Integumentary System Notes

Overview

• The integumentary system is the body's largest organ system.

• Comprises skin, hair, nails, and associated glands.

• Functions as a protective barrier, regulates temperature, and provides sensory information.

Components

1. Skin

• Epidermis:

  • Outermost layer, composed of stratified squamous epithelium.

  • Contains keratinocytes (produce keratin), melanocytes (produce melanin), and Langerhans cells (immune response).

• Dermis:

  • Beneath the epidermis, thicker layer.

  • Contains connective tissue, blood vessels, nerves, hair follicles, and glands.

  • Divided into two layers:

    • Papillary Layer: Contains dermal papillae, increases surface area for exchange.

    • Reticular Layer: Dense irregular connective tissue, provides strength and elasticity.

• Hypodermis (Subcutaneous Layer):

  • Not part of the skin but supports it.

  • Composed of loose connective tissue and fat, insulates and absorbs shock.

2. Hair

• Composed of keratinized cells.

• Functions: protection, regulation of body temperature, and sensory perception.

• Hair follicles are embedded in the dermis.

3. Nails

• Protect the distal phalanx and enhance fine touch.

• Composed of hard keratin.

• Nail growth occurs at the nail matrix.

4. Glands

• Sebaceous Glands:

  • Produce sebum (oil) to lubricate skin and hair.

• Sweat Glands:

  • Eccrine Glands: Regulate body temperature through sweat.

  • Apocrine Glands: Associated with hair follicles, produce thicker sweat, activated during stress or sexual arousal.

Functions

• Protection: Shields against pathogens, UV radiation, and physical injury.

• Temperature Regulation: Through sweat production and blood flow adjustments.

• Sensation: Contains receptors for touch, pressure, pain, and temperature.

• Metabolic Functions: Synthesizes vitamin D upon UV exposure, important for calcium metabolism.

• Excretion: Eliminates waste products through sweat.

Disorders

• Acne: Inflammation of sebaceous glands.