Histology Overview Quiz
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Questions and Answers

Which type of tissue is primarily specialized for contraction to generate force?

  • Muscular tissue (correct)
  • Epithelial tissue
  • Nervous tissue
  • Connective tissue

    • Histology is the study of tissues.

    True

    What connects cells to the underlying basement membrane?

    Hemidesmosomes

    Epithelial tissue forms _______ glands _______.

    <p>glands</p> Signup and view all the answers

    Which type of cell junction forms leakproof connections?

    <p>Tight junctions</p> Signup and view all the answers

    Match the type of tissue with its primary function:

    <p>Epithelial tissue = Covers and protects the body Connective tissue = Stores energy and aids immunity Muscular tissue = Generates body heat Nervous tissue = Detects and responds to stimuli</p> Signup and view all the answers

    Desmosomes resist ________ forces during contractions.

    <p>pulling</p> Signup and view all the answers

    Desmosomes and adherens junctions are the same in structure and function.

    <p>False</p> Signup and view all the answers

    What type of muscle tissue is characterized by long, multinucleate, striated fibers?

    <p>Skeletal muscle tissue</p> Signup and view all the answers

    Cardiac muscle tissue is under voluntary control.

    <p>False</p> Signup and view all the answers

    What is the primary function of neurons?

    <p>Generate electrical signals or nerve impulses</p> Signup and view all the answers

    Smooth muscle tissue facilitates constriction_ of airways and contractions of the urinary bladder.

    <p>constriction</p> Signup and view all the answers

    Match the type of muscle tissue with its characteristics:

    <p>Skeletal muscle tissue = Voluntary movement and striated Cardiac muscle tissue = Involuntary control and striated Smooth muscle tissue = Involuntary control and non-striated</p> Signup and view all the answers

    Which type of gland releases its products via rupture of the entire cell?

    <p>Holocrine</p> Signup and view all the answers

    Apocrine glands secrete products by exocytosis from the entire cell surface.

    <p>False</p> Signup and view all the answers

    Name one type of connective tissue that provides mechanical support to overlying tissues.

    <p>Mucoid connective tissue</p> Signup and view all the answers

    The most abundant protein in the body, making up about 25% of total protein, is _____

    <p>collagen</p> Signup and view all the answers

    What type of connective tissue contains adipocytes that store triglycerides?

    <p>Adipose connective tissue</p> Signup and view all the answers

    Epithelial tissue is typically vascularized.

    <p>False</p> Signup and view all the answers

    What is the primary component of the extracellular matrix (ECM) in connective tissues?

    <p>Protein fibres and ground substance</p> Signup and view all the answers

    Merocrine glands secrete their products through _____

    <p>exocytosis</p> Signup and view all the answers

    Which type of fiber in connective tissue is responsible for flexibility and elasticity?

    <p>Elastic fibers</p> Signup and view all the answers

    Macrophages are immune cells that serve a phagocytic function.

    <p>True</p> Signup and view all the answers

    What type of connective tissue includes areolar, adipose, and reticular connective tissues?

    <p>Loose connective tissue</p> Signup and view all the answers

    The component of connective tissue that connects cells and provides hydration is called the _____

    <p>extracellular matrix</p> Signup and view all the answers

    What type of gland is incorrectly termed as 'apocrine' but actually functions as a merocrine gland?

    <p>Sweat gland</p> Signup and view all the answers

    Match the following connective tissue types with their primary characteristics:

    <p>Adipose = Stores energy and insulates body Reticular = Filters substances like lymph Dense connective = Packed with protein fibers Loose connective = Sparsely distributed cells and fibers</p> Signup and view all the answers

    What layers make up the basement membrane?

    <p>Basal and reticular</p> Signup and view all the answers

    Gap junctions allow for efficient signal sharing between adjacent cells.

    <p>True</p> Signup and view all the answers

    What is the primary function of epithelial tissue?

    <p>Protection, secretion, absorption</p> Signup and view all the answers

    The superficial layer of cells in stratified squamous epithelium can be __________ off.

    <p>sloughed</p> Signup and view all the answers

    Which type of epithelial tissue lines blood vessels?

