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- 1. Comparative Anatomy of Respiratorysystem with special reference to Scoliodon, Rana, Varanus, Columba and Lepus
- 2. ü The developmentof the respiratory organs in vertebrates is closely related to the primitive pharynx, since the gills of aquatic vertebrates and the lungs of terrestrial vertebrates and aquatic mammals have pharyngeal embryology origin
- 3. ü Respiration isthe process of obtaining oxygen from the external environment & eliminating CO2. ü Acquisition of molecular oxygen (O2) from the external media (water and air) and the discharge of carbon dioxide (CO2) into the same milieu is the primary role of respiration ü External respiration - oxygen and carbon dioxide exchanged between the external environment & the body cells ü Internal respiration - cells use oxygen for ATP production (& produce carbon dioxide in the process) Water/ Air O2 CO2 CO2 O2 Respiratory organ
- 4. ü Vertebrates havedeveloped a variety of respiratory surfaces that all increase the surface area for exchange, thus allowing for larger bodies. ü A respiratory surface is covered with thin, moist epithelial cells that allow oxygen and carbon dioxide to exchange. ü Those gases can only cross cell membranes when they are dissolved in water or an aqueous solution, thus respiratory surfaces must be moist. Characteristic of respiratory organ
- 5. The system thathas evolved in each species depends on the environmental conditions, on body build and size, on animal’s patterns of movement and on its energy consumption
- 6.
- 7. Organ present forrespiration in fish 1) Gills 2) Air/ swim bladder Only present in crossoptergii and lung fishes (Assessory respiratory organ) A) Internal gills All fish B) External Gills Larvae of lung fish Polypterus Lepidosiren
- 8. ü Gills arerespiratory organ found in many aquatic organisms that extracts dissolved oxygen from water and excretes carbon dioxide. ü On the basis of location gills are of two types: 1) Internal gills 2) External gills Gills
- 9. ü Characteristic offishes ü Located in the gills slits and attached to visceral arches 1) Internal gills or true gills ü Gills usually consist of thin filaments of tissue, branches, or slender, tufted processes that have a highly folded surface to increase surface area. ü A high surface area is crucial to the gas exchange of aquatic organisms, as water contains only a small fraction of the dissolved oxygen that air does. Structure
- 10. ü The gillsare multifunctional organs that are responsible for the gas exchange (respiration) but also for the osmoregulation, acid-base regulation, and excretion of nitrogenous waste
- 11. Structure of truegills
- 14. ü Gills –finallydivided gill filament and lamellae ü Provide very large surface area for gas exchange
- 17. ü Each truegill is supported by a gill arch/gill cleft – a bony structure that is oriented vertically on the side of a fish, just behind its head. ü The gill arch provides the support to hold a number of comb- like structures called gill filaments. ü Gill filaments extend out horizontally from the gill arches. ü Each gill filament also called primary lamellae and the primary lamellae branch out into tiny secondary lamellae. ü The secondary lamellae, which are extremely numerous, are the site of gaseous exchange and form a fine sieve which ensures that all the water comes into close contact with the blood ü The secondary lamellae run parallel to the flow of the water and absorb oxygen from the water into the fish’s body.
- 18. Gills in elasmobranchand bony fishes Gills of elasmobranch (eg. Dog fish ) are general in structure . Gills of bony fishes are also basically similar but show the following differences 1) Operculum: bony flap or gill cover arises from the hyoid arch covers the gills, which opens by a Single slit like cresecent external gill opening 2) Interbranchial septm: The median septum is developed in elasmobranch and reduced in teleost 3) Spiracles : In elasmobranch and ganoids the first gill slit, between mandibular and hyoid arches, bears a reduced pseudobranch and opens to outside through small opening , spiracle. In chimaras and lung fish, teleost, spiracle become either closed or lost. 4) Number : 5-7 pairs in cartilaginous and 4 pairs in bony fishes
- 20. ü A singlerow of lamellae on one side of branchial septum forms only half the gill, called a demibranch or hemibranch. ü A septum with two attached elsmobranchs comprise a complete gill are holobranch.
- 21. Anatomy of respiratorysystem in Scoliodon
- 22. ü Respiration isaquatic ü Breathe by gills borne in a series of gill-pouches on either lateral side of the pharynx ü Water enters the mouth and after passing through the buccal cavity, pharynx, gill- pouches bearing gill-lamallae, goes out through the external gill-slits after bathing the gills ü Five pairs of gill- pouches bearing gills, arranged in a series behind the hyoid arch in the lateral walls of the pharynx. ü In Dogfish (Scoliodon), the hyoid arch bears only a hemibranch on its posterior surface, the first four branchial arches has holobranchs and the fifth branchial arch is without any gill (abranch). ü Thus, it has nine hemibranchs
- 24. ü Each gill-pouchhas two sets of gill-lamellae, one on its anterior wall and the other on the posterior. Each set of lamellae is a half gill or hemibranch, so that gill-pouch has two hemibranches ü Communicates with the cavity of the pharynx through a large internal branchial aperture and with the exterior through a narrow external branchial aperture (commonly called gill- slit) ü Interbranchial septa is raised into a series of horizontal folds to form lamelliforms branchial lamellae or gill-filaments ü Rich blood supply, and they have a very thin covering membrane through which blood is exposed to sea water for an exchange of gases.
