Tissues
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This document discusses the four basic types of tissues in the human body - epithelial, connective, muscular and nervous tissue. It focuses on epithelial tissues, which are classified based on their structure and function. There are two main types of epithelial tissue - covering/lining epithelium and glandular epithelium. Covering/lining epithelium forms surfaces and linings throughout the body, and is further classified based on cell arrangement (simple, stratified, pseudostratified) and cell shape (squamous, cuboidal, columnar, transitional). Glandular epithelium forms glands that secrete substances and is classified as endocrine if secreting hormones or exocrine if secreting other substances.
Tissues
- 1. TISSUES By Shaik Afsar, M.Pharm, (Ph.D) Department of Pharmacology Gokula Krishna College of Pharmacy, Sullurpet, Nellore Dist Mail ID: afsarsk_14@yahoo.com
- 2. TISSUES
- 3. DEFINITION A tissue is a group of cells that usually have a common embryonic origin and function together to carry out specialized activities. Histology is the science that deals with the study of tissues. Body tissues can be classified into four basic types according to structure and function. Tissues Epithelial tissue Connective tissue Muscular tissue Nervous tissue
- 4. Types of Tissues 1. Epithelial tissue covers body surfaces and lines hollow organs, body cavities, and ducts. It also forms glands. 2. Connective tissue protects and supports the body and its organs. Various types of connective tissue bind organs together, store energy reserves as fat, and help provide immunity to disease-causing organisms. 3. Muscular tissue generates the physical force needed to make body structures move and generates body heat. 4. Nervous tissue detects changes in a variety of conditions inside and outside the body and responds by generating action potentials (nerve impulses) that activate muscular contractions and glandular secretions.
- 5. CELL JUNCTIONS Tight Junction Adherens Desmosomes Hemidesmosomes Gap Junction Cell junctions are contact points between the plasma membranes of tissue cells.
- 9. EPITHELIAL TISSUE Covering And lining epithelium Glandular epithelium Arrangement of cells in layers Cell shapes Simple Stratified Pseudo stratified Squamous Cuboidal Columnar Transtitional Endocrine Exocrine Hormones Based on Structure Based on Function Unicellular Multicellular Merocrine Apocrine Holocrine
- 11. An epithelial tissue consists of cells arranged in continuous sheets, in either single or multiple layers. Epithelial tissue forms coverings and linings throughout the body. The Various surfaces of epithelial cells are 1. Apical Surface 2. Lateral Surface 3. Basal Surface The apical (free) surface of an epithelial cell faces the body surface, a body cavity, the lumen (interior space) of an internal organ. Apical surfaces may contain cilia or microvilli. The lateral surfaces of an epithelial cell face the adjacent cells on either side. Lateral surfaces may contain tight junctions, adherens junctions, desmosomes, and/or gap junctions. The basal surface of an epithelial cell is opposite the apical surface. The basal surfaces of the deepest layer of cells adhere to extracellular materials Such as basement membrane. Epithelial tissue may be divided into two types. 1. Covering and lining epithelium 2. Glandular epithelium
- 12. Covering and lining epithelium Arrangement of cells in layers Cell shapes Simple Stratified Pseudo stratified Squamous Cuboidal Columnar Transtitional
- 13. Covering and lining epithelium forms the outer covering of the skin and some internal organs. It also forms the inner lining of blood vessels, ducts, and body cavities, and the interior of the respiratory, digestive, urinary, and reproductive systems. covering and lining epithelial tissue are classified according to two characteristics: the arrangement of cells into layers and the shapes of the cells. 1. Arrangement of cells in layers. The cells are arranged in one or more layers depending on the functions the epithelium a) Simple b) Stratified c) Pseudostratified a) Simple epithelium : These are single layer of cells Functions: It functions in diffusion, osmosis, filtration, secretion, or absorption. b) Stratified epithelium : It consist of two or more layers of cells Functions: Protect underlying tissues in locations where there is wear and tear. c) Pseudostratified epithelium : Appears to have multiple layers of cells because the cell nuclei lie at different levels and not all cells reach the apical surface. Functions: Secretion of Mucous (Goblet Cells)
- 15. 2 Cell shapes. The cells vary in shape depending on their function. a. Squamous cells are arranged like floor tiles and are thin. Functions: Allows for the rapid passage of substances. b. Cuboidal cells are as tall as they are wide and are shaped like cubes or hexagons. They may have microvilli at their apical surface. Function: In either secretion or absorption. c. Columnar cells are much taller than they are wide, like columns. Their apical surfaces may have cilia or microvilli. Function: Protect underlying tissues, and they often are specialized for secretion and absorption. d. Transitional cells change shape, from flat to cuboidal, These cells are present mainly in organs like Urinary bladder. Function: Stretch (distend) to a larger size and then collapse to a smaller size.
