Lecture 6 - Tissues-AM PDF

THE CORE OF HEALTHCARE EDUCATION TOPIC: Tissues- ANP 101 (Presented by: A. Mogibelo) c 2021  Learning Outcomes At the end of this session the student should be able: Define...

THE CORE OF HEALTHCARE EDUCATION TOPIC: Tissues- ANP 101 (Presented by: A. Mogibelo) c 2021  Learning Outcomes At the end of this session the student should be able: Define a tissue Discuss the characteristics of the four basic types of tissues found in the human body Describe the structure, function and location of different types of tissues Explain the classification of the different types of tissues The Core of Quality Health Care Education 2  Introduction A tissue is made up of cells of similar structure working together to perform a particular function There are four basic types of tissues in the human body: - Muscle - Nervous - Epithelial - Connective The Core of Quality Health Care Education 3  Muscle Tissue Muscle tissue consists of specialized cells that can generate force and produce motion, produce heat and can maintain posture Firstly, muscles are categorized as striated or unstriated They are further categorized as voluntary or involuntary The Core of Quality Health Care Education 4  Cont… There are 3 muscle types: Skeletal (striated, voluntary control) Cardiac (striated, involuntary control) Smooth (unstriated, involuntary control) The Core of Quality Health Care Education 5  Skeletal Muscle Attached to the bones of the skeleton Striated – muscle tissue made up of alternating dark and light bands Controlled voluntarily Muscle cells are called muscle fibres The Core of Quality Health Care Education 6  Cardiac Muscle Makes up the walls of the heart Striated Involuntarily controlled Muscle cells branched with one centrally located nucleus Has intercalated discs The Core of Quality Health Care Education 7  Smooth Muscle Found in the walls of hollow organs e.g. stomach, intestines, airways, blood vessels etc. Unstriated Involuntarily controlled The Core of Quality Health Care Education 8  Nervous Tissue Consists of two types of cells: - Neurons (which carry electrical impulses) - Neuroglia (which are the support cells in the nervous system) A neuron consists of a cell body, axon, dendrites and supporting cells forming the myelin sheath The Core of Quality Health Care Education 9  Cont… Nervous tissue is found in the brain, spinal cord and nerves Nervous tissue transmits electrical signals from sensory receptors and to effectors The Core of Quality Health Care Education 10  Epithelial Tissue Epithelial tissue covers the surfaces of the body It forms the lining of hollow organs, body cavities, blood vessels, ducts and forms the walls of glands It covers the interior surfaces of the respiratory, digestive, urinary and reproductive systems The Core of Quality Health Care Education 11  Cont… There are two types of epithelial tissue: - Epithelial sheets/Covering and lining epithelium - Secretory glands/Glandular epithelium The Core of Quality Health Care Education 12  Characteristic of Epithelial Tissue Lines body surfaces, cavities and tubes. Structure related to function: Protection, Control permeability, neuroepithelium, Secretion & absorption. Consists of closely packed cells (Junctions) High rate of cell division: because apical surface cells slough off, wear out, and get damaged then replaced. Cells organized in continuous sheets of single or multiple layers Epithelium is avascular (no blood vessels) Exchange of nutrients and waste products between epithelium and underlying connective tissue occurs through diffusion Epithelia have sensors/receptors and a nerve supply The Core of Quality Health Care Education 13 Attachment to basement membrane: In epithelium apical surface differ with basal surface. Apical : free surface or superficial layer. Cilia Lateral: adjacent cells, junctions Basal : attached to basement membrane or deepest layer. Cell Junction? Basal and reticular lamina form basement membrane. 14  Cell junctions Cell junctions are contacts points between plasma membranes of tissue cells (Found in most epithelial, some muscles and nerve cells) Types of cell Junctions 1. Tight junctions: Weblike strands of transmembrane proteins, prevent leakage eg intestines, stomach, urinary bladder. 2. Adherens junctions: Dense layer of proteins (cadherins) 3. Desmosomes: Similar to adherens but don’t attach microfilaments. 4. Hemidesmosomes: Don’t attach adjacent cells but cells to basement membrane (Integrins). 5. Gap junctions: Connexins form tiny fluid filled tunnels. 