PowerLecture: Chapter 4

1. PowerLecture:Chapter 4 Tissues, Organs, and Organ Systems

2. Learning Objectives • Understand the various levels of animal organization (cells, tissues, organs, and organ systems). • Know the characteristics of the various types of tissues. Know the types of cells that compose each tissue type and cite some examples of organs that contain significant amounts of each tissue type. • Describe how the four principal tissue types are organized into an organ such as the skin.

3. Learning Objectives (cont’d) • Explain how the human body maintains a rather constant internal environment despite changing external conditions.

4. Impacts/Issues Stem Cells

5. Stem Cells • Stem cells are the first to form when a fertilized egg starts dividing. • Adults have stem cells in some tissues such as bone marrow and fat; these cells have shown some promise as therapy. • Embryonic stem cells can be coaxed to differentiate into many different types of cells, which can replace damaged or worn out body cells perhaps to an extent greater than adult stem cells.

6. Stem Cells • The human body is an orderly assembly of parts (anatomy). • A tissue is an aggregation of cells and intracellular substances functioning for a special­ized activity. • Various types of tissues can combine to form organs, such as the heart. • Organs may interact to form organ systems such as the digestive system. • Homeostasis allows for the stable functioning (physiology) of all our combined parts.

7. How Would You Vote? To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu. • Should researchers be allowed to start embryonic stem cell lines from human embryos that are not used for in vitro fertilization? • a. Yes, most unimplanted embryos are destroyed anyway; the potential of stem cells is too great to ignore. • b. No, any human embryo has the potential to become a human and so deserves protection from destruction.

8. Section 1 Epithelium: The Body’s Covering and Linings

9. Epithelium • Epithelial tissue covers the surface of the body and lines its cavities and tubes. • One surface is free and faces either the environment or a body fluid; the other adheres to a basement membrane, a densely packed layer of proteins and polysaccharides. • Cells are linked tightly together; there may be one or more layers.

10. free surface of epithelium simple squamous epithelium basement membrane connective tissue Fig. 4.1a, p. 69

11. Epithelium • There are two basic types of epithelia. • Simple epithelium is a single layer of cells functioning as a lining for body cavities, ducts, and tubes. • Simple epithelium functions in diffusion, secretion, absorption, or filtering of substances across the cell layer. • Pseudostratified epithelium is a single layer of cells that looks like a double layer; most of the cells are ciliated; examples are found in the respiratory passages and reproductive tracts. • Stratifiedepithelium has many layers—as in human skin.

12. Table 4.1, p. 68

13. Epithelium • Both simple and stratified epithelium can be subdivided into groups based on shape at the tissue surface: • Squamous epithelium consists of flattened cells; examples are found in the lining of the blood vessels. • Cuboidal epithelium has cube-shaped cells; examples are found in glands. • Columnar epithelium has elongated cells; examples are found in the intestine.

14. Fig. 4.2b-d, p. 70 cilia columnar cells basement membrane TYPE: Simple squamous DESCRIPTION: Friction-reducing slick, single layer of flattened cells COMMON LOCATIONS: Lining of blood and lymph vessels, heart; air sacs of lungs; peritoneum FUNCTION: Diffusion; filtration; secretion of lubricants TYPE: Simple cuboidal DESCRIPTION: Single layer of squarish cells COMMON LOCATIONS: Ducts, secretory part of small glands; retina; kidney tubules; ovaries, testes; bronchioles FUNCTION: Secretion; absorption TYPE: Simple columnar DESCRIPTION: Single layer of tall cells; free surface may have cilia, mucus-secreting glandular cells, microvilli COMMON LOCATIONS: Glands, ducts; gut; parts of uterus; small bronchi FUNCTION: Secretion; absorption; ciliated types move substances

15. Epithelium • Glands develop from epithelium. • Glands are secretory structures derived from epithelium that make and release specific substances, such as mucus. • Glands are classified according to how their products reach the site where they are used. • Exocrine glands often secrete through ducts to free surfaces; they secrete mucus, saliva, earwax, milk, oil, and digestive enzymes for example. • Endocrine glands have no ducts but distribute their hormones via the blood.

