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Anatomy & Physiology: Histology and Tissue Types

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  • What is histology?

    Histology is the study of the normal structures of tissues, which are groups of structurally and functionally related cells and their extracellular matrix performing common functions.

  • What are the four primary tissue types?

    Epithelial, connective, muscle, and nervous tissues, each defined by cell type, ECM amount/composition, and specific functions.

  • What are the two main components of the extracellular matrix (ECM)?

    The ECM consists of ground substance and protein fibers.

  • Name the three types of protein fibers in the ECM and their functions.

    Collagen fibers resist tension, elastic fibers allow stretch and recoil, and reticular fibers form supportive meshworks.

  • What are the three major types of cell junctions and their functions?

    Tight junctions prevent macromolecule passage, desmosomes allow extracellular fluid passage, and gap junctions permit small substance flow between cytoplasm of adjacent cells.

  • What are the main functions of epithelial tissues?

    Protection, immune defense, secretion, selective transport, and sensation.

  • How is epithelial tissue classified?

    By the number of cell layers (simple or stratified) and cell shape (squamous, cuboidal, or columnar).

  • What is the function of the basement membrane in epithelial tissue?

    It anchors epithelial tissue to underlying connective tissue, supports blood vessels, and acts as a barrier.

  • Where is simple squamous epithelium found and what is its function?

    Found in lung air sacs, kidney tubules, and blood vessels; adapted for rapid diffusion of gases and fluids.

  • What distinguishes pseudostratified columnar epithelium?

    It appears layered due to nuclei at different heights but is a single cell layer with all cells contacting the basement membrane; often ciliated.

  • What is the difference between keratinized and nonkeratinized stratified squamous epithelium?

    Keratinized has dead, keratin-filled apical layers for toughness (skin); nonkeratinized has living apical layers and remains moist (mouth, esophagus).

  • What are endocrine and exocrine glands?

    Endocrine glands secrete hormones into the bloodstream; exocrine glands release products onto epithelial surfaces via ducts.

  • Describe merocrine and holocrine secretion methods.

    Merocrine secretion releases products by exocytosis; holocrine secretion releases products when the entire cell ruptures and dies.

  • What are the main functions of connective tissues?

    Connecting and binding tissues, support, protection, and transportation (e.g., blood).

  • What are fibroblasts and their role in connective tissue?

    Fibroblasts are resident cells that produce protein fibers and ground substance of the ECM, especially collagen.

  • Where is loose connective tissue found and what is its function?

    Found beneath epithelium and in membranes; supports blood vessels and houses immune cells.

  • What distinguishes dense irregular from dense regular connective tissue?

    Dense irregular has disorganized collagen fibers resisting tension in multiple directions; dense regular has parallel fibers resisting tension in one direction.

  • What are the three types of cartilage and their characteristics?

    Hyaline: glossy, fine collagen, found in joints and fetal skeleton; fibrocartilage: dense collagen, strong and elastic, found in joints; elastic: elastic fibers, found in ear and larynx.

  • What are the three main bone cell types and their functions?

    Osteoblasts build bone, osteocytes maintain bone, and osteoclasts resorb bone.

  • What are the main cell types in blood and their functions?

    Erythrocytes transport oxygen, leukocytes provide immunity, and platelets aid in blood clotting.

  • What are the three types of muscle tissue and their control mechanisms?

    Skeletal: voluntary, striated; cardiac: involuntary, striated with intercalated discs; smooth: involuntary, nonstriated.

  • What is the function of intercalated discs in cardiac muscle?

    They contain gap junctions and modified tight junctions that allow coordinated contraction of heart muscle cells.

  • What are the main components of a neuron?

    The cell body (soma), axon (transmits impulses away), and dendrites (receive signals).

  • What functions do neuroglial cells perform?

    Support neurons by anchoring, monitoring extracellular fluid, speeding impulse transmission, and circulating cerebrospinal fluid.

  • What is tissue repair and what are the two main outcomes?

    Tissue repair replaces damaged cells by regeneration (same cell type) or fibrosis (scar tissue formation).

  • Which tissues typically regenerate and which heal by fibrosis?

    Epithelial and most connective tissues regenerate; cartilage, cardiac and skeletal muscle, and nervous tissue usually heal by fibrosis.

  • What factors affect tissue repair besides mitotic ability?

    Nutrition and blood supply significantly influence the tissue repair process.