chapter 6/Integumentary System

Overview of the Integumentary System

• The integumentary system is composed of the skin and its associated structures.
• Major components include the epidermis, dermis, subcutaneous layer, hair, nails, and various glands.

Layers of the Skin

Epidermis

• Structure: Outermost layer, consists of stratified squamous epithelium.
• Layers:
  • Stratum corneum (most superficial, keratinized, constantly shed)
  • Stratum basale (deepest, produces new epithelial cells)
• Functions: Protection from wear and tear, UV protection due to melanin.

Dermis

• Structure: Beneath the epidermis, composed of connective tissue, vascular.
• Contains: Hair follicles, sebaceous glands, sweat glands, sensory receptors, blood vessels.
• Functions: Nourishes epidermis, provides skin elasticity, sensory perception.

Subcutaneous Layer

• Structure: Beneath dermis, composed mainly of loose connective tissue and adipose tissue.
• Functions: Connects skin to underlying muscles, regulates temperature, provides insulation.

Accessory Structures

• Sebaceous (Oil) Glands:
  • Structure: Saclike glands associated with hair follicles.
  • Function: Secrete sebum that lubricates skin and hair.
• Sweat (Sudoriferous) Glands:
  • Structure: Coiled glands venting to skin surface.
  • Function: Release perspiration for thermoregulation and excretion of wastes.
• Hair: Composed of keratin, grows from a follicle; functions in insulation and protection.
• Nails: Protects distal ends of fingers and toes, assist in grasping objects.

Functions of the Integumentary System

• Protection against infection and dehydration.
• Regulation of body temperature (vasodilation and vasoconstriction).
• Sensory information collection via nerve endings and receptors.
• Minor excretion of waste products through sweat.
• Production of vitamin D.

Observations of Skin

• Skin color is influenced by:
  • Melanin: Brown pigment.
  • Hemoglobin: Red pigment.
  • Carotene: Yellowish-red pigment.
• Cyanosis: Bluish discoloration due to lack of oxygen.
• Jaundice: Yellow discoloration related to bile pigment.

Repair of the Integument

Steps in Wound Healing

1. Inflammation: Blood brings healing cells and factors.
2. New blood vessel growth.
3. Fibroblasts produce new connective tissue.
4. Epithelial cells proliferate to cover the wound.

• Factors Affecting Healing: Nutrition, blood supply, infection, age.

Aging Effects on the Integumentary System

• Thinning skin, formation of wrinkles, decreased pigmentation, reduced circulation.
• Changes in hair thickness and sweat gland activity.

Disorders of the Integumentary System

• Common Disorders:
  • Skin lesions (e.g., macules, papules, vesicles).
  • Pressure ulcers (decubitus ulcers, bedsores).
  • Burns (categorized by depth).
  • Skin cancer (basal cell, squamous cell, melanoma).
  • Infections (bacterial, viral, fungal).
  • Inflammatory conditions (dermatitis, psoriasis).
  • Accessory organ disorders (acne, alopecia).

Skin Cancer

• Most common cancer type in the US includes basal cell carcinoma, squamous cell carcinoma, and melanoma.
• Risk factors include sun exposure and skin type.

Inflammatory Disorders

• Dermatitis: Inflammation characterized by redness, heat, and itching.
• Psoriasis: Autoimmune condition characterized by rapid skin cell growth, leading to scaling and redness.

Pop Quiz & Review Points

• Important terms related to skin disorders, repairs, and functions should be memorized.
• Comprehension of mechanisms and changes associated with both normal and pathological states of the skin is crucial for exams.