© 2015 Pearson Education, Inc.

An Introduction to Tissues
Learning Outcomes 4-1 Identify the four major types of tissues in the body and describe their roles. 4-2 Discuss the types and functions of epithelial tissue. 4-3 Describe the relationship between structure and function for each type of epithelium. © 2015 Pearson Education, Inc.

Learning Outcomes 4-4 Compare the structures and functions of the various types of connective tissue. 4-5 Describe how cartilage and bone function as a supporting connective tissue. 4-6 Explain how epithelial and connective tissues combine to form four types of tissue membranes, and specify the functions of each. 4-7 Describe how connective tissue establishes the framework of the body. © 2015 Pearson Education, Inc.

Learning Outcomes 4-8 Describe the three types of muscle tissue and the special structural features of each type. 4-9 Discuss the basic structure and role of neural tissue. 4-10 Describe how injuries affect the tissues of the body. 4-11 Describe how aging affects the tissues of the body. © 2015 Pearson Education, Inc.

4-1 Four Types of Tissue Tissues
Are collections of cells and cell products that perform specific, limited functions Four types of tissue Epithelial tissue Connective tissue Muscle tissue Neural tissue © 2015 Pearson Education, Inc.

4-1 Four Types of Tissue Epithelial Tissue Connective Tissue
Covers exposed surfaces Lines internal passageways Forms glands Connective Tissue Fills internal spaces Supports other tissues Transports materials Stores energy © 2015 Pearson Education, Inc.

4-1 Four Types of Tissue Muscle Tissue Neural 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 © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Epithelia Glands
Layers of cells covering internal or external surfaces Glands Structures that produce secretions © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Characteristics of Epithelia
Cellularity (cell junctions) Polarity (apical and basal surfaces) Attachment (basement membrane or basal lamina) Avascularity Regeneration © 2015 Pearson Education, Inc.

Figure 4-1 The Polarity of Epithelial Cells.
Cilia Microvilli Apical surface Golgi apparatus Nucleus Mitochondria Basement membrane Basolateral surfaces

4-2 Epithelial Tissue Functions of Epithelial Tissue
Provide Physical Protection Control Permeability Provide Sensation Produce Specialized Secretions (glandular epithelium) © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Specializations of Epithelial Cells Polarity
Move fluids over the epithelium (protection) Move fluids through the epithelium (permeability) Produce secretions (protection and messengers) Polarity Apical surfaces Microvilli increase absorption or secretion Cilia (ciliated epithelium) move fluid Basolateral surfaces © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Maintaining the Integrity of Epithelia
Intercellular connections Attachment to the basement membrane Epithelial maintenance and repair © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Intercellular Connections
Support and communication CAMs (cell adhesion molecules) Transmembrane proteins Intercellular cement Proteoglycans Hyaluronan (hyaluronic acid) Glycosaminoglycans © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Intercellular Connections Cell junctions
Form bonds with other cells or extracellular material Tight junctions Gap junctions Desmosomes © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Tight Junctions Between two plasma membranes
Adhesion belt attaches to terminal web Prevents passage of water and solutes Isolates wastes in the lumen © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Gap Junctions Allow rapid communication
Are held together by channel proteins (junctional proteins, connexons) Allow ions to pass Coordinate contractions in heart muscle © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Desmosomes
CAMs, dense areas, and intercellular cement Spot desmosomes Tie cells together Allow bending and twisting Hemidesmosomes Attach cells to the basement membrane © 2015 Pearson Education, Inc.

4-2 Epithelial Tissue Attachment to the Basement Membrane
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 © 2015 Pearson Education, Inc.

Figure 4-2 Cell Junctions.
Interlocking junctional proteins Embedded proteins (connexons) Tight junction Tight junction Adhesion belt Terminal web Adhesion belt Gap junctions b Gap junctions permit the free diffusion of ions and small molecules between two cells. Spot desmosome c A tight junction is formed by the fusion of the outer layers of two plasma membranes. Tight junctions prevent the diffusion of fluids and solutes between the cells. A continuous adhesion belt lies deep to the tight junction. This belt is tied to the microfilaments of the terminal web. Hemidesmosome a This is a diagrammatic view of an epithelial cell, showing the major types of intercellular connections. Intermediate filaments Cell adhesion molecules (CAMs) Clear layer Basement membrane Dense layer Dense area e Hemidesmosomes attach a cell to extracellular structures, such as the protein fibers in the basement membrane. Proteoglycans d A spot desmosome ties adjacent cells together.

