Identify the body's four basic types of tissues and describe their roles. Describe the characteristics and functions of epithelial cells.

Transcription

1 Chapter 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. 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.

2 Tissues (4-1) Collections of cells and cell products that perform specific, limited functions Histology The study of tissues Four types of tissues 1. Epithelial 2. Connective 3. Muscle 4. Neural Checkpoint (4-1) 1. Define histology. 2. List the four basic types of tissues in the body. Epithelial Tissue (4-2) Covers body surfaces Lines cavities Lines tubular structures Serves essential functions Characteristics of Epithelial Tissue (4-2) Cellularity (cell junctions) Polarity (apical and basal surfaces) Attachment Avascularity

3 Regeneration Functions of Epithelia (4-2) Provide physical protection Control permeability Provide sensation Produce specialized secretions (glandular epithelium) Exocrine glands Endocrine glands Intercellular Connections (4-2) Support and communication Cell adhesion molecules (CAMs) Transmembrane proteins Intercellular cement Proteoglycans Three Common Cell Junctions (4-2) 1. Tight junctions 2. Gap junctions 3. Desmosomes Form bonds with other cells or extracellular material The Epithelial Surface (4-2) Apical surface is exposed

4 Basal surface is connected to deeper connective tissue with basement membrane Epithelial Renewal and Repair (4-2) Epithelia are replaced by mitosis Cell division of stem cells (germinative cells) Occurs near basement membrane Checkpoint (4-2) 3. List five important characteristics of epithelial tissue. 4. Identify four essential functions of epithelial tissue. 5. Identify the three main types of epithelial cell junctions. 6. What physiological functions are enhanced by the presence of microvilli or cilia on epithelial cells? Classification of Epithelia (4-3) Combines a cell shape with the number of layers of cells Example: Simple (one layer) cuboidal (square shape) 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

5 Squamous epithelia: thin and flat Cuboidal epithelia: square shaped Columnar epithelia: tall, slender rectangles Glandular Epithelia (4-3) Endocrine glands Release hormones: Into interstitial fluid and plasma No ducts Exocrine glands Produce secretions: Onto epithelial surfaces Through ducts Glandular Secretion (4-3) Merocrine secretion Produced in Golgi apparatus Released by vesicles (exocytosis) Example: sweat glands Apocrine secretion Produced in Golgi apparatus Released by shedding cytoplasm Example: mammary glands Glandular Secretion (4-3) Holocrine secretion Released by cells bursting, killing gland cells

6 Gland cells replaced by stem cells Example: sebaceous glands Types of Secretion (4-3) Serous glands Watery secretions Mucous glands Secrete mucins Mixed exocrine glands Both serous and mucous Checkpoint (4-3) 7. Identify the three cell shapes characteristic of epithelial cells. 8. 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? 9. Name the two primary types of glandular epithelia. Checkpoint (4-3) 10. The secretory cells of sebaceous glands fill with secretions and then rupture, releasing their contents. Which mechanism of secretion occurs in sebaceous glands? 11. Which type of gland releases its secretions directly into the extracellular fluid?

7 Connective Tissue (4-4) Provides a protective structural framework for other tissue types Three basic components 1. Specialized cells 2. Solid extracellular protein fibers 3. Fluid extracellular ground substance 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 Functions of Connective Tissue (4-4) Support and protection Transportation of materials Storage of energy reserves Defense of the body Three Major Types of Connective Tissue (4-4) 1. Connective tissue proper 2. Fluid connective tissues 3. Supporting connective tissues

8 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 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 Three Basic Types of Connective Tissue Fibers (4-4) 1. Collagen fibers Long, straight, unbranched Strong, but flexible Most common 2. Elastic fibers Branched and wavy After stretching, they will return to their original length Contain the protein elastin

9 Three Basic Types of Connective Tissue Fibers (4-4) 3. 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 Ground Substance (4-4) Clear, colorless, and viscous Fills spaces between cells and slows pathogen movement 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 Fluid Connective Tissues (4-4)

