HLSC 120 BN04 W2025 Introduction and Ch 3 Tissues Jan 9 2025 Class Notes PDF

CHAPTER 3 Tissues W2025  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue Introduction What are tissues? They are next step...

CHAPTER 3 Tissues W2025  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue Introduction What are tissues? They are next step after cells A collection of cells Tissues have a collective function or job May be hard (bone), semi-solid (fat) or liquid (blood) Histology: histo = tissue; ology = study Histology: microscopic study of tissues Pathologist: physician that examines tissue to help other physicians Four Types of Tissues Epithelial Connective Muscular Nervous Covers body tissues Protects and For contraction and Detects changes in supports body generation of force conditions inside Lines hollow organs, and organs and outside body body cavities, and ducts Generates heat that warms body if Generates action Forms glands needed (shivering) potentials The body interacts with Activate muscular internal and external contraction and environment through glandular secretions tissue.  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue Difference between Epithelial and Connective tissue Epithelial Connective Has cells tightly packed Has a few scattered cells together Cells are surrounded by large Has little or no extracellular amount of extracellular matrix matrix  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue Two Tissue Types 1. Surface (Proper) Surface (Proper) Epithelial Tissue Forms surface layers and therefore is not covered by any other tissues Avascular: does not have its own blood supply Provides coverings of skin and some internal organs Forms linings of vessels, ducts, and body cavities Body cavities such as: interior of respiratory, digestive, urinary, and reproductive systems Surface (Proper) Epithelial Tissue Classification of Surface ET: number of cell layers Simple ET (uni-laminar = one layer) Very thin - so able to allow diffusion, osmosis and filtration and absorption to pass through them Oxygen and carbon dioxide diffuse through simple ET in lungs Can function with absorption: absorption of fluids and other substances (absorbing nutrients from GI tract) Pseudostratified: Looks like more than one layer, but it’s not. Stratified (two or more layers) More layers = more protection, etc. Appears where there is considerable wear and tear. Surface (Proper) Epithelial Tissue Classification of surface ET: cell shape Squamish cells: Think “thin” / Function: rapid passage of substances through them Cuboidal cells: Cube shaped / Function: secretion or absorption Columnar cells: 1 Taller than wide (like columns) Function: protect underlying tissues (shock absorbers) / absorption) / have microvilli (1) = increase surface area for absorption Transitional (Urothelium) cells: Change shape: relaxed = Cuboidal / stretched = Squamish Example urinary bladder: cells can stretch to large size and collapse to smaller size Two Tissue Types Surface epithelium 2. Glandular Glandular Epithelial Tissue Primary function is secretion Gland: Glands are either endocrine or exocrine Glands are epithelium tissue that secretes substances (via ducts) onto either: A surface (exocrine) Into blood (endocrine) Glandular Epithelial Tissue Endocrine glands: Secretions enter interstitial fluid then diffuse into bloodstream (secretions called hormones) Example: thyroid hormone secreted by thyroid gland Exocrine glands: Secrete into ducts that empty onto a surface Many secretions would be harmful if they entered blood Example: pancreas secreting digestive juices Surface onto surface of small intestine epithelium  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue Connective Tissues Most abundant and diverse of four types of tissues Everywhere in body All connective tissue have three things in common 1. Develop from same cell (Mesenchyme) 2. They have different degrees of vascularity 3. Connective tissues are mostly composed of non-living material (extracellular matrix) Connective Tissues Composed of extracellular matrix and cells. Extracellular Matrix (ECM) = more important to connective tissue function than cells inside ECM composition = key to function of different connective tissue types Example: Marshmallow Jell-O Marshmallows inside Jell-O are cells of connective tissue Jell-O is extracellular matrix ECM (Jell-O) made up of two components: 1. Ground substance 2. Fibers Connective Tissues All connective tissue cells (marshmallows) have two phases 1. Immature phase Cells called “Blasts” (means forming) Function: secrete ground substance and fibers Creates unique extracellular matrix 2. Mature phase Blasts mature into “cytes” Function of cytes: maintain matrix health Connective Tissues: Functions Connective tissue functions: Binds things together Supports and strengthens Protects Compartmentalizes structure Adipose tissue (a connective tissue type) = primary location of stored energy reserves Blood (a connective tissue type) = transport system to service cells Connective Tissues Connective tissue is highly vascularized Provides blood supply to epithelial tissue Exceptions include cartilage and tendons (not highly vascularized nor associated with epithelial tissue) Consists of two basic elements: 1. Extracellular matrix (EM) 2. Cells First, let’s take a look at Extracellular Matrix and then… Cells Extracellular matrix (ECM) Material located between widely placed cells ECM Structure determines tissue function and qualities Bones: ECM is hard and inflexible Cartilage: ECM is firm but pliable http://www.mun.ca/biology/desmid/brian/BIOL2060/BIOL2060-17/CB17.html Extracellular matrix (ECM) Connective tissue properties based upon composition of extracellular matrix (ECM) ECM has two major components 1. Ground substance 2. Fibers (1) Ground substance Component between cells and fibers Supports cells, binds them together Provides medium for