BIO 110 - 04 - Tissue Level PDF

Professor Lindboom-Broberg (LB) Tissues Review Primary Tissues Levels of Organization Tissues  Trillions of cells in the body  Only about 200 different types of cells  Tissue: A collection of cells working together  Histology: Anatomical study of tissues  Primary Tissues (4)  Epitheli...

Professor Lindboom-Broberg (LB) Tissues Review Primary Tissues Levels of Organization Tissues  Trillions of cells in the body  Only about 200 different types of cells  Tissue: A collection of cells working together  Histology: Anatomical study of tissues  Primary Tissues (4)  Epithelial  Connective  Muscle  Nervous  Professor Lindboom-Broberg (LB) Epithelial Tissue Classifications Cell Attachments Epithelial Tissue Nomenclature Epithelium Glands Epithelial Tissue Epithelial Tissue  ​Epithelia  Anatomy 1+ layers of cells Avascular Cover external & internal surfaces Often contain scattered gland cells  Functions Protection from abrasion, dehydration Control permeability (absorption / secretion) Sensation Epithelial Tissue  ​Glands  Anatomy Derived from epithelia Predominantly secretory cells Two types 1. ​Exocrine glands o Secrete onto external surfaces 2. ​Endocrine glands o Secrete hormones into interstitial fluid  Function Produce secretions Epithelial Tissue  Surfaces  Apical: Exposed surface Exterior of body or internal space  Base: Attached to basal tissues  Basolateral surface: Base & lateral surfaces together  Polarity  A property noting structural differences between two ends Epithelial Tissue  Epithelial attachments  Barrier must hold together  Replacement with cell loss  Avascular Base must be attached to underlying tissue to obtain nutrients Epithelial Tissue  Epithelial cells shapes 1. ​Squamous Thin and flat (squama, plate or scale) 2. ​Cuboidal Cube-shaped Like little boxes 3. Columnar Taller than they are wide Slender rectangles Epithelial Tissue  Epithelial cell layers  Simple Epithelium: Single layer of epithelial cells Epithelial Tissue  Epithelial cell layers  Stratified Epithelium: Several layers of epithelial cells Found in areas that need protection from abrasion or chemical stress – Examples: surface of skin, lining of the mouth  Identification is done by looking at the top layer Underlying layers can be of a different shape Squamous Epithelium  Thin, flat, irregularly shaped cells  Top view – Cells look like fried eggs  Sectional – Nucleus found in thickest part  Simple squamous epithelium  Most delicate epithelium  Functions: absorption, diffusion  Locations: Peritoneum, capillaries, inside eye, lung alveoli  Stratified squamous epithelium  Superficial layer flattened  Functions: Sustain severe mechanical or chemical stress  Locations: Surface of skin and lines mouth, throat, esophagus, rectum, anus, vagina Squamous Epithelium  Stratified squamous epithelium  Two types 1. ​Keratinized – Superficial layers packed with keratin, a water-resistant protein – Tough and water resistant – Resists both mechanical stress and dehydration – Outer skin, hair, and nails 2. ​Non-keratinized – Resists abrasion but can dry out – Lines oral cavity, pharynx, esophagus, anus, vagina Cuboidal Epithelium  Cells resemble hexagonal boxes In sectional view, cells appear square  Nucleus near center of each cell  ​Simple cuboidal epithelium Functions: secretion and absorption Lines exocrine glands and ducts Lines parts of kidney tubules and thyroid gland  ​Stratified cuboidal epithelium Rare tissue Function: Selective absorption/secretion Locations: Sweat glands ducts and mammary glands Columnar Epithelium  Simple columnar epithelium Function: absorption or secretion takes place Locations: Stomach, intestine, gallbladder, uterine tubes, kidney ducts May have microvilli or cilia on apical surface  Stratified columnar epithelium Rare tissue Functions: Secretion, absorption, digestion, lubrication Locations: Large ducts such as salivary glands or pancreas Columnar Epithelium  Pseudostratified columnar epithelium  Key differences Cells of varying shapes Nuclei distance to base varies; NOT in a band along tissue Each cell contacts basement membrane  Cells usually have cilia  