Tissue Level of Organization Dr. Michael P. Gillespie.
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Transcript of Tissue Level of Organization Dr. Michael P. Gillespie.
Tissue Level of
Organization
Dr. Michael P. Gillespie
Tissue Types
• Four basic tissue types exist in the body.• 1. Epithelial tissue• 2. Connective tissue• 3. Muscle tissue• 4. Nervous tissue
2Dr. Michael P. Gillespie
Epithelial Tissue
• Epithelial tissue covers body surfaces and lines hollow organs, body cavities, and ducts. It also forms glands.
3Dr. Michael P. Gillespie
Connective Tissue
• 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.
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Muscle Tissue
• Muscle tissue generates the physical force needed to make body structures move.
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Nervous Tissue
• Nervous tissue detects changes in a variety of conditions inside and outside the body and responds by generating nerve impulses and help maintain homeostasis.
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Biopsy
• A biopsy (bio = life, -opsy = to view) is the removal of a sample of living tissue for microscopic examination.
• Used to diagnose disorders.
• Compared to normal tissue.
• Removed surgically or through needle and syringe.
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Cell Junctions
• Cell junctions are contact points between the plasma membranes of tissue cells.
• Functions• Forming seals between cells.• Anchoring cells to one another or to
extracellular material.• Channels between cells in a tissue
(passage of ions and molecules).
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9Dr. Michael P. Gillespie
Major Types of Cell Junctions
• Tight junctions
• Adherens junctions
• Desmosomes
• Hemidesmosomes
• Gap junctions
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Adherens Junctions
• Help epithelial cells resist separation.
• Located in epithelial cells.
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Desmosomes
• Attach cells to one another.
• Contribute to the stability of the cells and tissue.
• Found in the epidermis and between cardiac muscle cells.
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Hemidesmosomes
• Hemi – half. Hemidesmosomes lack links to adjacent cells.
• Anchor cells to the basement membrane.
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Gap Junctions
• Form fluid filled channels that connect adjacent cells.
• Ions and small molecules can diffuse from the cytosol of one cell to the next.
• Enable nerve impulses to travel more rapidly among cells.
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Epithelial Tissue
• Cells arranged in continuous sheets.
• Avascular – without blood vessels.
• Exchange of substances occurs by diffusion.
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Apical Surface
• Apical (free) surface – faces the body surface, a body cavity, the lumen (interior space) of an internal organ, or a tubular duct that receives secretions from cells.
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Lateral Surfaces
• The lateral surfaces of an epithelial cell face adjacent cells.
• The lateral surfaces may contain tight junctions, adherens junctions, desmosomes, and gap junctions.
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Basal Surface
• Opposite the apical surface.
• Anchored to the basement membrane.
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Basement Membrane
• Attaches to and supports the epithelial layer.
• Restricts the passage of larger molecules between the epithelial layer and connective tissue.
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20Dr. Michael P. Gillespie
Types of Epithelium
• Covering and lining epithelium• Forms the outer covering of skin and some
internal organs.• Forms the lining of blood vessels, ducts,
body cavities, and the interior of the respiratory, digestive, urinary, and reproductive systems.
• Glandular epithelium• Forms the secreting portion of glands (I.e.
thyroid, adrenal and sweat glands).
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Classification of Epithelium
• Classified by the # of layers.
• Classified by the shapes of cells.
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Arrangement of Cells in Layers
• Simple epithelium - single layer of cells• Functions in secretion and absorption
• Stratified epithelium – 2 or more layers of cells• Protects underlying tissues
• Pseudostratified epithelium – contains a single layer of cells, but the nuclei lie at different levels.• Some cells are ciliated or secrete mucus.
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Cell Shapes
• Squamous cells• Flat, thin cells that allow for rapid movement of
substances through them.
• Cuboidal cells• As tall as they are wide. Function in secretion
or absorption. May have microvilli.
• Columnar cells• Taller than they are wide. Specialized for
secretion or absorption.
• Transitional cells• Change shape as organs stretch and collapse.
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Types of Simple Epithelium
• Simple squamous epithelium
• Simple cuboidal epithelium
• Simple columnar epithelium• Nonciliated• Ciliated
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Types of Stratified Epithelium
• Stratified squamous epithelium• Keratinized• Nonkeratinized
• Stratified cuboidal epithelium
• Stratified columnar epithelium
• Transitional epithelium
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Pseudostratified Columnar Epithelium• Nonciliated
• Ciliated
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Simple Squamous Epithelium
• Single layer cells.
