Comparative account of respiratory organs in vertebrates

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1. Presented by – Bhavana Shrotriy M.Sc. 3 rd Sem Roll no - 1931008 C omparative account of respiratory organs in vertebrates

2. Respiration A process in living organisms involving the production of energy,typically with the intake of oxygen & the release of carbon dioxide from the oxidation of complex organic substances. Respiratory organs The set of organs involved in respiration are known as repiratory organs. It includes- 1. Lungs 2. Gills 3. Swim bladder 4. Skin etc.

3. Fishes

4. Respiration- Gills & Swim bladder 1. Gills It is the characteristic respiratory organ in aquatic animals. Gills are filamentous structure richly supplied with blood capillaries. Gills are of two types- 1. External gills 2. Internal gills Blood in the capillaries of the gills flows in the direction opposite that of the water current. The general structure of a mature gill is composed of following parts- 1.Gill bars 2.Gill rakers 3.Gill rays 4.Gill filament & gill lamellae

5. 2. Swim bladder or air bladder It is a gas filled pneumatic sac, lying dorsal to the digestive tract beneath the vertebral column. It doesn’t occur in elasmobranchs but found in all bony fishes. It arises as an outgrowth from the oesophageal region of the alimentary canal. structure & blood supply of teleostean swim bladder

6. Two types of air bladder are known- 1. Physostomous : If the air bladder retains connection with the gut via a pneumatic duct. Ex- In generalized groups of teleosts ( salmon,eel ) ,it serves as an respiratory organ 2 . Physoclistous : In this type, the duct becomes lost, hence it is closed or ductless air bladder . Ex-In specialized teleosts ( perch,cod ) , it is said to store oxygen to be utilized during deficiency. In lower fishes such as ganoids and lung fishes, the air bladder serves as a lung.

7. Amphibians

8. Respiration- lungs,bucco -pharyngeal cavity,gills & skin 1. Lungs Breathing on land in atmospheric air with the help of lungs is called pulmonary respiration. Lungs have 2 simple sacs. Lungs don’t have diaphragms & they force air into their lungs by moving their mouth.

9. 2. Bucco -pharyngeal cavity Respiration through lining of bucco - pharyngeal cavity is known as buccal respiration . In this, the mouth remains permanently closed while the nostrils remains open. The floor of the buccal cavity is alternately raised & lowered so that air is drawn into & expelled out. Glottis remains closed so that no air enters or leaves the lungs into buccal cavity. Mucous epithelial lining of buccal cavity is richly supplied with blood capillaries, oxygen in the air is absorbed by blood while carbon dioxide is given out.

10. 3. Skin Respiration through moist surface of the outer skin is known as cutaneous respiration . It goes on whether frog is in or out of water. It is practically the only mode of respiration when the frog is under water or hibernating. Skin is richly supplied with blood & is permeable to gases. Frogs always stays near water to keep their skin moist.

11. 4. Gills Respiration by means of external gills is known as branchial respiration . Made up of very thin blood vessels surrounded by water channels. When amphibians undergo metamorphosis into adult, gills are lost. Only present in Salamanders & Tadpoles.

12. Reptiles

13. Respiration – lungs Rely largely on lungs for gas exchange. Lungs are large & varied. Trachea & brochi are larger than amphibians & are supported by cartilaginous rings.

14. Birds

15. Respiration – lungs The intense activity of flight demands large supplies of oxygen, so that the respiratory system of birds is more complicated. A true diaphragm is absent in birds. The lungs are small & compact organs , continued into a unique system of air sacs . The expiration is more active process than inspiration. There are 9 major sacs- 1. Interclavicular 2. Cervical 3. Anterior thoracic 4. Posterior thoracic 5. Abdominal

16. Mammals

17. Respiration - lungs The essential organs of respiration are a pair of lungs, placed one on a either side of heart in the thoracic cavity. The lungs are pink coloured , soft, spongy, elastic &highly vascular organs. After entering a lung, the primary bronchus divides repeatedly into smaller secondary & tertiary bronchi. Terminal branches are called bronchioles. Each bronchiole divides into finer branches, the alveolar ducts, each terminating into several branching delicate blind air sacs or infundibula . The wall of each air sac is evaginated to form tiny, pocket like sacculations , alveoli. It is these millions of alveoli that provide the great surface area for gaseous exchange.

18. Characters Fishes Amphibians Reptiles Birds Mammals Respiratory organs Gills Gills in tadpole larva & lungs in adult Gills absent. Only lungs are present Only lungs Only lungs Lungs Absent 2 lungs, ovoid, suspended freely in peritoneal cavity, without lobes 2 l ungs, elongated, lying in thoracic cavity, without lobes 2 lungs, ovoid, attached dorsally to thoracic vertebrae & ribs, without lobes 2 lungs, large, enclosed in lateral pleural cavity of thorax, right lung-4 lobes, left lung- 2 lobes Peritoneum _ Completely enclosed by peritoneum Completely surrounded by peritoneum Dorsal attached side of lung not covered by peritoneum Surrounded by peritoneum on all sides Alveoli _ Present Present Lungs without alveoli Highly vascular alveoli Air sacs _ Absent Absent Non vascular air sacs connected with the lungs Absent Bucco -pharyngeal respiration Absent very effective Absent Absent Absent Cutaneous respiration Absent Present Absent Absent Absent

19. Reference Animal physiology by Mohan P. Arora Modern textbook of zoology vertebrates by R.L.Kotpal A textbook of Fish Biology and Fisheries by S.S.Khanna & H.R.Singh