Tissues

• Tissues


  The four basic types of tissue that make up the human body
• Four basic types of tissue

  • Epithelial tissue
  • Connective tissue
  • Muscular tissue
  • Nervous tissue
• Epithelial tissue


  May be divided into two types: Covering and lining epithelium, and Glandular epithelium
• Epithelial tissue


  • Lining epithelium forms the outer covering of the skin and the outer covering of some internal organs
  • It also lines body cavities
• Epithelial tissue can be arranged in layers
• Cell shapes in epithelial tissue

  • Simple squamous
  • Simple cuboidal
  • Simple columnar (nonciliated/ciliated)
  • Pseudostratied columnar (nonciliated/ciliated)
  • Stratified squamous (keratinized and non-keratinized)
  • Stratified cuboidal
  • Stratified columnar
  • Transitional
• Types of glands in epithelial tissue

  • Endocrine glands
  • Exocrine glands
• Epithelial tissue has various functions including covering, lining, and glandular functions
• Connective tissue


  One of the most abundant and widely distributed tissues in the body, with a variety of functions including binding, supporting, and strengthening other body tissues, protecting and insulating internal organs, compartmentalizing structures, transporting substances, storing energy reserves, and facilitating immune responses
• Connective tissue


  • Consists of cells and extracellular matrix, which includes protein fibers and ground substance
• Types of connective tissue cells

  • Fibroblasts
  • Macrophages
  • Plasma cells
  • Mast cells
  • Adipocytes
• Ground substance


  The component of connective tissue between the cells and fibers that supports cells, binds them together, and provides a medium for substance exchange
• Types of fibers in the extracellular matrix

  • Collagen fibers
  • Elastic fibers
  • Reticular fibers
• Collagen fibers


  • Branched and form networks, resist pulling forces, often in parallel bundles
• Elastic fibers


  • Composed of elastin surrounded by fibrillin, stretchy (can extend to 1.5x their length), promote flexibility and allow tissue to expand and recoil
• Reticular fibers


  • Branched networks that support blood vessel walls and provide a framework for soft organs
• Types of connective tissue

  • Loose connective tissue (areolar, adipose, reticular)
  • Dense connective tissue (dense regular, dense irregular, elastic)
• Cartilage


  • Consists of a dense network of collagen or elastic fibers embedded in chondroitin sulfate, with chondrocytes occurring singly or in groups within lacunae; has no blood supply so heals poorly
• Types of cartilage


  • Hyaline cartilage
  • Fibrocartilage
  • Elastic cartilage
• Bone


  • Supports soft tissues, protects delicate structures, generates movement with skeletal muscles, stores calcium and phosphorus, houses red and yellow bone marrow
• Blood and lymph


  Liquid connective tissues with a liquid extracellular matrix
• Membranes


  Flat sheets of pliable tissue that cover or line a part of the body, consisting of an epithelial layer and an underlying connective tissue layer
• Types of membranes


  • Mucous membranes
  • Serous membranes
  • Synovial membranes
• Muscular tissue


  • Consists of elongated muscle fibers that are highly specialized to generate force, producing motion, maintaining posture, and generating heat
• Types of muscular tissue

  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
• Skeletal muscle


  • Multinucleated structures with actin and myosin proteins arranged in striations, exhibiting voluntary control
• Smooth muscle


  • Spindle-shaped, shorter than skeletal muscle fibers, produce connective tissue, lack striations and sarcomeres
• Cardiac muscle


  • Striated and organized into sarcomeres, shorter than skeletal muscle fibers, one nucleus in the central region, many mitochondria and myoglobin, connected by intercalated discs to contract in a wave-like pattern
• Nervous tissue


  Consists of neurons that generate and conduct nerve impulses, and neuroglia that have protective and supportive functions
• Neurons


  • The cell body (soma) contains the nucleus and mitochondria, dendrites transfer nerve impulses to the soma, and the axon carries the action potential away to another excitable cell
• Types of neuroglia


  • Astrocytes
  • Microglia
  • Oligodendrocytes
  • Ependymal cells
• Tissue repair


  The process that replaces worn-out, damaged, or dead cells, originating from the stroma or parenchyma, which can lead to tissue regeneration or scar tissue formation (fibrosis)
• Aging


  Tissues heal slower and leave more obvious scars, extracellular components like collagen and elastic fibers change, bones lose calcium and minerals, fluid decreases in cartilage, tissues including muscles undergo atrophy, blood vessels and airways become more rigid, and the central nervous system loses mass and nerve transmission slows
• Sjögren's syndrome is a multisystem inflammatory disorder that can cause diminished lacrimal and salivary gland function, dryness of the skin and other mucosal surfaces, arthritis, nephritis, cytopenia, pneumonitis, vasculitis, peripheral neuropathy, myelopathy, cognitive disturbances, and an increased risk of lymphoma
• The hypodermis (subcutaneous tissue) is the deepest layer of skin that attaches to underlying muscles and bones.
• The dermis is the middle layer of skin that contains blood vessels, nerves, hair follicles, sweat glands, and oil glands.
• The epidermis is the outermost layer of skin, made up of several layers of cells.
• The epidermis is the outermost layer of skin that protects against injury and infection.
• The stratum basale is the innermost layer of the epidermis where new cells are produced through mitosis.
• The epidermis is the outermost layer of skin composed of stratified squamous epithelium with five layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.