ORGAN 29
ANIMALTISSUESAND SYSTEMS
ChapterOutline
IMPACTS,ISSUES:OPENORCLOSETHE STEMCELLFACTORIES? 29.1EPITHELIALTISSUE GeneralCharacteristics GlandularEpithelium CellJunctions 29.2CONNECTIVETISSUES SoftConnective Tissues Specialized Connective Tissues 29.3MUSCLETISSUES SkeletalMuscle Tissues CardiacMuscle Tissue Smooth Muscle Tissue 29.4NERVOUS TISSUE 29.5OVERVIEWOFMAJORORGAN SYSTEMS Development ofTissues andOrgans VertebrateOrganSystems 29.6VERTEBRATESKINEXAMPLEOFAN ORGAN SYSTEM SUMMARY SELFQUIZ CRITICALTHINKING
Objectives
1. 2. 3. 4. 5. Describethe various levelsofanimal organization. Know the characteristics ofthe four main tissues, noting their structure, function, and examples ofeach. Know the types ofcellsthat compose each tissue type, and citeexamples oforgans that contain significant amounts ofeachtissue type. Characterize each ofthe major organ systems ofthe human body. Describehow the four principal tissue types areorganized into an organ such astheskin.
KeyTerms
adhering junctions adipose tissue blood bone tissue cardiacmuscletissue cartilage celljunctions circulatory system connective tissue contract dense,irregular connective tissue dense,regular connective tissue dermis digestive system division oflabor ectoderm endocrine glands endocrine system endoderm epidermis epithelium, lia exocrine glands gap junctions germ layers glands integumentary system looseconnective tissue lymphatic system mesoderm microvilli musclefibers muscletissue muscular system nervous system nervous tissue neurons organ organ system reproductive system respiratory system simple columnar simple cuboidal simple squamous skeletalmuscletissue skeletalsystem smooth muscletissue
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Animal Tissues and Organ Systems
stem cells
stratified epithelium
tight junctions
urinary system
LectureOutline
Impacts,Issues:Open orClosethe Stem CellFactories? A. Stem cellsform when azygote firstbegins todivide. 1. Stem cellscandivide indefinitely without differentiating. 2. Theycanbecoaxed into forming many celltypes. B. Themost pliable ofstem cellscomesfrom human embryos. 1. Thesecellsmay beabletorepair damaged nervous tissue. 2. Butethicalissues have been raised because ofthe source ofthetissue. C. Thecellsofthe body areorganized into levels. 1. Atissue isagroup ofcellsthat performs acommon task. 2. Eachorgan consists ofdifferent tissues working together foracommon goal. 3. Organ systems consistoftwo ormore organs interacting foracommon task. 29.1 EpithelialTissue A. General Characteristics 1. Inthistissue,one surfaceisfreeand the other adheres toabasement membrane. 2. Simple epithelium isonecellthickand may have flat(squamous), cuboidal,orcolumnar cells. 3. Stratified epithelium has many layersas inhuman skin. B. Glandular Epithelium 1. Glands aresecretory organs derived from epithelium. 2. Exocrine glands often secrete through ducts tofreesurfaces;they secrete mucus, saliva, wax,milk,and soon. 3. Endocrine glands secrete hormones directly into intercellular fluid fordistribution by the blood. C. CellJunctions 1. Cellsarelinked tightly together with specialized junctions,providing both structural and functional links between individual cells. 2. Tight junctions provide sealstoprevent leaking acrossthe freeepithelialsurface;for example,epithelia inthe digestive tractprevent attack ofthe wallbyacids and enzymes. 3. Adhering junctions arelikespot welds that cement cellstogether, sothey function asa unit (forexample,skin). 4. Gap junctions arechannels that allow ionsand molecules toflow between the cytoplasm ofabutting cells. 29.2 Connective Tissues A. Most connective tissue contains cellsand fibers(collagen and /or elastin)secreted by fibroblasts,allscattered inaground substance.
