Tissues

1. Tissues Epithelial Tissues Connective Tissues Muscle Tissues Nervous Tissues

2. Objectives • Upon completion of this chapter, you should be able to: • Describe the general characteristics and functions of epithelial tissue. • Name the types of epithelium and identify an organ in which each is found. • Explain how glands are classified. • Describe the general characteristics of connective tissue. • Describe the major cell types and fibers of connective tissue.

3. Objectives • Upon completion of this chapter, you should be able to: • List the types of connective tissue that occur within the body. • Describe the major functions of each type of connective tissue. • Distinguish among the three types of muscle tissue. • Describe the general characteristics and functions of nervous tissue. • Complete the review activities at the end of the chapter.

4. Aids to Understanding Terms • adip- fat • chondr- cartilage • -cyt cell • epi- upon • -glia glue (bind cells together) • osseo- bone • phago- to eat • pseudo- false • squam- scale • strat- layer • stria- groove (alternating)

5. Epithelial Tissues • Covering and lining; glandular • Always has a free surface, while underside is anchored to connective tissue by a thin, nonliving layer called the basement membrane (lamina) • Lack blood vessels (nourished by substances diffusing from connective tissue) • Reproduce readily. • Protective barriers (skin, lining of mouth), secretion, absorption, excretion, and sensory reception

6. Epithelial Tissues • Classification • Arrangement • Simple ~ single layers of cells • Stratified ~ many layers of cells • Pseudostratified ~ one layer w/ cells of differing heights • Shape • Squamous ~ thin, flattened cells • Cuboidal ~ cubelike cells • Columnar ~ elongated cells • Transitional ~ expandable

7. Simple Squamous Epithelium • Single layer of thin, flattened cells • Occurs commonly where diffusion, osmosis, and filtration are taking place • air sacs of lungs • walls of capillaries • insides of blood and lymph vessels • covers membranes that line body cavities

8. Simple Cuboidal Epithelium • Single layer of cube-shaped cells w/ centrally located nucleus • Secretion, Absorption • Kidney tubules • Glands -- secretion of glandular products • salivary glands • pancreas • liver • ovaries

9. Simple Columnar Epithelium • Single layer of elongated cells w/ nuclei located near basement membrane • Protection, secretion, absorption • Lining of uterus • Lining of various organs of digestive tract, e.g., stomach and intestines • Microvilli often cover surface, increasing surface area for more effective absorption • Goblet cells scattered throughout, secreting protective fluid (mucus) onto free surface

10. Pseudostratified Columnar Epithelium • Nuclei located at two or more levels within cells • Cilia extend from free surface • Goblet cells scattered throughout tissue • Protection, secretion, movement of mucus and cells • Lines passages of respiratory system • Lines tubes of reproductive system

11. Stratified Squamous Epithelium • Many layers of cells; thick • Flattened near surface, cuboidal or columnar deeper • Protection • Skin (epidermis) • As older cells are pushed outward, they accumulate the protein keratin, harden, and die • Lines mouth cavity, throat • Lines vagina, anal canal

12. Transitional Epithelium • Also called uroepithelium • Specialized to undergo changes w/ tension • Contracted, several layers of cuboidal cells; distended, appears to contain only a few layers of cells • Distensibility, protection, barrier from diffusion • inner lining of urinary bladder • passageways of urinary system

13. Glandular Epithelium • Specialized to produce and secrete various substances into ducts or into body fluids • Found within columnar or cuboidal epithelium • Exocrine glands • glands that secrete products into ducts that open onto some internal or external surface • Endocrine glands • glands that secrete products into tissue fluid or blood

14. Types of Exocrine Glands • Unicellular glands • Single secretory cell • mucus-secreting goblet cell • Multicellular glands • Simple glands • communicate with surface by means of unbranched ducts • Compound glands • communicate with surface by means of branched ducts

15. Simple Glands • Simple tubular gland • intestinal glands of small intestines • Simple coiled tubular gland • Eccrine (sweat) glands of skin • Simple branched tubular gland • Mucous glands in small intestine • Simple branched alveolar gland • Sebaceous gland of skin

16. Compound Glands • Compound tubular gland • Bulbourethral glands of male • Compound alveolar gland • Salivary glands

17. Glandular Secretions • Merocrine glands • fluid product that is released through the cell membrane • salivary glands, pancreatic glands, certain sweat glands of skin • Apocrine glands • cellular product and portions of the free ends of glandular cells that are pinched off during secretion • mammary glands, certain sweat glands of skin • Holocrine glands • entire cells that are laden with secretory products • sebaceous glands of skin

18. Connective Tissues • Most abundant tissue in body • Many functions, esp. support, protection (against infection), repair, storage (fat), packaging, production of blood cells • Wide range of vascularity (mostly, good supplies) • Cells widely scattered in an intercellular matrix • Fibers and ground substance • Types of connective tissue vary in their proportions of cells, fibers, and ground substance

