Mammalian Digestive system-1.pptx

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1. ZOO 102 Organization of Mammalian Body. TOPIC: Digestive system of Mammals. Lecturer: Dr O.O Okwa (Associate Professor). Department of Zoology and Environmental Biology Faculty of Science Lagos State University.

2. WHAT IS DIGESTION? Mechanical Breakdown Chemical Breakdown of organic foods into smaller units for absorption. To reduce or convert to a more absorbable form that can be transported to the cells for use.

3. IMPORTANCE OF FEEDING AND DIGESTION. Mammals must eat to survive. Mammals need to maintain their highly ordered and complex nature. They need to promote vital activities of the body like energy release, growth and repair, secretions, storage and maintenance of internal osmotic Ph. All other systems will not function properly e.g. respiratory, muscular etc

4. Type of Digestion in mammals. Extracellular Digestion. * The digestive system can also be referred to as the gut, gastrointestinal or digestive tract or alimentary canal. Large and bulky food particles can be ingested. Enzymes are secreted into gut and the products of their action absorbed and assimilated. More specialised and efficient digestive tract. Digestive tract is smaller compared to that of lower animals. Food waste easily discarded in a complete digestive system.

5. ORGANS OF THE DIGESTIVE SYSTEM (A tube that commences at the mouth and ends at the Anus). 1. ORAL CAVITY OR MOUTH: Beginning of the digestive tract or gut. Provided with teeth and tongue for grasping, masticating and swallowing the food. The tongue also captures and gathers food. Three pairs of salivary glands which secretes saliva (750mls daily in man) which contains the enzyme amylase (Ptyalin) which acts on Carbs . The three glands are submaxillary, parotid and sublingual.

6. 2. PHARYNX Throat cavity for passage of food. Secretes no enzyme. Complex reception chamber receiving five openings from *Nasal cavity *Mouth *Middle ear *Oesophagus *Trachea via epiglottis. So it is advisable not to talk when eating.

7. 3.OESOPHAGUS OR GULLET. Distensible muscular tube a.k.a food pipe. Between the pharynx and stomach. Has no digestive enzymes. Opens to the stomach at the cardiac sphincter . The oesophagus is about 8 inches long, and is lined by moist pink tissue called mucosa in man which is protective .

8. 4. STOMACH Found between the oesophagus and small intestine. Muscular chamber that receives recently ingested food. Secretes mucus and enzymes, gastric juice and Hydrochloric acid. Macerates ,sterilizes and initiates food digestion especially of protein Has three main regions Cardiac (anterior), Fundus (central ) and Pyloric (posterior).

9. THE MAMMALIAN STOMACH.

10. 5. THE SMALL INTESTINE. Principal digestive and absorptive area of the gut. Divided into Duodenum, jejunum, ileum (6.7m long in man ). Has four histological layers: Mucosa, Submucosa , Muscularis externae and Serosa or Peritoneum. Has finger like projections called microvilli which increases the surface area for absorption and assimilation.

11. 6.LARGE INTESTINE OR COLON . Larger in diameter but shorter in length(1.8m in man). Starts at the coelic caecum and the vestigial vermiform appendix (has immune defense). Has no microvilli but has lubricating glands. It has ascending, transverse and descending and sigmoid portions. It terminates in the rectum and anus which discharge feaces by muscular action. Escorts wastes from the body.

12. THE HUMAN DIGESTIVE SYSTEM .

13. ACCESSORY ORGANS OF DIGESTION. LIVER: Empties bile into the duodenum by way of the bile duct leading from the gall bladder where bile was stored. SPLEEN: Filter for blood. It helps ward off infections and maintains body-fluid balance. PANCREAS: Pancreatic juice are produced and goes to the duodenum by pancreatic duct. MESSENTERIES: This holds the stomach, intestines, liver, spleen and pancreas in place. They also carry blood and lymph and nerves to the abdominal organs.

