Integumentary System Overview

Integumentary System

• The integumentary system comprises the skin and its appendages (sweat glands, oil glands, hair, and nails)
• The skin is the largest organ, accounting for approximately 7% of total body weight.

Integumentary Objectives

• Describe the epidermis, dermis, and hypodermis
• Understand the function of each skin layer
• Describe factors influencing skin color and appearance
• Identify skin appendages
• Identify various skin disorders
• Explain age-related skin changes

Skin

• Epidermis: Keratinized stratified squamous epithelium containing keratinocytes, melanocytes, Merkel cells and Langerhans cells. It has 5 layers (thick skin) or 4 layers (thin skin) - stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (absent in thin skin), and stratum corneum.
• Dermis: Connective tissue with blood vessels, nerve fibers, collagen, and elastin fibers. Contains cells and fibers typical of connective tissue proper.
• Hypodermis: Adipose tissue ("subcutaneous fatty tissue"). Holds the body together and provides resilience.

Skin Layers

• Epidermis (keratinized stratified squamous epithelium): Contains keratinocytes, melanocytes, Merkel cells, and Langerhans cells. Composed of 5 layers (thick skin) or 4 (thin skin). Stratum corneum is primarily dead keratinocytes and glycoprotein.
• Dermis: Connective tissue proper containing collagen and elastin fibers. Contains blood vessels and nerve fibers.
• Hypodermis: Composed primarily of adipose tissue/subcutaneous tissue. Supports the skin.

Keratin

• Keratin is a protein that is the main component of the stratum corneum (the outermost layer of the epidermis). It provides protection and water resistance.

Skin Color

• Skin color results from a combination of melanin, carotene, and hemoglobin.
• Melanin is based on tyrosine and ranges from yellow to brown to black.
• Carotene is obtained from vegetables, producing a yellow-orange color concentrated in the stratum corneum.
• Hemoglobin (oxygenated) is bright red, contributing a pinkish hue to Caucasian skin.

Significance of Skin Color

• Skin color changes temporarily or permanently due to various causes, from simple homeostatic responses to serious conditions.
• Pallor is abnormal paleness from low melanin levels or reduced blood flow, while erythema is increased redness from various factors.

Skin Disorders

• Bacterial infections (impetigo, boils)
• Viral infections (warts, herpes, shingles, chickenpox)
• Parasitic disorders (lice, scabies)
• Fungal infections (tinea [ringworm, athlete's foot, jock itch])
• Lesions (psoriasis, keloids, nevi [moles], bedsores)

Appendages of the Skin

• Hair: Dead keratinized cells from the hair follicle.
• Sebaceous glands: Secrete sebum (oil) for skin protection and conditioning.
• Sweat glands: Secrete sweat (mostly water), primarily for thermoregulation.
• Nails: Scale-like modifications of the epidermis.

Burns

• Serious threat to life.
• Causes rapid fluid loss, reduced blood flow, and increased risk of infection.
• Classified by severity as first, second, and third degree.

1st-degree burns

• Only affect the epidermis.
• Characterized by redness, swelling, and pain (e.g., sunburn).
• Heal in a few days.

2nd-degree burns

• Damage the epidermis and upper dermis.
• Characterized by blisters, redness, swelling, and pain.
• Heal in 3-4 weeks; slight infection possibility.

3rd-degree burns

• Destroy the entire skin thickness.
• May extend to the hypodermis or underlying tissues.
• Appear white, red, or blackened.
• Severe fluid loss and infection risk.
• Require extensive intervention for healing.

Rule of Nines

• Method for estimating the extent of burns on the body by percentage body areas. Used to assess the severity of burn injuries.

Thermoregulation & Homeostasis

• The skin plays a role in thermoregulation through vasodilation (increased blood flow) and vasoconstriction (reduced blood flow). Sweat glands also contribute via evaporation.

Skin Cancer

• Basal cell carcinoma
• Squamous cell carcinoma
• Melanoma

Aging

• During adolescence, androgens contribute to acne.
• Peak skin health is in the 20s and 30s.
• Middle age: Collagen decreases, skin becomes drier, less elastic, and wrinkles appear.
• Skin heals more slowly.

Explore the integumentary system, focusing on the structure and function of the skin and its appendages. Learn about the epidermis, dermis, hypodermis, skin disorders, and age-related changes in skin. Dive into the complexities of skin color and appearance.