exchange between blood and cells Active role in tissues development and functions Contains water and large organic molecules (polysaccharides and proteins) collectively known as GAG’s (glycosaminoglycans) Bristles projecting from GAG’s trap water and make ground substance more spine are GAG’s jelly-like Be able to identify images of different components of ECM Extracellular matrix (ECM) ECM has two major components 1. Ground substance 2. Fibers (2) Fibers Three types of ECM fibers 1. Collagen fibers Protein fibers: strongest and most abundant fibers (stronger than steel of same size) Resist pulling or stretching 2. Elastic fibers Contain protein elastin Strong but can be stretched up to 150% then return to normal length Plentiful in skin 3. Reticular fibers Made of collagen arranged in bundles with a coating of glycoproteins Provide support for walls of blood vessels and form a supporting framework around many “soft” organs (spleen, lymph nodes). First, let’s take a look at Extracellular Matrix and then… Cells Connective Tissue Cells Connective tissue cells vary according to type Fibroblasts: Large flat cells with branching processes Secretes fibers and ground substance Most common cell in connective tissue Macrophages: Develop from monocytes (WBC) and destroy bacteria by phagocytosis Plasma Cells Part of Adaptive Immune System Connective Tissue Cells Mast cells: Involved in triggering innate immunity inflammatory response White blood cells Not found in significant numbers in normal connective tissue Respond to infection/pathogens Examples: Neutrophils (destroy pathogens with phagocytosis) Eosinophils (migrate to sites of parasitic invasions) Adipocytes: Fat cells Store triglycerides Overview of Connective Tissue cells: Fibroblasts: most common and most important for development of ECM Others: mostly immune system cells and adipocytes Connective Tissue Cells: Immature/Mature All connective tissue cells (marshmallows) have two phases 1. Immature phase Cells are called “Blasts” (means forming) Function: secrete ground substance and fibers Create unique ECM 2. Mature phase Blasts mature into “Cytes” Cytes maintain extracellular matrix health We’ve taken a look at Immature phase Now let’s take a look at Mature Phase Mature Connective Tissue Three types of Mature Connective tissue A. Connective Tissue Proper Tendons and ligaments Flexible / ground substance has abundant fiber B. Supporting Connective Tissue Cartilage and bone Dense network of collagen and elastic fibers High tensile strength C. Liquid Connective Tissue Blood plasma  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue Membranes Membranes = flat sheets of pliable tissue Cover/line body parts Two types of membranes A: Epithelial Membranes B: Synovial Membranes Membranes A: Epithelial Membranes Majority of membranes Consist of epithelial layer attached to underlying connective tissue Three types of epithelial membranes: Mucous 1. Mucous membranes (or mucosa) line body cavities that open to exterior/ secrete mucus 2. Serous membranes (serosa) Line cavities that don’t open to exterior Serous Lines inner walls of body cavities and secretes lubricating fluid to reduce friction between opposing surface 3. Cutaneous membranes: covers surface of body (skin) Cutaneous Membranes B: Synovial Membranes (syn = together) Used when two bones articulate Do not open to exterior Lack epithelium thus they are not epithelial membranes Composed of synoviocytes (1) cells which secrete some component of synovial fluid Synovial fluid lubricates and nourishes cartilage covering bones and joints Synovial fluid contains macrophages 1  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue Muscular Tissue: Three types 1. Skeletal 2. Cardiac 3. Smooth Muscular Tissue: Skeletal Muscle Consists of long, cylindrical, striated fibers Multicellular with nuclei located at cells periphery Controlled voluntarily Usually attached to bones by tendons Muscular Tissue: Cardiac Muscle Have branched striated fibers and only a single centrally located nucleus Attached end to end by intercalated discs (1) Have gap junctions = provides a route for action potential to spread quickly throughout whole sections of heart muscle Involuntary control 1 Muscular Tissue: Smooth Muscle Lack striations (hence term “smooth”) Spindle shaped cells Cells have single centrally located nucleus Gap junctions Involuntary control  Tissues 1. Introduction / Types of Tissues 2. Comparison between Epithelial and Connective Tissue 3. Epithelial Tissue 4. Connective Tissue 5. Membranes 6. Muscular Tissue 7. Nervous Tissue  Nervous Tissue Nervous tissue consists of neurons and neuroglia Dendrites and axons project from main neuron body 98% of nervous tissue located in CNS Highly excitable: generate action potentials  Tissue 1 tissue Phonological Visuospatial chunks chunks Tissue Types Epithelial: covers / Connective: supports, protects / Muscular / Nervous Epithelial/ E:tightly packed cells, covers and Connective forms glands, interacts /avascular C: few cells lots of ECM, vascular /binds, supports, Epithelia SURFACE: - Squamish: passage tissue - Cuboidal: secretion, absorption - Columnar: shock absorption GLANULAR: endocrine (into blood) / exocrine (onto surface) Connective Composed of ECM and cells tissue - Cells: what marshmallows - ECM: orange Jello (fibers: protein, elastic, reticular) - Two phases: immature, mature  Tissue 2 tissue Phonological Visuospatial chunks chunks Epithelial Consists of epithelial layer and Membranes connective tissue layer Types: mucosa, serous, cutaneous (skin) Synovial Synovial: where two bones Membrane articulate / synoviocytes secrete lubricating synovial fluid Muscular Skeletal (multicellular, voluntary) tissue Cardiac (one nucleus, involuntary) Smooth (lack striations, single nucleus, usually involuntary Nervous Consists of neurons and neuroglia tissue Dendrites and axons Highly excitable: action potentials