Tissues and Membranes Overview

Tissues and Membranes

• Tissues are groups of similar cells working together, with shared structure and function.
• Membranes are thin sheets of tissue covering surfaces, lining body cavities, and surrounding organs.
• Four major tissue types: epithelial, connective, nervous, and muscular.
• Histology is the study of tissues.
• Epithelial tissue covers surfaces, lines cavities, and performs secretion, absorption, and protection.
  • Classified by cell shape (squamous, cuboidal, columnar) and layers (simple, stratified).
  • Simple squamous: thin, flat cells (e.g., walls of blood vessels).
  • Simple cuboidal: cube-shaped cells (e.g., kidney tubules).
  • Simple columnar: tall, narrow cells (e.g., digestive tract).
  • Pseudostratified columnar: appears layered but is single-layered (e.g., respiratory tract). Stratified squamous: multiple layers of cells (e.g., skin).
  • Stratified cuboidal: multiple layers of cuboidal cells (rare).
  • Stratified columnar: multiple layers of columnar cells (rare).
  • Transitional: specialized cells that change shape (e.g., urinary bladder).
• Connective tissue is the most abundant tissue type, providing support, connection, protection, and storage.
  • Found in blood, under skin, bone, around many organs.
  • Connects, protects, stores fat, and transports.
  • Composed of cells embedded in an extracellular matrix (liquid, gel-like, or solid).
  • Contains fibers like collagen (strong), elastin (stretchy), and reticular (fine collagen).
  • Types: loose connective (areolar, adipose, reticular), dense fibrous connective (tendons, ligaments, fascia), cartilage (hyaline, elastic, fibrocartilage), and bone (osseus tissue).
• Nervous tissue transmits electrical signals.
  • Contains neurons (transmit signals) and neuroglia (support neurons).
• Muscle tissue contracts to cause movement.
  • Types: skeletal (attached to bones), smooth (walls of internal organs), and cardiac (heart).
• Membranes include epithelial membranes (cutaneous, mucous, serous) and connective tissue membranes (synovial, periosteum, perichondrium, meninges, fascia)
• Protection, absorption, filtration, and secretion are among the crucial functions of epithelial membranes.
• Specialized functions of particular tissues, such as protection, secretion, support, and others are crucial.

Tissue Functions

• Protection: Skin and some types of epithelial tissue shield the body from the elements and pathogens.
• Absorption: Epithelial tissue in the digestive tract absorbs nutrients.
• Filtration: Epithelial tissue filters substances in structures like the kidneys.
• Secretion: Epithelial glands secrete hormones and other substances.
• Support: Connective tissue supports the body and connects its parts.
• Movement: Muscle tissue enables body movements; skeletal muscle controls movements.
• Conduction: Nervous tissue transmits information throughout the body.