ap-ch04

Copyright © 2010 Pearson Education, Inc.

C h a p t e r

4

The Tissue Level of

Organization

PowerPoint® Lecture Slides prepared by Jason LaPres

Lone Star College - North Harris


Four Types of Tissues

  Tissues are collections of cells and cell products that perform specific, limited functions

  Types of tissue   Epithelial tissue

 Covers exposed surfaces

 Lines internal passageways

 Forms glands


Four Types of Tissues

  Types of Tissue (cont’d)   Connective tissue

  Fills internal spaces   Supports other tissues   Transports materials   Stores energy

  Muscle tissue   Specialized for contraction   Skeletal muscle, heart muscle, and walls of hollow organs

  Neural tissue   Carries electrical signals from one part of the body to another


Epithelial Tissues

  Epithelia   Layers of cells covering internal or external

surfaces

  Glands   Structures that produce secretions


Epithelial Tissues

  Characteristics of Epithelia  Cellularity (cell junctions)

  Polarity (apical and basal surfaces)

  Attachment (basal lamina)

  Avascularity

 Regeneration


Epithelial Tissues

Figure 4–1 The Polarity of Epithelial Cells.


Epithelial Tissues

  Functions of Epithelial Tissue   Provide physical protection

 Control permeability

  Provide sensation

  Produce specialized secretions (glandular epithelium)


Epithelial Tissues

  Specializations of Epithelial Cells   Move fluids over the epithelium (protection)   Move fluids through the epithelium (permeability)   Produce secretions (protection and messengers)

  Free Surface and Attached Surface   Polarity

 Apical surfaces: – microvilli increase absorption or secretion –  cilia (ciliated epithelium) move fluid

 Basolateral surfaces


Epithelial Tissues

  Maintaining the Integrity of Epithelia

  Intercellular connections

  Attachment to basal lamina

  Epithelial maintenance and repair


Epithelial Tissues

  Intercellular Connections   Support and communication

  CAMs (cell adhesion molecules):

–  transmembrane proteins

  Intercellular cement:

–  proteoglycans

  Hyaluronan (hyaluronic acid):

–  glycosaminoglycans


Epithelial Tissues

  Intercellular Connections

  Cell junctions

  Form bonds with other cells or extracellular material:

–  occluding (tight) junctions

–  gap junctions

–  macula adherens (desmosomes)

Intercellular Connections


Epithelial Tissues   Cell Junctions

  Occluding (Tight) junctions—between two plasma membranes   Adhesion belt attaches to terminal web

  Prevents passage of water and solutes

  Isolates wastes in the lumen

  Gap junctions—allow rapid communication   Held together by channel proteins (junctional proteins,

connexons)

  Allow ions to pass

  Coordinate contractions in heart muscle


Epithelial Tissues

  Cell Junctions  Macula adherens (Desmosomes)

 CAMs, dense areas, and intercellular cement

 Spot desmosomes – tie cells together – allow bending and twisting

 Hemidesmosomes – attach cells to the basal lamina


Epithelial Tissues

  Attachment to the Basal Lamina   Clear layer (Lamina lucida)

  Thin layer   Secreted by epithelia   Barrier to proteins

  Dense layer (Lamina densa)   Thick fibers   Produced by connective tissue   Strength and filtration


Epithelial Tissues

Figure 4–2 Intercellular Connections


Epithelial Tissues

  Epithelial Maintenance and Repair

  Epithelia are replaced by division of

germinative cells (stem cells)

 Near basal lamina


Classification of Epithelia

  Singular epithelium; plural epithelia

  Classes of Epithelia   Based on shape

  Squamous epithelia: thin and flat

  Cuboidal epithelia: square shaped

  Columnar epithelia: tall, slender rectangles

  Based on layers   Simple epithelium: single layer of cells

  Stratified epithelium: several layers of cells



  Squamous Epithelia   Simple squamous epithelium

  Absorption and diffusion

  Mesothelium   Lines body cavities

  Endothelium   Lines heart and blood vessels



Figure 4–3 Squamous Epithelia.