- 18. I. SIMPLE EPITHELIUM A) Simple squamous epithelium Description: This tissue consists of a single layer of flat cells that resembles a tiled floor when viewed from the apical surface. The nucleus of each cell is a flattened oval or sphere and is centrally located. Location: The simple squamous epithelium that lines the heart, blood vessels, and lymphatic vessels is known as endothelium and also present at air sacs of lungs, glomerular (Bowman’s) capsule of kidneys, and inner surface of the tympanic membrane (eardrum); forms epithelial layer of serous membranes, such as the peritoneum, pericardium, and pleura. Functions: Filtration, diffusion, osmosis, and secretion in serous membranes.
- 20. B) Simple Cuboidal epithelium Description: It contains Single layer of cube-shaped cells; centrally located nucleus. Location: It is found in organelles such as thyroid gland and kidneys. It also covers the surface of ovaries and posterior surface of Eye. Functions: Secretion and Absorption.
- 21. B) Simple Columnar epithelium Description: The cells of simple columnar epithelium appear like columns, with oval nuclei near the base. Simple columnar epithelium exists in two forms: nonciliated simple columnar epithelium and ciliated simple columnar epithelium. i) Non-ciliated simple columnar epithelium Description: It mainly contains two types of cells, columnar epithelial cells with microvilli at their apical surface, and goblet cells (Secretes Mucous) Location: Linings of the digestive, respiratory, and reproductive tracts, and most of the urinary tract. Functions: Secretion and Absorption. ii) Ciliated simple columnar epithelium Description: Single layer of ciliated column-like cells with nuclei near base; contains goblet cells in some locations. Location: Lines some bronchioles (small tubes) of respiratory tract, uterine (fallopian) tubes, uterus, efferent ducts of the testes, some paranasal sinuses, central canal of spinal cord, and ventricles of the brain. Functions: Moves mucus and other substances by ciliary action.
- 23. C) Pseudostratified Columnar epithelium Description: Not a true stratified tissue; nuclei of cells are at different levels; all cells are attached to basement membrane, but not all reach the apical surface. When viewed from the side, these features give the false impression of a multilayered tissue, thus the name pseudostratified epithelium It exists in two forms: ciliated and nonciliated pseudostratified columnar epithelium i) Ciliated pseudostratified columnar epithelium Description: These cells that extend to the surface either secrete mucus (goblet cells) or bear cilia. Location: Lines the air ways of upper respiratory tract. Functions: These cells secretes mucus that traps foreign particles and the cilia sweep away mucus for eventual elimination from the body. ii) Non-ciliated pseudostratified columnar epithelium Description: It contains cells without cilia and lacks goblet cells. Location: Lines larger ducts of many glands, epididymis, and part of male urethra. Functions: Absorption and Protection.
- 25. II. STRATIFIED EPITHELIUM A) Stratified squamous epithelium Description: In contrast to simple epithelium, stratified epithelium has two or more layers of cells. Cells in the apical layer of this type of epithelium are flat; those of the deep layers vary in shape from cuboidal to columnar. It exists in two forms: Keratinized and Non-Keratinized Stratified squamous epithelium i) Keratinized stratified squamous epithelium Description: Contains a layer of keratin in the apical surface, a tough, fibrous protein. Location: Forms the superficial layer of the skin. Functions: Protect the skin and underlying tissues from heat, microbes, and chemicals. ii) Non-Keratinized stratified squamous epithelium Description: It does not contains a layer of keratin Location: Lining the mouth and esophagus, part of larynx, part of pharynx, and vagina, and covers the tongue. Functions: Protect the skin and underlying tissues from heat, microbes, and chemicals.
