Chapter 5 Tissues

1. Chapter 5Tissues

2. Principal Types of Tissue (Table 5-1) • Epithelial tissue – covering and lining • Connective tissue – specialized to support the body and its parts, connect and hold them together, transport substances through the body, and protect it from foreign invaders • Muscle tissue – produces movement, has cells that are specialized to contract • Nervous tissue – conductive tissue that communicates between various parts of the body

3. Extracellular Matrix (ECM) • Complex, nonliving material between cells in a tissue (Figure 5-1) • Some tissues have a large amount of ECM; other tissues have hardly any ECM • Different kinds of components give ECM in different tissues a variety of characteristics

4. Extracellular Matrix (ECM) • Components (Table 5-2) • Water • Proteins • Structural proteins • Collagen—strong, flexible protein fiber • Elastin—elastic fibers • Glycoproteins (Fibronectin & Laminin) - proteins with a few carbohydrate attachments • Proteoglycans • Hybrid molecules that are mostly carbohydrates attached to a protein backbone

5. Extracellular Matrix (ECM) • Functions • Helps bind tissues together structurally • ECM components bind to each other and to integrins in plasma membranes of cells • In some tissues, it is primarily intercellular junctions that hold cells together • Allows local communication among ECM and various cells—through connection via integrins in plasma membranes

7. Epithelial Tissue • Types and locations • Epithelium is divided into two types: • Membranous (covering or lining) epithelium • Glandular epithelium • Locations • Membranous epithelium—covers the body and some of its parts; lines the serous cavities, blood and lymphatic vessels, and respiratory, digestive, and genitourinary tracts • Glandular epithelium—secretory units of endocrine and exocrine glands

8. Epithelial Tissue • Functions • Protection – tough and impermeable, protects the body from mechanical and chemical injury and invading bacteria and other disease causing microorganisms • Sensory functions – structures that are specialized for sensation found around the skin, nose, eye and ear • Secretion – secretion products include: hormones, mucus, digestive juices, and sweat • Absorption – lining of the gut and exchange of gases in the lungs • Excretion – tubules in the kidneys

9. Epithelial Tissue • Generalizations about epithelial tissue • Limited intercellular matrix • Basement membrane attaches epithelial tissue to an underlying connective tissue layer • Avascular • Cells are in close proximity, with many desmosomes and tight junctions • Capable of reproducing itself, highly mitotic

10. Epithelial Tissue • Membranous (covering or lining) epithelium (Table 5-3) • Classification based on cell shape • Squamous • Cuboidal • Columnar • Pseudostratified columnar

11. Epithelial Tissue • Classification of epithelial tissue based on layers • Classifications based on layers of cells • Simple • Stratified • Transitional

13. Epithelial Tissue • Simple epithelium • Simple squamous epithelium (Figures 5-4 and 5-5) • One-cell layer of flat cells • Permeable to many substances • Examples: O2 & CO2 exchange in the lungs, movement of fluid and dissolved substances between the blood and across blood vessels by osmosis and filtration in the kidneys • Simple cuboidal epithelium (Figure 5-6) • One-cell layer of cuboidal cells • Found in many glands and ducts • Examples: secretion of substances such as tears and saliva, and in absorption, such as re-absorption of water by kidney cells

16. Epithelial Tissue • Simple epithelium (cont.) • Simple columnar epithelium (Figure 5-7) • Single layer of tall, column-shaped cells • Often lines hollow visceral structures • Nonciliated simple columnar epithelium – microvilli and goblet cells. Microvilli – finger like projections that increase surface area. Goblet Cells – secrete mucous. Line the G.I., Respiratory, Reproductive, and Urinary Tracts. • Ciliated simple columnar epithelium – cilia, line the upper respiratory tract, move particles towards the throat. Line the fallopian tubes. • Pseudostratified columnar epithelium (Figure 5-8) • Columnar cells of differing heights • Give the impression of a multi-layered tissue, this is why they are given the name • Found lining air passages of upper respiratory and segments of male reproductive system • Can have cilia or can have none • There function is secretion and movement of mucous by ciliary action

18. Epithelial Tissue • Stratified epithelium • Stratified squamous (keratinized) epithelium • Multiple layers of flat, squamous cells (Figure 5-9) • Cells filled with keratin • Covers outer skin on body surface • Stratified squamous (nonkeratinized) epithelium (Figure 5-10) • Lines vagina, cervix, mouth, and esophagus • Free surface is moist • Primary function is protection • Pap smear

