The Tissue Level of Organization 4 The Tissue Level of Organization

Chapter 4 Learning Outcomes 4-1 Identify the body's four basic types of tissues and describe their roles. 4-2 Describe the characteristics and functions of epithelial cells. 4-3 Describe the relationship between form and function for each type of epithelium. 4-4 Compare the structures and functions of the various types of connective tissues. © 2013 Pearson Education, Inc.

Chapter 4 Learning Outcomes 4-5 Explain how epithelial and connective tissues combine to form four types of tissue membranes, and specify the functions of each. 4-6 Describe the three types of muscle tissue and the special structural features of each. 4-7 Discuss the basic structure and role of neural tissue. 4-8 Explain how injuries affect the tissues of the body. 4-9 Describe how aging affects the tissues of the body. © 2013 Pearson Education, Inc.

Tissues (4-1) Collections of cells and cell products that perform specific, limited functions Histology The study of tissues Four types of tissues Epithelial Connective Muscle Neural © 2013 Pearson Education, Inc.

with special functions with multiple functions Figure 4-1 An Orientation to the Tissues of the Body. EPITHELIAL TISSUE That secrete and regulate EXTRACELLULAR MATERIAL AND FLUIDS CELLS • Covers exposed surfaces • Lines internal passageways and chambers • Produces glandular secretions Combine to form CONNECTIVE TISSUE TISSUES with special functions • Fills internal spaces • Provides structural support • Stores energy Combine to form MUSCLE TISSUE ORGANS with multiple functions • Contracts to produce active movement Interact in NEURAL TISSUE • Conducts electrical Impulses • Carries information ORGAN SYSTEMS Chapters 5–20 © 2013 Pearson Education, Inc.

Checkpoint (4-1) Define histology. List the four basic types of tissues in the body. © 2013 Pearson Education, Inc.

Epithelial Tissue (4-2) Covers body surfaces Lines cavities Lines tubular structures Serves essential functions © 2013 Pearson Education, Inc. 7

Characteristics of Epithelial Tissue (4-2) Cellularity (cell junctions) Polarity (apical and basal surfaces) Attachment Avascularity Regeneration © 2013 Pearson Education, Inc.

Functions of Epithelia (4-2) Provide physical protection Control permeability Provide sensation Produce specialized secretions (glandular epithelium) Exocrine glands Endocrine glands © 2013 Pearson Education, Inc.

Intercellular Connections (4-2) Support and communication Cell adhesion molecules (CAMs) Transmembrane proteins Intercellular cement Proteoglycans © 2013 Pearson Education, Inc.

Three Common Cell Junctions (4-2) Tight junctions Gap junctions Desmosomes Form bonds with other cells or extracellular material © 2013 Pearson Education, Inc.

Tight junction Adhesion belt Spot desmosome Gap junctions This is a Figure 4-2a Cell Junctions. Tight junction Adhesion belt Spot desmosome Gap junctions This is a Diagrammatic view of an epithelial cell, showing the major types of Intercellular connections. Hemidesmosome © 2013 Pearson Education, Inc.

A tight junction is formed by the fusion of the outer Figure 4-2b Cell Junctions. Interlocking junctional proteins Tight junction Tight junction Adhesion belt Spot desmosome Adhesion belt Gap junctions 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 deep to the tight junction is tied to the microfilaments of the cytoskeleton. Hemidesmosome © 2013 Pearson Education, Inc.

Figure 4-2c Cell Junctions. Tight junction Adhesion belt Spot desmosome Gap junctions Hemidesmosome Embedded proteins (connexons) Gap junctions permit the free diffusion of ions and small mol- ecules between two cells. © 2013 Pearson Education, Inc.

