Overview
This lecture covers the four main types of tissue membranes in the body, their locations, functions, and also explains the basics of inflammation and tissue healing after injury.
Types of Tissue Membranes
- Tissue membranes are thin sheets of cells lining body organs, cavities, and joints.
- Four types: mucous membranes, serous membranes, cutaneous (skin) membranes, and synovial membranes.
Mucous Membranes
- Line body cavities open to the external environment (e.g., respiratory, digestive, urinary tracts).
- Contain goblet cells that secrete mucus to trap debris and pathogens.
- Examples: nasal, oral, esophageal, bronchial, gastric mucosa.
Serous Membranes
- Line and cover internal body cavities and some organs (e.g., pericardium, pleura, peritoneum).
- Produce serous fluid to reduce friction as organs move (e.g., heart, lungs, intestines).
Cutaneous Membrane
- Refers to the skin, which protects against pathogens and prevents dehydration.
- Made of keratinized stratified squamous epithelium and underlying connective tissue (dermis, hypodermis).
- Contains sweat glands and sebaceous glands for secretion.
Synovial Membrane
- Lines movable joints (e.g., elbow, hip, knee).
- Produces synovial fluid to lubricate and nourish joint cartilage, reducing friction during movement.
Inflammation and Tissue Healing
- Inflammation is the body's initial response to injury, characterized by redness (rubor), heat (calor), pain (dolor), swelling (tumor), and loss of function (functio laesa).
- Redness and heat result from increased blood flow; pain alerts to injury; swelling contains damage; loss of function is due to tissue compromise.
- Acute inflammation is short-term; chronic is long-lasting.
- Healing starts with removal of debris/toxins, clot formation to stop bleeding, and granulation tissue formation for tissue regeneration.
- White blood cells are recruited by chemotaxis to fight infection and clean debris.
- New tissue forms from deep to superficial layers; repaired tissue may have reduced function compared to the original.
Key Terms & Definitions
- Tissue membrane — Thin sheet of cells lining or covering parts of the body.
- Mucous membrane — Lines body cavities open to the outside; secretes mucus.
- Serous membrane — Lines internal cavities; secretes serous fluid to reduce friction.
- Cutaneous membrane — The skin; a protective, keratinized epithelial membrane.
- Synovial membrane — Lines joint cavities; produces lubricating synovial fluid.
- Inflammation — Body’s response to injury with redness, heat, pain, swelling, and loss of function.
- Granulation tissue — New tissue forming during healing.
- Chemotaxis — Movement of white blood cells toward injury or infection.
Action Items / Next Steps
- Review the functions and locations of each tissue membrane.
- Understand the sequence and signs of inflammation and healing processes.