16. Section 2 Connective Tissue: Binding, Support, and Other Roles

17. Connective Tissue • Connective tissue binds together, supports, and anchors body parts; it is the most abundant tissue in the body. • Fibrous connective tissues and specialized connective tissues are both found in the body. • Fiber-like structural proteins and polysaccharides secreted by the cells make up a matrix (ground substance) around the cells that can range from hard to liquid.

18. Connective Tissue • Fibrous connective tissues are strong and stretchy. • Fibrous connective tissue takes different forms depending on cell type and the fibers/matrix produced.

19. Fig. 4.2a-d, p. 70 Loose connective tissue Dense, irregular connective tissue Dense, regular connective tissue Cartilage collagenous fiber ground substance with collagen fibers collagenous fibers collagenous fibers fibroblast fibroblast elastic fiber cartilage cell (chondrocyte)

20. Connective Tissue • Types and examples of fibrous connective tissue: • Loose connective tissue supports epithelia and organs, and surrounds blood vessels and nerves; it contains few cells and loosely arrayed thin fibers. • Dense, irregular connective tissue has fewer cells and more fibers, which are thick; it forms protective capsules around organs. • Dense, regular connective tissue has bundled collagen fibers lying in parallel; such arrangements are found in ligaments (binding bone to bone) and tendons (binding muscle to bone). • Elastic connective tissue contains fibers of elastin; this tissue is found in organs that must stretch, like the lungs.

21. Connective Tissue • Cartilage, bone, adipose tissue, and blood are specialized connective tissues. • Cartilage contains a dense array of fibers in a rubbery ground substance; cartilage can withstand great stress but heals slowly when damaged. • Hyaline cartilage has many small fibers; it is found at the ends of bones, in the nose, ribs, and windpipe. • Elastic cartilage, because of its elastin component, is able to bend yet maintain its shape, such as in the external ear. • Fibrocartilage is a sturdy and resilient form that can withstand tremendous pressure such as in the disks that separate the vertebrae.

22. Connective Tissue • Bone tissue is composed of collagen, ground substance, and calcium salts; minerals harden bone so it is capable of supporting and protecting body tissues and organs. • Adipose tissue cells are specialized for the storage of fat; most adipose tissue lies just beneath the skin.

23. compact bone tissue nucleus blood vessel cell bulging with fat droplet bone cell (osteocyte) TYPE: Bone tissue DESCRIPTION: Collagen fibers, matrix hardened with calcium COMMON LOCATIONS: Bones of skeleton FUNCTION: Movement, support, protection TYPE: Adipose tissue DESCRIPTION: Large, tightly packed fat cells occupying most of matrix COMMON LOCATIONS: Under skin, around heart, kidneys FUNCTION: Energy reserves, insulation, padding Fig. 4.2ef, p. 71

24. Connective Tissue • Blood is a fluid connective tissue involved in transport; plasma forms the fluid “matrix” and blood proteins, blood cells, and platelets compose the “fiber” portion of the tissue. Figure 4.3

25. Table 4.2, p. 71

26. Section 3 Muscle Tissue: Movement Figure 4.4

27. Muscle Tissue: Movement • Muscle tissuecontracts in response to stimulation, then passively lengthens; movement is a highly coordinated action. • There are three types of muscle: • Skeletal muscle tissue attaches to bones for voluntary movement; long muscle cells are bundled together in parallel arrays, which are enclosed in a sheath of dense connective tissue. skeletal muscle Figure 4.4a

28. Muscle Tissue: Movement cardiac muscle • Smooth muscle tissue contains tapered, bundled cells that function in involuntary movement; it lines the gut, blood vessels, and glands. • Cardiac muscle is composed of short cells that can function in units due to the signals that pass through special junctions that fuse the cells together; cardiac muscle is only found in the wall of the heart. smooth muscle Figure 4.4b-c

29. Section 4 Nervous Tissue: Communication

30. Nervous Tissue: Communication • Nervous tissue consists mainly of cells, including neurons (nerve cells) and support cells; nervous tissue forms the body’s communication network. • Neurons carry messages. • Neurons have two types of cell processes (extensions): branched dendrites pick up chemical messages and pass them to an outgoing axon. Figure 4.5a