• Flat cells.
• Location• Bowman’s capsule of kidneys• Air sacs of lungs• Lining of the heart• Lining of blood vessels• Lining of lymphatic vessels• Inner surface of the tympanic membrane
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29Dr. Michael P. Gillespie
Simple Cuboidal Epithelium
• Single layer of cells.
• Cells have an equal height and width.
• Functions of secretion and absorption.
• Location• Surface of ovary• Kidney tubules• Ducts of many glands• Secreting portions of some glands
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31Dr. Michael P. Gillespie
Simple Columnar Epithelium
• Single layer of cells.
• Cells are taller than they are wide.
• Location• Ciliated
• Upper respiratory tract• Uterine (Fallopian) tubes• Paranasal sinuses• Central canal of spinal cord
• Nonciliated• GI tract from stomach to anus• Ducts of many galnds• Gallbladder
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33Dr. Michael P. Gillespie
Stratified Squamous Epithelium
• 2 or more layers of cells• Apical layers of cells are flat• Deep layers vary in shape from cuboidal to
columnar
• Keratinized and nonkeratinized forms
• Location• Keratinized lines the surface of the skin• Nonkeratinized lines wet surfaces such as
the mouth, esophagus, epiglottis, vagina and tongue
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35Dr. Michael P. Gillespie
Stratified Cuboidal Epithelium
• 2 or more layers of cells
• Equal in height and width
• Location• Ducts of adult sweat glands and
esophageal glands• Part of male urethra
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37Dr. Michael P. Gillespie
Stratified Columnar Epithelium
• 2 or more layers of cells
• Taller than they are wide
• Basal layer contains shortened, irregularly shaped cells
• Only the apical layer has columnar cells
• Location• Part of urethra• Excretory ducts of some glands (I.e.
esophageal)• Anal mucous membrane• Conjunctiva of the eye
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39Dr. Michael P. Gillespie
Transitional Epithelium
• 2 or more layers of cells
• Variable in appearance
• Present in the urinary system
• Un-stretched it looks similar to stratified cuboidal epithelium
• Stretched it looks similar to stratified squamous epithelium
• Location• Urinary bladder• Portions of the ureters and urethra
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41Dr. Michael P. Gillespie
Pseudostratified Columnar Epithelium• Single layer of cells – appears to be more
than one layer due to uneven nuclei
• Some cells do not extend to the surface
• The cells that extend to the surface either secrete mucous (goblet cells) or bear cilia
• Location• Airways of the upper respiratory tract• Larger ducts of many glands• Epididymis• Part of male urethra
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43Dr. Michael P. Gillespie
Glandular Epithelium
• Function – secretion
• Gland – a single cell or group of cells that secrete substances into ducts, onto a surface, or into the blood.
• 2 types• Endocrine• Exocrine
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Endocrine Glands
• The secretions of endocrine glands enter the interstitial fluid and then diffuse directly into the bloodstream.
• These secretions do NOT flow through a duct.
• These secretions are called hormones.
• Examples• Pituitary, thyroid, and adrenal glands
45Dr. Michael P. Gillespie
Exocrine Glands
• Exocrine glands secrete their products into ducts that empty onto the surface of a covering and lining epithelium.
• Types of secretions• Mucus, sweat, oil, earwax, sailva,
digestive enzymes
• Examples• Sudoriferous (sweat) and salivary
glands
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47Dr. Michael P. Gillespie
Structural Classification of
Glands• Unicellular – single celled
• Multicellular – many celled – distinct organ
• Simple - unbranched
• Compound - branched
• Tubular – tubular secretory parts
• Acinar – rounded secretory portions
• Tubular Acinar
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Simple Glands
• Simple tubular• Glands in Large Intestine
• Simple branched tubular• Gastric glands
• Simple coiled tubular• Sweat glands
• Simple acinar• Glands of penile urethra
• Simple branched acinar• Sebaceous glands
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Compound Glands
• Compound tubular• Bulbourethral (Cowper’s) glands
• Compound acinar• Mammary glands
• Compound tubuloacinar• Acinar glands of the pancreas
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51Dr. Michael P. Gillespie
Functional Classification of Exocrine Glands
• Merocrine glands• The secretion is synthesizes on ribosomes on the
RER• Released from the cell in secretory vesicles• Most glands of the body
• Apocrine glands• Accumulate secretory products on the apical
surface, which then pinches off.
• Holocrine glands• Accumulate a secretory product in their cytosol.
The cell matures and ruptures, thus releasing its secretory product.