15 16  General Functions of Epithelia Protection Secretion Absorption Sensory reception Production of gametes (sperm & ova) The Core of Quality Health Care Education 17  Classification of Epithelia Epithelia are classified based on: ▪ Shape of cells ▪ Number of layers of cells The Core of Quality Health Care Education 18 Classification of Epithelia - shape of cell The 4 basic types of cells Squamous Cuboidal Columnar Transitional: change shape, from squamous to cuboidal and back. Found in organs that stretch and collapse to smaller size. 19  Types of epithelial tissues Combine arrangement of layers and cells shapes Examples: Simple squamous epithelium Simple cuboidal epithelium Simple columnar epithelium Pseudostratified columnar epithelium Stratified squamous epithelium Stratified cuboidal epithelium Stratified columnar epithelium Transitional epithelium 20  Recap 1. Identify the tissue types 2. Differentiate between the three muscle tissues. 3. What are the components of a typical neuron? 4. What is the basis for epithelial tissue classification? 5. For all tissue types: a. Description/composition b. Function c. Location The Core of Quality Health Care Education 21  Squamous Epithelium Consists of flat cells which are joined together like floor tiles Cells are thin which allows for rapid diffusion of substances The Core of Quality Health Care Education 22  Cuboidal Epithelium Consists of cube-shaped cells Make the secretory lining of glands which secrete substances e.g. as mucus, enzymes etc. Found in the lining of GI tract for absorption of fluids and digested food The Core of Quality Health Care Education 23  Columnar Epithelium Consists of tall and cylindrical cells May be specialized for secretion and absorption Cells good at protecting underlying tissues The Core of Quality Health Care Education 24  Transitional Epithelium Cells range in shape from squamous to columnar Cells may change shape when muscles of the organ stretch Found in the bladder The Core of Quality Health Care Education 25  Classification by Layers Epithelial cells may be arranged in single or multiple layers Number of layers of cells can be used to classify epithelia into: - Simple epithelium - Stratified epithelium - Pseudostratified columnar epithelium The Core of Quality Health Care Education 26  Guide in understanding tissues eg Composition/Description: Single layer of flattened cells, disk-shaped central nuclei Function: Filtration,diffusion, osmosis & secretion Location: lines heart, blood vessels, air sacs of lungs. Endothelium: Inner covering ( lymphatic vessels, Blood vessels and heart) Mesothelium: Middle Covering (serous membranes,ventral cavity) The Core of Quality Health Care Education 27  Simple Epithelium It consists of a single layer of cells Found in areas where there is diffusion, osmosis, filtration, secretion and absorption Simple epithelium can further be divided into: - Simple squamous epithelium - Simple cuboidal epithelium - Simple columnar epithelium The Core of Quality Health Care Education 28  Stratified Epithelium It consists of at least two layers of cells More durable, and found in areas where there is wear and tear (Get sloughed off) Name of stratified epithelium derived from superficial layer of cells The Core of Quality Health Care Education 29  Pseudostratified columnar epithelium ▪ All cells attached to basement membrane but nuclei at various depths ▪ Some cells do not reach surface, giving a false impression of multiple layers The Core of Quality Health Care Education 30 The Core of Quality Health Care Education 31  Glandular Epithelium Main function is secretion Forms lining of glands Mostly made up of columnar epithelium Two types: Endocrine (Secretions (Hormones) into interstitial fluid and then bloodstream, no ducts) – eg Pituitary gland Exocrine (Secrete their products into ducts and empty onto surface of a covering and lining epithelium eg skin surface or lumen of hollow organs. Eg of such glands: Sweat glands, salivary glands. The Core of Quality Health Care Education 32  Connective Tissue It is the most abundant type of tissue in the human body. Not exposed to outside body Vascular except Cartilages and tendons. The Core of Quality Health Care Education 33  Classification of connective tissues I. Embryonic connective tissue C. Cartilage (Supporting CT) A. Mesenchyme 1. Hyaline B. Mucous 2. Elastic II. Mature connective tissue 3. Fibrocartilage A. Loose (A connective tissue proper) 1. Areolar D. Bone tissue (Supporting CT) 2. Adipose 3. Reticular E. Liquid tissue 1. Blood B. Dense (A connective tissue proper) 2. Lymph 1. Dense regular 2. Dense irregular 3.Elastic  Functions of connective tissues Binds together, supports, strengthens other body tissues. Compartmentalizes structures (eg skeletal muscles). Establish a structural framework for the body. Transport fluids and dissolved materials. Protects and insulates internal organs. Major site of stored energy reserves (adipose tissue). Main site of immune responses (macrophages, WBC, Plasma cells).  