Integumentary System Overview and Functions

Sep 6, 2024

BSC 2085: Anatomy and Physiology 1

Lecture on the Integumentary System

Introduction

  • Instructor: Professor Mariah Evans
  • Focus: Skin and bones for the next exam.

Overview of the Integumentary System

  • Includes skin, hair, and nails.
  • Involves sweat glands and sebaceous glands.

Structure of Skin

  • Two Main Regions:
    • Epidermis: Superficial layer.
    • Dermis: Underlying layer.
  • Hypodermis: Beneath the skin, not a true skin layer but shares components.

Layers of the Epidermis

  • Thick Skin: 5 layers.
  • Thin Skin: 4 layers.
  • Layers (from deep to superficial):
    • Stratum Basale: Actively mitotic, basal layer.
    • Stratum Spinosum: Prickly layer with spiny keratinocytes.
    • Stratum Granulosum: Granular layer with keratohyalin granules.
    • Stratum Lucidum: Clear layer, only in thick skin.
    • Stratum Corneum: Horny layer, 20-30 layers of dead cells.

Cells in the Epidermis

  • Keratinocytes: Contain keratin.
  • Melanocytes: Produce melanin for skin color.
  • Dendritic (Langerhans) Cells: Immune function, phagocytize invaders.
  • Tactile (Merkel) Cells: Sensory receptors for touch.

Dermis

  • Layers:
    • Papillary Layer: Areolar connective tissue, tactile corpuscles.
    • Reticular Layer: Dense irregular connective tissue, collagen fibers.
  • Contains blood vessels and nerve fibers.

Skin Color

  • Melanin: Pigment protein for skin, eye, and hair color.
  • Carotene: Yellow-to-orange pigment.
  • Hemoglobin: Pinkish hue in fair-skinned individuals.

Sun Exposure and Skin Damage

  • UV damages DNA, can lead to cancer.
  • Destroys folic acid, necessary for DNA synthesis.
  • Photosensitivity from drugs (antibiotics, antihistamines).

Abnormal Skin Colors

  • Cyanosis: Blue skin, lack of oxygen.
  • Erythema: Redness from various causes.
  • Pallor: Pale skin, can indicate anemia or fear.
  • Jaundice: Yellow skin, often due to liver issues.
  • Bronzing: Indicative of steroid hormone imbalance.
  • Bruises: Blood clots under the skin.

Hair

  • Functions: Sensory, protection, heat retention.
  • Structure: Keratinized, color from melanin.
  • Hair growth cycles and thinning with age.
  • Alopecia: Hair loss.
  • Hirsutism: Excessive hair growth.

Nails

  • Made of hard keratin.
  • Fingernails have free edges without nerve endings.

Glands

  • Sweat Glands: Eccrine (most numerous), Apocrine (axillary/anogenital).
  • Sebaceous (Oil) Glands: Secrete sebum, lubricate skin and hair, can lead to acne.

Functions of Skin

  • Protection: Physical, chemical, and biological barriers.
  • Body Temperature Regulation: Sweating and blood flow.
  • Cutaneous Sensations: Sensory receptors for touch.
  • Metabolic Functions: Vitamin D synthesis.
  • Blood Reservoir: Holds 5% of blood volume.
  • Excretion: Nitrogenous wastes through sweat.

Skin Cancer and Burns

  • Types of Skin Cancer: Basal cell carcinoma, squamous cell carcinoma, malignant melanoma (most deadly).
  • Burns:
    • First Degree: Epidermal damage.
    • Second Degree: Affects dermis, blistering.
    • Third Degree: Full thickness, requires grafting.

Conclusion

  • Review of integumentary system structures and functions.