  Squamous Epithelia

  Stratified squamous epithelium

 Protects against attacks

 Keratin protein adds strength and water resistance



Figure 4–3 Squamous Epithelia.



  Cuboidal Epithelia

  Simple cuboidal epithelium

 Secretion and absorption

  Stratified cuboidal epithelia

 Sweat ducts and mammary ducts



Figure 4–4 Cuboidal Epithelia.



  Transitional Epithelium

  Tolerates repeated cycles of stretching and recoiling

and returns to its previous shape without damage

  Appearance changes as stretching occurs

  Situated in regions of the urinary system (e.g. urinary

bladder)



Figure 4–4 Cuboidal Epithelia.



  Columnar Epithelia

  Simple columnar epithelium

  Absorption and secretion

  Pseudostratified columnar epithelium

  Cilia movement

  Stratified columnar epithelium

  Protection



Figure 4–5 Columnar Epithelia.



  Glandular Epithelia   Endocrine glands

 Release hormones: –  into interstitial fluid –  no ducts

  Exocrine glands  Produce secretions:

–  onto epithelial surfaces –  through ducts

Mechanisms of Glandular Secretion



  Modes of Secretion in Glandular Epithelia   Merocrine secretion

  Is produced in Golgi apparatus   Is released by vesicles (exocytosis)   For example, sweat glands

  Apocrine secretion   Is produced in Golgi apparatus   Is released by shedding cytoplasm   For example, mammary gland

  Holocrine secretion   Is released by cells bursting, killing gland cells   Gland cells replaced by stem cells   For example, sebaceous gland



Figure 4–6 Modes of Glandular Secretion.



Figure 4–6a Modes of Glandular Secretion.



Figure 4–6b Modes of Glandular Secretion.



Figure 4–6 Modes of Glandular Secretion.



  Glandular Epithelia   Types of secretions

 Serous glands: – watery secretions

 Mucous glands: –  secrete mucins

 Mixed exocrine glands: –  both serous and mucous



  Glandular Epithelia  Gland structure

 Unicellular glands

– Mucous (goblet) cells are the only unicellular exocrine glands:

» scattered among epithelia

» for example, in intestinal lining



  Glandular Epithelia  Gland structure

 Multicellular glands: –  structure of the duct:

»  simple (undivided) »  compound (divided)

–  shape of secretory portion of the gland: »  tubular (tube shaped) »  alveolar or acinar (blind pockets)

–  relationship between ducts and glandular areas: »  branched (several secretory areas sharing one duct)



Figure 4–7 A Structural Classification of Exocrine Glands.


Connective Tissues

  Connect epithelium to the rest of the body (basal lamina)

  Provide structure (bone)

  Store energy (fat)

  Transport materials (blood)

  Have no contact with environment


Connective Tissues

  Characteristics of Connective Tissues   Specialized cells   Solid extracellular protein fibers   Fluid extracellular ground substance

  The extracellular components of connective tissues (fibers and ground substance) make up the matrix  Majority of tissue volume  Determines specialized function


Connective Tissues

  Classification of Connective Tissues  Connective tissue proper

 Connect and protect

  Fluid connective tissues  Transport

  Supportive connective tissues  Structural strength


Connective Tissues

  Categories of Connective Tissue Proper

  Loose connective tissue

  More ground substance, less fibers

  For example, fat (adipose tissue)

  Dense connective tissue

  More fibers, less ground substance

  For example, tendons


Connective Tissues

  Fibroblasts   Fibrocytes   Macrophages   Adipocytes   Mesenchymal cells

  Melanocytes   Mast cells   Lymphocytes   Microphages

Nine Cell Types of Connective Tissue Proper


Connective Tissues

  Connective Tissue Proper Cells   Fibroblasts

  The most abundant cell type: –  found in all connective tissue proper

–  secrete proteins and hyaluronan (cellular cement)

  Fibrocytes   The second most abundant cell type:

–  found in all connective tissue proper

–  maintain the fibers of connective tissue proper


Connective Tissues

  Connective Tissue Proper Cells   Macrophages

  Large, amoeba-like cells of the immune system: –  eat pathogens and damaged cells –  fixed macrophages stay in tissue –  free macrophages migrate

  Adipocytes   Fat cells:

–  each cell stores a single, large fat droplet

  Mesenchymal Cells   Stem cells that respond to injury or infection:

–  differentiate into fibroblasts, macrophages, etc.