Lines nasal cavities, trachea, larger airways in lungs, portions of male reproductive tract Columnar Epithelium  Columnar epithelium  Sectional view – Rectangular cells  Elongated nuclei in band close to basement membrane**  Types 1. ​Simple columnar epithelium** 2. ​Stratified columnar epithelium** 3. ​Pseudostratified columnar epithelium Transitional Epithelium  Transitional epithelium  Stratified epithelium that can stretch and recoil without damage  Changes in appearance Relaxed (e.g., empty bladder)—superficial cells cuboidal Stretched (e.g., full bladder)—superficial cells flattened  Locations: Only in urinary system Urinary bladder, ureters, urine-collecting chambers of kidneys Epithelium Histology Review Stratified Simple cuboidal Pseudostratified columnar columnar Simple Squamous Simple Columnar Transitional Stratified Squamous Stratified Cuboidal Epithelial Naming  Epithelium  Epi = upon  Epithelial tissue covering exterior surfaces  Endothelium  Endo = within, inside  Epithelial tissue of internal organs and cavities Blood vessels, heart, lymphatic tissue, etc.  Mesothelium  Meso = middle  Epithelial tissue of serous membranes Pericardium, pleura, peritoneum Glandular Epithelium  Collections of epithelia (or derived structures)  Can be scattered cells or complex organs  Produce secretions  Multicellular exocrine gland classification  Based on duct structure Simple: One duct that does not divide Compound: The duct divides one or more times Glandular Epithelium  Collections of epithelia (or derived structures)  Can be scattered cells or complex organs  Produce secretions  Categorized into two types 1. ​Endocrine glands Release secretions into interstitial fluid (inside) 2. ​Exocrine glands Release secretions into ducts onto epithelial surface (outside) Duct: Tubing that connects an exocrine gland to an exposed surface Glandular Epithelium  Unicellular exocrine gland classification  Mucous (goblet) cells Only unicellular exocrine gland Independent, scattered secretory cells in epithelium Secrete mucin mixes with water to form mucus  Professor Lindboom-Broberg (LB) Connective Tissue Generalizations Connective Tissue Proper Supporting Connective Tissue Fluid Connective Tissue Connective Tissue  Basic components shared by connective tissues 1. Specialized cells 2. Extracellular protein fibers 3. Fluid called ground substance  Extracellular Matrix Extracellular fibers and ground substance Surrounds the cells Accounts for majority of connective tissue volume  There are three categories of connective tissue Connective Tissue 1. ​Connective tissue proper  Contains many types of cells  Extracellular fibers in syrupy ground substance Loose (fibers create loose, open framework) Dense (fibers densely packed) Connective Tissue 2. ​Fluid connective tissue  Distinctive group of cells  Watery matrix Blood (within cardiovascular system) Lymph (within lymphatic system) Connective Tissue 3. S ​ upporting connective tissue  Less diverse cell population  More densely packed matrix Cartilage (solid, rubbery matrix) Bone (solid, crystalline matrix) Connective Tissue  Fixed Cells  Involved with maintenance, repair, energy storage  Fibroblasts: Synthesize extracellular fibers  Fibrocytes: Maintain extracellular fibers  Adipocytes: Stores lipids  Others Melanocytes synthesize melanin pigment Immune cells provide protection from infection and clean up debris – Fixed Macrophage – Mast Connective Tissue  Extracellular protein fibers Reticular fibers – Strong and form branching network Collagen fibers – Thick, very strong Elastic fibers – Slender, very stretchy  Ground substance Clear and colorless Viscous (syrupy) due to presence of proteoglycans and glycoproteins Loose Connective Tissue Proper 1. ​Areolar tissue Most common connective tissue proper Functions – Packing material of the body – Found around most organs, binding them together with elasticity Has all connective tissue proper cell types Loose Connective Tissue Proper 2. ​Adipose tissue Adipocyte: Specialized cell for the storage of lipids – Account for most of tissue volume Found deep to skin in various areas of body Forms layer of padding around