Comparative Anatomy of Digestive System of Vertebrates

Webinar about Digestive system of various vertebrates and its functions.

1. COMPARATIVE ANATOMY OF DIGESTIVE SYSTEM OF VERTEBRATES By Dr . T. RAMESH Assistant Professor of Zoology PG & Research Department of Zoology Vivekananda College Tiruvedakam, Madurai DT. [email protected]

2. Series of organs involved in the digestion of food, eaten absorption of digested food and expulsion of undigested wastes. It includes alimentary canal and its associated digestive glands. Actual plan of digestive system in all vertebrates are same. Within in basic plan some of specific components vary from one animal to another. Alimentary canal was developed during embryonic development and is lined with the endoderm, except the mouth and rectum,, which are have an ectodermic lining.

3. Digestive tract - ‘tube’ from mouth to vent or anus that functions in: INGESTION DIGESTION ABSORPTION EGESTION

4. ALIMENTARY CANAL 1. Mouth and Oral Cavity Teeth, Tongue & Oral Glands 2. Pharynx 3. Oesophagus 4. Stomach 5. Intestine GLANDS ASSOCIATED WITH DIGESTIVE SYSTEM Liver Pancreas

5. Differences in the anatomy of vertebrate digestive tracts is often correlated with the nature & abundance of food: 1. Readily absorbed (e.g., hummingbirds) vs. requiring extensive enzymatic activity (e.g., carnivores) 2. Constant food supply (e.g., herbivores) vs. scattered supply (e.g., carnivores)

6. It is anterior opening of oral cavity In Fish Cyclostomes-The mouth is a circular opening, Ganthostomes , generally the mouth is terminal, but in Elasmobranchs mouth is in ventral region. In fishes, the mouth margins of amphibians and most of the reptiles have small lips. In turtle, the lips of the birds and some mammals have been transformed into a horny beak of bill. In mammals the mouth is bounded by muscular lips. The mammalian mouth is specialised to serve as suckling and masticator organ. The oral cavity begins with mouth and end with pharynx.

7. Food is ingested through the mouth of the fish using jaws the food then passes through the pharynx (throat) into the Oesophagus and into the stomach Partial digestion takes place here using digestive juice (juice consists of enzymes and acid) Food proceeds to the intestine for more digestion and absorption into the circulatory medium of blood Between the stomach and the intestine there is usually a valve called the pyloric valve. beyond this valve, a duct from the liver and pancreas enter the intestine to secrete digestive enzymes including "pepsin and trypsin " into the food

8. Mouth and oral cavity The roof of it is formed by a series of skeletal elements Tongue A tongue that can be used for catching prey as well as sensory input. It varies greatly in size and importance. In anurans, the tongue is attached at the anterior end of the jaw. The muscular system of the tongue becomes better organized with a genio glossus as a protractor and a hyoglossus as a retractor Its sense organs are innervated by glosso pharyngeal nerve and its muscles by hypoglossal nerve

9. Oral Glands The glands of amphibians are few in number and are located on the roof of the mouth or on the tongue. In salamanders, mucous glands are located on the tongue Oesophagus and stomach Amphibians oesophagus is short, ciliated and well supplied with mucous glands. The stomach remains simple and straight or gently curved. The swallow their prey whole, with some chewing done in the oral cavities of some species so they possess voluminous stomachs

10. Intestine and Caeca Salamanders lack a value separating the small intestine from the large intestine Tadpoles haves long coiled intestines but adult amphibians have relatively short and simple digestive tubes ranging in the length from 1/2 to 3 and half time of the body length. A cloaca is present Digestive system of frog

11. Evolution of Frog Teeth Modern Amphibians have fewer simple teeth Live and Gall Bladder of frog The live in most amphibians is large with two lobes. the size of the liver is determined by its vital functions as a glycon and fat storage unit. Pancreas is present.

12. Alimentary canal starts with mouth and it is transverse aperture it is bounded with two jaws (upper and lower) The jaws has bear teeth (sharp and pointed). Mouth leads buccal cavity and the floor of the buccal cavity has a tongue. Oral glands- some reptiles secrete poison Buccal cavity followed pharynx and then oesophagus (narrow tube) it opens into stomach. intestine coiled small intestine and relatively short large intestine chamber at the end of digestive tract is called cloaca

13. Salivary glands- Unicellular, inside buccal cavity, secrete saliva Mucous glands- Unicellular, inside buccal cavity, secrete mucous Liver- size large & two lobes, secrete bile and it is stored at gall Bladder. Gall bladder is small in size attached with liver and it function is reservoir of bile. Pancreas- flat and elongated, secretes pancreatic juice which contain enzymes such as trypsin , amylopsin and lipase. Gastric glands- unicellular located inside stomach, secrete enzymes. Parietal glands- these are unicellular located inside the stomach secrete hydrochloric acid.

14. Birds has faster and more efficient digestive system than those of other vertebrates. their beaks or bills replace the lips and mouth of mammals and vary in shape. their tongue do helps manipulate food for swallowing. food passes through oesophagus on its way to stomach. Crop found only seed eating birds, it serves as food reservoir. Pigeons secretes pigeons milk and mucous. Birds have a two part of stomach. granular portion known as Proventriculus and the muscular portions known as Gizzard.

15. Digestive System of Bird

16. The mammalian digestive system consists of the alimentary canal (complete digestive tract and various accessory glands that secrete digestive juices into the canal through the ducts. The food is moved along the tract by the contraction of smooth muscles in thee wall of the canal. These rhythmic contraction waves are called peristalsis. the regular of passage of materials from one chamber by ring like valves called sphincters. The accessory glands of the mammalian digestive tract are three pairs of salivary glands, the pancreas, the liver and the storage organ the gall bladder.

17. Mouth: foodstuffs are broken down mechanically by chewing and saliva is added as a lubricant Pharynx: Out throat is the pharynx which leads to both he oesophagus and the windpipe(trachea). when a human swallows the top of the windpipe moves up so that its opening, the glottis, is blocked by a flap of cartilage called epiglottis. this help to ensure that the bolus enters the oesophagus. Oesophagus: a simple conduit between the mouth and stomach-important but only marginally interesting Stomach: where the real action begins- chemicals digestion of protein initiated and foodstuffs reduced to liquid form.

18. Liver: The centre of metabolic activity in the body- its major role in the digestive process is to provide bile salts to the small intestine which are critical for digestion and absorption of fats Pancreas: important roles as both an endocrine and exocrine organ.- provides a potent mixture of digestive enzymes to the small intestine which are critical for digestion of fat, carbohydrates and protein. Small intestine: the most exciting place to be in the entire digestive system. this is where the final stages of chemical digestion occur and where almost all nutrients are absorbed.

19. Large intestine: Major difference among species in extent and importance in all animals water in absorbed., bacterial fermentation takes place and feces are formed. in carnivores, that's about the extent of it, but in herbivores like the horse, the large intestine in huge and of critical importance for utilization of cellulose.

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