Mechanism of respiration in invertebrates.pptx

This ppt comprises a detailed note about mechanism of respiration in invertebrate animals .

1. Presentation on “mechanism of respiration in invertebrates” Department of Zoology, Dr. Harisingh Gour University, Sagar Submitted by Siddharth rajput MSc Zoology Roll no. (Y21265027) Session 2021-22

2. Introduction :- Respiration is the process in which oxygen is transported from outside environment to the cells/tissues of the organism with simultaneous transport of carbon dioxide in the opposite direction i.e., from tissues to the environment. The primary function of the respiratory system is to deliver oxygen to the cells/tissues of the organism and remove carbon dioxide from the tissues. The oxygen supplied to the tissues is used up by the cells in the breakdown of food stuff into carbon dioxide and water with the release of energy.

3. Continue ... In higher animals, respiration occurs as - external respiration, internal respiration and cellular respiration. External respiration refers to the exchange of oxygen and carbon dioxide across the respiratory surfaces such as skin, gills, lungs etc and involves two phases- Inspiration and Expiration Internal respiration refers to the transport of gases to and from the tissues by blood. Cellular respiration refers to the biochemical pathway by which food molecules (glucose) are oxidized to carbon dioxide and water in presence of oxygen with the release of energy in the form of ATP.

4. ORGANS OF RESPIRATION Different modes of respiration/respiratory organs are encountered among invertebrates General body surface - Respiration through general body surface occurs in protozoa, porifera, coelenterate, some annelids. It is referred to as direct diffusione.g. Protozoa. Skin/integument - The respiration through skin or integument is referred to as cutaneousrespiration. It occurs in many annelids such as oligochaetes, hirudinarians, and some polychaetes, some sipunculid worms, frogs, eels etc.

5. Gills- These are present in aquatic animals. Some poycheate worms,aquatic insects, crustaceans, molluscs etc. Different types of gills are found among animals. In mollusks, respiration through gills or ctenidia is called ctenidial respiration Lungs- Lungs include a variety of sac like structures that are richly supplied with blood vessels. Respiration through lungs is referred to as pulmonary respiration. In arthropods mechanism of respiration takes place through book lungs Trachea- are extensive network of air tubes found in insects. Tracheae carry air directly to the cells without blood (trachealrespiration). ORGANS OF RESPIRATION

6. Mechanism of respiration I n simplest forms of life, the respiratory gases diffuse in and out through the general body surface. Similarly, poriferans possess no respiratory organs but depend on the water that enters their body through ostia for the exchange of gases. Respiratory system is wanting in Coelenterates, Platyhelminthes and Aschelminthes .Respiration accours through simple diffusion. Annelids, arthropods, molluscs and vertebrates have special structures that carry out the function of respiration for the animal. The main respiratory organs are gills, lungs and trachea (in insects)

7. A) Mechanism of respiration in gills/gill like structures of invertebrates We know that gills are found in some annelids, mollusca and arthropoda. Let us learn about the mechanism of respiration in these organisms. Annelids In annelids some polychaetes such as Nereis, respiration occurs through the whole-body wall and also through flattened lobes of parapodia which possess extensive capillary network lying very close to the surface. Blood running through them gives up CO2 collected from tissues and receives oxygen dissolved in surrounding water. Water is constantly renewed by gentle undulations of body

8. Respiration in neries through parapodia

9. Respiration in sabella Annelida In fan worms, Sabella and Serpula that permanently remain in their tubes, radioles serve as the site for respirations . The pinnules of each radioles are covered by tracts of cilia. Fan worms pump water through the tube by means of peristaltic contractions of the body. The cilia of radioles generate water currents flowing over the radioles where gaseous exchange takes place. There is a single branchial sinus in a radiole through which blood flows in both directions in a tidal fashion. When the crown is retracted inside the tube sensing some danger, the radioles cease to function as respiratory organ.

