Digestive system of fish

Digestive system of fish

1. DIGESTIVE SYSTEM OF FISH OCN-1207 Marine Vertebrate

2. Presented By Group 1 Group 8 Samsun Naher BKH1718001F Bibhuti Chakma ASH1818037M Rahmat Ullah ASH1818047M Tanvir Hyder Shishir ASH1818057M Tanzim Akter BKH1818069F Zahid Hasan ASH1818036M Imtiaz Hossain ASH1818046M Sanjida Akter Nisa BKH1818056F Israt Mehe Jabin BKH1818067F Jannatul Kubra Afrin BKH1818077F

3. Digestion Digestion is the process of modifying and/or hydrolyzing feed and food polymers into molecules and elements that can be absorbed across the intestinal wall. In fish digestion, fish ingest food through the mouth and break it down in the esophagus. The intestine completes the process of digestion and nutrient absorption. Feeding is the first process of digestive system.

4. Digestive system Digestive system is the system by which ingested food is acted upon by physical and chemical means to provide the body with absorbable nutrients and to excrete waste products; in mammals the system includes the alimentary canal extending from the mouth to the anus, and the hormones and enzymes assisting in digestion. The structural components of a fish's digestive system include the mouth, teeth and gill rakers , esophagus, stomach, pylorus, pyloric caeca, pancreatic tissue (exocrine and endocrine), liver, gall bladder, intestine and anus. A fish's digestive system is adapted to their food habits.

5. Feeding mechanism Aquatic feeding mechanisms face a special difficulty as compared to feeding on land, Because the density of water is about the prey tends to be pushed away when the mouth is closed. Types of Mechanisms: Filter feeding Ram feeding Suction feeding Protrusion Pivot feeding

6. Filter feeding In filter feeding, the water flow is primarily generated by the organism itself, for example by creating a pressure, by active swimming, or by ciliary movements. Krill feeding under high phytoplankton concentration

7. Ram feeding Ram feeding, also known as lunge feeding, is a method of feeding underwater in which the predator moves forward with its mouth open, engulfing the prey along with the water surrounding it. Foraging Manta alfredi ram-feeding, swimming against the tidal current with its mouth open and sieving zooplankton from the water.

8. Suction feeding Suction feeding is a method of ingesting a prey item in fluids by sucking the prey into the predator's mouth. This is typically accomplished by the predator.

9. Lunge feeding Baleen whales feed on plankton by a technique called lunge feeding. Lunge feeding could be regarded as a kind of inverted suction feeding, during which a whale takes a huge gulp of water, which is then filtered through the baleens. School of adult Indian mackerel ram feeding on macroplankton Herring ram-feeding on a school of copepods

10. Protrusion Protrusion is the extension of the mouth or premaxilla towards the prey, via mechanical linkages. Protrusion is known only in modern bony fishes, which possess many forms of coupled linkages in their head. catching prey by protruding its jaw

11. Pivot feeding Pivot feeding is a method to transport the mouth towards the prey by an upward turning of the head, which is pivoting on the neck joint. Seahorses rely on stealth to ambush small prey such as copepods. They use pivot feeding to catch the copepod, which involves rotating their snout at high speed and then sucking in the copepod.

12. On the basis of feeding habits, the fishes are categorized- Herbivorous Carnivorous Omnivorous detrivorous

13. Herbivorous Herbivorous consume about 70% unicellular Algae, Filamentous algae And Aquatic plants. Herbivorous fishes have long and coiled intestine. Carnivorous The fishes in contrast to Herbivore have shorter gut, the intestine is straight, very little coils are present. Some of the carnivorous possess intestinal caecae . Parrotfish Barracuda

14. Omnivorous Omnivorous fishes are consuming both plant & animals. There gut length intermediates between carnivourous & herbivouras . Detrivorous They consume detrivorous alone with zooplanktons and phytoplanktons . The arrangement of gill rakers are such that it filters them from water.

15. The fishes can also be named on the basis of modification of buccopharynx Predator Grazers Strainers Suckers Parasitic

16. Predator They possess well developed grasping and holding teeth. Grazers They takes the food by bite. These fishes feed on plankton and on bottom organisms. Strainers They have effective straining or filtering adaptation due to the aregment of gill rakers forming sieve for straining the food material. Suckers The fishes have inferior mouth and sucking lips. Parasitic Almost fishes , the deep sea eel

17. BUCCOPHARYNX AND ITS MODIFICATION Non-tubular part

18. Non-tubular Part of Buccopharynx The Non-tubular part of alimentary canals are- Jaws Mouth Boccopharynx Pharyngeal organ Gill rakers

19. Jaws & Mouth The jaws hold the mouth. The main function of the jaws in vertebrate is helping in biting of food. In Fishes with suckers, the lips are mobile and plicate having fold or papillae. The mouth in some fishes is elongated as beak. .