Figure 4-2a Cell Junctions.
Tight junction Adhesion belt Terminal web Gap junctions Spot desmosome Hemidesmosome a This is a diagrammatic view of an epithelial cell, showing the major types of intercellular connections.

Figure 4-2b Cell Junctions.
Embedded proteins (connexons) b Gap junctions permit the free diffusion of ions and small molecules between two cells.

Figure 4-2c Cell Junctions.
Interlocking junctional proteins Tight junction Terminal web Adhesion belt c A tight junction is formed by the fusion of the outer layers of two plasma membranes. Tight junctions prevent the diffusion of fluids and solutes between the cells. A continuous adhesion belt lies deep to the tight junction. This belt is tied to the microfilaments of the terminal web.

Figure 4-2d Cell Junctions.
Intermediate filaments Cell adhesion molecules (CAMs) Dense area Proteoglycans d A spot desmosome ties adjacent cells together.

Figure 4-2e Cell Junctions.
Clear layer Basement membrane Dense layer e Hemidesmosomes attach a cell to extracellular structures, such as the protein fibers in the basement membrane.

4-2 Epithelial Tissue Epithelial Maintenance and Repair
Epithelia are replaced by division of germinative cells (stem cells) Near basement membrane © 2015 Pearson Education, Inc.

4-3 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 © 2015 Pearson Education, Inc.

Table 4-1 Classifying Epithelia (Part 1 of 2).

Table 4-1 Classifying Epithelia (Part 2 of 2).

Figure 4-3a Squamous Epithelia.
Simple Squamous Epithelium LOCATIONS: Mesothelia lining pleural, pericardial, and peritoneal cavities; endothelia lining heart and blood vessels; portions of kidney tubules (thin sections of nephron loops); inner lining of cornea; alveoli of lungs FUNCTIONS: Reduces friction; controls vessel permeability; performs absorption and secretion Cytoplasm Nucleus Connective tissue LM × 238 a Lining of peritoneal cavity

Figure 4-3b Squamous Epithelia.
Stratified Squamous Epithelium LOCATIONS: Surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina FUNCTIONS: Provides physical protection against abrasion, pathogens, and chemical attack Squamous superficial cells Stem cells Basement membrane Connective tissue b Surface of tongue LM × 310

Figure 4-4a Cuboidal and Transitional Epithelia.
Simple Cuboidal Epithelium LOCATIONS: Glands; ducts; portions of kidney tubules; thyroid gland Connective tissue FUNCTIONS: Limited protection, secretion, absorption Nucleus Cuboidal cells Basement membrane a Kidney tubule LM × 650

Figure 4-4b Cuboidal and Transitional Epithelia.
Stratified Cuboidal Epithelium LOCATIONS: Lining of some ducts (rare) FUNCTIONS: Protection, secretion, absorption Lumen of duct Stratified cuboidal cells Basement membrane Nucleus Connective tissue b Sweat gland duct LM × 500

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) © 2015 Pearson Education, Inc.

Figure 4-4c Cuboidal and Transitional Epithelia.
Transitional Epithelium LOCATIONS: Urinary bladder; renal pelvis; ureters FUNCTIONS: Permits expansion and recoil after stretching Epithelium (relaxed) Basement membrane Connective tissue and smooth muscle layers LM × 400 Empty bladder Epithelium (stretched) Basement membrane Connective tissue and smooth muscle layers LM × 400 Full bladder c Urinary bladder

Figure 4-5a Columnar Epithelia.
Simple Columnar Epithelium LOCATIONS: Lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys Microvilli Cytoplasm FUNCTIONS: Protection, secretion, absorption Nucleus Basement membrane Loose connective tissue a Intestinal lining LM × 350

Figure 4-5b Columnar Epithelia.
Pseudostratified Ciliated Columnar Epithelium LOCATIONS: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract Cilia Cytoplasm FUNCTIONS: Protection, secretion, move mucus with cilia Nuclei Basement membrane Loose connective tissue b Trachea LM × 350

Figure 4-5c Columnar Epithelia.
Stratified Columnar Epithelium LOCATIONS: Small areas of the pharynx, epiglottis, anus, mammary glands, salivary gland ducts, and urethra Loose connective tissue Deeper cells FUNCTION: Protection Superficial columnar cells Lumen Lumen Cytoplasm Nuclei Basement membrane c Salivary gland duct LM × 175

Merocrine Secretion Produced in Golgi apparatus Released by vesicles (exocytosis) For example, sweat glands Apocrine Secretion Released by shedding cytoplasm For example, mammary glands © 2015 Pearson Education, Inc.

