Chapter 33

1. Chapter 33 Animal Tissues and Organ Systems AP Biology Spring 2011

2. Chapter 33.1 Epithelial Tissue

3. General Characteristics • Epithelium: sheet like tissue of cells that are close together with little extracellular material between them • One free surface is exposed to outside environment or to some body fluid • Opposite side form basement membrane, incorporate adhesion proteins (integrins, cadherins). Anchor epithelium to other tissues.

4. Types of Epithelium • 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

5. Types of Epithelium • 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

6. Types of Epithelium • Simple Columnar: • Description: single layer of tall cells; free surface may have cilia, mucous secreting glandular cells, microvilli • Common Locations: glands, ducts, gut, part of uterus, small bronchi • Function: secretion, absorption, ciliated types move substances

7. Types of Epithelium • Simple Epithelium: cells form a layer that is only one cell thick • Stratified Epithelium: cells form two or more layers • Outer layer of skin: stratified squamous

8. Glandular Epithelium • Gland cells occur only in epithelia • Cells secrete products, that are used elsewhere • Glands: saclike, secretory organs that open to the free epithelial surface

9. Glandular Epithelium • Exocrine Glands: secrete oils, mucous, saliva, tears, milk, digestive enzymes, earwax • Ducts or tubes that open into free epithelial surface

10. Glandular Epithelium • Endocrine Glands: have no ducts, secrete their products, hormones, directly into interstitial fluid • Hormone molecules diffuse into neighboring blood capillaries, circulatory system transports them to target cells in needed tissues

11. Cell Junctions • Cell junctions connect adjoining cells • 3 types

12. Cell Junctions • Adhering Junctions: like spot welds, lock adjoining cells together • Profuse in skin and tissues subject to abrasion

13. Cell Junctions • Tight Junctions: stop most substances from leaking across a tissue • Rows of proteins fuse cells • Dissolved substances pass through cells to get to opposite surface • Selective about what enters

14. Cell Junctions • Gap Junctions: permit ions and small molecules to pass freely from cytoplasm of one cell to another • Open communication channels abundant in heart muscles and tissues where actions of cells must be swiftly coordinate

15. Chapter 33.2 Connective Tissues

16. Connective Tissue • Connective Tissue: consist of cells scattered within an extracellular matrix of their own secretions • Fibroblasts are main type of cell (except in blood) • Make and secrete structural fibers of collagen and elastin into matrix

17. Soft Connective Tissue • Loose Connective Tissue: fibroblasts and fibers dispersed widely through the matrix • Most common type in vertebrate body, helps hold organs and epithelia in place

18. Soft Connective Tissue • Fibrous, Irregular Connective Tissue: matrix is packed with many fibroblasts and collagen fibers that are positioned every which way • Dense irregular tissue is component of skin • Supports internal muscles, forms protective capsules around organs that do not stretch much

19. Soft Connective Tissue • Fibrous, Regular Connective Tissue: orderly rows of fibroblasts between parallel, tightly packed bundles of fibers • Organization prevents tares • Tendons and ligaments • Tendons connect skeletal muscles to bones • Ligaments attach bone to bone • Elastic fibers in tissue matrix facilitate movement in joints

20. Specialized Connective Tissue • Cartilage: tissue of fine collagen fibers packed in a rubbery, compression-resistant matrix • Specialized cells secrete rubbery chondrin, which imprisons them • Human skeleton started out as cartilage, bone tissue replaced most • No blood vessels, substances move by diffusion • Cells do not divide often in adults

21. Specialized Connective Tissue • Cartilage: • What parts of our bodies are still made up of cartilage? • Outer ear, nose, throat, protects and cushions joints between limb bones and between vertebral column bones • What organisms has a cartilage skeleton? • Sharks

22. Specialized Connective Tissue • Bone Tissue: hardened connective tissue with living cells imprisoned in their mineralized secretions • Main tissue of bones (organs that interact with muscles to move body and protect organs)

23. Specialized Connective Tissue • Adipose Tissue: energy reservoir • Cells get so swollen with stored fat that their nucleus and a few fibroblast nuclei are flattened and pushed to one side • Little extracellular matrix but many fine blood vessels that move fats to and from cells • Fat deposits form insulating layer under skin and cushion body parts; accumulate around some organs (kidneys, heart)

24. Specialized Connective Tissue • Blood: a connective tissue because its cellular components arise from stem cells in bone (connective tissue) • Blood cells suspended in plasma • Plasma: fluid extracellular matrix that functions in transport and heat transfer • Made of: water, gases, proteins, ions, sugars

25. Specialized Connective Tissue • Blood: • Plasma holds red blood cells (RBC), white blood cells (WBC) and platelets • RBC: get oxygen to metabolically active tissues and get rid of carbon dioxide and wastes • WBC: defend and repair tissues • Platelets: function in blood clotting

26. Chapter 33.3 Muscle Tissues

27. Muscle Tissues • In muscle tissues, cells contract • Forcefully shorten in response to stimulation, then relax and passively lengthen • Coordinated contractions of layers or rings of muscles move the whole body or its component parts

28. Skeletal Muscle Tissues • Skeletal Muscle Tissues: functional partner of bone or cartilage • Help move and maintain the positions of the body and its parts • Parallel arrays of long, cylindrical muscle fibers

29. Skeletal Muscle Tissues • Fibers are not single cells • Groups of cells fuse together and form each fiber • Ends up with multiple nuclei • Inside fiber are myofibrils: long strands with row after row of contractile units • Gives striated or striped appearance

30. Skeletal Muscle Tissues • Sarcomere: each unit; is contractile • It has parallel interacting arrays of contractile proteins: actin and myosin • Reflexes activate it, also can contract by thinking about it • Called “voluntary muscles”

31. Cardiac Muscle Tissue • Cardiac Muscle tissue: occurs only in heart wall • Contains sarcomeres and looks striated • Consists of single, branching cells that have a nucleus • “Involuntary muscle”: usually cannot make its cells contract by thinking about it

32. Cardiac Muscle Tissue • Cells abut at ends, where adhering junctions help keep them from being ripped apart during forceful contractions • All cells contract as a unit • Tissue has more mitochondria…why? • Needs continuous supply of ATP from aerobic respiration to keep heart beating nonstop

33. Cardiac Muscle Tissue • Heart Attack: • Cardiac muscle does not store as much glycogen • Glycolysis cannot do much when oxygen is scarce • If something ends the flow of oxygen, cardiac cells will falter or die

34. Smooth Muscle Tissue • Smooth Muscle Tissue: in the wall of many soft internal organs, including the stomach, bladder and uterus • Single, unbranching cells, tapered at both ends, with one centrally positioned nucleus • Not striated • Contains actin and myosin, which are anchored to plasma membrane by intermediate filaments

35. Smooth Muscle Tissue • Contracts more slowly than skeletal • Contractions can be sustained longer • Contractions drive many internal events • Propel material through gut • Shrink diameter of arteries • Close sphincters