Chapter 3 Membranes &

Integumentary System (p. 81- 107)

Skin

• Our skin is an organ• It makes up about 15% of your total body weight

• Considered the “Integumentary System” because it…

• Contains glands and sensory receptors

• Grows hair and nails

Membranes

• Surround and help protect the body’s surfaces

• 2 Categories

• 1. Epithelial membranes

• 2. Connective Tissue membranes

Epithelial Membranes

• Provide a lining for internal and external surfaces of the body

• Epithelial membranes are composed of…

• Sheet of epithelial cells

• Underlying layer of connective tissue

Epithelial Membranes

• There are 3 types of epithelial membranes

• 1. Mucous Membranes

• 2. Serous Membranes

• 3. Cutaneous Membranes

Mucous Membranes

• Mucous: slippery solution that protects mucous membranes and aids in transporting substances

• Line body cavities that open to the outside world

• Respiratory tract (nose, lungs)

• Digestive tract (mouth, stomach)

• Urinary tract (bladder)

• Reproductive tract

Serous Membranes

• Serous fluid: a thin, clear fluid that serves as a lubricant between the parietal and visceral membranes to minimize friction and “wear and tear” on organs

• Line body cavities that are closed to the outside world

• Pleura (around the lungs)

• Pericardium (around the heart)

• Peritoneum (around the abdominal cavity)

Cutaneous Membrane

• What we know as “skin”

• Keratinizing stratified squamous epithelium

• Underlying dense fibrous connective tissue

• Dry membrane when sweat is not present

• Contain sweat glands

Connective Tissue Membranes

• The only membrane only made up of connective tissue

• Include no epithelial cells

• Only one type: Synovial membranes

• Line capsules that surround synovial joints (shoulders and knees)

• Serve as cushions for tendons and ligaments surrounding joints

• Synovial fluid: clear fluid which provides cushioning and reduces friction and wear on moving structures

Functions of the Integumentary System

• 1. Protection• First line of defense

• Outermost layer of skin contains keratin

• Tough protein also in hair and nails

Functions of Integumentary System

• 2. Water Barrier• Keratin and natural skin oils serve as a water

barrier

• Lessens evaporation of water

• Prevents water entering body while swimming or bathing

Functions of Integumentary System

• 3. Temperature Regulation• Sweat glands and capillaries lie close to surface of

the skin

• Body is hot capillaries dilate allows heat to leave

• Sweat glands activate, sweat evaporates, skin cools

• Body is cold capillaries constrict blood flow moves toward core of body to minimize heat loss

Functions of Integumentary System

• 4. Vitamin D Production• Melanocytes: specialized cells in the skin that produce

melanin

• Melanin: pigment that protects the body against harmful UV rays

• UVB rays convert modified cholesterol molecules into vitamin D

• Vitamin D: essential for bone health

Functions of Integumentary System

• 5. Waste Elimination• Sweating eliminates chemical waste products from the body

• Urea, uric acid, salts

**Sweat is acidic and helps protect the body against bacterial infections!**

Functions of Integumentary System

• 6. Sensory Perception• Cutaneous sensory receptors are part of the

nervous system

• Transmit nerve signals from the skin to the central nervous system

• Touch, pressure, vibration, pain, temperature