Figure 4-6 Modes of Glandular Secretion.
(a) Merocrine secretion In merocrine secretion, the product is released from secretory vesicles at the apical surface of the gland cell by exocytosis. Secretory vesicle Golgi apparatus Nucleus TEM × 3039 Salivary gland (b) Apocrine secretion Apocrine secretion involves the loss of apical cytoplasm. Inclusions, secretory vesicles, and other cytoplasmic components are shed in the process. The gland cell then grows and repairs itself before it releases additional secretions. Mammary gland Breaks down Golgi apparatus Hair Secretion Regrowth 1 2 3 4 Sebaceous gland Hair follicle (c) Holocrine secretion Holocrine secretion occurs as superficial gland cells burst. Continued secretion involves the replacement of these cells through the mitotic divisions of underlying stem cells. 3 Cells burst, releasing cytoplasmic contents 2 Cells form secretory products and increase in size 1 Cell division replaces lost cells Stem cell

Figure 4-6a Modes of Glandular Secretion.
(a) Merocrine secretion In merocrine secretion, the product is released from secretory vesicles at the apical surface of the gland cell by exocytosis. Salivary gland Secretory vesicle Golgi apparatus Mammary gland Nucleus TEM × 3039 Hair Sebaceous gland Hair follicle

Figure 4-6b Modes of Glandular Secretion.
Salivary gland (b) Apocrine secretion Apocrine secretion involves the loss of apical cytoplasm. Inclu- sions, secretory vesicles, and other cytoplasmic components are shed in the process. The gland cell then grows and repairs itself before it releases additional secretions. Mammary gland Breaks down Golgi apparatus Hair Secretion Regrowth 1 2 3 4 Sebaceous gland Hair follicle

Figure 4-6c Modes of Glandular Secretion.
Salivary gland (c) Holocrine secretion Holocrine secretion occurs as superficial gland cells burst. Contin- ued secretion involves the replacement of these cells through the mitotic divisions of underlying stem cells. Mammary gland 3 Cells burst, releasing cytoplasmic contents 2 Cells form secretory products and increase in size Hair 1 Cell division replaces lost cells Sebaceous gland Stem cell Hair follicle

Glandular Epithelia Gland structure Unicellular glands Mucous (goblet) cells are the only unicellular exocrine glands Scattered among epithelia For example, in intestinal lining © 2015 Pearson Education, Inc.

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) © 2015 Pearson Education, Inc.

SIMPLE GLANDS Duct Gland cells SIMPLE TUBULAR SIMPLE COILED TUBULAR
Figure 4-7 A Structural Classification of Exocrine Glands (Part 1 of 2). SIMPLE GLANDS Duct Gland cells SIMPLE TUBULAR SIMPLE COILED TUBULAR SIMPLE BRANCHED TUBULAR Examples: Examples: Examples: •Intestinal glands •Merocrine sweat glands •Gastric glands •Mucous glands of esophagus, tongue, duodenum SIMPLE ALVEOLAR (ACINAR) SIMPLE BRANCHED ALVEOLAR Examples: Examples: •Not found in adult; a stage in development of simple branched glands •Sebaceous (oil) glands

COMPOUND ALVEOLAR (ACINAR) COMPOUND TUBULOALVEOLAR
Figure 4-7 A Structural Classification of Exocrine Glands (Part 2 of 2). COMPOUND GLANDS COMPOUND TUBULAR COMPOUND ALVEOLAR (ACINAR) COMPOUND TUBULOALVEOLAR Examples: Examples: Examples: •Mucous glands (in mouth) •Bulbourethral glands (in male reproductive system) •Testes (seminiferous tubules) •Mammary glands •Salivary glands •Glands of respiratory passages •Pancreas

4-4 Connective Tissue Characteristics of Connective Tissue
Specialized cells Solid extracellular protein fibers Fluid extracellular ground substance The Extracellular Components of Connective Tissue (Fibers and Ground Substance) Make up the matrix(surrounds the cell) Majority of tissue volume Determines specialized function © 2015 Pearson Education, Inc.

4-4 Connective Tissue Occur throughout the body, but they are never exposed to the outside. Highly vascularized Contain sensory receptors that detect pain, pressure, temperature,and other stimuli. Functions of Connective Tissue Establishing a structural framework for the body Transporting fluids and dissolved materials Protecting delicate organs Supporting, surrounding, and interconnecting other types of tissue Storing energy reserves, especially in the form of triglycerides Defending the body from invading microorganisms © 2015 Pearson Education, Inc.

