Chapter 4: Skin and Body Membranes Pages 109-112

What are Body Membranes? Layers of tissues that serve to: Cover body surfaces Line body cavities Form protective sheets around organs Membranes are classified according to tissue types If you think about the function of a tissue, you can figure out where you’ll find specific membranes © 2015 Pearson Education, Inc.

Classification of Body Membranes There are two major membrane systems: Epithelial Membranes Connective Membranes There is a pattern to membrane arrangement, especially around organs Once you remember the pattern, you can predict the specific arrangement © 2015 Pearson Education, Inc.

Functions of Membranes Epithelial membranes- these cover or line There are three groups: Cutaneous membranes Mucous membranes Serous membranes Connective tissue membranes- cushion, line/cover, lubricate to prevent friction Synovial membranes

Epithelial: Cutaneous Membranes This is your skin a dry membrane Two main layers: epidermis and dermis Epidermis: (superficial) Composed of stratified squamous epithelium Dermis: (lies deep to the epidermis) Mostly dense, fibrous connective tissue the basement membrane © 2015 Pearson Education, Inc.

• Sebaceous (oil) gland • Hair follicle • Hair root Figure 4.3 Skin structure. Hair shaft Dermal papillae Epidermis Papillary layer Pore Appendages of skin • Eccrine sweat gland • Arrector pili muscle Dermis Reticular layer • Sebaceous (oil) gland • Hair follicle • Hair root Hypodermis (subcutaneous tissue) Cutaneous vascular plexus Nervous structures • Sensory nerve fiber Adipose tissue • Lamellar corpuscle • Hair follicle receptor (root hair plexus)

Epithelial: Mucous Membranes Epithelial layer that rests on a connective tissue layer lamina propria: Underlying loose connective tissue that forms the basement membrane Mucous membranes line all body cavities that open to the exterior body surface Mouth/nose, esophagus, digestive tract, bronchi Wherever there is a need to absorb and/or secrete © 2015 Pearson Education, Inc.

Figure 4.1b Classes of epithelial membranes. Mucous Membranes Mucosa of nasal cavity Mucosa of mouth Esophagus lining Mucosa of lung bronchi (b) Mucous membranes line body cavities open to the exterior.

Epithelial: Serous Membranes Lines open body cavities that are closed to the exterior of the body such as the: Abdominal cavity Thoracic cavity (Exceptions are the dorsal cavity and joints) Serous membranes occur in pairs Pairs are separated by serous fluid This arrangement allows organs to slide past one-another w/o friction

The Pairing System Parietal layer: lines a portion of the wall of the ventral body cavity; like a perimeter lining Visceral layer: covers the outside of the organ This tissue is actually an extension of the parietal layer, but it folds back on itself to form the visceral layer © 2015 Pearson Education, Inc.

Figure 4.1d Classes of epithelial membranes. Outer balloon wall (comparable to parietal serosa) Air (comparable to serous cavity) Inner balloon wall (comparable to visceral serosa) (d) A fist thrust into a flaccid balloon demonstrates the relationship between the parietal and visceral serous membrane layers.

Specific serous membranes: Peritoneum Abdominal cavity Pleura Around the lungs Pericardium Around the heart © 2015 Pearson Education, Inc.

Figure 4.1c Classes of epithelial membranes. SEROUS MEMBRANES Parietal pleura Parietal peritoneum Visceral pleura Visceral peritoneum Parietal pericardium Visceral pericardium (c) Serous membranes line body cavities closed to the exterior.

Connective: Synovial Made only of connective tissue Lines fibrous capsules surrounding joints: Lines bursae Bursae are sacs containing synovial fluid Lines tendon sheaths Tendon sheaths are an elongated bursa sac Secretes a lubricating fluid to reduce friction © 2015 Pearson Education, Inc.

Figure 4.2 A typical synovial joint. Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous layer Articular capsule Synovial membrane

Bursa sac in the shoulder joint