Gap junctions Gap junctions Figure 4-2d-e Cell Junctions. Tight junction Tight junction Adhesion belt Adhesion belt Spot desmosome Spot desmosome Gap junctions Gap junctions Hemidesmosome Hemidesmosome Intermediate filaments Dense area Basement membrane Cell adhesion molecules (CAMs) Proteoglycans Hemidesmosomes attach a cell to extracellular structures, such as the protein fibers in the basement membrane. A spot desmosome ties adjacent cells together. © 2013 Pearson Education, Inc.

The Epithelial Surface (4-2) Apical surface is exposed Basal surface is connected to deeper connective tissue with basement membrane © 2013 Pearson Education, Inc.

Cilia Microvilli Nucleus Mitochondria Basement membrane Figure 4-3 The Surfaces of Epithelial Cells. Cilia Microvilli Apical surface Golgi apparatus Nucleus Mitochondria Basement membrane © 2013 Pearson Education, Inc.

Epithelial Renewal and Repair (4-2) Epithelia are replaced by mitosis Cell division of stem cells (germinative cells) Occurs near basement membrane © 2013 Pearson Education, Inc.

Checkpoint (4-2) List five important characteristics of epithelial tissue. Identify four essential functions of epithelial tissue. Identify the three main types of epithelial cell junctions. What physiological functions are enhanced by the presence of microvilli or cilia on epithelial cells? © 2013 Pearson Education, Inc.

Classification of Epithelia (4-3) Combines a cell shape with the number of layers of cells Example: Simple (one layer) cuboidal (square shape) © 2013 Pearson Education, Inc.

Cell Layers and Cell Shapes (4-3) Classification is based on layers Simple epithelium: single layer of cells Stratified epithelium: several layers of cells Classification is based on shape Squamous epithelia: thin and flat Cuboidal epithelia: square shaped Columnar epithelia: tall, slender rectangles © 2013 Pearson Education, Inc.

Table 4-1 Classifying Epithelia © 2013 Pearson Education, Inc.

Simple Squamous Epithelium Figure 4-4a Simple Epithelia. Simple Squamous Epithelium LOCATIONS: Epithelia lining ventral body cavities; lining heart and blood vessels; portions of kidney tubules (thin sections of nephron loops); inner lining of cornea; alveoli (air sacs) of lungs Cytoplasm Nucleus FUNCTIONS: Reduces friction; controls vessel permeability; performs absorption and secretion Connective tissue LM x 238 Lining of peritoneal cavity © 2013 Pearson Education, Inc.

Simple Cuboidal Epithelium Figure 4-4b Simple 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 Kidney tubule LM x 650 © 2013 Pearson Education, Inc.

Simple Columnar Epithelium Figure 4-4c Simple 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 Connective tissue Intestinal lining LM x 350 © 2013 Pearson Education, Inc.

Stratified Squamous Epithelium Figure 4-5a Stratified Epithelia. Stratified Squamous Epithelium LOCATIONS: Surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina Squamous superficial cells Stem cells FUNCTIONS: Provides physical protection against abrasion, pathogens, and chemical attack Basement membrane Connective tissue Surface of tongue LM x 310 © 2013 Pearson Education, Inc.

Pseudostratified Ciliated Columnar Epithelium Figure 4-5b Stratified Epithelia. Pseudostratified Ciliated Columnar Epithelium LOCATIONS: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract Cilia Cytoplasm Nuclei FUNCTIONS: Protection, secretion, move mucus with cilia Basement membrane Connective tissue Trachea LM x 350 © 2013 Pearson Education, Inc.

Transitional Epithelium Figure 4-5c Stratified Epithelia. Transitional Epithelium LOCATIONS: Urinary bladder; renal pelvis; ureters Epithelium (relaxed) FUNCTIONS: Permits expansion and recoil after stretching Basement membrane Connective tissue and smooth muscle layers LM x 400 Empty bladder Epithelium (stretched) Basement membrane Connective tissue and smooth muscle layers Full bladder LM x 400 Urinary bladder © 2013 Pearson Education, Inc.