4-4 Connective Tissue Classification of Connective Tissues
Connective tissue proper Connect and protect Fluid connective tissues Transport Supporting connective tissues Structural strength © 2015 Pearson Education, Inc.

4-4 Connective Tissue Categories of Connective Tissue Proper
Loose connective tissue More ground substance, fewer fibers For example, fat (adipose tissue) Dense connective tissue More fibers, less ground substance For example, tendons © 2015 Pearson Education, Inc.

Connective Tissue Proper Cell Populations
Fixed Fibroblasts Fibrocytes Adipocytes Mesenchymal cells Mobile Macrophages Mast cells Lymphocytes Microphages Melanocytes © 2015 Pearson Education, Inc.

4-4 Connective Tissue Fibroblasts Fibrocytes
The most abundant cell type Found in all connective tissue proper Secrete proteins and hyaluronan (cellular cement) Fibrocytes The second most abundant cell type Maintain the fibers of connective tissue proper Spindle shaped cells that maintain connective tissue fibers of connective tissue proper. © 2015 Pearson Education, Inc.

4-4 Connective Tissue Adipocytes Mesenchymal Cells 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. © 2015 Pearson Education, Inc.

4-4 Connective Tissue Macrophages
Large, phagocytic, amoeba-like cells of the immune system Eat pathogens and damaged cells Fixed macrophages stay in tissue Free macrophages migrate © 2015 Pearson Education, Inc.

4-4 Connective Tissue Mast Cells
Small, mobile connective tissue cells that are common near blood vessels Stimulate inflammation after injury or infection Release histamine (stimulates local inflammation) and heparin (anticoagulant that enhances blood flow and reduces development of blood clots. Basophils are leukocytes (white blood cells) that also contain histamine and heparin. They enter damaged cells and enhance inflammation process © 2015 Pearson Education, Inc.

4-4 Connective Tissue Lymphocytes
Specialized immune cells in lymphatic (lymphoid) system For example, lymphocytes may develop into plasma cells (plasmocytes) that produce antibodies which fight off disease. © 2015 Pearson Education, Inc.

4-4 Connective Tissue Microphages Melanocytes Phagocytic blood cells
Attracted to the site of an infection or injury Respond to signals from macrophages and mast cells For example, neutrophils and eosinophils Melanocytes Synthesize and store the brown pigment melanin which gives tissue it dark color. Also abundant in the eyes and the dermis of the skin. © 2015 Pearson Education, Inc.

4-4 Connective Tissue Connective Tissue Fibers Collagen fibers
Reticular fibers Elastic fibers © 2015 Pearson Education, Inc.

4-4 Connective Tissue Collagen Fibers
Most common fibers in connective tissue proper Long, straight, and unbranched Strong and flexible Resist force in one direction For example, tendons connect muscle to bone and ligaments connect bone to bone. © 2015 Pearson Education, Inc.

4-4 Connective Tissue Reticular Fibers
Network of branching interwoven fibers (stroma) Strong and flexible Resist force in many directions Stabilize functional cells (parenchyma) and structures For example, sheaths around organs © 2015 Pearson Education, Inc.

4-4 Connective Tissue Elastic Fibers Contain elastin Branched and wavy
Return to original length after stretching For example, elastic ligaments of vertebrae © 2015 Pearson Education, Inc.

4-4 Connective Tissue Ground Substance
Is clear, colorless, and viscous Fills spaces between cells and slows pathogen movement (molasses) © 2015 Pearson Education, Inc.

Figure 4-8 The Cells and Fibers of Connective Tissue Proper.
Reticular fibers Mast cell Melanocyte Elastic fibers Fixed macrophage Plasma cell Free macrophage Collagen fibers Blood in vessel Fibroblast Mesenchymal cell Adipocytes (fat cells) Ground substance Lymphocyte

4-4 Connective Tissue Embryonic Connective Tissues
Are not found in adults Mesenchyme (embryonic star shaped stem cells) The first connective tissue in embryos Mucous connective tissue (Wharton’s jelly) Loose embryonic connective tissue, umbilical cord © 2015 Pearson Education, Inc.

Figure 4-9a Embryonic Connective Tissues.
Blood vessel Mesenchymal cells LM × 136 Mesenchyme This is the first connective tissue to appear in an embryo. a

Figure 4-9b Embryonic Connective Tissues.
Blood vessel Mesenchymal cells Mucous connective tissue (Wharton’s jelly) LM × 136 This sample was taken from the umbilical cord of a fetus. b

4-4 Connective Tissue Loose Connective Tissues
The “packing materials” of the body Three types in adults Areolar Adipose Reticular © 2015 Pearson Education, Inc.

