New Recording 34

Body Membranes

• Body membranes serve essential functions and can be classified based on their tissue origins.

Epithelial Membranes

• Arise from epithelial tissue.

• Major types include:

  • Mucous Membrane

    • Covers body cavities that open to the exterior (e.g., mouth, nose, genital areas).

    • Always moist, with mucus produced by specialized cells.

  • Serous Membrane

    • Covers organs and cavities not open to the exterior (e.g., pleura around lungs, pericardium around heart).

    • Notable for having two layers:

      • Parietal Layer: outer layer that lines the cavity.

      • Visceral Layer: inner layer that covers the organs.

    • Contains serous fluid in the cavity between the layers to cushion organs.

  • Cutaneous Membrane

    • The skin itself, providing a protective barrier.

Connective Tissue Membranes

• Composed of connective tissue.

• Synovial Membrane

  • Found in joints, covering bones and cartilage.

  • Provides lubrication to prevent friction and pain in joints.

Functions and Importance of Membranes

• Membranes are crucial for protecting organs and facilitating various physiological functions.

• Serous membranes allow movement of organs without friction through lubrication.

• During medical diagnosis, serous fluid may be withdrawn from the space for testing.

Skin Overview

• The skin is the heaviest organ of the body and serves various vital functions.

• Major functions include:

  • Protection: Acts as the first line of defense against pathogens.

  • Regulation: Controls water loss, electrolytes, and temperature.

  • Sensory Perception: Hosts numerous sensory receptors for touch, pressure, temperature, and pain.

  • Vitamin D Production: Assists in synthesis of the active form of vitamin D.

Skin Structure

• Composed of two main layers:

  • Epidermis: Outermost layer, thinner than dermis; mostly made up of dead cells. Contains:

    • Multiple layers:

      • Stratum Basale: innermost, actively reproducing cells.

      • Stratum Spinosum: cells begin to shrink and die.

      • Stratum Granulosum: cells are dead but contain granules.

      • Stratum Lucidum: only present in thick skin (e.g., palms).

      • Stratum Corneum: outermost layer of dead, keratin-filled cells, providing waterproofing.

  • Dermis: Thicker layer beneath epidermis containing blood vessels, sensory receptors, hair follicles, and glands.

• Hypodermis: Below the dermis, primarily composed of fat, providing insulation and anchoring.

Integumentary System

• The integumentary system comprises the skin and its appendages, playing a vital role in protection and sensation.

• Melanin: Pigment in skin cells that determines color and offers protection against UV radiation.