- 27. B) Stratified Cuboidal epithelium Description: It contains Two or more layers of cells in which the cells in the apical layer are cube-shaped. Location: It is found in Ducts of adult sweat glands and esophageal glands and part of male urethra. Functions: Protection and limited secretion and absorption. C) Stratified Columnar epithelium Description: It contains Several layers of irregularly shaped cells; only the apical layer has columnar cells. Location: It Lines part of urethra, large excretory ducts of some glands, such as esophageal glands, small areas in anal mucous membrane, and part of the conjunctiva of the eye. Functions: Protection and secretion.
- 29. D) Transitional epithelium Description: Transitional epithelium, a type of stratified epithelium, is present only in the urinary system and has a variable appearance. In its relaxed or unstretched state, transitional epithelium looks like stratified cuboidal epithelium, except that the cells in the apical layer tend to be large and rounded. As the tissue is stretched, its cells become flatter, giving the appearance of stratified squamous epithelium. Location: It Lines urinary bladder and portions of ureters and urethra. Functions: It allows the urinary bladder to stretch to hold a variable amount of fluid without rupturing.
- 30. Glandular epithelium Endocrine Exocrine Hormones Based on Structure Based on Function UnicellularMulticellular Merocrine Apocrine Holocrine Simple Compound Simple Tubular Simple Branched Tubular Simple Coiled Tubular Simple Acinar Simple Branched acinar Compound Tubular Compound Acinar Compound Tubular Acinar Goblet Cells Ductless Secretes through Ducts
- 31. Glandular Epithelium The function of glandular epithelium is secretion, which is accomplished by glandular cells that often lie in clusters deep to the covering and lining epithelium. A gland may consist of a single cell or a group of cells that secrete substances into ducts (tubes), onto a surface, or into the blood. All glands of the body are classified as either endocrine or exocrine. i) Endocrine glands: Description: The secretions of endocrine glands enter the interstitial fluid and then diffuse directly into the bloodstream without flowing through a duct (Hence these are also called as Ductless glands). These secretions, called hormones. Location: They includes pituitary gland at base of brain, pineal gland in brain, thyroid and parathyroid glands near larynx(voice box), adrenal glands superior to kidneys, pancreas near stomach, ovaries in pelvic cavity, testes in scrotum, and thymus in thoracic cavity. Functions: Produce hormones that regulate various body metabolic and physiological activities to maintain homeostasis
- 32. ii) Exocrine glands: Description: Exocrine glands secrete their products into ducts that empty onto the surface of a covering and lining epithelium such as the skin surface or the lumen of a hollow organ. The secretions of exocrine glands include mucus, sweat, oil, earwax, saliva, and digestive enzymes. Location: Examples of exocrine glands include sudoriferous (sweat) glands, and salivary glands, which secrete saliva. Note: Some glands of the body, such as the pancreas, ovaries, and testes, are mixed glands that contain both endocrine and exocrine tissue. Functions: Produce sweat to help lower body temperature , saliva contains mucus and digestive enzymes.
- 33. I) Structural Classification of Exocrine Glands Exocrine glands are classified as unicellular or multicellular. Unicellular glands are single-celled. (Eg: Goblet cells) Multicellular glands, composed of many cells (Eg: sudoriferous, sebaceous (oil), and salivary glands.) Multicellular glands are categorized according to two criteria: (1) Whether their ducts are branched or unbranched and (2) The shape of the secretory portions of the gland. If the duct of the gland does not branch, it is a simple gland. If the duct branches, it is a compound gland. Glands with tubular secretory parts are tubular glands; those with rounded secretory portions are acinar glands, also called alveolar glands. Tubuloacinar glands have both tubular and rounded secretory parts. Combinations of these features are the
- 37. II) Functional Classification of Exocrine Glands The functional classification of exocrine glands is based on how their secretions are released. Types: Merocrine, Apocrine, Holocrine
- 38. CONNECTIVE TISSUE Connective tissue Structure/Anatomy Cells Extra cellular matrix Fibroblast Macrophages Plasma Cells Mast Cells Adipocytes WBC Wandering Fixed Ground Substance Fibers Collagen Fibers Elastic Fibers Reticular Fibers Water Organic Molecules Polysacharides Proteins Proteoglycans Adhesion Proteins Eg: Fibronectin Hyaluronic acid Chondrotin Sulphate Dermaton Sulphate Keratan Sulphate
- 39. Connective tissue is one of the most abundant and widely distributed tissues in the body. Functions: It binds together, supports, and strengthens other body tissues; protects and insulates internal organs; compartmentalizes structures such as skeletal muscles; serves as the major transport system within the body (blood, a fluid connective tissue); is the primary location of stored energy reserves (adipose, or fat, tissue); and is the main source of immune responses. General Features of Connective Tissue Connective tissue consists of two basic elements: 1) Extracellular matrix and 2) Cells. A connective tissue’s extracellular matrix is the material located between its widely spaced cells. The extracellular matrix consists of protein fibers and ground substance, the material between the cells and the fibers.