    <p>Simple squamous epithelium</p> Signup and view all the answers

    Keratinized stratified squamous epithelium is found lining the inside of the vagina.

    <p>False</p> Signup and view all the answers

    What type of epithelium is found lining the urinary bladder?

    <p>Transitional epithelium</p> Signup and view all the answers

    The __________ glands secrete substances that diffuse directly into the bloodstream.

    <p>endocrine</p> Signup and view all the answers

    Match the type of epithelial tissue with its function:

    <p>Simple cuboidal = Secretion and absorption Ciliated pseudostratified = Sweeping mucus Stratified squamous = Protection against abrasion Transitional = Stretching to accommodate fluid</p> Signup and view all the answers

    What are the shapes of epithelial cells classified as?

    <p>Squamous, cuboidal, and columnar</p> Signup and view all the answers

    Exocrine glands release their secretions directly into the bloodstream.

    <p>False</p> Signup and view all the answers

    Name a fluid that simple cuboidal epithelium is specialized to absorb.

    <p>Water</p> Signup and view all the answers

    The __________ epithelium can appear stratified due to the varying depths of nuclei.

    <p>pseudostratified</p> Signup and view all the answers

    Match the following epithelial types with their locations:

    <p>Ciliated simple columnar = Bronchioles and oviducts Nonkeratinized stratified squamous = Vagina Simple squamous = Blood vessel lining Stratified cuboidal = Sweat and salivary glands</p> Signup and view all the answers

    What do goblet cells secrete?

    <p>Mucus</p> Signup and view all the answers

    Which connective tissue is primarily responsible for resisting pulling along any axis?

    <p>Dense irregular connective tissue</p> Signup and view all the answers

    Elastic connective tissue consists primarily of collagen fibers.

    <p>False</p> Signup and view all the answers

    What type of cartilage provides strength and stretch, and is found in structures such as the external ear?

    <p>elastic cartilage</p> Signup and view all the answers

    The connective tissue that primarily forms the fetal skeleton before ossification is _________.

    <p>hyaline cartilage</p> Signup and view all the answers

    What term refers to the repeating units of compact bone?

    <p>Osteons</p> Signup and view all the answers

    Blood is primarily composed of liquid plasma and various types of connective tissues.

    <p>False</p> Signup and view all the answers

    What secretes synovial fluid to lubricate joints?

    <p>synoviocytes</p> Signup and view all the answers

    The connective tissue covering the heart is known as _________.

    <p>pericardium</p> Signup and view all the answers

    Which of the following types of muscle tissue is responsible for involuntary contractions?

    <p>Both B and C</p> Signup and view all the answers

    Match the type of membrane to its main characteristic:

    <p>Mucous membrane = Lines cavities open to external environment Serous membrane = Lines internal cavities not exposed to the outside Cutaneous membrane = The skin Synovial membrane = Lines joints and secretes synovial fluid</p> Signup and view all the answers

    Fibrocartilage is the weakest type of cartilage and lacks a perichondrium.

    <p>False</p> Signup and view all the answers

    What is the main function of chondrocytes within cartilage?

    <p>to maintain the cartilage matrix</p> Signup and view all the answers

    Lymph consists largely of ________ lymphocytes after exiting lymph nodes.

    <p>differentiated</p> Signup and view all the answers

    Which type of connective tissue primarily consists of adipose tissue?

    <p>Loose connective tissue</p> Signup and view all the answers

    What provides a smooth surface between bones at joints?

    <p>hyaline cartilage</p> Signup and view all the answers

    Study Notes

    Tissue Definition

    • Tissues are groups of similar cells that work together to perform a specific function.
    • Tissues arise from a common ancestor called a progenitor cell.
    • The study of tissues is called Histology.

    Tissue Types

    • Four main types of tissues in the human body:
      • Epithelial tissue
      • Connective tissue
      • Muscular tissue
      • Nervous tissue

    Epithelial Tissue

    • Covers and protects external surfaces of the body and lines internal hollow organs.
    • Forms glands.
    • Specialized for exchange with the environment (internal and external).