31. Nervous Tissue: Communication • A cluster of processes from different neurons is called a nerve. • Nerves move messages throughout the body. • Neuroglia are support cells. • Glial cells (neuroglia) make up 90 percent of the nervous system. Neuroglia provide physical support for neurons. • Other glial cells provide nutrition (astrocytes), clean-up, and insulation services (Schwann cells). Figure 4.5b

32. Table 4.4, p. 85

33. Section 5 Cell Junctions: Holding Tissues Together

34. Cell Junctions • Epithelial cells tend to adhere to one another by means of specialized attachment sites. • Tight junctions link cells of epithelial tissues to form seals that keep molecules from freely crossing the epithelium. • Adhering junctions are like spot welds in tissues subject to stretching. • Gap junctions link the cytoplasm of adjacent cells; they form communication channels.

35. Cell Junctions • Sites of cell-to-cell contact are especially profuse when substances must not leak from one body compartment to another.

36. Fig. 4.6, p. 74 cell basement membrane intermediate filaments protein channel plaques TIGHT JUNCTION ADHERING JUNCTION GAP JUNCTION

37. Section 6 Tissue Membranes: Thin, Sheetlike Covers

38. Tissue Membranes • Epithelium membranes pair with connective tissue. • Mucous membranes line the tubes and cavities of the digestive, respiratory, and reproductive systems where embedded glands secrete mucus. • Serous membranes such as those that line the thoracic cavity occur in paired sheets and do not contain glands. • Cutaneous membranes are hardy and dry—and better known as skin.

39. Tissue Membranes • Membranes in joints consist only of connective tissue. • Synovial membranes line the sheaths of tendons and the capsule-like cavities around certain joints. • Their cells secrete fluid that lubricates the ends of the moving bones.

40. Fig. 4.7, p. 75 mucous membrane serous membrane cutaneous membrane (skin) synovial membrane

41. Section 7 Organs and Organ Systems

42. Organs and Organ Systems • An organ is a composite of two or more tissue types that act together to perform one or more functions; two or more organs that work in concert form an organ system. • The major cavities of the human body are: cranial, spinal, thoracic, abdominal, and pelvic.

43. Fig. 4.8a, p. 76 cranial cavity spinal cavity thoracic cavity abdominal cavity pelvic cavity

44. Fig. 4.8b, p. 76 SUPERIOR (of two body parts, the one closer to head) distal (farthest from trunk or from point of origin of a body part) frontal plane (aqua) midsagittal plane (green) proximal (closest to trunk or to point of origin of a body part) ANTERIOR (at or near front of body) POSTERIOR (at or near back of body) transverse plane (yellow) INFERIOR (of two body parts, the one farthest from head)

45. Organs and Organ Systems • Eleven organ systems (integumentary, nervous, muscular, skeletal, circulatory, endocrine, lymphatic, respiratory, digestive, urinary, and reproductive) contribute to the survival of the living cells of the body.

46. Section 8 The Integument – Example of an Organ System

47. The Integument • Humans have an outer covering called the integument, which includes the skin and the structures derived from epidermal cells including oil and sweat glands, hair, and nails. • The skin performs several functions: • The skin covers and protects the body from abrasion, bacterial attack, ultraviolet radia­tion, and dehydration.

48. The Integument • It helps control internal temperature. • Its receptors are essential in detecting environmental stimuli. • The skin produces vitamin D. • Epidermis and dermis—the two layers of skin.

49. outer epidermal layer (all dead cells) keratinized cells being flattened rapidly dividing cells of epidermis dermis Fig. 4.10b, p. 79

50. The Integument • Epidermis refers to the thin, outermost layers of cells consisting of stratified, squamous epithelium. • Keratinocytes produce keratin; when the cells are finally pushed to the skin surface, they have died, but the keratin fibers remain to make the outermost layer of skin (the stratum corneum) tough and waterproof. • Deep in the epidermis are melanin-producing cells (melanocytes); melanin, along with carotene and hemoglobin, contribute to the natural coloration of skin. • Langerhans cells and Granstein cells are two important cells in skin that contribute to immune function.