Glandular Epithelia (4-3) Endocrine glands Release hormones: Into interstitial fluid and plasma No ducts Exocrine glands Produce secretions: Onto epithelial surfaces Through ducts © 2013 Pearson Education, Inc.

Glandular Secretion (4-3) Merocrine secretion Produced in Golgi apparatus Released by vesicles (exocytosis) Example: sweat glands Apocrine secretion Released by shedding cytoplasm Example: mammary glands © 2013 Pearson Education, Inc.

Glandular Secretion (4-3) Holocrine secretion Released by cells bursting, killing gland cells Gland cells replaced by stem cells Example: sebaceous glands © 2013 Pearson Education, Inc.

Figure 4-6 Mechanisms of Glandular Secretion. Secretory vesicle Golgi apparatus Nucleus TEM x 3039 Merocrine. In merocrine secretion, the contents of secretory vesicles are discharged at the apical surface of the gland cell by exocytosis. Salivary gland Mammary gland Breaks down Golgi apparatus Secretion Regrowth Apocrine. Apocrine secretion involves the loss of apical cytoplasm. Inclusions, secretory vesicles, and other cytoplasmic components are shed in the process. The gland cell then undergoes growth and repair before it releases additional secretions. Hair Sebaceous gland Cells burst, releasing cytoplasmic contents Hair follicle Cells produce secretion, increasing in size Cell division replaces lost cells Stem cell Holocrine. Holocrine secretion occurs as superficial gland cells burst. Continued secretion involves the replacement of these cells through the mitotic division of underlying stem cells. © 2013 Pearson Education, Inc.

Merocrine. In merocrine secretion, the contents of secretory Figure 4-6a Mechanisms of Glandular Secretion. Secretory vesicle Golgi apparatus Nucleus TEM x 3039 Merocrine. In merocrine secretion, the contents of secretory vesicles are discharged at the apical surface of the gland cell by exocytosis. Salivary gland Mammary gland Hair Sebaceous gland Hair follicle © 2013 Pearson Education, Inc. 33

Figure 4-6b Mechanisms of Glandular Secretion. Salivary gland Mammary gland Breaks down Golgi apparatus Secretion Regrowth Apocrine. Apocrine secretion involves the loss of apical cytoplasm. Inclusions, secretory vesicles, and other cytoplasmic components are shed in the process. The gland cell then undergoes growth and repair before it releases additional secretions. Hair Sebaceous gland Hair follicle © 2013 Pearson Education, Inc. 34

Salivary gland Hair Hair follicle Stem cell Figure 4-6c Mechanisms of Glandular Secretion. Salivary gland Mammary gland Hair Sebaceous gland Cells burst, releasing cytoplasmic contents Hair follicle Cells produce secretion, increasing in size Cell division replaces lost cells Stem cell Holocrine. Holocrine secretion occurs as superficial gland cells burst. Continued secretion involves the replacement of these cells through the mitotic division of underlying stem cells. © 2013 Pearson Education, Inc. 35

Types of Secretion (4-3) Serous glands Mucous glands Watery secretions Mucous glands Secrete mucins Mixed exocrine glands Both serous and mucous © 2013 Pearson Education, Inc.

Table 4-2 A Classification of Exocrine Glands © 2013 Pearson Education, Inc.

Checkpoint (4-3) Identify the three cell shapes characteristic of epithelial cells. Using a light microscope, you examine a tissue and see a simple squamous epithelium on the outer surface. Can this be a sample of skin surface? Name the two primary types of glandular epithelia. © 2013 Pearson Education, Inc.

Checkpoint (4-3) The secretory cells of sebaceous glands fill with secretions and then rupture, releasing their contents. Which mechanism of secretion occurs in sebaceous glands? Which type of gland releases its secretions directly into the extracellular fluid? © 2013 Pearson Education, Inc.