    Connective Tissue

    • Protects and supports the body & internal organs.
    • Connects organs, stores energy, and aids immunity.

    Muscular Tissue

    • Composed of specialized cells that contract to generate force.
    • Generates body heat

    Nervous Tissue

    • Detects and responds to stimuli.
    • Generates electrical signals called nerve impulses, which trigger muscle or gland action.

    Cell Junctions

    • Points of contact between adjacent cells.
    • Five main types:
      • Tight junctions
      • Adherens junctions
      • Desmosomes
      • Hemidesmosomes
      • Gap junctions

    Tight Junctions

    • Mediated by transmembrane proteins and form leakproof connections between cells.
    • Found in the lining of the stomach, intestines, and urinary bladder.

    Adherens Junctions

    • Connect adjacent cells and are mediated by transmembrane proteins and cytoplasmic proteins called plaques.
    • Plaques connect transmembrane proteins to microfilaments (actin).
    • Resist pulling forces.

    Desmosomes

    • Connect adjacent cells and resist contraction.
    • Similar structure to adherens junctions, but plaques connect transmembrane proteins to intermediate filaments.
    • Prevents tearing of the epidermis and ripping of heart muscle cells.

    Hemidesmosomes

    • Anchor cells to underlying tissues.
    • Connect cells to the basement membrane via transmembrane glycoproteins that connect intermediate filaments to laminin proteins.
    • Resist abrasion
    • Anchor skin to underlying connective tissues.

    Gap Junctions

    • Protein channels connecting the membranes of adjacent cells.
    • Channels are called connexons.
    • Protein subunits that form channels are called connexins.
    • Assist in coordination of cell and tissue function by allowing efficient signal sharing.
    • Found between nerves at electrical synapses, allowing ion flow.

    Epithelial Tissue Structure and Function

    • Protects the body from injury, including abrasion, irradiation, invasion, and moisture loss.
    • Secretes enzymes, fluids, or hormones.
    • Absorbs nutrients.
    • Classified based on the number of cell layers and the shape of the cells in the tissue.

    Number of Layers

    • Simple = One layer.
    • Stratified = Multiple layers.
    • Pseudostratified = Single layer that appears as multiple layers.

    Cell Shape

    • Squamous or flat, like tiles.
    • Cuboidal, or shaped like dice.
    • Columnar, or long and rectangular, like wooden beams.
    • Transitional, or variable in shape depending on whether the tissue is stretched.

    Epithelial Cell Polarization

    • Epithelial cells are polarized, meaning they have distinct faces or ends.
    • Apical surface faces the inside of an organ, vessel, duct, or the external environment.
    • Basal surface faces underlying tissues (usually connective tissue).
    • Lateral surface faces adjacent cells.

    Surface Epithelium

    • The covering and lining of the body.

    Simple Squamous Epithelium

    • Specialized for filtration of body fluids and diffusion of nutrients and gases.
    • Endothelium lines blood vessels.
    • Mesothelium forms the epithelial layer of serous membranes.

    Simple Cuboidal Epithelium

    • Specialized for secretion of hormones and other substances and the absorption of water and other solutes.
    • Found lining kidney tubules and the thyroid gland.

    Non-Ciliated Simple Columnar Epithelium

    • Specialized for mucus secretion and absorption of nutrients.
    • Includes goblet cells and gastrointestinal cells with microvilli.

    Ciliated Simple Columnar Epithelium

    • Cilia at the apical surface move mucus produced by goblet cells.
    • Specialized for protection from invasion and fluid loss.
    • Found in bronchioles and oviducts.

    Non-Ciliated Pseudostratified Columnar Epithelium

    • Nuclei appear at different depths, giving the appearance of stratified tissue.
    • Specialized for absorption of substances and secretion of saliva.
    • Lines the epididymis and part of the male urethra.

    Ciliated Pseudostratified Columnar Epithelium

    • Possesses cilia to sweep mucus over the surface of the tissue.
    • Specialized for protection from invasion.
    • Lines a majority of the upper respiratory tract.

