillae contain capillary loops, Meissner’s corpuscles

( light touch), and free nerve endings ( pain )• Reticular layer

– Accounts for approximately 80% of the thickness of the skin– Dense irregular Collagen fibers in this layer add strength and

resiliency to the skin– Has a rich blood supply – Location of several types of glands and sensory receptors– Contains hair follicles and associated nerve and arrector pili

muscle

Page 17: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Hair Function and Distribution

• Functions of hair include:– Thermoregulation

• When skin senses cold piloerector muscles are stimulated. Hair becomes erect and goose bumps form.

– Hair protects against physical trauma, heat loss, and sunlight.

– Provide sensory perception.– Hair is distributed over the entire skin surface

except palms, soles, and lips, nipples and portions of the external genitalia.

Page 18: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Hair

Page 19: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Sweat Glands

• Different types prevent overheating of the body; secrete cerumen and milk– Eccrine (Merocrine) sweat glands – found in palms,

soles of the feet, and forehead. • Are found all over the body. Cool body off.

– Apocrine sweat glands – found in axillary and anogenital areas.

• Ceruminous glands – modified apocrine glands in external ear canal that

secrete cerumen. ( ear wax) • Mammary glands

– specialized sweat glands that secrete milk.

Page 20: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Sebaceous Glands

• Sebaceous Glands – Simple alveolar glands found all over the

body.– Secrete an oily secretion called sebum.– Soften skin when stimulated by hormones.

Page 21: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Glands

Page 22: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Hypodermis

• Subcutaneous layer deep to the skin.

• Composed of adipose and areolar connective tissue.

• Functions to insulate and cushion the body the body.

• Adipose provides a source of energy for ATP production.

Page 23: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Deep Fascia

• Dense fibrous connective tissue– surrounds the muscles, bones, nerves and blood vessels.

Page 24: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Skin Color

• Three pigments contribute to skin color– Melanin – yellow to reddish-brown to black

pigment, responsible for dark skin colors• Freckles and pigmented moles – result from local

accumulations of melanin.

– Carotene – yellow to orange pigment, most obvious in the palms and soles of the feet.

– Hemoglobin – reddish pigment responsible for the pinkish hue of the skin.

Page 25: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Assessment of Skin color

• Cyanosis is a bluish discoloration of the skin or mucous membranes • caused by lack of oxygen in the blood.

• Yellowish color • may indicate cirrhosis of the liver due to accumulating bile

pigments in body tissue.• Pallor or Blanching:

• can be sign of anemia or emotional or physical stress ( Heart Attack)

• Black and Blues: • Bruises caused by blood escapes circulation and clots

underneath the skin. • Red color( erythema)

• indicate fever, allergy, infection inflammation and embarrassment.

Page 26: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Skin Cancer

• Most skin tumors are benign and do not metastasize however:

• The three major types of skin cancer are:a) Basal cell carcinoma

b) Squamous cell carcinoma

c) Melanoma

Page 27: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2
Page 28: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Basal Cell Carcinoma (a)

• Least malignant and most common skin cancer.

• Stratum basale cells proliferate and invade the dermis and hypodermis.

• Slow growing and do not often metastasize.

• Can be cured by surgical excision in 99% of the cases.

Page 29: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Squamous Cell Carcinoma (b)

• Arises from keratinocytes of stratum spinosum.

• Arise most often on scalp, ears, and lower lip.

• Grows rapidly and metastasizes if not removed.

• Prognosis is good if treated by radiation therapy or removed surgically.

Page 30: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Melanoma (c)

• Cancer of melanocytes is the most dangerous type of skin cancer because it is:– Highly metastatic– Resistant to chemotherapy

• Treated by wide surgical excision accompanied by immunotherapy.

• Chance of survival is poor if the lesion is over 4 mm thick.

Page 31: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Melanoma

• Melanomas have the following characteristics (ABCDE rule)– A: Asymmetry; the two sides of the pigmented

area do not match. – B: Border is irregular and exhibits indentations.– C: Color (pigmented area) is black, brown, tan,

and sometimes red or blue.– D: Diameter is larger than 6 mm. (size of a

pencil eraser)– E: Evolution : Is the mole changing?

Page 32: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Burns• Hot water, sunlight,

radiation, electric shock or acids and bases.– Death from fluid loss and

infection.

First-degree – only the epidermis is damaged– Symptoms include

localized redness, swelling, and pain.

Page 33: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Second-degree – epidermis and upper regions of dermis are damaged.– Symptoms mimic first

degree burns, but blisters also appear.

Page 34: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

• Third-degree – entire thickness of the skin is damaged.– Burned area appears

gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed.)

Page 35: The Integumentary System. Skin (Integument ) Overview of the Skin Largest organ of the body (15% of body weight) Skin thickness variable, normally 1-2

Rule of Nines

• Estimates the severity of burns

• Burns considered critical if:– Over 25% of the body

has second-degree burns

– Over 10% of the body has third-degree burns

• third-degree burns on face, hands, or feet.