- 41. Connective Tissue Cells The types of connective tissue cells vary according to the type of tissue and include the following: Cells Fibroblast Macrophages Plasma Cells Mast Cells Adipocytes WBC 1) Fibroblasts are large, flat cells with branching processes. They are present in several connective tissues, and usually are the most numerous. Fibroblasts migrate through the connective tissue, secreting the fibers and certain components of the ground substance of the extracellular matrix.
- 42. 2) Macrophages develop from monocytes, a type of white blood cell. Macrophages have an irregular shape with short branching projections and are capable of engulfing bacteria and cellular debris by phagocytosis. They are of two types like: 1) Fixed macrophages 2) Wandering macrophages 3) Plasma cells are small cells that develop from a type of white blood cell called a B lymphocyte. Plasma cells secrete antibodies, thus are important part of body immune system. They are found in many places in the body, most plasma cells reside in connective tissues, especially in the gastrointestinal and respiratory tracts. They are also abundant in the salivary glands, lymph nodes, spleen, and red bone marrow.
- 43. 4) Mast cells are abundant alongside the blood vessels that supply connective tissue. They produce histamine, a chemical that dilates small blood vessels as part of the inflammatory response, the body’s reaction to injury or infection. In addition, researchers have recently discovered that mast cells can bind to, ingest, and kill bacteria. 5) Adipocytes, also called fat cells or adipose cells, are connective tissue cells that store triglycerides (fats). They are found deep to the skin and around organs such as the heart and kidneys. 6) White blood cells are not found in significant numbers in normal connective tissue. However, in response to certain conditions they migrate from blood into connective tissues. For example, neutrophils gather at sites of infection, and eosinophils migrate to sites of parasitic invasions and allergic responses.
- 44. Connective Tissue Extracellular Matrix Extra cellular matrix Ground Substance Fibers Collagen Fibers Elastic Fibers Reticular Fibers Water Organic Molecules Polysacharides Proteins Proteoglycans Adhesion Proteins Eg: Fibronectin Hyaluronic acid Chondrotin Sulphate Dermaton Sulphate Keratan Sulphate
- 45. The extracellular matrix consists of two major components: (1) Ground substance and (2) Fibers. Ground substance : ground substance is the component of a connective tissue between the cells and fibers. The ground substance may be fluid, semifluid, gelatinous, or calcified. The ground substance supports cells, binds them together, stores water, and provides a medium through which substances are exchanged between the blood and cells Ground Substance Water Organic Molecules Polysacharides Proteins Proteoglycans Adhesion Proteins Eg: Fibronectin Hyaluronic acid Chondrotin Sulphate Dermaton Sulphate Keratan Sulphate Glycosamino glycans
- 46. 1) Hyaluronic acid is a viscous, slippery substance that binds cells together, lubricates joints, and helps maintain the shape of the eyeballs. 2) Chondroitin sulfate provides support and adhesiveness in cartilage, bone, skin, and blood vessels. 3) Dermaton sulphate is present in The skin, tendons, blood vessels, and heart valves 4) Keratan sulfate is present in bone, cartilage, and the cornea of the eye. Fibers Collagen Fibers Elastic Fibers Reticular Fibers Fibers Three types of fibers are embedded in the extracellular matrix between the cells: collagen fibers, elastic fibers, and reticular fibers. They function to strengthen and support connective tissues.
- 47. Collagen fibers are very strong and resist pulling forces, but they are not stiff, which allows tissue flexibility. Chemically, collagen fibers consist of the protein collagen, Collagen fibers are found in most types of connective tissues, especially bone, cartilage, tendons, and ligaments. Elastic fibers forms branch and join together to form a network within a tissue. An elastic fiber consists of molecules of the protein elastin surrounded by a glycoprotein named fibrillin, which adds strength and stability. Elastic fibers are plentiful in skin, blood vessel walls, and lung tissue. Reticular fibers consisting of collagen arranged in fine bundles with a coating of glycoprotein, provide support in the walls of blood vessels and form a network around the cells in some tissues. Like collagen fibers, reticular fibers provide support and strength.