19. Epithelial Tissue • Stratified epithelium (cont.) • Stratified cuboidal epithelium • Two or more rows of cells are typical • Located in sweat gland ducts and pharynx • Stratified columnar epithelium • Multiple layers of columnar cells • Only most superficial cells are typical in shape • Rare • Located in segments of male urethra and near anus

20. Epithelial Tissue • Stratified epithelium (cont.) • Stratified transitional epithelium (Figure 5-11) • Located in lining of hollow viscera subjected to stress (e.g., urinary bladder) • Often 10 or more layers thick • Protects organ walls from tearing

21. Epithelial Tissue • Glandular epithelium • Specialized for secretory activity • Exocrine glands—discharge secretions into ducts that empty at the surface of covering and lining epithelium or directly onto a free surface. • secretions include mucus, perspiration, oil, wax, and digestive enzymes, and salivary glands. • Endocrine glands—“ductless” glands; discharge secretions directly into the blood or interstitial fluid. The thyroid and pituitary glands are examples.

23. Connective Tissue • Functions • Connect – connects tissues and muscles to each other, muscles to bones, and bones to bones • Supports – forms a supporting framework for the body and its organs • Transports – bloods components to cells in the body • Defends – fend off foreign invaders and other microrganisms

24. Connective Tissue • Cells of CT • Fibroblasts - secrete a gel-like substance that forms the ground substance and fibers of the matrix. They are present in all connective tissue. • Macrophages - engulf bacteria by phagocytosis • Plasma Cells - secrete antibodies, which are proteins that attack or neutralize foreign substances in the body. • Mast Cells - secrete heparin, prostaglandins, and histamine (chemical that dilates small blood vessels during inflammation or injury). • Adipocytes – store fat • Leukocytes (white blood cells) – not found in significant numbers in tissue, but can migrate from the blood to the tissue.

25. Connective Tissue • Four main types (Table 5-6): • Fibrous • Loose, ordinary (areolar) • Adipose • Reticular • Dense • Irregular • Regular (collagenous and elastic) • Bone • Compact bone • Cancellous bone • Cartilage • Hyaline • Fibrocartilage • Elastic • Blood

26. Connective Tissue • Fibrous connective tissue • Loose, ordinary (areolar) connective tissue (Figure 5-15) • One of the most widely distributed of all tissues • Intercellular substance is prominent and consists of collagenous and elastic fibers loosely interwoven and embedded in a soft, viscous ground substance • Several kinds of cells present: notably, fibroblasts and macrophages; also mast cells, plasma cells, fat cells, and some white blood cells (Figure 5-16) • Function—stretchy, flexible connection

28. Connective Tissue • Adipose tissue (Figures 5-17 and 5-18) • Similar to loose connective tissue but contains mainly fat cells (adipocytes) • Functions—protection, insulation, support, and food reserve • Reticular tissue (Figure 5-19) • Forms framework of spleen, lymph nodes, and bone marrow • Consists of network of branching reticular fibers with reticular cells overlying them • Functions—defense against microorganisms and other injurious substances; reticular meshwork filters out injurious particles, and reticular cells phagocytose them

29. Inflammation • Inflammatory Response – p. 167

30. Connective Tissue • Dense fibrous tissue • Matrix consists mainly of fibers packed densely and relatively few fibroblast cells • Irregular—fibers intertwine irregularly to form a thick mat, found in areas of the body where tensions are exerted in various directions • Dermis, heart valves, periosteum • Regular—bundles of fibers are arranged in regular, parallel rows • Tendons and ligaments • Elastic—mostly elastic fibers in ECM (Figure 5-23), provides stretch and strength • Lungs and arteries • Locations—composes structures that need great tensile strength, such as tendons and ligaments; also dermis and outer capsule of kidney and spleen • Function—furnishes flexible connections that are strong or stretchy

34. Connective Tissue • Bone tissue • Highly specialized connective tissue type • Cells—osteocytes—embedded in a calcified matrix • Inorganic component of matrix accounts for 65% of total bone tissue • Functions: • Support • Protection • Point of attachment for muscles • Reservoir for minerals • Supports blood-forming tissue