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53Dr. Michael P. Gillespie
Connective Tissue Functions
• Binds together, supports, and strengthens other body tissues
• Protects and insulates internal organs
• Compartmentalizes structures such as skeletal muscles
• Major transport system within the body (blood is a fluid CT)
• Major site of stored energy reserves (adipose tissue)
• Main site of immune responses
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Features of Connective Tissue
• 2 Basic element• Cells• Matrix
• Fills the wide spaces between the cells• Determines the tissue’s qualities
• In cartilage it is pliable• In bone it is hard and not pliable
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Features of CT continued…
• Does not usually occur on body surfaces, with the exception of areolar which lines joint cavities.
• Usually highly vascular, with the exception of cartilage (avascular) and tendons (scanty).
• Contains a nerve supply with the exception of cartilage.
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Types of CT Cells
• Fibroblasts
• Macrophages
• Plasma cells
• Mast cells
• Adipocytes
• White blood cells
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58Dr. Michael P. Gillespie
Fibroblasts
• Fibro = fibers
• Secrete fibers and ground substance of the matrix
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Macrophages
• Macro = large; -phages = eaters
• Develop from monocytes (type of WBC)
• Engulf bacteria and cellular debris by phagocytosis
• Fixed macrophages – reside in a particular tissue
• Wandering macrophages – roam tissues and gather at sites of infection or inflammation
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Plasma Cells
• Develop from WBCs
• Secrete antibodies which attack foreign substances in the body
• Part of the immune system
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Mast Cells
• Produce histamine which dilates small blood vessels
• Part of the inflammatory response
• Reaction to injury or infection
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Adipocytes
• Adipose cells (fat cells)
• Store triglycerides (fats)
• Found below the skin and around organs such as the heart and kidneys
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White Blood Cells
• Migrate to CT under certain conditions
• Neutrophils – respond to infection
• Eosinophils – respond to parasites and allergic responses
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Connective Tissue Matrix
• Ground Substance• Supports cells, binds them together, and
provides a medium for the exchange of substances
• Fibers• Strengthen and support CTs• Types
• Collagen fibers – strong but not stiff (flexible)• Elastic fibers – smaller in diameter than collagen –
stretch and return to their original shape• Reticular fibers – support to walls of blood vessels, form
a network around tissues, form basement membrane
65Dr. Michael P. Gillespie
Marfan Syndrome
• An inherited disorder caused by a defective fibrillin gene
• Abnormal development of elastic fibers.
• Predominant structures affected:• Periosteum of the bones• Ligament that suspends the lens of the eye• Walls of large arteries
• Features:• Tall with disproportionately long arms, legs, and digits• Blurred vision from displacement of the lens• Weakening of the aorta (susceptible to burst)
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67Dr. Michael P. Gillespie
Classification of Connective Tissue
• Embryonic CT – present in the embryo and fetus• Mesenchyme – all CT arises from this• Mucous CT (Wharton’s jelly) – umbilical cord
• Mature CT – present in the newborn• Loose CT• Dense CT• Cartilage• Bone Tissue• Blood Tissue• Lymph
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Embryonic Connective Tissue
• Mesenchyme
• Mucous CT
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70Dr. Michael P. Gillespie
71Dr. Michael P. Gillespie
Loose Connective Tissue
• Areolar CT
• Adipose Tissue
• Reticular CT
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73Dr. Michael P. Gillespie
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75Dr. Michael P. Gillespie
Dense Connective Tissue
• Dense regular CT
• Dense irregular CT
• Elastic CT
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Cartilage
• Hyaline cartilage
• Fibrocartilage
• Elastic cartilage
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Loose Connective Tissue
• The fibers are loosely intertwined and many cells are present
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Areolar Connective Tissue
• Widely distributed throughout the body
• Contains fibroblasts, macrophages, plasma cells, mast cells, adipocytes, and WBCs
• Fiber types• Collagen, elastic, and reticular
• Combined with adipose tissue it forms the subcutaneous layer
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80Dr. Michael P. Gillespie
Adipose Connective Tissue
• Loose CT
• Adipocytes (adipo = fat) – store triglycerides
• Good insulator
• Energy Reserve
• Supports and protects organs
• Cytoplasm and nucleus are pushed to the periphery of the cell from large triglyceride droplet
• New blood vessels form with new adipose tissue (can lead to hypertension)