Connective Tissue (4-4) Provides a protective structural framework for other tissue types Three basic components Specialized cells Solid extracellular protein fibers Fluid extracellular ground substance © 2013 Pearson Education, Inc.

Characteristics of Connective Tissue (4-4) The extracellular components of connective tissues (fibers and ground substance) make up the matrix Majority of tissue volume Determines specialized function © 2013 Pearson Education, Inc.

Functions of Connective Tissue (4-4) Support and protection Transportation of materials Storage of energy reserves Defense of the body © 2013 Pearson Education, Inc.

CONNECTIVE TISSUES Figure 4-7 Major Types of Connective Tissue. CONNECTIVE TISSUE PROPER FLUID CONNECTIVE TISSUES SUPPORTING CONNECTIVE TISSUES LOOSE DENSE BLOOD LYMPH CARTILAGE BONE Fibers create loose, open framework Flows within cardiovascular system Flows within lymphatic system Fibers densely packed Solid, rubbery matrix Solid, crystalline matrix © 2013 Pearson Education, Inc.

Three Major Types of Connective Tissue (4-4) Connective tissue proper Fluid connective tissues Supporting connective tissues © 2013 Pearson Education, Inc.

Cells of Connective Tissue Proper (4-4) Fibroblasts Most abundant cells in connective tissue proper Produce connective tissue fibers and ground substance Macrophages Scattered throughout the matrix Phagocytize damaged cells or pathogens that enter the tissue Release chemicals that mobilize the immune system © 2013 Pearson Education, Inc.

Cells of Connective Tissue Proper (4-4) Fat cells (adipocytes) Permanent residents Number of fat cells vary Mast cells Small, mobile cells often found near blood vessels Cytoplasm is packed with vesicles Filled with chemicals that are released to begin body's defensive activities after an injury or infection © 2013 Pearson Education, Inc.

Three Basic Types of Connective Tissue Fibers (4-4) Collagen fibers Long, straight, unbranched Strong, but flexible Most common Elastic fibers Branched and wavy After stretching, they will return to their original length Contain the protein elastin © 2013 Pearson Education, Inc.

Three Basic Types of Connective Tissue Fibers (4-4) Reticular fibers Made of same protein subunits as collagen fibers, but arranged differently Thinner than collagen fibers Form branching, interwoven framework in various organs Least common © 2013 Pearson Education, Inc.

Ground Substance (4-4) Clear, colorless, and viscous Fills spaces between cells and slows pathogen movement © 2013 Pearson Education, Inc.

Types of Connective Tissue Proper (4-4) Loose connective tissue "Packing materials" of the body More ground substance, fewer fibers Example: fat (adipose tissue) Dense connective tissue Tough, strong, and durable More fibers, less ground substance Example: tendons © 2013 Pearson Education, Inc.

Mast cell Fibroblast Stem cell Figure 4-8 Cells and Fibers of Connective Tissue Proper. Reticular fibers Mast cell Elastic fibers Fixed macrophage Antibody producing cell Free macrophage Collagen fibers Blood in vessel Fibroblast Stem cell Adipocytes (fat cells) Ground substance White blood cell © 2013 Pearson Education, Inc.

Areolar Tissue Figure 4-9a Loose Connective Tissues. LOCATIONS: Beneath dermis of skin, digestive tract, respiratory and urinary tracts; between muscles; around blood vessels, nerves, and around joints Collagen fibers Mast cell Fat cell Fibroblasts FUNCTIONS: Cushions organs; provides support but permits independent movement; phagocytic cells provide defense against pathogens Elastic fibers Macrophage Areolar tissue LM x 400 © 2013 Pearson Education, Inc.

Adipose Tissue Adipose tissue LOCATIONS: Deep to the skin, Figure 4-9b Loose Connective Tissues. Adipose Tissue LOCATIONS: Deep to the skin, especially at sides, buttocks, breasts; padding around eyes and kidneys Adipocytes FUNCTIONS: Provides padding and cushions shocks; insulates (reduces heat loss); stores energy LM x 300 Adipose tissue © 2013 Pearson Education, Inc.