4-4 Connective Tissue Areolar Tissue Least specialized Open framework
Viscous ground substance absorbs shock Elastic fibers Holds blood vessels and capillary beds For example, under skin (subcutaneous layer) Common injection site for drugs because it has an extensive blood supply © 2015 Pearson Education, Inc.

4-4 Connective Tissue Adipose Tissue
Contains many adipocytes (fat cells) Two types of adipose tissue White fat Brown fat © 2015 Pearson Education, Inc.

4-4 Connective Tissue White fat Brown 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 breakdown accelerates, releasing energy Absorbs energy from surrounding tissues © 2015 Pearson Education, Inc.

4-4 Connective Tissue 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 © 2015 Pearson Education, Inc.

4-4 Connective Tissue Reticular Tissue Provides support
Complex, three-dimensional network Supportive fibers (stroma) Support functional cells (parenchyma) Reticular organs Spleen, liver, lymph nodes, and bone marrow © 2015 Pearson Education, Inc.

Figure 4-10a Loose Connective Tissues.
Areolar Tissue LOCATIONS: Within and deep to the dermis of skin, and covered by the epithelial lining of the digestive, respiratory, and urinary tracts; between muscles; around joints, blood vessels, and nerves Fibrocytes Macrophage Collagen fibers FUNCTIONS: Cushions organs; provides support but permits independent movement; phagocytic cells provide defense against pathogens Mast cell Elastic fibers Areolar tissue from pleura LM × 380 a Areolar tissue

Figure 4-10b Loose Connective Tissues.
Adipose Tissue LOCATIONS: Deep to the skin, especially at sides, buttocks, and breasts; padding around eyes and kidneys FUNCTIONS: Provides padding and cushions shocks; insulates (reduces heat loss); stores energy Adipocytes (white adipose cells) LM × 300 b Adipose tissue

Figure 4-10c Loose Connective Tissues.
Reticular Tissue LOCATIONS: Liver, kidney, spleen, lymph nodes, and bone marrow FUNCTIONS: Provides supporting framework Reticular fibers Reticular tissue from liver LM × 375 c Reticular tissue

4-4 Connective Tissue 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 © 2015 Pearson Education, Inc.

4-4 Connective Tissue 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 © 2015 Pearson Education, Inc.

Figure 4-11a Dense Connective Tissues.
Dense Regular Connective Tissue LOCATIONS: Between skeletal muscles and skeleton (tendons and aponeuroses); between bones or stabilizing positions of internal organs (ligaments); covering skeletal muscles; deep fasciae Collagen fibers FUNCTIONS: Provides firm attachment; conducts pull of muscles; reduces friction between muscles; stabilizes positions of bones Fibroblast nuclei a Tendon LM × 440

4-4 Connective Tissue 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) © 2015 Pearson Education, Inc.

Figure 4-11b Dense Connective Tissues.
Dense Irregular Connective Tissue LOCATIONS: Capsules of visceral organs; periostea and perichondria; nerve and muscle sheaths; dermis FUNCTIONS: Provides strength to resist forces from many directions; helps prevent overexpansion of organs, such as the urinary bladder Collagen fiber bundles b Deep dermis LM × 111

4-4 Connective Tissue Elastic Tissue Made of elastic fibers
For example, elastic ligaments of spinal vertebrae © 2015 Pearson Education, Inc.

Figure 4-11c Dense Connective Tissues.
Elastic Tissue LOCATIONS: Between vertebrae of the spinal column (ligamentum flavum and ligamentum nuchae); ligaments supporting penis; ligaments supporting transitional epithelia; in blood vessel walls Elastic fibers FUNCTIONS: Stabilizes positions of vertebrae and penis; cushions shocks; permits expansion and contraction of organs Fibroblast nuclei c Elastic ligament LM × 887

4-4 Connective Tissue 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 © 2015 Pearson Education, Inc.

4-4 Connective Tissue Fluid Elements of Connective Tissues
Extracellular Plasma Interstitial fluid Lymph © 2015 Pearson Education, Inc.

Figure 4-12 Formed Elements in the Blood (Part 1 of 3).
Red blood cells, or erythrocytes (e-RITH-ro-sits), are responsible for the transport of oxygen (and, to a lesser degree, of carbon dioxide) in the blood. ˉ ˉ Red blood cells Red blood cells account for about half the volume of whole blood and give blood its color.