Connective Tissues

  Connective Tissue Proper Cells  Melanocytes

 Synthesize and store the brown pigment melanin

 Mast Cells  Stimulate inflammation after injury or infection:

–  release histamine and heparin

 Basophils are leukocytes (white blood cells) that also contain histamine and heparin


Connective Tissues

  Connective Tissue Proper Cells

  Lymphocytes

  Specialized immune cells in lymphoid (lymphatic) system:

–  For example, lymphocytes may develop into plasma cells

(plasmocytes) that produce antibodies

  Microphages

  Phagocytic blood cells:

–  respond to signals from macrophages and mast cells

–  For example, neutrophils and eosinophils


Connective Tissues

  Connective Tissue Fibers

  Collagen fibers

  Most common fibers in connective tissue proper

  Long, straight, and unbranched

  Strong and flexible

  Resist force in one direction

  For example, tendons and ligaments


Connective Tissues

  Connective Tissue Fibers  Reticular fibers

 Network of interwoven fibers (stroma)

 Strong and flexible

 Resist force in many directions

 Stabilize functional cells (parenchyma) and structures

 For example, sheaths around organs


Connective Tissues

  Connective Tissue Fibers

  Elastic fibers

 Contain elastin

 Branched and wavy

 Return to original length after stretching

 For example, elastic ligaments of vertebrae


Connective Tissues

  Ground Substance

  Is clear, colorless, and viscous

  Fills spaces between cells and slows

pathogen movement


Connective Tissues

Figure 4–8 The Cells and Fibers of Connective Tissue Proper.


Connective Tissues

  Embryonic Connective Tissues

  Are not found in adults

 Mesenchyme (embryonic stem cells)

 The first connective tissue in embryos

 Mucous connective tissue

 Loose embryonic connective tissue


Connective Tissues

Figure 4–9 Connective Tissues in Embryos.


Connective Tissues

  Loose Connective Tissues

  The packing materials of the body

  Three types in adults

 Areolar

 Adipose

 Reticular


Connective Tissues

  Areolar Tissue   Least specialized

  Open framework

  Viscous ground substance

  Elastic fibers

  Holds blood vessels and capillary beds   For example, under skin (subcutaneous layer)


Connective Tissues

  Adipose Tissue   Contains many adipocytes (fat cells)   Types of adipose tissue

  White fat: –  most common –  stores fat –  absorbs shocks –  slows heat loss (insulation)

  Brown fat: –  more vascularized –  adipocytes have many mitochondria –  when stimulated by nervous system, fat break down

accelerates, releasing energy –  absorbs energy from surrounding tissues


Connective Tissues

  Adipose Tissue  Adipose cells

 Adipocytes in adults do not divide: – expand to store fat – shrink as fats are released

 Mesenchymal cells divide and differentiate:

– to produce more fat cells – when more storage is needed


Connective Tissues

  Reticular Tissue

  Provides support

  Complex, three-dimensional network

  Supportive fibers (stroma)

  Support functional cells (parenchyma)

  Reticular organs

  Spleen, liver, lymph nodes, and bone marrow


Connective Tissues

Figure 4–10 Adipose and Reticular Tissues.


Connective Tissues

  Dense Connective Tissues

 Connective tissues proper, tightly packed with

high numbers of collagen or elastic fibers

 Dense regular connective tissue

 Dense irregular connective tissue

 Elastic tissue


Connective Tissues

  Dense Regular Connective Tissue

  Tightly packed, parallel collagen fibers

 Tendons attach muscles to bones

 Ligaments connect bone to bone and stabilize

organs

 Aponeuroses attach in sheets to large, flat

muscles


Connective Tissues

Figure 4–11 Dense Connective Tissues.