- 48. Classification of Connective Tissues I. Embryonic connective tissue A. Mesenchyme B. Mucous connective tissue II. Mature connective tissue A. Loose connective tissue 1. Areolar connective tissue 2. Adipose tissue 3. Reticular connective tissue B. Dense connective tissue 1. Dense regular connective tissue 2. Dense irregular connective tissue 3. Elastic connective tissue C. Cartilage 1. Hyaline cartilage 2. Fibrocartilage 3. Elastic cartilage D. Bone tissue E. Liquid connective tissue 1. Blood 2. Lymph
- 49. I. Embryonic connective tissue A. Mesenchyme: Description: Consists of irregularly shaped mesenchymal cells embedded in a semifluid ground substance that contains reticular fibers. Location: Under skin and along developing bones of embryo; some mesenchymal cells are found in adult connective tissue, especially along blood vessels. Function: Forms all other types of connective tissue.
- 50. B. Mucous connective tissue Description: Consists of widely scattered fibroblasts embedded in a viscous, jellylike ground substance that contains fine collagen fibers. Location: Umbilical cord of fetus. Function: Support.
- 51. II. Mature Connective Tissue A. Loose Connective Tissue The fibers of loose connective tissue are loosely intertwined between cells. 1) Areolar connective tissue: Description: Consists of fibers (collagen, elastic, and reticular) and several kinds of cells (fibroblasts, macrophages, plasma cells, adipocytes, and mast cells) embedded in a semifluid ground substance. Location: Subcutaneous layer deep to skin; papillary (superficial) region of dermis of skin; lamina propria of mucous membranes; and around blood vessels, nerves, and body organs. Function: Strength, elasticity, and support.
- 52. 2. Adipose tissue Description: Consists of adipocytes, cells specialized to store triglycerides (fats) as a large centrally located droplet; nucleus and cytoplasm are peripherally located. Location: Subcutaneous layer deep to skin, around heart and kidneys, yellow bone marrow, and padding around joints and behind eyeball in eye socket. Function: Reduces heat loss through skin, serves as an energy reserve, supports, and protects. In newborns, brown adipose tissue generates considerable heat that helps maintain proper body temperature.
- 53. 3. Reticular connective tissue Description: A network of interlacing reticular fibers and reticular cells. Location: Stroma (supporting framework) of liver, spleen, lymph nodes; red bone marrow, which gives rise to blood cells; reticular lamina of the basement membrane; and around blood vessels and muscles. Function: Forms stroma of organs; binds together smooth muscle tissue cells; filters and removes worn-out blood cells in the spleen and microbes in lymph nodes.
- 54. B. Dense connective tissue :Dense connective tissue contains more numerous, thicker, and denser fibers (packed more closely) but considerably fewer cells than loose connective tissue. 1. Dense regular connective tissue Description: Extracellular matrix looks shiny white; consists mainly of collagen fibers regularly arranged in bundles; fibroblasts present in rows between bundles. Location: Forms tendons (attach muscle to bone), most ligaments (attach bone to bone), and aponeuroses (sheet like tendons that attach muscle to muscle or muscle to bone). Function: Provides strong attachment between various structures.
- 55. 2. Dense irregular connective tissue Description: Consists predominantly of collagen fibers randomly arranged and a few fibroblasts. Location: Fasciae (tissue beneath skin and around muscles and other organs), reticular (deeper) region of dermis of skin, periosteum of bone, perichondrium of cartilage, joint capsules, membrane capsules around various organs (kidneys, liver, testes, lymph nodes), pericardium of the heart, and heart valves. Function: Provides strength.
- 56. 3. Elastic connective tissue Description: Consists predominantly of freely branching elastic fibers; fibroblasts are present in spaces between fibers. Location: Lung tissue, walls of elastic arteries, trachea, bronchial tubes, true vocal cords, suspensory ligament of penis, and some ligaments between vertebrae. Function: Allows stretching of various organs.