White blood cells White blood cells, or leukocytes (LOO-ko-sits; leuko-, white), help defend the body from infection and disease. ˉ ˉ Neutrophil Eosinophil Basophil Monocytes are phagocytes similar to the free macrophages in other tissues. Lymphocytes are uncommon in the blood but they are the dominant cell type in lymph, the second type of fluid connective tissue. Eosinophils and neutrophils are phagocytes. Basophils promote inflammation much like mast cells in other connective tissues.

Platelets Platelets are membrane-enclosed packets of cytoplasm that function in blood clotting. These cell fragments are involved in the clotting response that seals leaks in damaged or broken blood vessels.

4-4 Connective Tissue Lymph Extracellular fluid
Collected from interstitial space Monitored by immune system Transported by lymphatic (lymphoid) system Returned to venous system © 2015 Pearson Education, Inc.

4-4 Connective Tissue Fluid Tissue Transport Systems
Cardiovascular system (blood) Arteries Capillaries Veins Lymphatic (lymphoid) system (lymph) Lymphatic vessels © 2015 Pearson Education, Inc.

4-5 Supporting 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 © 2015 Pearson Education, Inc.

Cartilage Structure No blood vessels Chondrocytes produce antiangiogenesis factor Perichondrium Outer, fibrous layer (for strength) Inner, cellular layer (for growth and maintenance) © 2015 Pearson Education, Inc.

Figure 4-13a The Growth of Cartilage.
Matrix New matrix Chondrocyte Lacuna Chondrocyte undergoes division within a lacuna surrounded by cartilage matrix. As daughter cells secrete additional matrix, they move apart, expanding the cartilage from within. a Interstitial growth

Figure 4-13b The Growth of Cartilage.
Fibroblast Dividing stem cell Perichondrium New matrix Immature chondrocyte Chondroblasts Older matrix Mature chondrocyte Cells in the cellular layer of the perichondrium differentiate into chondroblasts. These immature chondroblasts secrete new matrix. As the matrix enlarges, more chondroblasts are incorporated; they are replaced by divisions of stem cells in the perichondrium. b Appositional growth

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 © 2015 Pearson Education, Inc.

Figure 4-14a Types of Cartilage.
Hyaline Cartilage LOCATIONS: Between tips of ribs and bones of sternum; covering bone surfaces at synovial joints; supporting larynx (voice box), trachea, and bronchi; forming part of nasal septum FUNCTIONS: Provides stiff but somewhat flexible support; reduces friction between bony surfaces Chondrocytes in lacunae Matrix LM × 500 a Hyaline cartilage

Figure 4-14b Types of Cartilage.
Elastic Cartilage LOCATIONS: Auricle of external ear; epiglottis; auditory canal; cuneiform cartilages of larynx FUNCTIONS: Provides support, but tolerates distortion without damage and returns to original shape Chondrocytes in lacunae Elastic fibers in matrix LM × 358 b Elastic cartilage

Figure 4-14c Types of Cartilage.
Fibrocartilage LOCATIONS: Pads within knee joint; between pubic bones of pelvis; intervertebral discs FUNCTIONS: Resists compression; prevents bone-to-bone contact; limits movement Chondrocytes in lacunae Fibrous matrix LM × 400 c Fibrocartilage

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 © 2015 Pearson Education, Inc.

Figure 4-15 Bone. Fibrous layer Canaliculi Periosteum Cellular layer Osteocytes in lacunae Matrix Osteon Central canal Blood vessels Osteon LM × 375

Table 4-2 A Comparison of Cartilage and Bone.

4-6 Membranes Membranes Physical barriers
Line or cover portions of the body Consist of: An epithelium Supported by connective tissue © 2015 Pearson Education, Inc.

4-6 Membranes Four Types of Membranes Mucous membranes
Serous membranes Cutaneous membrane Synovial membranes © 2015 Pearson Education, Inc.

4-6 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 © 2015 Pearson Education, Inc.

Figure 4-16a Types of Membranes.
Mucous secretion Epithelium Lamina propria (areolar tissue) a Mucous membranes are coated with the secretions of mucous glands. These membranes line the digestive, respiratory, urinary, and reproductive tracts.

4-6 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 © 2015 Pearson Education, Inc.

4-6 Membranes Three Serous Membranes Pleura Peritoneum Pericardium
Lines pleural cavities Covers lungs Peritoneum Lines peritoneal cavity Covers abdominal organs Pericardium Lines pericardial cavity Covers heart © 2015 Pearson Education, Inc.