    Stratified Squamous Epithelium

    • May be keratinized.
    • The superficial layer of cells can be sloughed off, protecting from abrasion.
    • Keratin is filamentous, insoluble, and provides great tensile strength, imparting mechanical strength to tissues.
    • Specialized for protection from abrasion, fluid loss, ultraviolet radiation, and invasion.
    • Nonkeratinized stratified squamous epithelium lines the vagina.
    • Keratinized stratified squamous epithelium covers the body as part of the epidermis.

    Stratified Cuboidal Epithelium

    • Rare.
    • Specialized to protect ducts and tubes from abrasion.
    • Found lining sweat and esophageal glands, and parts of the male urethra.

    Stratified Columnar Epithelium

    • Specialized for protection from invasion and secretion of tears.
    • Found in esophageal glands, parts of the conjunctiva of the eye.

    Transitional Epithelium and Urothelium

    • At rest, tissue appears cuboidal.
    • When stretched, tissue appears squamous.
    • Lines hollow organs that expand for fluid storage.
    • Found in the urinary bladder, portions of the ureters, and urethra.

    Glandular Epithelium

    • Responsible for secretion to protect the body.
    • Glands can be classified as exocrine or endocrine.
    • Glands are epithelial tissues that secrete substances into or onto surfaces or into the blood.
    • Exocrine glands secrete substances a short distance.
    • Endocrine glands secrete substances that diffuse into the blood and circulate to target tissues.
    • Mixed glands have both exocrine and endocrine tissues, such as the pancreas.

    Endocrine Glands

    • Secrete hormones into interstitial fluid, which then diffuses into the blood and circulates to target tissues.
    • Hormones regulate homeostasis in many ways.

    Exocrine Glands

    • Secrete products into ducts, which carry them to the surface of the body or into a hollow organ.
    • Include sweat, oil, and earwax glands, digestive/salivary glands, and pancreatic glands that secrete into the small intestine.
    • Exocrine glands can be further classified as unicellular or multicellular.
    • Unicellular glands comprise a single cell, such as goblet cells.
    • Most are multicellular glands.

    Multicellular Exocrine Glands

    • Can also be classified by function, based on how their secretions are released.
    • Three types:
      • Merocrine
      • Apocrine
      • Holocrine

    Merocrine Glands

    • Products leave glandular epithelial cells via exocytosis.
    • Most of the body's glands are merocrine glands.
    • The "apocrine" sweat glands are actually merocrine glands

    Apocrine Glands

    • Secrete products only from the apical face of cells.
    • Products exit the cells via exocytosis.
    • Example: Mammary glands secreting breastmilk.

    Holocrine Glands

    • Collect products in the cytosol.
    • Mature cells rupture, and the leaked contents are secreted.
    • Includes sebaceous glands. Example: Acne.

    Connective Tissue

    • Generally not found at body surfaces.
    • Contains both nerves and blood vessels (with some exceptions).
    • Two components:
      • Extracellular Matrix (ECM)
        • Protein fibers + ground substance.
        • Can be liquid, solid, or gel-like.
      • Cells
        • Sparsely distributed throughout the matrix.

    Cells of Connective Tissue

    • All cells of connective tissue descend from embryonic mesenchymal cells.
    • Includes:
      • Fibroblasts: Most abundant, secrete the ECM of loose and dense connective tissue.
      • Macrophages: Phagocytic immune cells that reside in tissues.
      • Plasma cells: Immune cells that secrete antibodies.
      • Mast cells: Immune cells immobilized in tissues that secrete inflammatory chemicals.
      • Adipocytes: Cells of adipose tissue that store triglycerides.
      • Leukocytes, or white blood cells: Do not typically reside in connective tissues but can migrate there during infection or invasion.

    ECM of Connective Tissues

    • External to the cell, complexes of polysaccharides and proteins connect the cell to other cells, forming the extracellular matrix.
    • Extensively hydrated.
    • The cells of connective tissue secrete the ECM.
    • Ground substance is the material between cells and fibers in connective tissue.
    • Gives the tissue its liquid, gel-like, or solid properties.

