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VAN-504, Lecture - 02 Epithelia and their modifications. Connective tissue and its components including blood and bone
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Tissues Definition: a group of closely associated cells that perform related functions and are similar in structure. Four basic types of tissue function Epithelium covering Connective tissue support Muscle tissue movement Nervous tissue control
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Epithelial Tissues General Characteristics
1.Epithelial tissue is widespread throughout the body, covers organs, and lines body surfaces. 2.Epithelial tissues - - are anchored to a basement membrane - are made up of tightly packed cells - contain little intercellular material - generally lack blood vessels, Avascular but innervated - are replaced frequently, regeneration 3.Polarity - Free upper (apical) surface - Lower (basal) surface contributing basal lamina to basement membrane
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Epithelia (plural) Epithelium: sheet of cells that covers a body surface or lines a body cavity; also form most of the body’s glands Functions: Protection Absorption Sensory reception Secretion Filtration Formation of slippery surfaces for movement
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Epithelial tissues function in
Epithelial tissues function in protection, secretion, absorption, excretion, and sensory reception.
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Epithelium Have one free (unattached) surface or edge called the apical surface Exposed to body’s exterior or to the cavity of an internal organ Lower surface of an epithelium rests on a basement membrane Structureless material secreted by both the epithelial cells and the connective tissue cells
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Classification of Epithelia
According to thickness “simple” - one cell layer “stratified” – more than one layer of cells (which are named according to the shape of the cells in the apical layer) According to shape “squamous” – wider than tall “cuboidal” – as tall as wide “columnar” - taller than wide
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Classification of Epithelium
According to relative number of cell layers Simple (one layer of cells) Stratified (more than one cell layer)
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Classification of Epithelium
According to the shape of cells Squamous (cells flattened like scales) Cuboidal (cube-shaped) Columnar (shaped like columns)
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Simple Squamous Epithelium
Simple squamous (SS) tissue is composed of flat, scale-like cells that usually forms membranes. Single row of flat cells It lines the walls of blood vessels, pulmonary alveoli (Shown in slide), and the lining of the heart, lung, peritoneal cavities glomeruli, endothelium, and serosa Permits diffusion of substances Secretes serous fluid
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Simple Squamous Epithelium
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Simple Cuboidal Epithelium
This tissue is composed of a single layer of cube-like cells with microvilli. Absorption and secretion, mucus production It lines the walls of kidney tubules, covers the surface of ovaries, and is common in glands and their ducts, Liver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules
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Simple Cuboidal Epithelium
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Simple Cuboidal Epithelium
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Simple Columnar Epithelium
This tissue is composed of a single layer of tall narrow cells. - oval nuclei in basal half of cell It often includes mucus-producing goblet cells. It often lines the digestive tract, uterus, kidney and uterine tubes Absorption and secretion; mucus secretion.
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Simple Columnar Epithelium
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Simple Columnar Epithelium
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Pseudo stratified Epithelium
Secretes and propels respiratory mucus Although this tissue appears stratified, it is actually composed of a single layer of cells of different types. some not reaching free surface. Although their nuclei are found at different levels, It give layer stratified look. Each cell adjoins the basal membrane (BM). This tissue lines the larger respiratory passageways. It is often ciliated.
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Pseudo stratified Epithelium
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Pseudo stratified Columnar Epithelium
Main functions: absorption and secretion Ciliated variety lines respiratory tract Mucus produced by goblet cells traps dust and other debris Cilia propel mucus upward and away from the lungs
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Stratified Epithelia More than one layer of cells
Named for shape of surface cells exception is transitional epithelium Deepest cells on basement membrane Variations keratinized epithelium has surface layer of dead cells Non keratinized epithelium lacks the layer of dead cells
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Stratified: regenerate from below
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Keratinized Stratified Squamous
Multilayered epithelium covered with dead squamous cells, packed with keratin epidermal layer of skin
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Nonkeratinized Stratified Squamous
Multilayered surface epithelium forming moist, slippery layer Tongue, oral mucosa, esophagus and vagina
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Stratified Cuboidal Epithelium
Two or more cell layers; surface cells square Secretes sweat; produces sperm and hormones Sweat gland ducts; ovarian follicles and seminiferous tubules Stratified cuboidal epithelium (SC) is found in the ducts of sweat glands and surrounds Graafian follicles of ovaries (shown below
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Stratified Cuboidal Epithelium
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Transitional Epithelium
Multilayered epithelium surface cells that change from round to flat when stretched allows for filling of urinary tract ureter and bladder Shape of cells depends upon the amount of stretching It lines organs of the urinary system.
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Transitional Epithelium
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Ciliated Epithelium Some epithelial membranes are made up of cells with cilia, tiny projections that beat in unison to move mucus along the surface. Ciliated epithelia in the trachea, for example, sweep debris out of the respiratory tract.
