tissues groups of cells with a common function four primary tissues: epithelia connective...

Tissues Groups of cells with a common function Four primary tissues: Epithelia Connective tissues Muscle Nervous

Epithelial Tissues Line body cavities and cover surfaces Glandular epithelia: epithelial cells adapted to make up glands: Exocrine glands: secretion into ducts to exterior of body Endocrine glands: secretion into the blood to carry chemical messages throughout the body Functions of epithelium Protection Absorption, secretion, and ion transport Filtration Forms slippery surfaces

2013 Pearson Education, Inc. Studying Human Tissue: Microscopy Tissue is fixed Preserved Cut Sliced thin enough to transmit light or electrons Stained Enhances contrast

2013 Pearson Education, Inc. Characteristics of Epithelial Tissue: Polarity Cells have polarity Apical surface (upper free) exposed to exterior or cavity Basal surface (lower, attached) Both surfaces differ in structure and function

2013 Pearson Education, Inc. Apical Surface of Epithelial Tissues May be smooth & slick Most have microvilli (e.g., brush border of intestinal lining) Increase surface area Some have cilia (e.g., lining of trachea)

2013 Pearson Education, Inc. Basal Surface of Epithelial Tissues Noncellular basal lamina Glycoprotein and collagen fibers lies adjacent to basal surface Adhesive sheet Selective filter Scaffolding for cell migration in wound repair

Epithelial Tissues: Attachments Basement membrane: Structural support Attaches epithelial layer to underlying tissues Junctions: hold epithelial cells together: Tight junctions: nothing passes Adhesion junctions/spot desmosomes: some movement between cells Gap junctions: protein channels

Lateral Surface Features Cell Junctions Tight junctions (zona occludens) close off intercellular space Found at apical region of most epithelial types Some proteins in plasma membrane of adjacent cells are fused Prevent molecules from passing between cells of epithelial tissue

Tight Junction

Lateral Surface Features Cell Junctions Adherens junctions (zonula adherens) anchoring junction Transmembrane linker proteins attach to actin microfilaments of the cytoskeleton and bind adjacent cells Along with tight junctions, form the tight junctional complex around apical lateral borders of epithelial tissues

Lateral Surface Features Cell Junctions Desmosomes two disc-like plaques connected across intercellular space Plaques of adjoining cells are joined by proteins called cadherins Proteins interdigitate into extracellular space Intermediate filaments insert into plaques from cytoplasmic side

Desmosome

Lateral Surface Features Cell Junctions Gap junctions passageway between two adjacent cells Let small molecules move directly between neighboring cells Cells are connected by hollow cylinders of protein

Gap Junction

Epithelial Tissues

Special Characteristics of Epithelia

2013 Pearson Education, Inc. Classification of Epithelia All epithelial tissues have two names One indicates number of cell layers Simple epithelia = single layer of cells Stratified epithelia = two or more layers of cells Shape can change in different layers One indicates shape of cells Squamous Cuboidal Columnar In stratified epithelia, epithelia classified by cell shape in apical layer

Epithelial Tissues: Classification Shape: Squamous: flattened cells, line vessels, part of lungs, body surface Cuboidal: cube shaped, form lining of tubules, glandular tissue Columnar: column shaped; line respiratory, digestive, reproductive tracts

Epithelial Tissues: Classification Number of layers: Simple/single layered: adapted for diffusion across cell barriers; line glands, and respiratory, digestive, reproductive systems Stratified/multiple layered: protection, skin surface

Naming Epithelia Naming the epithelia includes both the layers (first) and the shape of the cells (second) i.e. stratified cuboidal epithelium The name may also include any accessory structures Goblet cells Cilia Keratin Special epithelial tissues (don t follow naming convention) Pseudostratified Transitional

Simple Squamous Epithelium Function Passage of materials by passive diffusion and filtration Secretes lubricating substances in serosae Location Renal corpuscles Alveoli of lungs Lining of heart, blood and lymphatic vessels Lining of ventral body cavity (serosae)

Simple Squamous Epithelium Simple squamous lining the walls of the capillary

Simple Cuboidal Epithelium Description single layer of cube-like cells with large, spherical central nuclei Function secretion and absorption Location kidney tubules, secretory portions of small glands, ovary & thyroid follicles

Simple Cuboidal Epithelium

Simple Columnar Epithelium Description Single layer of column-shaped (rectangular) cells with oval nuclei Some bear cilia at their apical surface May contain goblet cells Function Absorption; secretion of mucus, enzymes, and other substances Ciliated type propels mucus or reproductive cells by ciliary action

Simple Columnar Epithelium Location Non-ciliated form Lines digestive tract, gallbladder, ducts of some glands Ciliated form Lines small bronchi, uterine tubes, uterus