- 26. b) External Gills üExternal gills are formed as branching outgrowths from the exposed outer epithelium of gill ü Arches not from the pharyngeal pouches. ü They are temporary organs found only in the larval stages ü They occur in the larva of lampreys, a few bony fishes including Polypterus, lung fishes (Lepidosiren)
- 27. 2) Swim bladder/Air bladder Origin of lungs in higher vertebrates ü Most vertebrates develop an out pocketing of pharynx or oesophagus that becomes one or a pair of sacs (swim bladders or lungs) filled with gases derived directly or indirectly from the atmosphere. ü Similarities between swim bladders & lungs indicate they are the same organs. ü Vertebrates without swim bladders or lungs include cyclostomes, cartilaginous fish, and a few teleosts (e.g., flounders and other bottom- dwellers).
- 28. During the ontogenesisof higher vertebrates, the pharyngeal pouches fail to open to the outside ü In higher vertebrates, the pharyngeal pouches just remain during the embryonic period, where they undergo several changes, but very few or none of their initial characteristics are presented in adults. ü In amniotes, as in humans, only the first pair of pharyngeal pouches remains, giving origin bilaterally, the eustachian tube and middle ear
- 29.
- 30. ü Most adultamphibians and all amniotes breathe by means of lungs ü In an embryo a hollow out pushing of single midventral diverticulum (lung primordial) the ventral wall of the pharynx. ü It grows backwards and divides into two, right and left lung buds. The undivided proximal portion develops into trachea and larynx, and opens into pharynx by glottis.
- 31. ü In lowerforms, the lungs are hollow bags, but in higher forms the ridges increase in number and unite with one another across the lumen of the lung to convert it into a solid but spongy structure with innumerable air spaces ü In mammals, the internal surface area of lungs may be thirty times that of the external surface area of the body Lungs and Duct Larynx Trachea Lungs Proper
- 32. 1) Larynx Amphibia ü Beginningsof larynx are seen in Amphibia ü Simplest condition (Nectrus), it is supported by a pair of lateral cartilages, bounding the slit-like glottis ü In Anura, inner lining of laryngotracheal chamber forms two muscular bands, or vocal cords, which vibrate to produce various calls Birds ü It is small and rudimentary in birds and another organ is present , the syrinx ü Syrinx : located at the lower end of trachea responsible for sound production. ü Syrinx tympanum formed of last tracheal cartilage. Reptiles ü Larynx is scarcely developed in reptiles
- 33. Mammals ü Larynx reachesits greatest point of evolution in mammals ü Besides paired arytenoid and single thyroid cartilage is added on ventral surface of larynx ü Vocal cords reach maximum differentiation in mammals ü A flap of muscular epiglottis is present in front of glottis and is characteristic of mammals ü In singing birds, paired of vibratory membrane called membrane semilunaris which extend dorsoventrally near the junction of bronchi and trachea.
- 34. 2) Trachea Amphibia ü Tracheais extremely short or absent in Anura ü It is merged with the larynx to form laryngotracheal chamber Reptiles ü Simple in reptiles as in amphibians or may be long in long-necked reptiles such as turtles, trachea is long and convoluted ü Tracheal cartilages are sometimes in the form of complete rings Birds ü In birds, the trachea is long. In swans and cranes, trachea is longer than the neck and tracheal rings are complete and ossified. Mammals ü Trachea in mammals is variable and tracheal rings are usually incomplete on the upper side
- 35. 3) Lungs Amphibians ü Inamphibians the lungs are simple, sac-like structures with a central large cavity. ü In aquatic amphibians the inner surface of lungs is smooth. ü In frogs and toads the inner walls contain numerous folds lined with alveoli so as to increase the respiratory surface. ü They are richly vascular and lined with mucous epithelium whose cells are columnar and ciliated.
- 36. Structure of respiratory systemin Rana (Frog)
- 37. Structure of respiratorysystem in Rana (Frog)
- 38. Respiratory tract consistsof: ü External nostril ü Nasal chambers ü Internal nostrils ü Bucco-pharyngeal cavity ü Glottis: On the floor of pharynx, the median slit-like glottis is present Glottis opens into larynx. ü Laryngo-tracheal chamber: Larynx or laryngo-tracheal chamber is a thin walled. Cartilages (2 arytenoid + 1 cricoid) support the walls of larynx Its internal lining forms a pair of elastic horizontal bands, the vocal cords. The characteristic croaking is produced because of the vibrations formed when the air from lungs is forced outside. Only male frogs have vocal sacs so as to amplify the croaking sound. ü From larynx, bronchus leads to each lung ü Two bronchi
- 41. Lungs in Rana: üLungs are ovoid in structure. ü They are thin-walled and highly elastic sacs ü They are suspended freely inside the peritoneal body cavity, one on either side of the heart ü Peritoneum covers the lung externally. ü The inner surface of each lung is divided by septa (a network of folds) into many small air sacs or alveoli, leaving a clear large central cavity. ü The alveoli are lined by thin epithelium ü This epithelium is richly supplied with blood capillaries that contains de- oxygenated blood for gaseous exchange. ü O2 in the inhaled air diffused to blood whereas CO2 is released into alveoli.
- 43. Lungs in Amphibian:Simple, sac-like structure