Chapters 1-4.docx - Chapter 1 Introduction to Comparative...

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Chapter 1Introduction to Comparative Vertebrate AnatomyComparative AnatomyConcerned with phylogenesisSurvival structure of adaptationPhylum Chordata: THE BIG FOURInvertebratesVertebratesProtochordates - no vertebral columnCharacteristics: notochord; dorsal hollowCNS; post anal tail; endostyleTaxonomic Relationship of Protochordate andVertebratesKingdom AnimaliaPhylum ChordataSubphylum UrochordataSubphylum CephalochordataSubphylum CraniataHagfish (without vertebrate)Vertebrata (with vertebrates)Chordates- (+) notochord in the embryonic stageCraniates- chordates with neurocranium or braincaseVertebrates- chordates with vertebrateThe Craniate Body- primitive or plesiomorphic;develops similar or identical patterns of embryonicdevelopment3 regional components: head (sense organs,brain, jaws, gills) trunk and post anal tailCoelom - viscera; has a body wall consistsof muscle, vertebral column and ribsNeck - narrow extension of trunk ofamphibians, reptiles, mammals; no coelom;has vertebrae, muscles, spinal cord, nerves,esophagus, trachea, lymphatics and bloodvesselsTail - commences at the anus or vent; postanal; in adults - coccyx (tail bone)Appendages - pectoral and pelvicBilateral symmetry - left and right sides aremirror images of each otherTransverse plane- left - right and dorso -ventral axis, when cut - cross sectionFrontal plane - left - right and longitudinalaxes, when cut - frontal sectionFrontal plane or coronal- dorsoventral;anterior-posteriorSagittal plane- longitudinal; left and rightsides of the bodyParasagittal- sections parallel to thesagittal planeTransverse- up and lower portionMetamerism - serial repetition of structuresin the longitudinal axisBody PlanesCraniateCharacteristicsCraniumThree part brainSingle semicircularcanalUnicellular senseorgansNeural crest and itsderivation cartilageVertebralCharacteristicsVertebral columnTwo part brainTwo semicircularcanalsMulticellularLateral line systemmulticellular neuromastHas a number of tissuespecializationNotochord- first to appear in craniate embryos; itbecomes incorporated in the floor of skull; except inhagfish (Myxine glutinosa) - part of the trunk andtail are surrounded by cartilaginous and bonyvertebraeVertebrae- provides more rigid supportComponents: centrum, neural arch, spinalcord, basal process, hemal arch (sharksand fishes)
Fate of the NotochordLampreys - it grows along with the anusFishes - persist in the trunk and tailReptiles and mammals - obliterated duringthe developmentPulpy nucleus - vestige that remains inmammal but not in reptilesSignificance: serves as a common ancestrybetween craniates and protochordatesPharynxVital part of the craniate embryoProduces the gills of fishesLungs of tetrapodsSkeleton and musculature of the jawsEndocrine glands that regulate themetabolism of cell which maintain Calciumlevels in bones, tissues, and circulatorybloodGives rise to middle ear cavity in tetrapodsContributes to immune system during thefetal lifePharyngeal Pouches- arises as diverticula of theendoderm of the foregut; persist as gill slits infishes and amphibians; close permanently in othervertebratesPharyngeal Arches- serves as support in the gillslits of fishesDorsal Hollow Central Nervous System- brainand spinal cordCranial and spinal nerves connect the CNSPNS nerves- ganglia and plexusesIntegument- epidermis and dermis

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