Pseudostratified Columnar Epithelium Description All cells originate at basement membrane Only tall cells reach the apical surface May contain goblet cells and bear cilia Nuclei lie at varying heights within cells Gives false impression of stratification Function secretion of mucus; propulsion of mucus by cilia

Pseudostratified Columnar Epithelium Locations Non-ciliated type Ducts of male reproductive tubes Ducts of large glands Ciliated variety Lines trachea and most of upper respiratory tract

Stratified Epithelia Contain two or more layers of cells Regenerate from below Major role is protection Are named according to the shape of cells at apical layer

Stratified Squamous Epithelium Description Many layers of cells squamous in shape Deeper layers of cells appear cuboidal or columnar Thickest epithelial tissue adapted for protection

Stratified Squamous Epithelium Specific types Keratinized contain the protective protein keratin Surface cells are dead and full of keratin Non-keratinized forms moist lining of body openings Function Protects underlying tissues in areas subject to abrasion Location Keratinized forms epidermis Non-keratinized forms lining of esophagus, mouth, and vagina

Stratified Squamous Epithelium Non-keratinized vs. Keratinized

Stratified Cuboidal Epithelium Description generally two layers of cube-shaped cells Function protection Location Forms largest ducts of sweat glands Forms ducts of mammary glands and salivary glands

Stratified Columnar Epithelium Description several layers; basal cells usually cuboidal; superficial cells elongated Function protection and secretion Location Rare tissue type Found in male urethra and vas deferens, largest ducts of salivary glands, nasopharynx

Transitional Epithelium Description Basal cells usually cuboidal or columnar Superficial cells dome- shaped or squamous Function stretches and permits distension of urinary bladder Location Lines ureters, urinary bladder and part of urethra

Glandular Epithelium Ducts carry products of exocrine glands to epithelial surface Include the following diverse glands Mucus-secreting glands Sweat and oil glands Salivary glands Liver and pancreas Mammary glands May be: unicellular or multicellular

2013 Pearson Education, Inc. Exocrine Glands Secretions released onto body surfaces (skin) or into body cavities More numerous than endocrine glands Secrete products into ducts Examples include mucous, sweat, oil, and salivary glands

2013 Pearson Education, Inc. Unicellular Exocrine Glands The only important unicellular glands are mucous cells and goblet cells Found in epithelial linings of intestinal and respiratory tracts All produce mucin Dissolves in water to form mucus Slimy protective, lubricating coating Mucin + water mucus

2013 Pearson Education, Inc. Microvilli Golgi apparatus Rough ER Nucleus Secretory vesicles containing mucin Figure 4.4 Goblet cell (unicellular exocrine gland).

Connective Tissues

Exocrine Vs. Endocrine Glands Endocrine Gland Characteristics: Ductless glands Secrete substances directly into bloodstream Produce molecules called hormones Which is Which?

Connective Tissue Most diverse and abundant tissue Main classes Connective tissue proper Blood Fluid connective tissue Cartilage Bone tissue Components of connective tissue: Cells (varies according to tissue) Matrix Protein fibers (varies according to tissue) Ground substance (varies according to tissue) Common embryonic origin mesenchyme Supporting connective tissues

2013 Pearson Education, Inc. Major Functions of Connective Tissue Binding and support Protecting Insulating Storing reserve fuel Transporting substances (blood)

2013 Pearson Education, Inc. Structural Elements of Connective Tissue Three elements Ground substance Fibers Cells Composition and arrangement varies in different connective tissues

2013 Pearson Education, Inc. Ground Substance Unstructured material that fills space between cells Medium through which solutes diffuse between blood capillaries and cells Components Interstitial fluid Cell adhesion proteins ("glue" for attachment) Proteoglycans Protein core + large polysaccharides (chrondroitin sulfate and hyaluronic acid) Trap water in varying amounts, affecting viscosity of ground substance

Ground Substance Interstitial (tissue) fluid within which are one or more of the molecules listed below: Hyaluronic acid: a polysaccharide. Very slippery; serves as a good lubricant for joints. Common in most connective tissues. Proteoglycans: protein and polysaccharide complex. Polysaccharides called glyocosaminoglycans (chondroitin sulfate, keratin sulfate). Protein part attaches to hyaluronic acid. Able to trap large amounts of water. Adhesive molecules: hold proteoglycan aggregates together. Chondronectin in cartilage, osteonectin in bone, fibronectin in fibrous connective tissue. Functions as a molecular sieve through which nutrients diffuse between blood capillaries and cells

2013 Pearson Education, Inc. Connective Tissue Fibers Three types of fibers provide support Collagen Strongest and most abundant type Tough; provides high tensile strength Elastic fibers Networks of long, thin, elastin fibers that allow for stretch and recoil Reticular Short, fine, highly branched collagenous fibers (different chemistry and form than collagen fibers) Branch, forming networks that offer more "give"

Extracellular Matrix - ECM ECM has 3 major components 1. Protein fibers 2. Ground substance 3. Fluid Protein fibers Collagen fibers. Composed of the protein collagen. Strong, flexible, inelastic; great tensile strength (i.e. resist stretch). Perfect for tendons, ligaments Elastic fibers. Contain molecules of protein elastin that resemble coiled springs. Returns to its original shape after stretching or compression. Perfect for lungs, large blood vessels Reticular fibers. Formed from fine collagenous fibers; form branching networks ( stroma). Fill spaces between tissues and organs.