    Protein Fibers of the ECM

    • Three types:
      • Collagen fibers: Most abundant protein in the body (25% of total protein). Great tensile strength from parallel bundle arrangement. Helps tissues resist compression.
      • Elastic fibers: Thinner than collagen fibers. Made of a protein called elastin. Can stretch and return to resting length – elasticity. Resists tearing and shear.
      • Reticular fibers: Made of bundled collagen + glycoproteins. Thinnest fiber. Supports multiple tissues (e.g., blood vessel walls). Form part of the basement membrane.

    Differences Between Epithelial and Connective Tissues

    • The ratio of extracellular matrix to the number of cells is the main difference between epithelial and connective tissues.
    • Apparent under a light microscope.
    • Epithelial tissues contain more cells than connective tissues.
    • Both are the most common and widely- distributed tissues in the human body.

    Other Differences Between Epithelial and Connective Tissues

    • Epithelial tissue is not vascularized, while connective tissue typically is vascularized.
    • Epithelial tissue typically forms the most superficial layer and is not covered by other tissues.
    • Epithelial tissue is often found overlying connective tissues. They are usually arranged this way to reflect the function of an organ.

    Embryonic Connective Tissues

    • Two types:
      • Mesenchymal tissue: Contains mesenchymal cells in a semifluid ground substance + reticular fibers. Becomes nearly all types of connective tissues (e.g., the first skeleton of the developing embryo).
      • Mucoid connective tissue: Sparsely distributed fibroblasts within a gel-like ground substance and thin collagen fibers. Provides mechanical support to overlying tissue (e.g., the umbilical cord).

    Mature Connective Tissues

    • Two main categories:
      • Loose connective tissue: Sparsely distributed cells and fibers. Includes areolar connective tissue, adipose tissue, and reticular connective tissue.
      • Dense connective tissue: Packed with protein fibers but fewer cells than loose connective tissue. Can be regular, irregular, or elastic.

    Loose Connective Tissues

    • Includes:
      • Areolar connective tissue: Widely distributed throughout the body. All three fibers plus a variety of cells in a semifluid ground substance. Functions to support, reinforce, and provide stretch to organs. Serves as “packing material" for body cavities.
      • Adipose connective tissue: Contains adipocytes that store triglycerides in a large central droplet (white adipose tissue). Insulates the body and stores energy; supports and protects internal organs.
      • Reticular connective tissue: Made of tightly-woven reticular fibers plus fibroblasts. Filters substances, such as lymph in the spleen and lymph nodes. Called the stroma in these organs.

    Dense Connective Tissues

    • Includes
      • Dense regular connective tissue: Packed collagen fibers + sparse fibroblasts.. Great tensile strength. Found in tendons, ligaments, and aponeuroses.
      • Dense irregular connective tissue: Made of irregularly arranged collagen fibers + few fibroblasts. Resists pulling along any axis. Found in the fasciae (wrap muscles) and the pericardium (surrounds the heart).
      • Elastic connective tissue: Made of elastic fibers + few fibroblasts. Provides elasticity to organs. Found in lung tissue, walls of elastic arteries, the trachea, and bronchial tubes.

    Supporting Connective Tissues: Cartilage

    • Thick collagen fibers embedded in a gel-like ground substance.
    • ECM contains extensively hydrated proteoglycans like chondroitin sulfate. This strongly resists compressional forces.
    • Cells are special fibroblasts called chondrocytes that reside in spaces called lacunae.
    • Not vascularized and heals slowly.
    • Some types are covered by perichondrium, a layer of new chondrocytes containing blood vessels.

    Classification of Cartilage

    • Three types:
      • Hyaline cartilage: Most abundant cartilage in the body. Overlaid by the perichondrium. Provides a smooth surface between bones at joints. Comprises the fetal skeleton before ossification (hardening into bone).
      • Fibrocartilage: Lacks perichondrium. Strongest type of cartilage. Found at the pubic symphysis, intervertebral discs, and menisci of knee joints.
      • Elastic cartilage: Overlaid by perichondrium. Functions to provide strength and stretch; shapes some structures. Forms the auricle (external ear), eustachian tubes, and the epiglottis.

    Bone Tissue

    • Can be compact or spongy.
    • Compact bone consists of repeating units called osteons.
    • Osteons include rings of calcified ECM that contain:
      • Lacunae containing the cells of bone tissue: osteocytes.
      • A central canal containing blood vessels and nerves.