eyes and kidneys Loose Connective Tissue Proper 3. ​Reticular tissue Many reticular (thin) fibers forming network Provides support/structure and resists distortion Found in liver, kidney, spleen, lymph nodes, and bone marrow Dense Connective Tissue Proper  Most volume occupied by extracellular fibers 1. ​Dense regular connective tissue Thick collagen fibers arranged in parallel bundles – Strength in one direction Found in cords (tendons, ligaments) or sheets Dense Connective Tissue Proper 2. ​Dense irregular connective tissue  Thick collagen fibers arranged in random directions Strength in many directions  Stromal tissue  Found covering visceral organs; in superficial layers of bones, cartilages, and peripheral nerves; in dermis of skin Dense Connective Tissue Proper 3. ​Elastic tissue  More elastic fibers than collagen  Is springy and resilient  Found between vertebrae, in ears, walls of large blood vessels, erectile tissues of penis Fluid Connective Tissue 1. Blood components Plasma: Watery matrix Formed elements: Cells suspended in plasma – Red blood cells (transport oxygen) – White blood cells (bodily defense) – Platelets (involved in clotting response) Red blood cells Platelet White blood cells Fluid Connective Tissue 1. Lymph Watery matrix Located in lymphatic vessels Majority of cells are white blood cells Functions to maintain solute levels, blood volume, and alert immune system of infection Supporting Connective Tissue  Part of supporting connective tissue  Small chambers called lacunae (lacus, lake) Inside lacunae are cells – Cartilage = Chondrocyte (chondros, cartilage) – Bone = Osteocyte (os, bone)  Matrix Cartilage contains rubbery chondroitin sulfates Bone contains rigid calcium salts  Vasculature Cartilage = Avascular Bone = Vascular Supporting Connective Tissue 1. ​Hyaline cartilage  Most common cartilage  Glassy matrix appearance (hyalos, glassy)  Reduces friction & provides stiff but flexible support  Found between ribs and sternum, covering bones in mobile joints, part of nasal septum, supporting respiratory passageways Precursor to bone Supporting Connective Tissue 2. ​Elastic cartilage  Chondrocytes suspended in a mesh network of elastic fibers  Distorts without damage and returns to original shape  Found in external ear and smaller internal structures Supporting Connective Tissue 3. ​Fibrocartilage  Durable and tough (strongest cartilage) Parallel collagen fibers in direction of stress  Resists compression, prevents bone-to-bone contact, and limits relative movement  Found in knee joint, between pubic bones, and in intervertebral discs Supporting Connective Tissue  Osseous (os, bone) tissue (bone tissue)  Connective tissue with solid, crystalline matrix Small volume of ground substance 2/3 of matrix is calcium salts (provide strength) Many collagen fibers (provide flexibility)  Strong, somewhat flexible, resistant to shattering  Cells Osteoblasts build osseous tissue Osteocytes maintain the tissue Osteoclasts break down osseous tissue  Types of osseus tissue 1. ​Compact bone 2. ​Spongy bone Bone  Professor Lindboom-Broberg (LB) Membranes Four Membranes Fascia Membranes  Line or cover body surfaces  Typically consist of epithelium supported by connective tissue  Four types in the body 1. Mucous membranes 2. Serous membranes 3. Cutaneous membrane 4. Synovial membranes Membranes 1. ​Cutaneous membrane  Covers exterior surface of body (skin)  Relatively thick, waterproof, and usually dry  Composed of: Keratinized stratified squamous epithelium Layer of areolar tissue Underlying dense irregular connective tissue Membranes 2. ​Mucous membranes  Line passageways open to the exterior of the body Digestive, respiratory, reproductive, urinary tracts  Must be kept moist to facilitate movement, absorption, or secretion  Lubricated by mucus or bodily fluids  Composed of Simple columnar OR pseudostratified columnar epithelium Supported by areolar connective tissue (lamina propria) Membranes 3. ​Serous membranes (serosae)  Three serous membranes reduce internal friction Pleura (pleural cavity and lungs) Pericardium (pericardial cavity and heart) Peritoneum (peritoneal cavity and