Connective Tissues

  Dense Irregular Connective Tissue

  Interwoven networks of collagen fibers

 Layered in skin

 Around cartilages (perichondrium)

 Around bones (periosteum)

 Form capsules around some organs (e.g., liver,

kidneys)


Connective Tissues



Connective Tissues

  Elastic Tissue

 Made of elastic fibers

 For example, elastic ligaments of spinal vertebrae


Connective Tissues



Connective Tissues

  Fluid Connective Tissues

  Blood and lymph

  Watery matrix of dissolved proteins

  Carry specific cell types (formed elements)

 Formed elements of blood

–  red blood cells (erythrocytes)

– white blood cells (leukocytes)

–  platelets


Connective Tissues

  Fluid Elements of Fluid Connective

Tissues

  Extracellular

 Plasma

  Interstitial fluid

 Lymph


Connective Tissues

Figure 4–12 Formed Elements of the Blood.


Connective Tissues

  Lymph

  Extracellular fluid

 Collected from interstitial space

 Monitored by immune system

 Transported by lymphoid (lymphatic) system

 Returned to venous system


Connective Tissues

  Fluid Tissue Transport Systems  Cardiovascular system (blood)

 Arteries

 Capillaries

 Veins

  Lymphoid (lymphatic) system (lymph)  Lymphatic vessels


Supportive Connective Tissues

  Support soft tissues and body weight

  Cartilage

  Gel-type ground substance

  For shock absorption and protection

  Bone

  Calcified (made rigid by calcium salts, minerals)

  For weight support



  Cartilage Matrix

  Proteoglycans derived from chondroitin sulfates

  Ground substance proteins

  Chondrocytes (cartilage cells) surrounded by

lacunae (chambers)



  Cartilage Structure

  No blood vessels:

 Chondrocytes produce antiangiogenesis factor

  Perichondrium:

 Outer, fibrous layer (for strength)

  Inner, cellular layer (for growth and maintenance)



Figure 4–13 The Growth of Cartilage.



  Types of Cartilage   Hyaline cartilage

  Stiff, flexible support   Reduces friction between bones   Found in synovial joints, rib tips, sternum, and trachea

  Elastic cartilage   Supportive but bends easily   Found in external ear and epiglottis

  Fibrous cartilage (fibrocartilage)   Limits movement   Prevents bone-to-bone contact   Pads knee joints   Found between pubic bones and intervertebral discs



Figure 4–14 The Types of Cartilage.



  Bone or osseous tissue   Strong (calcified: calcium salt deposits)   Resists shattering (flexible collagen fibers)

  Bone cells or osteocytes   Arranged around central canals within matrix   Small channels through matrix (canaliculi) access

blood supply   Periosteum

  Covers bone surfaces   Fibrous layer   Cellular layer



Figure 4–15 Bone.


Membranes

  Membranes

  Are physical barriers

  That line or cover portions of the body

 Consist of

 An epithelium

 Supported by connective tissues


Membranes

  Four Types of Membranes

 Mucous membranes

  Serous membranes

 Cutaneous membrane

  Synovial membranes


Membranes

  Mucous membranes (mucosae)   Line passageways that have external connections

  In digestive, respiratory, urinary, and reproductive tracts

  Epithelial surfaces must be moist   To reduce friction

  To facilitate absorption and excretion

  Lamina propria   Is areolar tissue


Membranes

  Serous Membranes   Line cavities not open to the outside

  Are thin but strong

 Have fluid transudate to reduce friction

 Have a parietal portion covering the cavity

 Have a visceral portion (serosa) covering the organs


Membranes

  Three Serous Membranes   Pleura:

 Lines pleural cavities  Covers lungs

  Peritoneum:  Lines peritoneal cavity  Covers abdominal organs

  Pericardium:  Lines pericardial cavity  Covers heart


Membranes

Figure 4–16 a,b Membranes.


Membranes

  Cutaneous membrane   Is skin, surface of the body

  Thick, waterproof, and dry

  Synovial membranes   Line moving, articulating joint cavities

  Produce synovial fluid (lubricant)

  Protect the ends of bones

  Lack a true epithelium


Figure 4–16 c,d Membranes.