35. Connective Tissue • Compact bone (Figures 5-25 and 5-26) • Osteon (Haversian system) • Structural unit of bone • Spaces for osteocytes called lacunae • Matrix present in concentric rings called lamellae • Canaliculi are canals that join lacunae with the central Haversian canal • Cell types: • Osteocyte—mature, inactive bone cell • Osteoblast—active, bone-forming cell • Osteoclast—bone-destroying cell • Formation (ossification) (Figure 5-24) • In membranes—e.g., flat bones of skull • From cartilage (endochondral)—e.g., long bones, such as the humerus

36. Connective Tissue • Cancellous bone (Figures 5- 25 and 5-27) • Trabeculae—thin beams of bone • Supports red bone marrow • Myeloid tissue—a type of reticular tissue • Produces blood cells • Called spongy bone because of its spongelike appearance

38. Connective Tissue • Cartilage • Chondrocyte is the only cell type present • Lacunae house cells, as in bone • Avascular—therefore, nutrition of cells depends on diffusion of nutrients through matrix • Heals slowly after injury because of slow nutrient transfer to the cells

39. Connective Tissue • Types • Hyaline (Figure 5-28) • Appearance is shiny and translucent • Most prevalent type of cartilage • Located on the ends of articulating bones • Fibrocartilage (Figure 5-29) • Strongest and most durable type of cartilage • Matrix is semirigid and filled with strong, white fibers • Found in intervertebral disks and pubic symphysis • Serves as shock-absorbing material between bones at the knee (menisci) • Elastic (Figure 5-30) • Contains many fine, elastic fibers • Provides strength and flexibility • Located in external ear and larynx

40. Connective Tissue • Blood • A liquid tissue (Figure 5-31) • Contains neither ground substance nor fibers • Composition of whole blood • Liquid fraction (plasma) is the matrix—55% of total blood volume • Formed elements contribute 45% of total blood volume • Red blood cells, erythrocytes • White blood cells, leukocytes • Platelets, thrombocytes

41. Connective Tissue • Blood (cont.) • Functions • Transportation • Regulation of body temperature • Regulation of body pH • White blood cells destroy bacteria • Circulating blood tissue is formed in the red bone marrow by a process called hematopoiesis; the blood-forming tissue is sometimes called hematopoietic tissue

43. Muscle Tissue • Types (Table 5-7) • Skeletal, or striated voluntary (Figure 5-32) • Smooth, or nonstriated involuntary, or visceral (Figures 5-33 and 5-34) • Cardiac, or striated involuntary (Figure 5-35) • Microscopic characteristics • Skeletal muscle—threadlike cells with many cross striations and many nuclei per cell • Smooth muscle—elongated, narrow cells, no cross striations, one nucleus per cell • Cardiac muscle—branching cells with intercalated disks (formed by abutment of plasma membranes of two cells)

46. Nervous Tissue • Functions—rapid regulation and integration of body activities • Specialized characteristics • Excitability • Conductivity • Organs • Brain • Spinal cord • Nerves

47. Nervous Tissue • Cell types (Table 5-7) • Neuron—conducting unit of system (Figure 5-36) • Cell body, or soma • Processes • Axon (single process)—transmits nerve impulse away from the cell body • Dendrites (one or more)—transmit nerve impulse toward the cell body and axon • Neuroglia—special connecting, supporting, coordinating cells that surround the neurons

49. Tissue Repair • Tissues have a varying capacity to repair themselves; damaged tissue regenerates or is replaced by scar tissue • Regeneration—growth of new tissue (Figure 5-37) • Scar—dense fibrous mass; unusually thick scar is a keloid (Figure 5-38) • Epithelial and connective tissues have the greatest ability to regenerate • Muscle and nervous tissues have a limited capacity to regenerate

50. Body Membranes • Membranes are thin tissue layers that cover surfaces, line cavities, and divide spaces or organs (Figure 5-39, Table 5-8) • Epithelial membranes are the most common type (Figure 5-40) • Cutaneous membrane (skin) • Primary organ of integumentary system • One of the most important organs • Composes approximately 16% of body weight • Serous membrane (serosa) • Parietal membranes—line closed body cavities • Visceral membranes—cover visceral organs • Pleura—surrounds a lung and lines the thoracic cavity • Peritoneum—covers the abdominal viscera and lines the abdominal cavity