Dissecting Rat and Trout

Dissecting Rat and Trout

1. LABORATORY RAT

   • Domain = Eukarya
     • Kingdom = Animalia
       • Phylum = Vertebrata
         • Class = Mammalia
           • Order = Rodentia
             • Family = Muridae
               • Genus = Rattus
                 • Species = norvegicus
   • Larynx
     • Protect opening of airway from large food parcels
     • Glottic cleft = narrowest area, surrounded by vocal folds
       • Vocal fouls vibrate as air moves past to regenerate voice
   • Oesophagus
     • Narrower than expected, can stretch to accommodate bolus
   • Pectoral muscles
     • Forelimbs closer to midline and retracts leg during locomotion- prevent limbs splaying out
   • Lungs deflate
     • Without tension in intrapleural fluid to support, collapse due to elastic recoil
     • Pneumothorax
   • Common carotid arteries from aortic arch to head
     • Carotid sinus baroreceptors
       • Bifurcation of comon carotid
   • Aortic arch
     • Asymmetrical branching
       • Left = subclavian and common carotid arteries
       • Right = arteries form brachiocephalic trunk
   • Diaphragm
     • Separates abdominal and thoracic cavities
   • Pylorus
     • Constricted region between duodenum and stomach, under sphincter muscle control. Limits food/ card into duodenum
   • Caecum
     • Microbial fermentation centre
   • Brown fat
     • Non-shivering thermogenesis in thermoregulation

2. TROUT

   • Domain = Eukarya
     • Kingdom = Animalia
       • Subphylum = Vertebrata
         • Class = Actinopterygii
           • Infraclass = Teleostei
             • Order = Salmoniformes
               • Family = Salmonidae
                 • Genus = Onchorhynchus
                   • Species = mykiss
   • Lateral line
     • Hair cells associated
     • Senses change in pressure and movement in water
     • Evolved into inner ear?
   • 4 pairs of gill arches
   • Ventricle
     • Flimsier than rat as blood pressure lower so less cardiac muscle needed
   • Aorta
     • Ventral = carries deoxygenated blood to gills via afferent brachial arteries
     • Dorsal = formed from efferent brachial arteries recombining, carries oxygenated blood to tissues
       • Efferent doesn't fill with latex as too viscous to penetrate through tiny gill channels
   • Pyloric caeca
     • Increase gut SA to improve absorption
       • Otherwise shorter and simpler than rat
   • Swim Bladder
     • Contains air, maintain neutral buoyancy
       • Others can have almost pure oxygen/ use as supplementary respiratory organ to extract oxygen from air, or to make/ receive sound

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