20. Mouth Structure of Fishes

21. Mouth Structure of Fishes

22. Buccopharynx These modification are- Teeth Pharyngeal pad Gill rakers

23. Pharyngeal Organ It has two parts – A Caudal A blind sac

24. Gill rackers The gill rackers in both the cartilaginous and bony fishes have undergone specialization for feeding. The gill rackers allow the soil food to go to- gullet only water is allowed to pass through gills to outside.

25. BUCCOPHARYNX AND ITS MODIFICATION Tubular part

26. Esophagus Esophagus is the part of the alimentary canal which connects the throat to the stomach. In humans and other vertebrates it is a muscular tube lined with mucous membrane. The esophagus and stomach are separated by external constriction.

27. Stomach is the internal organ in which the major part of the digestion of food occurs, being (in humans and many mammals) a pear-shaped enlargement of the alimentary canal linking the oesophagus to the small intestine. The predatory and carnivore fishes have stomach. The cyprinidae family has no stomach but possesses intestinal bulb. Stomach

28. Division of Stomach Esox I Shape Anguilla J Shape Raja U Shape Cottus V Shape Mugil Y Shape CS- Cardiac stomach; I- intestine; M- mascle ; PS- pyloric stomach O- oesophagus

29. Intestine The intestines of fish consist of two segments, the small intestine and the large intestine. The small intestine is further divided into the duodenum and other parts. Provisory the proximal part of the intestine is known as duodenum, the middle, the ileum while the distal end is rectum. Intestine in fishes one continuous organ and its parts are usually differentiated histologically one by gradual changes in the nature of mucosal layers.

30. Intestinal caecae Fish caecae have no relationship with any caecal appendages of other Vertebrate. The caecae develop from intestinal wall, they should be designated as intestinal caeca instead of pyloric.

31. Rectum Morphologically there is no distinction between the intestine. Anus It is the posterior opening of alimentary canal. The region of the anus facing the exterior has the exterior has the epithelium continuous with the skin

32. Histology of Gut

33. Histology of Gut The gut is made up of usual four layers- 1. Serosa 2. Muscularis externa 3. Submucosa 4. Mucosa

34. The stomach possesses board mucosal folds subdivided into primary and secondary folds. The mucosa contains gastric glands-

35. In the Intestine, the mucosal, folds called villi, which have intestinal glands-

36. Innervation of Gut The alimentary canal of fishes is innervated by sympathetic and parasympathetic components of autonomic nervous system.

37. Metabolism of Fish

38. Metabolisms The term of metabolism is commonly used to refer specifically to the breakdown of food and it’s transformation into energy.

39. Consists of Metabolism Two process- Catabolism Anabolism

40. Importance factors of Metabolism Mainly metabolism itself relies on three factors- Respiration and Nutrition to supply metabolites. Osmoregulation Excretion to get rid of all the poisons and other waste products produce as side effects.

41. What makes up fish metabolism? The factors which can influence metabolism- Size Age Activity Condition Environment

42. Essential and Non-essential Amino acids of Fish’s metabolism : Essential Amino acid Arginine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophane Valine Non-essential Amino acid Alanine Asspergine Aspertic Acid Cystine Glutamic Acid Glutamine Glycine Proline Serinr Tyrosine

43. Gastro-intestinal Hormone In Fish Digestion

44. Gastrointestinal hormone Gastrointestinal hormones constitute a group of hormones produced from specialized endocrine cells of the stomach, pancreas and small intestine,which are secreted directly into the bloodstream. The gastrointestinal tract  ( digestive tract , GI tract ,  GIT ,  gt , or  alimentary canal ) is an organ system which takes in food, digests it to extract and absorb energy and nutrients, and expels the remaining waste as faces. The GIT of fish and other vertebrates are challenged with a diversity of functional demands caused by changes and differences in inputs and environmental conditions.

45. Major gastrointestinal hormones are Secretin, Cholecystokinin , Gastrin, Gastric Inhibitory Peptide(GIP) Vesoactive Intestinal Peptide(VIP) etc.

46. Secretin Secreted by the lining of the duodenum (S cells) in response to acid entering from the stomach. secretin acts on the pancreas to increase the output of bicarbonate, which neutralizes the acid. It also increases the release of enzymes from the pancreas and reduce gastric secretion.

47. Cholecystokinin Released by the duodenum (I cells) in response to fats and acid. cholecystokinin causes the gallbladder to squeeze bile into the duodenum It stimulates the production of pancreatic enzymes, which pass into the duodenum through the pancreatic duct.

48. Gastrin Secreted mainly by cells in the stomach, Gastric antrum (G cell) in response to eating food (especially protein) gastrin causes the stomach to produce more acid and stimulates contraction of muscle in the wall of part of the stomach, ileum, and colon. This contraction propels food through the digestive tract.