14. PROCESS OF DIGESTION. Ingestion : Food intake. Digestion: Mechanical and chemical breakdown of food. Absorption and assimilation : Incorporation of digested food into system. Egestion: Expulsion of undigested food by defeacation.

15. DIGESTION IN THE MOUTH. Food is broken down mechanically by the teeth. Food is mixed with saliva (Ph 6.7-6.8) which contains enzyme amylase. Amylase acts on carbohydrate foods and splits into two glucose fragments. Saliva mucin lubricates food for ease of swallowing. The tongue pushes the food bolus towards the pharynx.

16. DIGESTION IN THE STOMACH. Gastric juice which contains Pepsinogen, pro-rennin ,lipase and HcL are secreted by reflex action. HcL activates Pepsinogen to enzyme pepsin and pro-rennin to rennin which is found in suckling mammals. HcL also lowers the Ph of the stomach(1.5-2.0) and sterilizes the stomach content There is hydrolysis of protein by pepsin which breaks peptide bond to give polypeptides. Products of digestion is now called Chyme.

17. DIGESTION IN THE SMALL INTESTINE. Bile (Ph 8) from the liver contains no enzymes but salts (sodium taurocholate and sodium glycocholate) reduces the surface tension of fats and enhances emulsification. Pancreatic juice neutralizes acidic Chyme from the stomach. contains Trypsin and Chymotrypsin which acts on protein. contains carbonxylpeptidase (splits amino acids), carbohydrase amylase and lipase which works more rapidly.

18. Intestinal juices Effective only in neutral or alkaline medium. Activators Secretin: stimulates flow of pancreatic juice. Cholescystokinin: contraction of gall bladder inhibitor Enterogastrone: inhibits acid secretion from stomach Enzymes: Aminopeptidase: splits off amino acids Maltase, sucrase, lactase and invertase Absorption : Food materials already broken down are absorbed into the bloodstream.

19. DIGESTION IN THE LARGE INTESTINE . Chyle more watery and low in nutrients is now in the L.I. Water and minerals are re-absorbed to form semi solid feaces (SSF). SSF consists of undigested food residue ,bile pigments, bacteria and heavy metals The bile pigments ( biliribin and biliverdin ) color the feaces. Egestion or defeacation, a co- ordinated muscular action by the rectal walls eliminates feaces via anus.

20. FEEDING MECHANISMS: Teeth & Tongue 1. Mammalian teeth. Heterodont (different types) & Diphyodont (2 successive)dentition. INCISORS : Biting, snipping and cutting. CANNINES: Seizing, piercing and tearing. PREMOLARS& MOLARS: Shearing, slicing, grinding and crushing. Toothless Mammals : Baleen whales, Monotremes , Anteaters, Pangolin

21. Exceptions Polyphyodont dentition : Teeth are replaced continuously throughout life e.g. Manatees, Elephants, Dugongs and Kangaroos Monophyodont dentition : Teeth are never replaced in life e.g. Beluga whale, Narwhal whale, Dolphin, Mice , Rat

22. TEETH STRUCTURE

23. 2. The Tongue The tongue is a muscular organ in the mouth of most vertebrates that manipulates food for mastication, chewing and is used in the act of swallowing as well as articulating speech. It is of importance in the digestive system and is the primary organ of taste in the gustatory system . The tongue also serves as a natural means of cleaning the teeth in non humans. . The tongue is used for crushing food against the hard palate , during mastication and manipulation of food for softening prior to swallowing .

24. Typically a human tongue is around 3.3 inches (8.5 centimeters) for men and 3.1 inches (7.9 cm) for women. Some animals have tongues that are specially adapted for catching prey. For example, insectivorous animals like chameleons , frogs , and anteaters have prehensile tongues. In mammals such as dogs and cats , the tongue is often used to clean the fur and body by licking and serve as a heat regulator.