Figure 4-16b Types of Membranes.
Transudate Mesothelium Areolar tissue b Serous membranes line the ventral body cavities (the peritoneal, pleural, and pericardial cavities).

4-6 Membranes Cutaneous Membrane Synovial Membranes
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 © 2015 Pearson Education, Inc.

Figure 4-16c Types of Membranes.
Epithelium Areolar tissue Dense irregular connective tissue c The cutaneous membrane, or skin, covers the outer surface of the body.

Figure 4-16d Types of Membranes.
Articular (hyaline) tissue Synovial fluid Capsule Capillary Adipocytes Areolar tissue Synovial membrane Epithelium Bone d Synovial membranes line joint cavities and produce the fluid within the joint.

4-7 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 = fascia The body’s framework of connective tissue Layers and wrappings that support or surround organs © 2015 Pearson Education, Inc.

4-7 Internal Framework of the Body
Three Types of Fasciae Superficial fascia Deep fascia Subserous fascia © 2015 Pearson Education, Inc.

Connective Tissue Framework of Body
Figure 4-17 The Fasciae. Body wall Connective Tissue Framework of Body Body cavity Superficial Fascia • Between skin and underlying organs • Areolar tissue and adipose tissue • Also known as subcutaneous layer or hypodermis Skin Deep Fascia • Bound to capsules, tendons, and ligaments • Dense connective tissue • Forms a strong, fibrous internal framework Subserous Fascia • Between serous membranes and deep fascia • Areolar tissue Rib Serous membrane Cutaneous membrane

4-8 Muscle Tissue Muscle Tissue Specialized for contraction
Produces all body movement Three types of muscle tissue Skeletal muscle tissue Large body muscles responsible for movement Cardiac muscle tissue Found only in the heart Smooth muscle tissue Found in walls of hollow, contracting organs (blood vessels; urinary bladder; respiratory, digestive, and reproductive tracts) © 2015 Pearson Education, Inc.

4-8 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) © 2015 Pearson Education, Inc.

4-8 Muscle Tissue Skeletal Muscle Cells Long and thin
Usually called muscle fibers Do not divide New fibers are produced by stem cells (myosatellite cells) © 2015 Pearson Education, Inc.

Figure 4-18a Types of Muscle Tissue.
Skeletal Muscle Tissue Cells are long, cylindrical, striated, and multinucleate. LOCATIONS: Combined with connective tissues and neural tissue in skeletal muscles Striations Nuclei FUNCTIONS: Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, and urinary tracts; generates heat; protects internal organs Muscle fiber LM × 180 a Skeletal muscle

4-8 Muscle Tissue Cardiac Muscle Cells Smooth Muscle Cells
Called cardiocytes Form branching networks connected at intercalated discs Regulated by pacemaker cells Smooth Muscle Cells Small and tapered Can divide and regenerate © 2015 Pearson Education, Inc.

Figure 4-18b Types of Muscle Tissue.
Cardiac Muscle Tissue Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercalated discs. Nuclei Cardiac muscle cells LOCATION: Heart FUNCTIONS: Circulates blood; maintains blood pressure Intercalated discs Striations LM × 450 b Cardiac muscle

Figure 4-18c Types of Muscle Tissue.
Smooth Muscle Tissue Cells are short, spindle- shaped, and nonstriated, with a single, central nucleus. LOCATIONS: Found in the walls of blood vessels and in digestive, respiratory, urinary, and reproductive organs Nuclei FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels Smooth muscle cells LM × 235 c Smooth muscle

4-9 Neural 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 is concentrated in the central nervous system Brain Spinal cord © 2015 Pearson Education, Inc.

4-9 Neural Tissue Two Types of Neural Cells Neurons Neuroglia
Nerve cells Perform electrical communication Neuroglia Supporting cells Repair and supply nutrients to neurons © 2015 Pearson Education, Inc.

4-9 Neural Tissue Cell Parts of a Neuron Cell body Dendrites
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 © 2015 Pearson Education, Inc.