Reticular Tissue Reticular tissue LOCATIONS: Liver, kidney, spleen, Figure 4-9c 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 x 375 Reticular tissue © 2013 Pearson Education, Inc.

Dense Regular Connective Tissue Figure 4-10a 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 relative positions of bones Fibroblast nuclei Tendon LM x 440 © 2013 Pearson Education, Inc.

Dense Irregular Connective Tissue Figure 4-10b Dense Connective Tissues. Dense Irregular Connective Tissue LOCATIONS: Capsules of visceral organs; periostea and perichondria; nerve and muscle sheaths; deep dermis of the skin FUNCTIONS: Provides strength to resist forces applied from many directions; helps prevent overexpansion of organs such as the urinary bladder Collagen fiber bundles Deep dermis LM x 111 © 2013 Pearson Education, Inc.

Fluid Connective Tissues (4-4) Blood and lymph Watery matrix of dissolved proteins Carry specific cell types (formed elements) Formed elements of blood Red blood cells White blood cells Platelets © 2013 Pearson Education, Inc.

Supporting Connective Tissues (4-4) Cartilage Gel-type ground substance For shock absorption and protection Bone Calcified (made rigid by calcium salts, minerals) For weight support © 2013 Pearson Education, Inc.

Cartilage (4-4) Cartilage matrix Chondrocytes (cartilage cells) Proteoglycans derived from chondroitin sulfates Ground substance proteins Chondrocytes (cartilage cells) Surrounded by lacunae (chambers) © 2013 Pearson Education, Inc.

Cartilage Structure (4-4) Avascular Chondrocytes found in pockets called lacunae Perichondrium Outer, fibrous layer (for strength) Inner, cellular layer (for growth and maintenance) © 2013 Pearson Education, Inc.

Three Major Types of Cartilage (4-4) 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 Fibrocartilage Limits movement Prevents bone-to-bone contact Pads knee joints Found between pubic bones and intervertebral discs © 2013 Pearson Education, Inc.

Figure 4-11a 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 Chondrocytes in lacunae FUNCTIONS: Provides stiff but somewhat flexible support; reduces friction between bony surfaces Matrix LM x 500 Hyaline cartilage © 2013 Pearson Education, Inc.

Elastic Cartilage Figure 4-11b Types of Cartilage. Elastic cartilage LOCATIONS: Auricle of external ear; epiglottis; auditory canal; cuneiform cartilages of larynx Chondrocyte In lacuna FUNCTIONS: Provides support, but tolerates distortion without damage and returns to original shape Elastic fibers in matrix LM x 358 Elastic cartilage © 2013 Pearson Education, Inc.

Figure 4-11c 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 x 400 Fibrocartilage © 2013 Pearson Education, Inc.

Bone (4-4) Or osseous tissue Bone cells or osteocytes Strong (hard calcium compounds) Resists shattering (flexible collagen fibers) Bone cells or osteocytes Arranged around central canals within matrix Small channels through matrix (canaliculi) access blood supply © 2013 Pearson Education, Inc.

Periosteum (4-4) Covers bone surfaces Fibrous layer Cellular layer © 2013 Pearson Education, Inc.

Lacunae (contain osteocytes) LM x 375 Figure 4-12 Bone. Fibrous layer Canaliculi Periosteum Cellular layer Lacunae (contain osteocytes) Matrix Osteon Central canal Blood vessels Osteon LM x 375 © 2013 Pearson Education, Inc.

Table 4-3 A Comparison of Cartilage and Bone © 2013 Pearson Education, Inc.

Checkpoint (4-4) Identify several functions of connective tissues. List the three types of connective tissues. Which type of connective tissue contains primarily triglycerides? Lack of vitamin C in the diet interferes with the ability of fibroblasts to produce collagen. What effect might this interference have on connective tissue? Which two types of connective tissue have a fluid matrix? © 2013 Pearson Education, Inc.