2013 Pearson Education, Inc. Cells "Blasts" cells Immature forum; mitotically active; secrete ground substance and fibers Fibroblasts in connective tissue proper Chondroblasts in cartilage Osteoblasts in bone Hematopoietic stem cells in bone marrow "Cyte" cells Mature form; maintain matrix Chondrocytes in cartilage Osteocytes in bone

Connective Tissue Cells Fibroblasts - secrete the proteins needed for fiber synthesis and components of the extracellular matrix Adipose or fat cells ( adipocytes ) - Common in some tissues (dermis of skin); rare in some (cartilage) Mast cells -Common beneath membranes; along small blood vessels. Can release heparin, histamine, and proteolytic enzymes in response to injury. Leukocytes (WBCs) - Respond to injury or infection Macrophages - Derived from monocytes (a WBC). Phagocytic; provide protection Chondroblasts - form cartilage Osteoblasts - form bone Hematopoietic stem cells - form blood cells Undifferentiated mesenchyme (stem cells). Have potential to differentiate into adult cell types.

2013 Pearson Education, Inc. Other Cell Types in Connective Tissues Fat cells Store nutrients White blood cells Neutrophils, eosinophils, lymphocytes Tissue response to injury Mast cells Initiate local inflammatory response against foreign microorganisms they detect Macrophages Phagocytic cells that "eat" dead cells, microorganisms; function in immune system

Connective Tissue Proper - Classifications Loose Connective Tissue Areolar Reticular Adipose Dense Connective Tissue (also called fibrous connective tissues ) Regular Irregular Elastic

2013 Pearson Education, Inc. Areolar Connective Tissue Support and bind other tissues Universal packing material between other tissues Most widely distributed Provide reservoir of water and salts Defend against infection Store nutrients as fat Fibroblasts Loose arrangement of fibers Ground substance When inflamed soaks up fluid edema

Areolar Connective Tissue Description Gel-like matrix with: all three fiber types (collagen, reticular, elastic) for support Ground substance is made up by glycoproteins also made and secreted by the fibroblasts. Cells fibroblasts, macrophages, mast cells, white blood cells, adipocytes Highly vascular tissue

Areolar Connective Tissue Location Widely distributed under epithelia Packages organs Surrounds capillaries

2013 Pearson Education, Inc. Adipose Tissue White fat Similar to areolar but greater nutrient storage Cell is adipocyte Stores nutrients Scanty matrix Richly vascularized Shock absorption, insulation, energy storage Brown fat Use lipid fuels to heat bloodstream not to produce ATP

Adipose Tissue Description Closely packed adipocytes Have nucleus pushed to one side by fat droplet Function Provides reserve food fuel Insulates against heat loss Supports and protects organs Location Under skin Around kidneys Behind eyeballs, within abdomen and in breasts

2013 Pearson Education, Inc. Reticular Connective Tissue Resembles areolar but fibers are reticular fibers Fibroblasts called reticular cells Supports free blood cells in lymph nodes, the spleen, and bone marrow

Reticular Connective Tissue Description network of reticular fibers in loose ground substance Function form a soft, internal skeleton (stroma) supports other cell types Location lymphoid organs Lymph nodes, bone marrow, and spleen

2013 Pearson Education, Inc. Dense Regular Connective Tissue Closely packed bundles of collagen fibers running parallel to direction of pull White structures with great resistance to pulling Fibers slightly wavy so stretch a little Fibroblasts manufacture fibers and ground substance Few cells Poorly vascularized

Dense Regular Connective Tissue Description Primarily parallel collagen fibers Fibroblasts and some elastic fibers Poorly vascularized Function Attaches muscle to bone Attaches bone to bone Withstands great stress in one direction Location Tendons and ligaments Aponeuroses Fascia around muscles

2013 Pearson Education, Inc. Dense Irregular Connective Tissue Same elements but bundles of collagen thicker and irregularly arranged Resists tension from many directions Dermis Fibrous joint capsules Fibrous coverings of some organs

Dense Irregular Connective Tissue Description Primarily irregularly arranged collagen fibers Some elastic fibers and fibroblasts Function Withstands tension Provides structural strength Location Dermis of skin Submucosa of digestive tract Fibrous capsules of joints and organs

2013 Pearson Education, Inc. Elastic Connective Tissue Some ligaments very elastic Those connecting adjacent vertebrae Many of larger arteries have in walls

2013 Pearson Education, Inc. Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows tissue to recoil after stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Photomicrograph: Elastic connective tissue in the wall of the aorta (250x). Aorta Heart Elastic fibers Figure 4.8f Connective tissues.