NEUROGLIA (supporting cells)
Figure 4-19 Neural Tissue. NEURONS NEUROGLIA (supporting cells) Nuclei of neuroglia • Maintain physical structure of tissues • Repair tissue framework after injury • Perform phagocytosis • Provide nutrients to neurons • Regulate the composition of the interstitial fluid surrounding neurons Cell body Axon Dendrites Nucleolus Nucleus of neuron LM × 600 Dendrites (contacted by other neurons) Contact with other cells Axon (conducts information to other cells) Microfibrils and microtubules Cell body (contains nucleus and major organelles) Nucleus Nucleolus Mitochondrion A representative neuron (sizes and shapes vary widely)

Figure 4-19 Neural Tissue (Part 1 of 3).
Nuclei of neuroglia Cell body Axon Dendrites Nucleolus Nucleus of neuron LM × 600

NEUROGLIA (supporting cells) • Maintain physical structure of tissues • Repair tissue framework after injury • Perform phagocytosis • Provide nutrients to neurons • Regulate the composition of the interstitial fluid surrounding neurons

Dendrites (contacted by other neurons) Contact with other cells Axon (conducts information to other cells) Microfibrils and microtubules Cell body (contains nucleus and major organelles) Nucleus Nucleolus Mitochondrion A representative neuron (sizes and shapes vary widely)

4-10 Tissue Injuries and Repair
Tissues Respond to Injuries To maintain homeostasis Cells restore homeostasis with two processes Inflammation Regeneration © 2015 Pearson Education, Inc.

The Process of Inflammation As cells break down: Lysosomes release enzymes that destroy the injured cell and attack surrounding tissues Tissue destruction is called necrosis © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

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 © 2015 Pearson Education, Inc.

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) © 2015 Pearson Education, Inc.

The Process of Regeneration 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) © 2015 Pearson Education, Inc.

Figure 4-20 Inflammation and Regeneration (Part 1 of 5).
Mast Cell Activation When an injury damages connective tissue, mast cells release a variety of chemicals. This process, called mast cell activation, stimulates inflammation. Mast cell Histamine stimulates Exposure to Pathogens and Toxins Injured tissue contains an abnormal concentration of pathogens, toxins, wastes, and the chemicals from injured cells. When a tissue is injured, a general defense mechanism is activated.

Mast Cell Activation When an injury damages connective tissue, mast cells release a variety of chemicals. This process, called mast cell activation, stimulates inflammation. Mast cell Mast Cell Histamine Heparin Prostaglandins INFLAMMATION Inflammation produces several familiar indications of injury, including swelling, redness, heat (warmth), pain, and sometimes loss of function. Inflammation may also result from the presence of pathogens, such as harmful bacteria, within the tissues. The presence of these pathogens constitutes an infection. Increased Blood Flow Increased Vessel Permeability Pain In response to the released chemicals, blood vessels dilate, increasing blood flow through the damaged tissue. Vessel dilation is accompanied by an increase in the permeability of the capillary walls. Plasma now diffuses into the injured tissue, so the area becomes swollen. The abnormal conditions within the tissue and the chemicals released by mast cells stimulate nerve endings that produce the sensation of pain. PAIN

Increased Local Temperature Increased Oxygen and Nutrients Increased Phagocytosis Removal of Toxins and Wastes The increased blood flow and permeability causes the tissue to become warm and red. Vessel dilation, increased blood flow, and increased vessel permeability result in enhanced delivery of oxygen and nutrients. Phagocytes in the tissue are activated, and they begin engulfing tissue debris and pathogens. Enhanced circulation carries away toxins and wastes, distributing them to the kidneys for excretion, or to the liver for inactivation. O2 Toxins and wastes Regeneration Regeneration is the repair that occurs after the damaged tissue has been stabilized and the inflammation has subsided. Fibroblasts move into the area, laying down a collagenous framework known as scar tissue. Over time, scar tissue is usually “remodeled” and gradually assumes a more normal appearance. Inflammation Subsides Over a period of hours to days, the cleanup process generally succeeds in eliminating the inflammatory stimuli.

4-11 Aging and Tissue Aging and Tissue Structure
Speed and efficiency of tissue repair decrease with age, due to: Slower rate of energy consumption (metabolism) Hormonal alterations Reduced physical activity © 2015 Pearson Education, Inc.

4-11 Aging and Tissue Effects of Aging
Chemical and structural tissue changes Thinning epithelia and connective tissues Increased bruising and bone brittleness Joint pain and broken bones Cardiovascular disease Mental deterioration © 2015 Pearson Education, Inc.

4-11 Aging and Tissue Aging and Cancer Incidence
Cancer rates increase with age Twenty-five percent of all people in the United States develop cancer Cancer is the #2 cause of death in the United States Environmental chemicals and cigarette smoke cause cancer © 2015 Pearson Education, Inc.

© 2015 Pearson Education, Inc.

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