25. Tongue structure The tongue is covered with moist, pink tissue called mucosa. The epithelium on the tongue’s upper, or dorsal surface is keratinised Tiny bumps called papillae give the tongue its rough texture dorsally but the bottom is smooth. Thousands of taste buds cover the surfaces of the papillae. 50 - 150 taste receptor cells inside each taste bud. Taste buds are collections of nerve-like cells that connect to nerves running into the brain It is sensitive and kept moist by saliva , and is richly supplied with nerves and blood vessels .

26. The Tongue in the mouth. .

27. The Tongue and taste The tongue has many nerves that help detect and transmit taste signals to the brain. All parts of the tongue can detect four major common tastes; the commonly described “taste map” of the tongue is a myth that doesn’t really exist. Different receptors taste different flavors, bunched in four places on the tongue The four common tastes are sweet, sour, bitter, and salty. A fifth taste, called umami , results from tasting glutamate (present in MSG). Good Taste increases appetite.

28. The Use of Prehensile Tongues : in mammals e.g. Giraffe and Pangolin

29. Caution : Strong teeth and healthy Tongue helps in mechanical digestion . Different receptors taste different flavors, these various receptors are bunched in four places on the tongue

30. FEEDING HABITS OF MAMMALS . HERBIVOROUS MAMMALS: Features of the digestive tract. Have well developed molars and long digestive tracts. Plants are more difficult to digest than flesh. Ruminants : (chew the cud) have four chambered stomach viz Omasum , Abomasum , reticulum and rumen e.g. Cattle, Antelope, some kangaroos Diverticulum : Horses and Rabbits have a pouch called diverticulum for fermentation and absorption of food.

31. 2. Feed on plant vegetation Browsers or grazers on grasses e.g. ungulates like Horses, Swine, Antelopes, Sheep, Goats , Zebra and Cattle. Gnawers and Nibblers on vegetation e.g. Rodents , Rabbits and Kangaroos

32. CARNIVOROUS MAMMALS. Feed on the flesh of other animals they capture They have very strong teeth e.g. Jaguar, Kodiak bear Highly developed canines and locomotive power Acute senses of smell and sight. Digestive tract are shorter and simple because meat is easy to digest e.g. Lions, Tiger, Foxes, Cheetah, Leopard, Killer whales, Polar bears

33. INSECTIVOROUS MAMMALS. Feed on insects : Moles, Shrew, Microbats, Anteaters, Raccoons, Pangolin, Armadillos . Giant panda Aardvark

34. OMNIVOROUS MAMMALS. *Live on both plant and Animal food. *All teeth well developed Pigs Rats NP-Bears Primates Sug.gliders Man.

35. Diverse kinds of mammalian digestive system.

36. NUTRITION IN MAMMALS. Nutrition is the sum of the processes by which living organism receives food materials from there environment and uses them to promote vital activities. Such materials are called Nutrients. Organic nutrients are Carbohydrates, Protein, Fats & oils and Vitamins. Inorganic nutrients are mineral salts and water. A balanced diet must contain all these nutrients in the right proportion.

37. ORGANIC NUTRIENTS AND FUNCTIONS: They are obtained from living organisms Carbohydrates *Fuel for energy demands of the body. *Synthesis of various substances and structures like protoplasmic. *Stored temporary as glycogen in the liver. *They supply heat as a result of burning activity.

38. DEFICIENCY AND SOURCES OF CARBOHYDRATES. Deficiency: Fatigue due to insufficient glucose Sources * Starches from plant food e.g. rice, yam, maize *Sugars e.g. glucose, fructose, galactose, sucrose, lactose, maltose and cellulose.

39. PROTEIN AND FUNCTIONS . Needed for synthesis of body protein and other nitrogen compounds in the body. They contain amino acids which are constituents of body tissue and replacement of tissue. They are required for production of enzymes, hormones, haemoglobin and plasma proteins. Source of energy in place of carbohydrates.