Checkpoint (4-4) Identify the two types of supporting connective tissue. Why does cartilage heal slower than bone? © 2013 Pearson Education, Inc.

Tissue Membranes (4-5) Membranes Are physical barriers Line or cover portions of the body Consist of: An epithelium Supported by connective tissues © 2013 Pearson Education, Inc. 71

Four Types of Tissue Membranes (4-5) Mucous membranes Serous membranes Cutaneous membrane Synovial membranes © 2013 Pearson Education, Inc.

Figure 4-13 Tissue Membranes. Mucous membranes are coated with the secretions of mucous glands. These membranes line the digestive, respiratory, urinary, and reproductive tracts. Mucous secretion Epithelium Lamina propria (areolar tissue) Serous membranes line the ventral body cavities (the perito-neal, pleural, and pericardial cavities). Serous fluid Epithelium Areolar tissue The cutaneous membrane, or skin, covers the outer surface of the body. Epithelium Areolar tissue Dense irregular connective tissue Articular (hyaline) cartilage Synovial membranes line joint cavities and produce the fluid within the joint. Synovial fluid Capsule Capillary Adipocytes Areolar tissue Synovial membrane Epithelium Bone © 2013 Pearson Education, Inc.

Mucous Membranes (4-5) Also known as 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 Made of areolar tissue © 2013 Pearson Education, Inc.

Figure 4-13a Tissue Membranes. Mucous membranes are coated with the secretions of mucous glands. These membranes line the digestive, respiratory, urinary, and reproductive tracts. Mucous secretion Epithelium Lamina propria (areolar tissue) © 2013 Pearson Education, Inc.

Serous Membranes (4-5) 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 © 2013 Pearson Education, Inc.

Three Serous Membranes (4-5) Pleura Lines pleural cavities Covers lungs Peritoneum Lines peritoneal cavity Covers abdominal organs Pericardium Lines pericardial cavity Covers heart © 2013 Pearson Education, Inc.

Figure 4-13b Tissue Membranes. Serous membranes line the ventral body cavities (the perito-neal, pleural, and pericardial cavities). Serous fluid Epithelium Areolar tissue © 2013 Pearson Education, Inc.

The Cutaneous Membrane (4-5) Is skin Covers the surface of the body Thick, waterproof, and dry © 2013 Pearson Education, Inc.

Figure 4-13c Tissue Membranes. The cutaneous membrane, or skin, covers the outer surface of the body. Epithelium Areolar tissue Dense irregular connective tissue © 2013 Pearson Education, Inc.

Synovial Membranes (4-5) Line moving, articulating joint cavities Produce synovial fluid (lubricant) Protect the ends of bones Lack a true epithelium © 2013 Pearson Education, Inc.

Figure 4-13d Tissue Membranes. Articular (hyaline) cartilage Synovial membranes line joint cavities and produce the fluid within the joint. Synovial fluid Capsule Capillary Adipocytes Areolar tissue Synovial membrane Epithelium Bone © 2013 Pearson Education, Inc.

Checkpoint (4-5) Identify the four types of tissue membranes found in the body. How does a plasma (cell) membrane differ from a tissue membrane? What is the function of fluids produced by serous membranes? The lining of the nasal cavity is normally moist, contains numerous mucous cells, and rests on a layer of areolar tissue. Which type of membrane is this? © 2013 Pearson Education, Inc.

Three Types of Muscle Tissue (4-6) Skeletal muscle tissue Large body muscles responsible for movement Cardiac muscle tissue Found only in the heart Smooth muscle tissue Found in walls of blood vessels Found around hollow organs such as the urinary bladder Around the respiratory, digestive, and reproductive tracts © 2013 Pearson Education, Inc.