10. Mechanism of respiration in Mollusc’s gill or ctenidia Aquatic respiration takes place by ctenidium in molluscs which is an important organ of the mantle cavity. In molluscs, water is drawn into the mantle cavity by the beating of the cilia of gill epithelium or muscular pumping. Pila possesses monopectinate type of gill. During aquatic respiration, Pila keeps its head and foot fully extended. Two nuchal lobes form channel like structures facilitates the entry and exit of water current. The water enters the mantle cavity through left nuchal lobe. This flow of water is maintained by the alternate protrusion and retraction of the head and by the beating of cilia on the lamellae of ctenidium. While water flows over the gill the exchange of gases takes place between the water and the blood vessels of gills. The oxygenated blood in the gill filaments is sent back to the heart through the efferent blood vessel.

11. Respiration in unio In Unio, the lateral cilia of the gill filaments and cilia lining the mantle generate current of water under the influence which the water enters the body of Unio through inhalant siphon. Thereafter the water enters the water tubes of the gill lamina through ostia. In the water tubes, the water flows upwards to enter the suprabranchial chambers. During the movement of water, exchange of gases takes place. The water flows backwards and reaches the cloacal chambers and moves out of the body through exhalent siphon.

12. Mechanism of respiration in book lungs of arthropods The movement of air in and out of the book lungs is controlled by the contraction and relaxation of dorso-ventral and atrial muscles. When these muscles contract, book lungs are compressed and air in interlamellar spaces is forced out into atrial chamber. From atrial chamber air is expelled to the exterior through stigmata . When these muscles relax, the book lungs resume their normal shape so that fresh air enters first into the atrial chamber and then into interlamellar spaces. Thus, interlamellar spaces are filled with fresh air and exchange of gases takes place between air of interlamellar spaces and venous blood through the membranous walls of lamellae. Blood gets oxygenated and the carbon dioxide is passed out along the expelled air.

13. Mechanism of gaseous exchange in the tracheal system of insects Respiratory exchange in the tracheal system occurs partly by diffusion and partly by ventilation as found in a vertebrate lung. Tracheae open to exterior through spiracles. Through these spiracles air enters the trachea when they are open. After reaching tracheae, the air passively moves into the tracheoles as the partial pressure within the tracheoles is lower than that of the trachea. From tracheoles, air enters the tips of fine branches of tracheoles which are filled with fluids. This fluid takes up the oxygen and diffuses inwards to the tissues or active cells through the tracheolar walls The tracheolar walls are very thin with an approximate thickness of only 40-70 nm.

14. Continue... the gases those diffuse from tracheoles to the tissues move through the fluid in the tracheoles, the tracheolar wall and the cell membrane ultimately to reach cells/tissues where oxygen is utilized and carbon dioxide is produced. When the air is expelled outside (during expiration), the tracheolar fluid again fills into the tracheole tips. CO2 produced mostly diffuses out through the tracheae . Small insects such as Drosophila may get sufficient oxygenby diffusion alone but forms that weigh more than 1g or that are highly active require some degree of ventilation to fulfill their high demands for oxygen. Ventilation in large and active insects is brought about by the changes in tracheal volume, which in turn are caused by the movements of abdominal muscles

15. Mechanism of respiration in invertebrates having lung or lung like structures Pulmonary sac Aerial respiration in Pila is observed when the animal is in water or out on land. When it is in water, it comes near to the water surface and then extends its left nuchal lobe to form a tube-like structure, called siphon . The opening of the siphon projects above the water surface through which air enters the pulmonary sac through pulmonary aperture. Air always backs through this path. To maintain the inflow and outflow, the alternate expansion and contraction of the pulmonary sac takes place. Epitaenia is raised to push the mantle wall and hence the air is not allowed to enter the branchial chamber. The wall of the pulmonary sac contains blood vessels and sinuses whose blood takes up oxygen of the air and gives out carbon dioxide.

16. Mechanism of respiration in Pulmonate lung In terrestrial pulmonates such as Limax, mantle cavity is transformed into a pulmonary sac or lung for aerial respiration. Roof of the pulmonary lung is richly supplied with blood vessels. Alternate muscular contraction and relaxation of mantle floor, lower or raise it, causing the air to rush in and out of the mantle cavity through pulmonary aperture. Compression of mantle cavity increases the partial pressure of oxygen and facilitates its absorption.

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