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Chapter Twenty Nine
B. SoftConnective Tissues 1. Looseconnective tissue supports epithelia and organs, and surrounds blood vesselsand nerves;itcontains fibroblast cellsand fibersplus macrophages. 2. Dense,irregular connective tissue has thicker fibersand more ofthem, but fewer cells;it forms protective capsules around organs. 3. Dense,regular connective tissue has itsfibersinparallel;thisisthe arrangement found intendons (muscletobone)and ligaments (bone tobone). C. Specialized Connective Tissue 1. Cartilage contains adense array offibersinajellylikeground substance. a. Itcushions and maintains the shape ofbody parts;itresistscompression and is resilient. b. Locations include theends ofbones,parts ofthe nose,external ear,and disks between vertebrae. 2. Adipose tissue cellsarespecialized forthe storage offat,which canbeused asan energy reserve and ascushions topad organs. 3. Bonetissue storesmineral salts,produces blood cells,and provides support and protection tothebody and itsorgan systems. Bonesalsowork with musclestoperform movement. 4. Blood transports oxygen, wastes,hormones, and enzymes;italsocontains clotting factorstoprotect against bleeding and components toprotect against diseasecausing agents. 29.3 MuscleTissues A. Muscletissue contracts inresponse tostimulation, then passively lengthens. B. Therearethree types ofmuscledefined bytheir appearance,location,and function. 1. Skeletalmuscle tissue attaches tobones forvoluntary movement; itcontains striated, multinucleated, long cells. 2. Cardiac (heart)muscleiscomposed ofshort,striated cellsthat canfunction inunits. 3. Smooth muscle tissue contains spindle shaped cells;itlinesthe gut,blood vessels,and glands;itsoperation isinvoluntary. 29.4 Nervous Tissue A. Nervous tissue exerts the greatest control over the body's responsiveness tochanging conditions. 1. Neurons areexcitablecells,organized aslinesofcommunication throughout the body. 2. Neuroglia arediverse cellsthat protect and metabolically support the neurons. B. Sensory neurons detect stimuli;interneurons coordinate thebodysresponses;motor neurons relay signals tomusclesand glands forresponse. 29.5 Overview ofMajorOrgan Systems A. Development ofTissues and Organs 1. During development, shortly after fertilization three primary germ layers giverisetoall tissues and organs. 2. Theectoderm becomes the nervous system and outer layer ofskin. 3. Themesoderm becomes the muscles,connective tissue,and the lining ofbody cavities. 4. Theendoderm becomes the epithelium ofthe gut and theinternal organs. B. Vertebrate Organ Systems 1. Organ systems perform specialized functions. 2. Figure 29.13brieflydescribes eachofthe organ systems (integumentary, muscular, skeletal,nervous, endocrine,circulatory,lymphatic,respiratory, digestive,urinary, and reproductive) that contribute tothe survival oftheliving cellsofthe vertebrate body. 3. Theformation and function ofthe organs areoutcomes ofalongterm program of growth and development. 29.6 Vertebrate SkinExample ofan Organ System
Animal Tissues and Organ Systems 3
A. Theouter covering ofanimal bodies interfaceswith the environment and iscalled the integument. 1. Invertebrates,the integument consists ofskin and the structures derived from epidermal cells,such asscales,feathers,hair,beaks,horns,nails,and soforth. 2. Theskin consists ofan outer epidermis and an underlying dermis. 3. Theskin has several functions. a. Theskin covers and protectsthe body from abrasion,bacterialattack,ultraviolet radiation, and dehydration. b. Itsreceptors areessentialindetecting environmental stimuli. c. Ithelps controlinternal temperature. d. Inhumans, the skin produces vitamin D. B. TheDermis 1. Thedermis liesbeneath the epidermis and ismostly adense connective tissue with elastin and collagen fibers. a. Itsdense connective tissue cushions the body against everyday stretching and mechanicalstresses. b. Adipose tissue and looseconnective tissue insulate orcushion some body parts. c. Blood vessels,lymph vessels,and receptors ofsensory nerves areembedded inthe tissue. d. Sweat glands help dissipate heat,and oilglands lubricate and soften the skin,plus they produce secretions that reduce bacterialpopulations onthe skin. C. TheEpidermis 1. Epidermis isastratified squamous epithelium. a. Theepidermis variesamong vertebrates. b. Asanimals evolved from lifeinwater tolifeonland, their outer layer adapted. The epidermis has keritanocytes that make atough, waterproof layer. c. Keritanocytes alsobecame specialized toclaws,nails,beaks,fur,and hair. 2. Epidermis contains melanocytes and dendriticcells. a. Melanocyte cellsproduce melanin pigment that darkens the skin and protects against thesunsrays;hemoglobin and carotene alsocontribute toskin color. b. Dendriticcellsalertthe immune system tothreats from viruses and bacteria. 1) Thesecellsarephagocytes and engulfviruses and bacteria that they encounter inthe skin. 2) UVradiation damages these cells,making them more vulnerable tocold sores aHerpes simplex infection. D. Suntans and ShoeLeather Skin 1. UVlight stimulates melanocytes tomake more melanin, resulting inatan. 2. Continued exposure tothe sunsrays causes lossofelasticity and the dwindling of glandular secretionsin short,aging. 3. UValsoharms DNA,which canresult inskin cancer. Evolution E. ofSkinColor 1. UVradiation stimulates thebody tomake vitamin D,but italsocauses the breakdown offolate,which isoften deficient inthe diet.