19. Connective Tissues • Major Cell Types • Fibroblasts • widely distributed, large, star-shaped cells • secrete proteins that become fibers • Macrophages • Motile cells that are sometimes attached to fibers • clear foreign particles from tissues by phagocytosis • Mast cells • large, usually located near blood vessels • release substances that may help prevent blood clotting (heparin) and promote inflammation (histamine)

20. Connective Tissues • Connective Tissue Fibers • Collagenous fibers (white fibers) • thick, threadlike fibers of collagen with great tensile strength • hold structures together • Elastic fibers (yellow fibers) • bundles of microfibrils composed of elastin; elastic • provide elastic quality to parts that stretch • Reticular fibers • thin fibers of collagen (major structural protein of body) • form supportive networks within tissues

21. Loose (Areolar) Connective Tissue • Binds organs together • Holds tissue fluids • Located beneath the skin, between muscles, and beneath epithelial tissues • Cells are mainly fibroblasts, located some distance apart and separated by gel-like ground substance that contains many collagenous and elastic fibers

22. Adipose Tissue • Protection, insulation, and storage of fat • Located beneath the skin, around the kidneys, behind the eyeballs, and on the surface of the heart • Contain large fat droplets that cause nuclei to be pushed close to cell membrane

23. Fibrous Connective Tissue • Binds organs together • Located in tendons (connect muscles to bones), ligaments (connect bones to bones at joints), protective white layer of eyeball, and deep layer of skin • Contains many closely packed, thick, collagenous fibers and a fine network of elastic fibers; few cells -- fibroblasts • Blood supply relatively poor -- slow repair

24. Elastic Connective Tissue • Provides elastic quality • Located between adjacent vertebrae, in walls of arteries and airways • Consists mainly of yellow, elastic fibers in parallel strands or branching networks

25. Reticular Connective Tissue • Support • Located in walls of liver, spleen, and lymphatic organs • Composed of thin, collagenous fibers arranged in a three-dimensional network

26. Cartilage • Supports parts, provides frameworks and attachments, protects underlying tissues, and forms structural models for many developing bones • Chondrocytes occupy small chambers called lacunae and are completely surrounded by matrix • Enclosed in a covering of fibrous connective tissue called the perichondrium (location of blood supply) • Lacks direct blood supply • Three types: hyaline, elastic, and fibrocartilage

27. Hyaline Cartilage • Support, protection, provides framework • Located in ends of bones, nose, and rings in walls of respiratory passages • Most common type of cartilage • Role in the growth of most bones and repair of bone fractures

28. Elastic Cartilage • Support, protection, provides flexible framework • Located in framework of external ear and part of larynx • Matrix contains many elastic fibers

29. Fibrocartilage • Support, protection, shock absorption • Located between bony parts of backbone, pelvic girdle, and knee • Very tough; many collagenous fibers

30. Bone (Osseous Tissue) • Support, protection, provides framework • Located in bones of skeleton • Most rigid connective tissue, due largely to calcium phosphate and calcium carbonate in matrix • Protects vital parts in the cranial and thoracic cavities, and serves as attachment for muscles • Contains red marrow -- forms blood cells • Matrix deposited in thin layers called lamellae • Osteocytes clustered in concentric circles around osteonic (Haversian) canals

31. Blood • Cells (red, white, platelets) are suspended in a fluid intercellular matrix called plasma • Most blood cells form in hematopoietic tissues in red marrow within the hollow parts of certain bones

32. Muscle Tissues • Contractile; elongated cells (muscle fibers) • Three types: skeletal, smooth muscle, cardiac muscle • Skeletal muscle tissue • found in muscles attached to bones • controlled by conscious effort (voluntary muscle tissue) • cells have many nuclei, plus alternating light and dark cross-markings called striations • Responsible for moving head, trunk, and limbs, as well as movements involved with facial expressions, writing, talking, singing, chewing, swallowing, and breathing

33. Muscle Tissues • Smooth Muscle Tissue • Lacks striations; single, centrally located nucleus • Found in walls of hollow internal organs (stomach, intestines, urinary bladder, uterus, blood vessels) • Involuntary muscle tissue • Responsible for moving food through GI tract, constricting blood vessels, and emptying bladder • Cardiac Muscle Tissue • Only in the heart; involuntary muscle tissue • striated cells joined end to end by intercalated disk • single nucleus

34. Nervous Tissue • Found in the brain, spinal cord, and peripheral nerves • Basic cells -- nerve cells or neurons plus neuroglial cells (support and bind components of nervous tissue together, carry on phagocytosis, supply nutrients to neurons by connecting them to blood vessels) • Coordinate, regulate, and integrate many body functions