10 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 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 Cartilage (4-4) Cartilage matrix Proteoglycans derived from chondroitin sulfates Ground substance proteins Chondrocytes (cartilage cells) Surrounded by lacunae (chambers) Cartilage Structure (4-4) Avascular Chondrocytes found in pockets called lacunae Perichondrium

11 Outer, fibrous layer (for strength) Inner, cellular layer (for growth and maintenance) Three Major Types of Cartilage (4-4) 1. Hyaline cartilage Stiff, flexible support Reduces friction between bones Found in synovial joints, rib tips, sternum, and trachea 2. Elastic cartilage Supportive but bends easily Found in external ear and epiglottis 3. Fibrocartilage Limits movement Prevents bone-to-bone contact Pads knee joints Found between pubic bones and intervertebral discs Bone (4-4) Or osseous tissue 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 Periosteum (4-4) Covers bone surfaces Fibrous layer

12 Cellular layer Checkpoint (4-4) 12. Identify several functions of connective tissues. 13. List the three types of connective tissues. 14. Which type of connective tissue contains primarily triglycerides? 15. 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? 16. Which two types of connective tissue have a fluid matrix? Checkpoint (4-4) 17. Identify the two types of supporting connective tissue. 18. Why does cartilage heal slower than bone? Tissue Membranes (4-5) Membranes Are physical barriers Line or cover portions of the body Consist of: An epithelium Supported by connective tissues Four Types of Tissue Membranes (4-5)

13 1. Mucous membranes 2. Serous membranes 3. Cutaneous membrane 4. Synovial membranes 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 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 Three Serous Membranes (4-5) 1. Pleura Lines pleural cavities Covers lungs 2. Peritoneum

14 Lines peritoneal cavity Covers abdominal organs 3. Pericardium Lines pericardial cavity Covers heart The Cutaneous Membrane (4-5) Is skin Covers the surface of the body Thick, waterproof, and dry Synovial Membranes (4-5) Line moving, articulating joint cavities Produce synovial fluid (lubricant) Protect the ends of bones Lack a true epithelium Checkpoint (4-5) 19. Identify the four types of tissue membranes found in the body. 20. How does a plasma (cell) membrane differ from a tissue membrane? 21. What is the function of fluids produced by serous membranes? 22. The lining of the nasal cavity is normally moist, contains numerous mucous cells, and rests on a layer of areolar

15 tissue. Which type of membrane is this? Three Types of Muscle Tissue (4-6) 1. Skeletal muscle tissue Large body muscles responsible for movement 2. Cardiac muscle tissue Found only in the heart 3. 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 Functions of Muscle Tissue (4-6) Specialized for contraction Produces all body movement Checkpoint (4-6) 23. Identify the three types of muscle tissue in the body. 24. Voluntary control is restricted to which type of muscle tissue? 25. Which type of muscle tissue has small, tapering cells with single nuclei and no obvious striations? Neural Tissue (4-7)

16 Also called nervous or nerve tissue Specialized for conducting electrical impulses Rapidly senses internal or external environment Processes information and controls responses Neural Tissue (4-7) Concentrated in the central nervous system Brain Spinal cord Two Kinds of Neural Cells (4-7) 1. Neurons Nerve cells Perform electrical communication 2. Neuroglia Supporting cells Repair and supply nutrients to neurons 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

17 Checkpoint (4-7) 26. A tissue contains irregularly shaped cells with many projections, including some several centimeters long. These are probably which type of cell? 27. Why are both skeletal muscle cells and axons also called fibers? Tissue Injuries and Repair (4-8) Tissues respond to injuries to maintain homeostasis Cells restore homeostasis with two processes 1. Inflammation 2. Regeneration Inflammation (4-8) Inflammatory response The tissue's first response to injury Signs and symptoms include: Swelling Heat Redness Pain Inflammatory Response (4-8) Can be triggered by: Trauma (physical injury) Infection (the presence of harmful pathogens)

18 Checkpoint (4-8) 28. Identify the two phases in the response to tissue injury. 29. What signs and symptoms are associated with inflammation? 30. What is fibrosis? Aging Tissue (4-9) With age: Rate of tissue repair declines Cancer rates increase 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 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

19 Checkpoint (4-9) 31. Identify some age-related factors that affect tissue repair and structure.