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Glandular Epithelium A gland is defined as one or more cells responsible for secreting a particular product Two major gland types Endocrine gland Ductless since secretions diffuse into blood vessels All secretions are hormones Examples include pituitary, pancreas, ovaries, testes Exocrine gland Secretions empty through ducts to the epithelial surface Include sweat and oil glands
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Endocrine and Exocrine Glands
Secrete substances composed of epithelial tissue Exocrine glands connect to surface with a duct (epithelial tube) Endocrine glands secrete (hormones) directly into bloodstream Mixed organs do both liver, gonads, pancreas Unicellular glands – endo or exocrine goblet or intrinsic cells of stomach wall
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Connective Tissue Connective tissue
Connective tissue proper (examples: fat tissue, fibrous tissue of ligaments) Cartilage Bone Blood Widely spaced cells separated by fibers and ground substance Most abundant and variable tissue type Functions connects organs gives support and protection (physical and immune) stores energy and produces heat movement and transport of materials
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Cells of Connective Tissue
Fibroblasts produce fibers and ground substance Macrophages phagocytize foreign material and activate immune system arise from monocytes (WBCs) Neutrophils wander in search of bacteria Plasma cells synthesize antibodies arise from WBCs Mast cells secrete heparin inhibits clotting histamine that dilates blood vessels Adipocytes store triglycerides
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Fibers of Connective Tissue
Collagen fibers (white fibers) tough, stretch resistant, yet flexible tendons, ligaments and deep layer of the skin Reticular fibers thin, collagen fibers coated with glycoprotein framework in spleen and lymph nodes Elastic fibers (yellow fibers) thin branching fibers of elastin protein stretch and recoil like rubberband (elasticity) skin, lungs and arteries stretch and recoil
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Connective Tissue Ground Substance
Gelatinous material between cells absorbs compressive forces Consists of 3 classes of large molecules glycosaminoglycans – chondroitin sulfate disaccharides that attract sodium and hold water role in regulating water and electrolyte balance Proteoglycan (bottlebrush-shaped molecule) create bonds with cells or extracellular macromolecules adhesive glycoproteins protein-carbohydrate complexes bind cell membrane to collagen outside the cells
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Classes of Connective Tissue
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Fibrous Connective Tissue Types
Loose connective tissue gel-like ground substance between cells types areolar reticular adipose Dense connective tissue fibers fill spaces between cells types vary in fiber orientation dense regular connective tissue dense irregular connective tissue
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Areolar Tissue Loose arrangement of fibers and cells in abundant ground substance Underlies all epithelia, between muscles, passageways for nerves and blood vessels
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Areolar Tissue
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Reticular Tissue Loose network of reticular fibers and cells
Forms supportive stroma (framework) for lymphatic organs Found in lymph nodes, spleen, thymus and bone marrow
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Reticular Tissue
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Adipose Tissue Empty-looking cells with thin margins; nucleus pressed against cell membrane Energy storage, insulation, cushioning subcutaneous fat and organ packing brown fat (hibernating animals) produces heat
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Adipose Tissue
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Dense Regular Connective Tissue
Densely, packed, parallel collagen fibers compressed fibroblast nuclei Tendons and ligaments hold bones together and attach muscles to bones
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Dense regular Connective Tissue
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Dense Irregular Connective Tissue
Densely packed, randomly arranged, collagen fibers and few visible cells withstands stresses applied in different directions deeper layer of skin; capsules around organs
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Dense Irregular Connective Tissue
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Cartilage Supportive connective tissue with rubbery matrix
Chondroblasts produce matrix called chondrocytes once surrounded No blood vessels diffusion brings nutrients and removes wastes heals slowly Types of cartilage vary with fiber types hyaline, fibrocartilage and elastic cartilage
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Hyaline Cartilage Rubbery matrix; dispersed collagen fibers; clustered chondrocytes in lacunae supports airway, eases joint movements Ends of bones at movable joints; sternal ends of ribs; supportive material in larynx, trachea, bronchi and fetal skeleton
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Hyaline Cartilage
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Elastic Cartilage Hyaline cartilage with elastic fibers
Provides flexible, elastic support external ear and epiglottis
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Elastic Cartilage
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Fibrocartilage Hyaline cartilage with extensive collagen fibers (never has perichondrium) Resists compression and absorbs shock pubic symphysis, meniscus and intervertebral discs
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Fibrocartilage
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Bone Spongy bone - spongy in appearance
delicate struts of bone covered by compact bone found in heads of long bones Compact bone - solid in appearance more complex arrangement cells and matrix surround vertically oriented blood vessels in long bones
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Bone Tissue (compact bone)
Calcified matrix in lamellae around central canal Osteocytes in lacunae between lamellae Skeletal support; leverage for muscles; mineral storage
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Bone
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Blood Variety of cells and cell fragments; some with nuclei and some without Nonnucleated pale pink cells or nucleated white blood cells Found in heart and blood vessels
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Blood
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Mast Cell
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Lymphocytes
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Microphages
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Nervous Tissue Nervous tissue Neurons Supporting cells
Large cells with long cell processes surrounded by smaller glial cells lacking processes Internal communication between cells in brain, spinal cord, nerves and ganglia
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Nervous Tissue
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Muscle Tissue Elongated cells stimulated to contract
Exert physical force on other tissues move limbs push blood through a vessel expel urine Source of body heat 3 histological types of muscle skeletal, cardiac and smooth
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Skeletal Muscle Long, cylindrical, unbranched cells with striations and multiple peripheral nuclei movement, facial expression, posture, breathing, speech, swallowing and excretion
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Skeletal Muscle
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Cardiac Muscle Short branched cells with striations and intercalated discs one central nuclei per cell Pumping of blood by cardiac (heart) muscle
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Cardiac Muscle
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Smooth Muscle Short fusiform cells; nonstriated with only one central nucleus sheets of muscle in viscera; iris; hair follicles and sphincters swallowing, GI tract functions, labor contractions, control of airflow, erection of hairs and control of pupil
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Smooth Muscle
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