Skin and Body Membranes I and II Types of Body Membranes

Cutaneous, mucus, serous

The Integumentary System (Skin)

Skin Structure (epidermis, dermis)

Skin Color (pigments and body conditions)

Appendages of the Skin (oil & sweat, hair, nails)

Diseases/Injuries to Skin (infections, burns, cancer)

Changes in the Skin Over a Lifetime

Mucous Membranes: Prone to Dessication

Also:

Urethra

Vaginal tract

Digestive tract, anus

Nostrils

Epithelium of the esophagus

Found lining the inside edges of organs or tracts

that empty into the exterior of the body

Serous Membranes- Thin linings of organs and body wall

• Parietal serosae line internal body walls

• Visceral serosae cover internal organs

Connective Tissue Membrane Synovial membrane

Cutaneous Membrane

Functions of the Integumentary System1. Protection (chemical, physical, biological)

2. Body temperature regulation ( perspiration, dermal vessels)

3. Cutaneous sensations (temperature, touch, and pain)

4. Metabolic functions (synthesis of vitamin D precursor and collagenase; chemical conversion of carcinogens and some hormones

5. Blood reservoir—up to 5% of body’s blood volume

6. Excretion—nitrogenous wastes and salt in sweat

Skin Structure

Epidermis Keratinized stratified squamous epithelium

Cells of epidermis

Keratinocytes—produce fibrous protein keratin

Melanocytes

10–25% of cells in lower epidermis

Produce brown pigment melanin

Epidermal dendritic (Langerhans) cells—macrophages that help activate immune system

Tactile (Merkel) cells—touch receptors

Detail of Epidermal Skin Structure

Melanocyte

Melanin granule

Tactile (Merkel) cell

Sensorynerve ending Epidermal

dendritic cell

Dermis

KeratinocytesStratum corneum20-30 layers of dead keratinized cells; glycolipids in interstitial spaces.

Stratum granulosumThree to five layers of flattened cells,organelles deteriorating; cytoplasm full of released lipids

Stratum spinosumSeveral layers of keratinocytes unified by desmosomes.

Stratum basaleone row of actively mitotic stem cells; melanocytes and epidermaldendritic cells.

Desmosomes

Mnemonic: Basically, the spinning by granny is loose and corny.

Stratum lucidumVery thin layer of dead, translucent keratinocytes; only palms, soles of feet

Dermis Strong, flexible connective tissue

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

Two layers:

Papillary

Reticular

Skin Structure

Figure 5.1

Epidermis

Hair shaft

Dermis Reticularlayer

Papillarylayer

Hypodermis(superficial fascia)

Dermal papillae

Pore

Subpapillaryvascular plexus

Appendagesof skin

• Eccrine sweat gland• Arrector pili muscle• Sebaceous (oil) gland• Hair follicle• Hair rootNervous structures

• Sensory nerve fiber• Pacinian corpuscle• Hair follicle receptor (root hair plexus)

Cutaneous vascularplexus

Adipose tissue

Layers of the Dermis: Papillary Layer Papillary layer

Areolar connective tissue with collagen and elastic fibers and blood vessels

Dermal papillae contain:

Capillary loops

Meissner’s corpuscles (touch se0nsing)

Free nerve endings .1

Layers of the Dermis: Reticular Layer Reticular layer

~80% of the thickness of dermis

Collagen fibers provide strength and resiliency

Elastic fibers provide stretch-recoil properties

Pacinian corpuscles (pressure and vibration sensing)

Normal Skin Color Determinants Chemicals in the Skin

Melanin

Carotene

Hemoglobin

Body Conditions

Erythmea (from embarrassment, fever, tension)

Pallor/Blanching (stress, etc.)

Jaundice from liver disease

Bruises from hematomas

Cyanosis from low blood oxygen

Appendages of the Skin Derivatives of the epidermis

Sweat glands

Oil glands

Hairs and hair follicles

Nails

Cutaneous Glands: Sebaceous & SweatEccrine (Merocrine)

Sweat Glands

water

salts

vitamin C

metabolic wastes

ammonia

urea

uric acid

lactic acid

Sebaceous glands

(holocrine)

Sebum

- fragmented cells

- fatty acids

- Low pH

(antibacterial)

Apocrine sweat glands confined to axillary and genital areas

- Sebum: sweat + fatty substances and proteins

-Ducts connect to hair follicles

-Functional from puberty onward (as sexual scent glands?)

Specialized apocrine include

- Ceruminous glands

- Mammary glands

Appendages of the Skin: Hair Hair and Hair Follicles

Appendages of the Skin: Hair

Hair follicle

and arrector

pili muscle

Appendages of the Skin: Nails Finger Nail and Nail Bed

(Eponychium)

Abnormal or Injured Skin Conditions Infections and Allergies of the Skin

Athletes foot (caused by tinea pedia fungus)

Boils and carbuncles (caused by inflammation and/or bacterial infection of oil glands or follicles

Cold sores (caused by viruses like Herpes)

Contact dermatitis (caused by allergic reaction)

Impetigo (caused by staph bacteria)

Psoriasis (scaly skin caused by overproduction and of cells)

Burns Heat, electricity, radiation, certain chemicals

Burn

(tissue damage, denatured protein, cell death)

Immediate threat:

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

Abnormal or Injured Skin ConditionsThe Rule of Nines for Estimating Burned Surface Area

Burns are critical if:

• >25% has second-degree

• >10% has third-degree

• Any of face, hands, or feet with third-degree

Abnormal or Injured Skin Conditions

Burns

First-degree burns

Only epidermis is damaged

Skin is red and swollen

Second degree burns

Epidermis and upper dermis are damaged

Skin is red with blisters

Third-degree burns

Destroys entire skin layer

Burn is gray-white or black

Partial

thickness burns

Full

thickness

burn

Abnormal or Injured Skin ConditionsCancers (Cause: UV, freq. irritation)

Basal cell carcinoma

Least dangerous

Most common type

Arises from stratum basale

Squamous cell carcinoma

Arises from stratum spinosum

Metastasizes to lymph nodes

Early removal allows a good chance of cure

Abnormal Conditions: Skin Cancer Types

Malignant melanoma

Most deadly of skin cancers

Cancer of melanocytes

Metastasizes rapidly to lymph and blood vessels

Detection uses ABCD rule

ABCD Rule in Detecting Melanoma

Skin Tags (Acrochordons/ Cutaneous Papillomas)

Skin tags are benign growths that are not cancerous

Skin Changes Over a Lifetime

lanugo milia acne

dermatitis

vernix caseosa aging skin