Functions of Muscle Tissue (4-6) Specialized for contraction Produces all body movement © 2013 Pearson Education, Inc.

Skeletal Muscle Tissue Figure 4-14a Muscle Tissue. Skeletal Muscle Tissue Cells are long, cylindrical, striated, and multinucleate. Nuclei LOCATIONS: Combined with connective tissues and neural tissue in skeletal muscles 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 Striations LM x 180 Skeletal muscle © 2013 Pearson Education, Inc.

Cardiac Muscle Tissue Cardiac muscle Figure 4-14b Muscle Tissue. Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercalated discs. Nucleus Cardiac muscle cells LOCATION: Heart FUNCTIONS: Circulates blood; maintains blood (hydrostatic) pressure Intercalated discs Striations LM x 450 Cardiac muscle © 2013 Pearson Education, Inc.

Smooth Muscle Tissue Smooth muscle Figure 4-14c 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 Nucleus Smooth muscle cell FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels LM x 235 Smooth muscle © 2013 Pearson Education, Inc.

Checkpoint (4-6) Identify the three types of muscle tissue in the body. Voluntary control is restricted to which type of muscle tissue? Which type of muscle tissue has small, tapering cells with single nuclei and no obvious striations? © 2013 Pearson Education, Inc.

Neural Tissue (4-7) Also called nervous or nerve tissue Specialized for conducting electrical impulses Rapidly senses internal or external environment Processes information and controls responses © 2013 Pearson Education, Inc.

Neural Tissue (4-7) Concentrated in the central nervous system Brain Spinal cord © 2013 Pearson Education, Inc.

Two Kinds of Neural Cells (4-7) Neurons Nerve cells Perform electrical communication Neuroglia Supporting cells Repair and supply nutrients to neurons © 2013 Pearson Education, Inc.

Cell Parts of a Neuron (4-7) 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 © 2013 Pearson Education, Inc.

Neuron Photomicrograph of neuron cell body Brain Nuclei of Cell body Figure 4-15 Neural Tissue. Brain Nuclei of neuroglia Cell body Nucleus of neuron Spinal cord Cell body Axon terminals Axon Dendrites Axon LM x 600 Neuron Photomicrograph of neuron cell body © 2013 Pearson Education, Inc.

Checkpoint (4-7) A tissue contains irregularly shaped cells with many projections, including some several centimeters long. These are probably which type of cell? Why are both skeletal muscle cells and axons also called fibers? © 2013 Pearson Education, Inc.

Tissue Injuries and Repair (4-8) Tissues respond to injuries to maintain homeostasis Cells restore homeostasis with two processes Inflammation Regeneration © 2013 Pearson Education, Inc.

Inflammation (4-8) Inflammatory response The tissue's first response to injury Signs and symptoms include: Swelling Heat Redness Pain © 2013 Pearson Education, Inc.

Inflammatory Response (4-8) Can be triggered by: Trauma (physical injury) Infection (the presence of harmful pathogens) © 2013 Pearson Education, Inc.

Checkpoint (4-8) Identify the two phases in the response to tissue injury. What signs and symptoms are associated with inflammation? What is fibrosis? © 2013 Pearson Education, Inc.

Aging Tissue (4-9) With age: Rate of tissue repair declines Cancer rates increase © 2013 Pearson Education, Inc.

Aging and Tissue Structure (4-9) Speed and efficiency of tissue repair decrease with age due to: Slower rate of energy consumption (metabolism) Hormonal alterations Reduced physical activity © 2013 Pearson Education, Inc.

Aging and Cancer Incidence (4-9) Cancer rates increase with age 1 in 4 people in the United States develops cancer Cancer is the #2 cause of death in the United States Environmental chemicals and cigarette smoke cause cancer © 2013 Pearson Education, Inc.

Checkpoint (4-9) Identify some age-related factors that affect tissue repair and structure. © 2013 Pearson Education, Inc.