Cartilage Characteristics: Firm, flexible tissue Contains no blood vessels or nerves Matrix contains up to 80% water Cell type chondroblasts and chondrocytes Types: Hyaline Elastic Fibrocartilage

2013 Pearson Education, Inc. Cartilage Lacks nerve fibers Up to 80% water - can rebound after compression Avascular Receives nutrients from membrane surrounding it Perichondrium

Hyaline Cartilage Description Imperceptible collagen fibers (hyaline = glassy) Chodroblasts produce matrix Chondrocytes lie in lacunae Function Supports and reinforces Resilient cushion Resists repetitive stress Location Ends of long bones Costal cartilage of ribs Cartilages of nose, trachea, and larynx Location

Elastic Cartilage Description Similar to hyaline cartilage More elastic fibers in matrix Function Maintains shape of structure Allows great flexibility Location Supports external ear Epiglottis

Fibrocartilage Description Matrix similar, but less firm than hyaline cartilage Thick collagen fibers predominate Function Tensile strength and ability to absorb compressive shock Location Intervertebral discs Pubic symphysis Discs of knee joint

Connective Tissue Supports and Connects Body Parts: Basement Membrane Fibrous connective tissue: Loose: surrounds many organs, lines cavities around blood vessels Dense: tendons, ligaments, deeper layers of skin Elastic: surrounds stomach and bladder, maintains shape Reticular: internal framework of soft organs (liver) and lymphatic system

2013 Pearson Education, Inc. Bone Also called osseous tissue Supports and protects body structures Stores fat and synthesizes blood cells in cavities More collagen than cartilage Has inorganic calcium salts Osteoblasts produce matrix Osteocytes maintain the matrix Osteons structural units Richly vascularized

Bone Tissue Function Supports and protects organs Provides levers and attachment site for muscles Stores calcium and other minerals Stores fat Marrow is site for blood cell formation Location Bones

Blood Tissue Description red and white blood cells in a fluid matrix Function transport of respiratory gases, nutrients, and wastes Location within blood vessels Characteristics An atypical connective tissue Consists of cells surrounded by fluid matrix

2013 Pearson Education, Inc. Blood Also contains white blood cells and platelets Fibers are soluble proteins that precipitate during blood clotting

Muscle Tissue Types Skeletal muscle tissue Cardiac muscle tissue Smooth muscle tissue

2013 Pearson Education, Inc. Muscle Tissue Highly vascularized Responsible for most types of movement Three types Skeletal muscle tissue Found in skeletal muscle Voluntary Cardiac muscle tissue Found in walls of heart Involuntary Smooth muscle tissue Mainly in walls of hollow organs other than heart Involuntary

Muscle Tissue: Contracts for Movement Skeletal muscle: Moves body parts Voluntary, multinucleated Cardiac muscle: Function in the heart Involuntary, single nucleus Smooth muscle: Surrounds hollow structures Involuntary, single nucleus

Skeletal Muscle Tissue Characteristics Long, cylindrical cells Multinucleate Obvious striations Function Voluntary movement Manipulation of environment Facial expression Location Skeletal muscles attached to bones (occasionally to skin)

Cardiac Muscle Tissue Function Contracts to propel blood into circulatory system Characteristics Branching cells Uni-nucleate Intercalated discs Location Occurs in walls of heart

Smooth Muscle Tissue Characteristics Spindle-shaped cells with central nuclei Arranged closely to form sheets No striations Function Propels substances along internal passageways Involuntary control Location Mostly walls of hollow organs

Nervous Tissue

2013 Pearson Education, Inc. Nervous Tissue Main component of nervous system Brain, spinal cord, nerves Regulates and controls body functions Neurons Specialized nerve cells that generate and conduct nerve impulses Neuroglia Supporting cells that support, insulate, and protect neurons

Nervous Tissue: Transmit Impulses Neuron: specialized nervous system cell: Structural components: cell body, dendrites, axon Glial cells: support cells to neurons

Nervous Tissue Function Transmit electrical signals from sensory receptors to effectors Location Brain, spinal cord, and nerves Description Main components are brain, spinal cord, and nerves Contains two types of cells Neurons excitatory cells Neuroglial - supporting cells

tissues groups of cells with a common function four primary tissues: epithelia connective...

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