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2.
One hypothesis regarding the variation ofskin coloramong people indifferent parts of the world considers the amount ofsun exposure ineachenvironment. a.People with high exposure tosun produce more melanin asprotection from UV radiation. b.People with low sun exposure have fewer melanocytes.
Suggestions forPresenting theMaterial
Although this chapter includes briefdiscussions ofcellfunctions, embryonic tissues, and human organ systems, the main topic istissues.There isreally no need fordetails ofbody systems listed in thischapter because each willbediscussed inlater chapters. Thepresentation oftissues willbemore meaningful ifslides areshown during your lecture. Even though the structure of bone and the types of muscles are introduced here, the skeletal system and muscle physiology aretopicsdiscussed more fullyinlater chapters. It is difficult for students to think of bone as a living tissue. What most ofus have seen in the dogsmouth isthe nonliving portion ofatissue one author hascalled living reinforced concrete. Useone ofvideos on ThomsonNOW orthe Multimedia Manager tointroduce this chapter. These arehelpful ingrabbing theinterest ofstudents.
Classroom andLaboratoryEnrichment
Select slides of various types of tissues for projection onto a large screen. Ask the students to identify the type oftissue and where itisfound inthe body. Invite an athlete who has suffered a knee injury and has had corrective surgery to describe the damage and reconstructive process. During the discussion ofbone, pass a cleaned bone (from ameat market) around the classroom. Comment on the nonliving and living composition ofthe bone. Another option isto demonstrate that bone has both organic and mineral components by soaking one chicken bone in acetic acid (to remove minerals) and by heating another in an oven at a high temperature (to remove organic material). Toshow that bone ishard but not indestructible, treat bone fragments with avariety ofcommon laboratory acids and alkalis. Have prepared microscope slides ofeach tissue type available forstudent viewing. Useamodel ofthe various tissues toillustrate their structure. Exhibitavertebrate embryonic orfetalskeleton that isspecially stained toshow the cartilage. Take the opportunity to educate this young audience on skin carecauses, prevention, and the statisticsofthedisease.Severalcompanies offercomprehensive posters onskin cancer. Explore stem research further (seemore questions onImpacts,Issuessection). Depending on your course structure you may want to talk now about osteoporosis. What isit? How can itbeprevented? What changes can you make asayoung adult that may help prevent you from getting the disease? Have each student orlabgroup selectan organ and report on the organ system itbelongs to,and the various tissue and types that make up that organ.
Animal Tissues and Organ Systems
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Impacts, IssuesClassroom Discussion Ideas
Why arestem cellssovaluable and sought after inembryologicalresearch? What arethecharacteristicsofstem cells? Where do embryonic stem cellscome from? Why do some groups labelstem cellresearch asunethical? What aretheminimal tasks that aliving celland organism must perform toremain alive? How do you feelabout stem cellresearch? Inyour mind isthere adifference between adult stem cellresearch and embryonic stem cellresearch?