- 57. C. Cartilage: It consists of a dense network of collagen fibers and elastic fibers firmly embedded in chondroitin sulfate, a gel-like component of the ground substance. Cartilage can endure considerably more stress than loose and dense connective tissues. The strength of cartilage is due to its collagen fibers. 1. Hyaline cartilage: Description: Consists of a bluish-white, shiny ground substance with thin, fine collagen fibers and many chondrocytes; most abundant type of cartilage. Location: Ends of long bones, anterior ends of ribs, nose, parts of larynx, trachea, bronchi, bronchial tubes, and embryonic and fetal skeleton. Function: Provides smooth surfaces for movement at joints, as well as flexibility and support.
- 58. 2. Fibro cartilage: Description: Consists of chondrocytes scattered among thick bundles of collagen fibers within the extracellular matrix. Location: Pubic symphysis (point where hip bones join anteriorly), intervertebral discs (discs between vertebrae), menisci (cartilage pads) of knee, and portions of tendons that insert into cartilage. Function: Support and fusion.
- 59. 2. Elastic cartilage: Description: Consists of chondrocytes located in a threadlike network of elastic fibers within the extracellular matrix. Location: Lid on top of larynx (epiglottis), part of external ear (auricle), and auditory (eustachian) tubes. Function: Gives support and maintains shape.
- 60. D. Bone Tissue : Cartilage, joints, and bones make up the skeletal system. Bones store calcium and phosphorus; house red bone marrow, which produces blood cells; and contain yellow bone marrow, a storage site for triglycerides. The Bone tissue is of two types 1. Compact bone tissue 2. Spongy bone tissue 1. Compact bone tissue: It consist of osteon (Haversian System) that contains Lamellae, Lacuna, Oesteocytes, Haversian canal and canaliculi. 2. Spongy bone tissue: It consist of thinn columns called trabeculae, spaces between trabaculae are filled with red bone marrow. Location: Both Compact and Spongy bone tissue makeup the various parts of bones of the body Functions: Support, protection, storage; houses blood-forming tissue; serves as levers that act with muscle tissue to enable movement.
- 62. E. Liquid connective tissue 1. Blood Description: Consists of blood plasma and formed elements: red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). Location: Within blood vessels (arteries, arterioles, capillaries, venules, and veins) and within the chambers of the heart. Function: Red blood cells transport oxygen and some carbon dioxide; white blood cells carry on phagocytosis and are involved in allergic reactions and immune system responses; platelets are essential for the clotting of blood.
- 63. 1. Lymph Description: Lymph is the extracellular fluid that flows in lymphatic vessels. It is a connective tissue that consists of several types of cells in a clear liquid extracellular matrix that is similar to blood plasma. Lymph nodes includes many lymphocytes, a type of white blood cell, Location: Present in Lymphatic vessels and lymph modes. Function: Responsible for immune system
- 64. MUSCULAR TISSUE Muscular tissue consists of elongated cells called muscle fibers or myocytes that can use ATP to generate force. As a result, muscular tissue produces body movements, maintains posture, and generates heat. It also provides protection. Based on its location and certain structural and functional features, muscular tissue is classified into three types: skeletal, cardiac, and smooth 1. Skeletal muscle tissue Description: It is usually attached to the bones of the skeleton. Skeletal muscle is considered voluntary because it can be made to contract or relax by conscious control. It is Long, cylindrical, striated fibers with many peripherally located nuclei; voluntary control. Location: Usually attached to bones by tendons. Function: Motion, posture, heat production, and protection.
- 66. 2. Cardiac muscle tissue Description: It contains Branched striated fibers with one or two centrally located nuclei; contains intercalated discs; involuntary control. Location: Heart wall. Function: Pumps blood to all parts of the body.
- 67. 3. Smooth muscle tissue Description: Spindle-shaped (thickest in middle and tapering at both ends), nonstriated fibers with one centrally located nucleus; involuntary control. Location: Iris of the eyes, walls of hollow internal structures such as blood vessels, airways to the lungs, stomach, intestines, gallbladder, urinary bladder, and uterus. Function: Motion (constriction of blood vessels and airways, propulsion of foods through gastrointestinal tract, contraction of urinary bladder and gallbladder).
- 68. NERVOUS TISSUE Description: Consists of neurons (nerve cells) and neuroglia. Neurons consist of a cell body and processes extending from the cell body (multiple dendrites and a single axon). Neuroglia do not generate or conduct nerve impulses but have other important supporting functions. Location: Nervous system. Function: Exhibits sensitivity to various types of stimuli, converts stimuli into nerve impulses (action potentials), and conducts nerve impulses to other neurons, muscle fibers, or glands.