visceral organs)  Composed of… Simple squamous mesothelium Supported by areolar connective tissue  Delicate and never connected to exterior  Watery serous fluid coats surface Membranes 4. ​Synovial membrane  Lines freely movable joint cavities  Lubricates joint cavity with aqueous synovial fluid  Provides nutrients to cartilage cells  Composed of… Not true epithelium – Contains gaps between cells Areolar connective tissue Fascia  Fasciae: (fascia, band) Surrounds and supports organs  Made of connective tissue  Three types of layers 1. ​Superficial fascia – Under skin (= hypodermis) – Areolar and adipose tissue 2. ​Deep fascia – Continuous with capsules, ligaments, and tendons – Dense irregular connective tissue – Strong, fibrous internal framework 3. ​Subserous fascia – Between serous membranes and deep fascia – Consists entirely of areolar tissue Fascia  Professor Lindboom-Broberg (LB) Muscle Tissue Skeletal Muscle Tissue Cardiac Muscle Tissue Smooth Muscle Tissue Muscle Tissue  Specialized for contraction to cause movement  Movement of the body  Movement of blood around the cardiovascular system  Movement of materials within internal organs & structures  Three types  Skeletal muscle tissue Moves the body  Cardiac muscle tissue Moves blood within the heart and through blood vessels  Smooth muscle tissue Moves fluids and solids within internal organs Muscle Tissue 1. ​Skeletal muscle tissue  Myocytes (muscle cells) Elongated, cylindrical, striated (banded) cells Multinucleated  Functions Move and stabilizes skeleton Guard entrances and exits to digestive, respiratory, urinary tracts Generate heat Protect internal organs Muscle Tissue 2. ​Cardiac muscle tissue  Only in the heart  Myocytes (cells) Short, branched, striated Uninucleate Interconnected with special junctions (intercalated discs) that synchronize muscle contractions  Functions to move blood and maintain blood pressure Muscle Tissue 3. ​Smooth muscle tissue  Found throughout body (skin, blood vessel walls, many organs of various systems)  Short, spindle-shaped, nonstriated, uninucleated cells  Functions Move food, urine, and reproductive secretions Control diameter of respiratory passageways and blood vessels  Professor Lindboom-Broberg (LB) Nervous Tissue Neurons Neuroglia Nervous Tissue  Nervous tissue  Specialized for conduction of electrical impulses (communication)  98% found in brain and spinal cord  Two classifications of nervous tissue cells 1. ​Neurons (neuros, nerve) – Signaling cells, star-like shapes 2. ​Neuroglia or glial cells (glia, glue) – Supporting cells, much smaller “dots” Nervous Tissue 1. Neurons  Transfer information around body and perform information processing  Vary in size and shape Longest cells in body are neurons (up to 1 meter) Nervous Tissue  Neuroglia  Several different cell types  Provide support for neurons and the nervous system Nutrients Clean up Repair & maintenance Environmental regulation Protection  Primary Tissues So far… Epithelial Connective Muscle Nervous  4 primary tissue types Membranes  4 membranes Cutaneous Mucous  Made of different tissues Serous Synovial  3 fascia wrappings Fascia  Made of different tissues Superficial Deep Subserous  Cells and tissues work together to provide functions  …what happens when they break? Tissue Injury  Tissues coordinate their response to restore homeostasis  Two restoration processes  Inflammation  Regeneration Tissue Injury  Tissues coordinate their response to restore homeostasis 1. Tissue Injury  Pathogens enter the body  Pathogens and injured cells release chemical signals 2. Defense cells are activated 3. Initiate inflammation  Body temperature increases  Blood vessels dilate 4. Recruit additional cells  Immune cells move into site  Clean up and removal of waste 5. Tissue regeneration (scar or replacement) Tissue Injury  Each tissue develops at different rates  Each tissue has a different ability to regenerate  Epithelial, connective (except cartilage), and smooth muscle regenerate well  Other muscle types and neural tissue regenerate poorly, if at all  In tissues that regenerate poorly, scar tissue replaces tissues that do not regenerate