40. DEFICIENCY AND SOURCES OF PROTEIN. Marasmus : General undernourishment. Kwashiorkor : Protein malnourishment. Ill health, impaired development, wound healing and increased susceptibility to infection. Sources First class protein: Animal sources e.g. beef, fish Second class protein: Plant sources e.g. beans, soya milk

41. FATS AND OILS FUNCTIONS. Provide energy and heat for the body. Hold vital organs in place and protect from injury. Essential constituents of protoplasm and precusor for prostaglandins hormone. Has good satiety value and slows hunger. Subcutaneous fat acts as insulators preventing loss of heat. Assist in Absorption of the fat soluble vitamins (ADEK).

42. DEFICIENCY AND SOURCES OF FATS AND OILS Deficiency occurs only in malabsorption of fats. Patients fed intravenously without fat for a long time. Saturated fats might cause Arteriosclerosis. Sources Saturated fat: Animal fat e.g. mutton, butter, cheese Unsaturated fat: Plant fat. e.g. vegetable oil.

43. Vitamins: Fat soluble TYPES OTHER NAMES FUNCTIONS DEFICIENCY SOURCES A (A1 & A2) Retinol Healthy epithelial tissue & Normal cell growth Visual photochemistry Dark adaptation Developments of bones and teeth Smooth skin Mucous membrane infections Keratomalacia Night blindness Xeropthalmia or dry eye Growth retardation Dried and rough skin. Carrots Green and yellow Leafy Vegetables. D (D2 & D3) Calciferol, Sunshine vitamin Absorption of calcium from intestine and calcification of the skeleton. Rickets in children Osteomalacia in adults Dental caries. Skin irradiation with U.V Sunlight E Tocopherol, Antisterility vitamin Reproduction, body tissues and membranes. Sterility and abortion muscular weakness, anaemia Green plant tissues, grains K Antihaemorragic vitamin Blood clotting, prevents neonatal breeding and haemorrage. Bleeding, anaemia, haemorrage, less ability for blood clot. Green vegetables. Tomatoes.

44. VITAMINS : WATER SOLUBLE Types Other names Functions Deficiency Sources B1 Thiamine Co-enzyme in pyruvate metabolism Nervous system degeneration (Beriberi),cessation of growth and heartbeat. Eggs ,cereals yeast. B2 Riboflavin Flavoprotein co-enzyme Non specific digestive disturbances and ariboflavinosis Milk, yeast, cereals. B3 Niacin. Maintains nervous system & digestion, carbohydrate metabolism and keeps the skin healthy. Pellagra, dermatitis Nervous disorders, loss of appetite Green leaves yeast, kidney, cereals, eggs B12 Cyanocobalamin Red blood formation and treatment of pernicious anaemia. Pernicious anaemia Liver, Kidney Heart Bacteria in stomach C Ascorbic acid Formation of connective tissue,collagen fibres, RBCs. necessary for wound healing and protein metabolism. Unite bones. Scurvy. haemorrage Bone degeneration and anaemia. Death may occur. Citrus fruits Tomatoes Fresh veggies Black currant,

45. INORGANIC NUTRIENTS: are not obtained from living organisms . * Mineral salts Calcium: For Bones, teeth,nerves,heart& blood. Iron: For Haemoglobin and enzymes. Phosphorus : For Bones and Teeth Iodine : Prevents goitre of thyroid gland. Fluorine: For teeth and skeleton Sodium: For blood plasma and osmotic balance. Potassium: Present in body cells Zinc: for wound healing and growth. Magnesium: For soft tissues, teeth and bones. Copper : Promotes RBC production with iron.

46. WATER AS AN IMPORTANT INORGANIC NUTRIENT. Involved in chemical reactions of the body. Basis of intra and extra cellular fluids. Aids digestion and excretion. Protoplasmic constituent. Constituents of body secretions and excretions. Universally taken to quench thirst. Prevents friction of joints in lubricating fluids like synovial fluid. 65-70% of total body weight.

47. THANKS FOR LISTENING . Hope you enjoyed the lecture? Any comments or questions?