    Liquid Connective Tissues

    • Includes:
      • Blood: A liquid ECM called blood plasma + blood cells. Transports oxygen, nutrients, gases, wastes, immunological cells and compounds, hormones, and platelets. Blood resides within blood vessels and the heart.
      • Lymph: A liquid tissue comprised of different things, depending on the location in the body. Less protein than blood plasma. Exiting lymph nodes, lymph consists mainly of lymphocytes. Exiting the small intestine, lymph consists mainly of dietary fats.

    Anatomical Membranes

    • Not biological or plasma membranes!
    • Sheets of flexible tissues that cover or line a portion of the body.
    • Usually epithelial layer + connective tissue.
    • Include mucous membranes, serous membranes, cutaneous membranes (skin). Synovial membranes consist only of connective tissue (no epithelium) and line joints.

    Mucous Membranes

    • Epithelial layer varies widely; connective layer is called the lamina propia, made of areolar connective tissue.
    • Line body cavities that are open to the external environment and prevent fluid loss.
    • Protect the body from invaders.
    • Secrete enzymes to assist digestion and absorption.
    • Lines the digestive, respiratory, reproductive, and part of the urinary tract.

    Serous Membranes

    • Only lines cavities and organs not exposed to the external environment.
    • Made of areolar connective tissue covered by mesothelium.
    • Mesothelium secretes serous fluid, which lubricates organs and walls.

    Cutaneous Membranes

    • Includes skin.
    • Most superficial layer = epidermis.
    • Deep to the epidermis is the dermis.
    • Epidermis is made of keratinized stratified squamous epithelia.
    • Dermis is made of dense irregular and areolar connective tissues.

    Synovial Membranes

    • Described as "uncooked egg" in appearance.
    • Made of layers of synviocytes that secrete synovial fluid to lubricate joints and nourish tissues.
    • Deep to these are layers of areolar and adipose connective tissues.

    Muscular and Nervous Tissues: Excitable Cells

    • Excitable cells:
      • Detect electrical stimuli and respond by producing action potentials.
      • May result in a nerve impulse or release of neurotransmitters.

    Muscular Tissue

    • Made of unique cells called muscle fibers or myocytes.

    • Contract to move bones.

    • Generates heat.

    • Three types:

      • Skeletal
      • Cardiac
      • Smooth### Skeletal Muscle Tissue

    • Long, multinucleate, striated tissue.

    • Produces voluntary movement, maintains posture, and generates heat.

    • Attaches to bones via tendons.

    Cardiac Muscle Tissue

    • Branched, striated fibers with a single nucleus.
    • Cells joined by gap junctions for more rapid electrical signal conduction.
    • Under involuntary control.
    • Collectively forms the myocardium or heart wall.

    Smooth Muscle Tissue

    • Long, nonstriated fibers in an irregularly-shaped cell with a single nucleus.
    • Thickened middle to cells.
    • Cells joined by gap junctions to coordinate involuntary muscle contractions.
    • Facilitates peristalsis, constriction of airways, contractions of the urinary bladder and gallbladder.

    Nervous Tissue

    • Two types of cells make up nervous tissue:
      • Neurons: Consist of a cell body, dendrites, and an axon. Generate electrical signals or nerve impulses.
      • Neuroglia: Do not generate electrical impulses. Synthesize myelin, a coating on neuronal axons to increase electrical signal transmission speed.

    Summary of Tissues

    • Tissues are composed of cells and extracellular matrix (ECM).
    • Epithelial tissues cover and line the body.
      • Can secrete/absorb substances such as hormones and nutrients.
      • Can protect from mechanical injury such as abrasion.
    • Connective tissues join epithelial tissues to deeper tissues and support the body.
    • Muscular tissue moves the body and generates heat.
    • Nervous tissue coordinates and controls the body's response to stimuli.

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    Test your knowledge on histology, the study of tissues. This quiz covers various types of tissue, their specializations, and unique characteristics. Perfect for students learning about human biology or advanced anatomy.

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