49. Gastric inhibitory peptide Secreted by the lining of the duodenum (K cells) Reduce gastric acid secretion and intestinal motility Stimulates insulin release

50. Vasoactive intestinal peptide (VIP) VIP is widely distributed throughout the central and peripheral nervous systems. Secreted from enteric nerve Increase water and electrolyte secretion from pancreas and gut. It simulates smooth-muscle relaxation, both in the alimentary tract and in the systemic vasculature. The VIP and PP are classified as candidate hormone.

51. Others Pancreas secrete two important hormone: Insulin Glucagon Insulin secreted from beta cell while glucagon secreted by alpha cell. Somatostatin is present in the stomach and pancreas of fishes. They are called paracrine substances. It differs from hormone because it diffuses locally to the target cell instead of releasing into blood. It inhibits the release of insulin and glucagon from the pancreas.

52. Digestion of carbohydrate

53. Carbohydrate The term carbohydrates was originally derived from a large group of Organic compounds occurring in foods and living tissues including sugars, Starch and cellulose. It contain hydrogen and oxygen in the same ratio as a water (2:1) and typically can be broken down to reduce energy in the animal body.

54. The enzymes which break down the carbohydrates in the gut of fishes are: Amylase Lactase Saccharsases /sucrase Cellulase.

55. Process of carbohydrate Digestion Mouth Stomach Pancrease and small intestine Large intestine (Colon) Amylase Starch Maltose Maltase Glucose Sucrose Sucrase Glucose+ Fructose

56. Digestion of Protein

57. Protein Proteins are large biomolecules, or macsomolecules , consisting of one or more long chains of amino acid residues. Protein is an important component of every cell in the body. Proteins is an important building blocks of bones, muscles, cartilage, skin and blood.

58. Enzymes that’s required for the digestion of Protein Pepsin (Stomach of carnivora's fishes) Trypsin ( Intestine [alkaline medium], Pancreas intestinal caecae ) Chymotrypsin Erypsin (Collection of peptidases are known as erypsin , found in intestine)

59. Digestion of proteins Protein digestion beings in fish mouth. The fishes which possess in stomach are generally carnivorous & secret pepsin enzyme from gastric mucosa. The pepsin is protease enzyme, it can break down protein. The stomach produce HCl, which is needed to activate protein digestion. The pancrease release trypsin, another digestive enzyme, into the small intestine. The protein molecules are reduced in size until they can pass through the intestinal wall. Once the protein molecules are reduced to their smallest component parts, they are ready to enter bloodstream.

60. Digestion of Lipid

61. Lipid A lipid is a biomolecule that is soluble in nonpolars solvents. Non-polar solvents are typically hydrocarbons used to dissolbe others neutrally occurring hydrocarbon lipid molecules that do not dissolve in water, including fatty acids, waxes sterols, fat-soluble vitamins.

62. For the digestion of Lipids lipases enzyme is required. Lipases enzyme is secreted as- Lingual lipases Pancreatic lipases Enteric lipases

63. Digestion of Lipid Pancreatic lipases is a powerful lipolytic enzyme. It’s digests triglycerides into monoglycerides. Lipase can break them into the smaller parts that can enter the intestinal vili for digestion. However, lipid digestibility varies between species & developmental stage, feeding rate, water temperature lipid source & its melting point.

64. Absorption of Fish

65. Absorption Absorption is the process by which one thing absorbs or is absorbed by another. Absorption efficiencies are about 97% for the protein fraction, and 91% for the total food consumed; they do not vary appreciably among the individuals of different body weights.

66. How Nutrients can enter absorptive cells? Nutrients can enter (or exit) absorptive cells following a concentration gradient by simple diffusion or via the paracellular route. Absorption of nutrients as studied in vitro generally appears to occur at a faster rate in tissues from the proximal intestinal regions compared to more distal regions in most but not all fish species studied for example, sturgeon.

67. Types of Absorption: Protein/Peptide/Amino Acid Absorption Lipid Absorption Carbohydrate Absorption Pigment Absorption Synthesis and Absorption of Vitamins Minerals Absorption Phosphorus Absorption Calcium Absorption Magnesium Absorption Iodide Absorption Iron Absorption

68. Protein/Peptide/Amino Acid Absorption The carnivorous European eel is the teleostean species in which nutrient transport processes have been most systematically studied. As indicated investigators suggest the presence of at least four distinct - dependent amino acid transport systems in the eel: an acidic, a basic and a neutral amino acid transport system, analogous to the mammalian systems  

69. Lipid Absorption The absorption of the various lipid classes in fish is not well understood but is presumed to occur as in mammals. Fatty acids released from the micelles are thought to be absorbed by diffusion or facilitated transport.

70. Carbohydrate Absorption In various fish species investigated, the monosaccharides D-glucose and D-galactose appear to be transported by the same transporter across the brush border membrane, SGLT1, and in a similar manner as in mammals

71. Minerals Absorption Minerals are important components of structural and physiological processes. Elements such as calcium, phosphorus and magnesium are required at high levels for bone and scale formation and also have critical roles in intracellular processes such as cell signaling and energy metabolism.