Membranes


Internal Framework of the Body

  Connective tissues   Provide strength and stability

  Maintain positions of internal organs

  Provide routes for blood vessels, lymphatic vessels, and nerves

  Fasciae   Singular form is fascia

 The body’s framework of connective tissue

 Layers and wrappings that support or surround organs



  Three Types of Fasciae

  Superficial fascia

 Deep fascia

  Subserous fascia



Figure 4–17 The Fasciae.


Muscle Tissue

  Specialized for contraction   Produces all body movement   Three types of muscle tissue

  Skeletal muscle   Large body muscles responsible for movement

  Cardiac muscle   Found only in the heart

  Smooth muscle   Found in walls of hollow, contracting organs (blood vessels;

urinary bladder; respiratory, digestive, and reproductive tracts)


Muscle Tissue

  Classification of Muscle Cells

  Striated (muscle cells with a banded appearance)

  Nonstriated (not banded; smooth)

  Muscle cells can have a single nucleus

  Muscle cells can be multinucleate

  Muscle cells can be controlled voluntarily

(consciously)

  Muscle cells can be controlled involuntarily

(automatically)


Muscle Tissue

  Skeletal Muscle Cells

  Are long and thin

  Are usually called muscle fibers

 Do not divide

 New fibers are produced by stem cells

(myosatellite cells)


Muscle Tissue

Figure 4–18 Muscle Tissue.


Muscle Tissue

  Cardiac muscle cells   Are called cardiocytes   Form branching networks connected at

intercalated discs   Are regulated by pacemaker cells

  Smooth muscle cells   Are small and tapered

 Can divide and regenerate


Muscle Tissue

Figure 4–18 Muscle Tissue.


Neural Tissue

  Also called nervous or nerve tissue

  Specialized for conducting electrical impulses

 Rapidly senses internal or external

environment

  Processes information and controls responses


Neural Tissue

  Neural tissue is concentrated in the

central nervous system

 Brain

  Spinal cord


Neural Tissue

  Two Kinds of Neural Cells

 Neurons

 Nerve cells

 Perform electrical communication

 Neuroglia

 Supporting cells

 Repair and supply nutrients to neurons


Neural Tissue

  Cell Parts of a Neuron

  Cell body   Contains the nucleus and nucleolus

  Dendrites   Short branches extending from the cell body

  Receive incoming signals

  Axon (nerve fiber)   Long, thin extension of the cell body

  Carries outgoing electrical signals to their destination


Neural Tissue

Figure 4–19 Neural Tissue.


Tissue Injuries and Repair

  Tissues respond to injuries to maintain

homeostasis

 Cells restore homeostasis with two processes

  Inflammation

 Regeneration



  Inflammation = inflammatory response   The tissue’s first response to injury

  Signs and symptoms of the inflammatory response include   Swelling

  Redness

  Heat

  Pain



  Inflammatory Response

 Can be triggered by

 Trauma (physical injury)

  Infection (the presence of harmful pathogens)



  The Process of Inflammation   Damaged cells release chemical signals into the

surrounding interstitial fluid   Prostaglandins   Proteins   Potassium ions

  As cells break down   Lysosomes release enzymes   That destroy the injured cell   And attack surrounding tissues   Tissue destruction is called necrosis



  The Process of Inflammation

  Necrotic tissues and cellular debris (pus) accumulate

in the wound   Abscess:

–  pus trapped in an enclosed area

  Injury stimulates mast cells to release   Histamine

  Heparin

  Prostaglandins



  The Process of Inflammation  Dilation of blood vessels

  Increases blood circulation in the area  Causes warmth and redness  Brings more nutrients and oxygen to the area  Removes wastes

  Plasma diffuses into the area  Causing swelling and pain

  Phagocytic white blood cells  Clean up the area



Figure 4–20 An Introduction to Inflammation.



  Regeneration

 When the injury or infection is cleaned up

 Healing (regeneration) begins



  The Process of Regeneration   Fibrocytes move into necrotic area

  Lay down collagen fibers

  To bind the area together (scar tissue)

  New cells migrate into area   Or are produced by mesenchymal stem cells

  Not all tissues can regenerate   Epithelia and connective tissues regenerate well

  Cardiac cells and neurons do not regenerate (or regenerate poorly)

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