Additional IdeasforClassroom Discussion
Why isblooda liquidconsidered aconnectivetissue? Isthere any validity tothe cynicsobservation that beauty queens are justexposing alotofwell placed dead cells? Rising blood sugar levels after a meal normally trigger insulin secretion, which in turn causes glucose to be converted to glycogen for storage. How is this similar to the response of an air conditioner thermostat torising room temperature? What isliposuction? Does itpermanently remove adipose tissue from the treated areas? Why is there alimittothe amount ofadipose tissue that canbesafelyremoved from the body atonetime? Astronauts who orbited the Earth early in the space program experienced considerable loss of bone mass under gravityfreeconditions. How was thisremedied insubsequent flights?
How Would YouVote? Classroom Discussion Ideas
Monitor the voting for the online question. This question ofwhat source can,or cannot, be used for stem cell research is unfortunately clouded by political and religious stances. From a purely biologicalresearch standpoint, the value ofthese cellsto the advancement ofscience outweighs the question oftheir source. Have students complete classroom polling using the JoinIn clickers.
TermPaperTopics,LibraryActivities,andSpecial Projects
Osteoporosis isatopicofcurrent interest,especially towomen. Research osteoporosis and present ways the disease canbeprevented. What roles, if any, do estrogen replacement therapy and exercise play in the prevention of osteoporosis? We are warned toprotect our skin from the sun by using sun block preparations. What chemical substances areeffectiveinthese preparations, and how do they work? Consider thepros and consofstem cellresearch.With your research,state adefinitive position on your support orrejection ofstem cellresearch.
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Chapter Twenty Nine
Possible Responses toCritical ThinkingQuestions
1. Tattooing and body piercing for the attachment of jewelry are ways for some to express themselves.Bothofthese procedures areminiature surgeries. No one would letasurgeon cut and probe his/her body with unsterile instruments. Wetrust surgicalpersonnel areresponsible tocareforour health and safety.There areregulatory agenciesthat willinspect and ensure that standards are met. However, in the small, outoftheway piercing and tattooing shops, a different mindset may hold. These artists may bemore concerned with the finallook than with procedural niceties. So as always, buyer beware. Check out the conditions of the room, instruments, and operator. Ask toseethe instruments. Are they insterile wrappers? Isthere an autoclave inuse?Doesthe technician know what steriletechnique even means? Blood and adipose tissues are classified as connective tissue, perhaps because they fit most closely to that classification without creating an entirely different class of tissues. However, they are atypical connective tissue in several ways: blood has no collagen or elastin as other connectives do; both blood and adipose have no fibers. The characteristic ground substance so familiar to connective tissue is redefined in blood and adipose: for blood it becomes the liquid plasma in which the formed elements move; for adipose the ground substance (lipid molecules)ismore prevalent insidethe cellsrather than surrounding them. When deciding whether to test the safety of cosmetic products on laboratory grown tissues (LGTs) or on living animals, perhaps a twophase approach should be envisioned. Why not beginwith testing on LGTs?We know that these tissues are fairly close to the real thing, or they would berejected by the bodies onto which they are grafted. Tosome criticsoftesting on living animals, this might be sufficient. Butcan we always be sure that the LGTsare going to reactinexactly the same way astissues inthe living animal will?Certainly itwould beatragedy tohave toadmit toaperson suffering harm from acosmetic,Well,we never tested iton a real human .Perhaps the second phase oftesting onliveanimals would require fewer animals based onthe testing onLGTs,but Ibelieve such trialswillprobably benecessary justtobesure. (1)Some ofthe tissues that would keep the meerkats body warm would be epithelial in the epidermis and dermis. Adipose (fat) would provide insulation. Ifthe meerkat shivers, even skeletal muscle (controlled by neurons) would contribute abit ofheat. (2)Moving the body of course would involve primarily muscle tissue, again driven by impulses from the nervous system. (3)Digestion and absorption willbedone by epithelial tissue lining the digestive tract. Smooth muscle tissue will be moving the food along by peristaltic actions. Of course, cardiac muscle will be pumping the blood to the digestive tract capillaries to pick up the nutrients. Most ofthe tissues mentioned above willbeheld together byconnective tissues. It seems plausible that vampire stories could have originated from people with porphyria. Avoiding the sun and garlicand fanglike teeth allrelate tovampires. Thehunger forblood that vampires have could stem from the impact on hemoglobin metabolism. Tracing historical texts to the time period that vampire and werewolf stories originated may provide some more insight astohow the firstvampire storiesoriginated.
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Animal Tissues and Organ Systems
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