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82Dr. Michael P. Gillespie
Liposuction
• Lip = fat; suction lipectomy ectomy = to cut out
• Suctioning out small sections of adipose tissue
• Complications• Fat emboli (clots)• Fluid depletion• Injury to internal structures• Severe postoperative pain
83Dr. Michael P. Gillespie
Reticular Connective Tissue
• Forms the stroma (supporting framework) of the liver, spleen, and lymph nodes
• Binds together smooth muscle cells
• Reticular fibers in the spleen filter blood and remove worn-out blood cells
• Reticular fibers in the lymph nodes filter lymph and remove bacteria
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85Dr. Michael P. Gillespie
Dense Connective Tissue
• More numerous, thicker, denser fibers and fewer cells than loose CT
• Dense Regular CT – tendons and most ligaments
• Dense Irregular CT – heart valves, perichondrium, periosteum
• Elastic CT – lung tissue, elastic arteries
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87Dr. Michael P. Gillespie
88Dr. Michael P. Gillespie
89Dr. Michael P. Gillespie
Cartilage
• Dense network of cartilage fibers and elastic fibers
• Endures more stress than loose and dense CT
• Chondrocytes = mature cartilage cells
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Hyaline Cartilage
• Most abundant cartilage in the body
• Weakest of the 3 types of cartilage
• Flexible
• Located in joints – reduces friction and shock
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92Dr. Michael P. Gillespie
Fibrocartilage
• Strongest of the 3 types of cartilage
• Strength and rigidity
• Located in intervertebral discs
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94Dr. Michael P. Gillespie
Elastic Cartilage
• Provides strength and elasticity
• Maintains the shape of external structures
• Located in the ear
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96Dr. Michael P. Gillespie
Bone Tissue
• The basic unit of compact bone is an osteon or Haversian system
• 4 parts of the osteon• Lamellae = little plates – concentric rings of
matrix – consist of mineral salts• Lacunae = little lakes – spaces btwn. Lamellae
that contain osteocytes• Canaliculli = little canals – contain processes of
osteocytes – routes for nutrients and waste products
• Central (Haversian) canal – contains blood vessels and nerves
97Dr. Michael P. Gillespie
98Dr. Michael P. Gillespie
Blood Tissue
• Connective Tissue with a liquid matrix called blood plasma – pale yellow fluid (mostly water) with dissolved substances: nutrients, wastes, enzymes, plasma proteins, hormones, gases, ions
• Suspended• Red blood cells• White blood cells• Platelets
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100Dr. Michael P. Gillespie
Lymph
• Extracellular fluid that flows in lymphatic vessels
• Contains lymphocytes (type of WBC) and dietary lipids
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Elephantiasis
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Membranes
• Flat sheets of pliable tissue that cover or line a part of the body
• Two types• Epithelial
• Mucous membrane• Serous membrane• Cutaneous membrane of the skin
• Synovial
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Mucous Membranes
• Lines a body cavity that opens directly to the exterior
• Line digestive, respiratory, reproductive tracts and much of the urinary tract
• Goblet cells secrete mucous
104Dr. Michael P. Gillespie
Serous Membranes
• Serous = watery
• Line body cavities that do NOT open directly to the exterior
• Two layers• Parietal (pariet = wall) – attached to the cavity wall• Visceral (viscer = body organ) – attaches to the
organs inside the cavity
• Secretes serous fluid
• Pleura / pericardium / peritoneum
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Synovial Membranes
• Syn = together
• Line the cavities of freely moveable joints
• Secrete synovial fluid which lubricates and nourishes the joint
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Muscle Tissue
• Consists of elongated cells called muscle fibers
• Produces body movements, maintains posture, and generate heat
• Types• Skeletal muscle tissue• Cardiac muscle tissue • Smooth muscle tissue
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Skeletal Muscle Tissue
• Attaches to bones of the skeleton
• Striated
• Voluntary
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109Dr. Michael P. Gillespie
Cardiac Muscle Tissue
• Forms the wall of the heart
• Striated
• Involuntary
• Fibers attach to one another via intercalated discs (intercalat = to insert between)
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111Dr. Michael P. Gillespie
Smooth Muscle Tissue
• Located in the walls of hollow internal structures
• Involuntary
• Lacks striations (smooth)
• Located in blood vessels, airways to lungs, stomach, intestines, gallbladder, and urinary bladder
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113Dr. Michael P. Gillespie
Nervous Tissue
• Two types of cells• Neurons – nerve cells• Neuroglia (glia = glue) – supporting
structures
• Parts of Neurons• Cell body• Dendrites• Axon
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115Dr. Michael P. Gillespie