Cont..Functions 1. Binding and support 2. Protection 3. Insulation 4. Transportation The Core of Quality Health Care Education 36  General Features of Connective Tissue Made up of two basic elements – cells and Extracellular matrix The matrix consists of bundles of fibers and ground substance Ground substance is the gel found between cells and fibers Matrix is produced by tissue cells and can be solid, fluid, semi-fluid, gelatinous, fibrous or calcified. The Core of Quality Health Care Education 37  Connective Tissue Cells Consists of mature (fully developed) and immature (not fully developed) cells Immature cells have a name ending in –blast e.g. chondroblasts in cartilage and osteoblasts in bone Blast cells secrete the matrix Mature cells have a name ending in –cyte e.g. osteocytes in bone and chondrocytes in cartilage Mature cells mainly involved in maintaining the matrix The Core of Quality Health Care Education 38  Connective Tissue Matrix Made up of fibers and ground substance Ground substance supports and binds cells together and also provides medium for exchange of substances between blood and tissue cells Fibers strengthen and support connective tissue The are three types of fibers found in the matrix: - Collagen (strong and resistant to pulling forces) - Elastin (can stretch) - Fibronectin (promotes cell adhesion and holds cells in position, associated with reticular) The Core of Quality Health Care Education 39  Types of Connective Tissue Fibers Collagen (bone, cartilage, ) Long, straight and unbranched. Flexible, yet strong formed from the protein collagen (fibrous protein subunits) Eg Tendons (skeletal muscles to bones), Ligaments (Connect bones) Elastin (lungs, blood vessels, ear cartilage) smaller diameter fibers formed from protein elastin surrounded by glycoprotein (fibrillin) can stretch up to 150% of relaxed length and return to original shape Reticular (spleen and lymph nodes). From reticulum. thin, branched fibers that form framework (collagen and glycoprotein) of organs Produced by fibroblasts  Cartilage Network of fibers in rubbery ground substance Resilient and can endure more stress than loose or dense connective tissue No nerve fibres, avascular, lots of water, firmly bound collagen fibers and some elastic fibers Chondroblasts produce new matrix, chondrocytes maintain matrix after skeleton has stopped growing 3 main types Hyaline cartilage Fibrocartilage Elastic cartilage Figure 4.4  Classification of Connective Tissue Loose connective tissue - Fibers loosely arranged around cells Dense connective tissue - Consists of numerous and thicker fibers crowded around connective tissue cells The Core of Quality Health Care Education 43  Examples of Loose and Dense Connective Tissue Loose Connective Tissue Dense Connective Tissue Areolar Tendons Adipose (fat) tissue Ligaments The Core of Quality Health Care Education 44  Revision 1. Name the tissue types shown in the figures below (A, B, C, D, E) The Core of Quality Health Care Education 45 2. From the list of the major tissue types, enter the appropriate answer in the answer blanks. Muscle tissue, Connective tissue, Epithelium tissue, Nervous tissue a. _________________forms membranes. b. __________________supports and reinforces body organs. c. ______________________cell shorten to exert force. d. _____________________is the basis of the major controlling system of the body. e. ___________________forms endocrine and exocrine glands. f. _____________________uses electrochemical signals to carry out it’s functions. The Core of Quality Health Care Education 46 3. Structurally, why is the simple columnar epithelium more resistant to being torn apart than simple squamous epithelium? 4. What is the epithelial tissue lining the stomach and most of the intestines? 5. What is the epithelial lining the inside of the mouth? 6. What is the epithelial tissue lining the nasal cavity? The Core of Quality Health Care Education 47  REFERENCES 1. Gilroy, AM. (2013). Anatomy: An essential Textbook. Thieme 2. Marieb, EN, (2015). Essentials of Human Anatomy and Physiology. 11th Edition. Pearson 3. Marieb, EN & Hoehn, K (2007). Human Anatomy and Physiology. 9th Ed. Pearson, Boston. 4. Drake RL, Vogl AW, Mitchell AWM (2010). Gray’s Anatomy for Students. 2nd Ed. Churchill Livingstone, Elsevier. 5. Tortora, G. J., Derrickson, B. (2013). Principles of Anatomy and Physiology. 14th Edition. John Wiley and Sons, Inc. THE CORE OF QUALITY HEALTH CARE EDUCATION 48