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The digestive system [2010].pptm
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- 2. M.Bregar (mbregar@gmail.com) 2 Digestive System: group of organs which processes food mechanically & chemically, so it can be absorbed into the circulatory system. Processing of food takes place across the alimentary canal in distinct stages.
- 3. M.Bregar (mbregar@gmail.com) 3 Events taking place can be classified as:
- 4. M.Bregar (mbregar@gmail.com) 4 The stages are: Ingestion: Food enters into the system. Digestion: Break down of food into simpler forms, allowing for absorption. Is both mechanical & chemical. Absorption: The movement of nutrients into the circulatory system. Means nutrients have entered into the blood. Egestion / Excretion: The elimination of waste materials. Any food material not processed is eliminated as fecal matter.
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- 6. M.Bregar (mbregar@gmail.com) 6 After ingestion, carries food through digestion until excretion Food is moved through the canal via smooth muscle Various enzymes will enter into the tube at different points to process food chemically.
- 7. M.Bregar (mbregar@gmail.com) 7 The digestive system processes nutrients into more usable forms. Nutrients: any material needed by an organism to live and grow. Think of nutrients as providing the building materials & energy to make and sustain life.
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- 9. M.Bregar (mbregar@gmail.com) 9 Nutrients can be classified as: Micronutrients Macronutrients Materials used by living organisms for growth & energy. Substances which help carry out metabolism including: Vitamins Minerals Water
- 10. M.Bregar (mbregar@gmail.com) 10 Macronutrients are broken down into 3 basic groups.
- 11. M.Bregar (mbregar@gmail.com) 11 Proteins Carbohydrat es Preferred energy source. Known as saccharides (sugars: simple vs complex) Broken down into amino acids Used for growth, repair, and in life Fats Known as lipids Used in making tissue & hormones. Important for body’s
- 12. M.Bregar (mbregar@gmail.com) 12 Breakdown of food into simpler forms by chemical means. For Example: Carbohydrates are broken down into simple sugars Proteins are broken down into peptides and amino acids Fats become emulsified, eventually forming fatty acids Chemical digestion is made possible by biological catalysts referred to as enzymes which are specific.
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- 15. M.Bregar (mbregar@gmail.com) 15 Enzymes are protein molecules which assist in carrying out metabolic activity (chemical reactions), including chemical digestion.
- 16. M.Bregar (mbregar@gmail.com) 16 Enzymes are involved in the catabolic (break down) and anabolic (building) reactions which take place in metabolism.
- 18. M.Bregar (mbregar@gmail.com) 18 The speed at which a chemical reaction takes place is referred to as a rate of reaction. Reaction rates can be increased or decreased…
- 19. Using HEAT to speed up reactions 19 M.Bregar (mbregar@gmail.com)
- 20. SURFACE AREA & Chemical Reactions 20 M.Bregar (mbregar@gmail.com)
- 21. M.Bregar (mbregar@gmail.com) 21 Problem: Why can’t we use heat to speed up chemical reactions in the body?
- 22. M.Bregar (mbregar@gmail.com) 22 An enzyme’s 3 dimensional shape is key to enzymes completing activities.
- 23. M.Bregar (mbregar@gmail.com) 23 A protein whose shape has changed, loses its ability to function. This is called denaturation Human proteins denature at _______________
- 24. M.Bregar (mbregar@gmail.com) 24 At what temperature is enzyme activity optimal?
- 25. M.Bregar (mbregar@gmail.com) 25 What can you conclude about a thermophiles natural environment?
- 26. M.Bregar (mbregar@gmail.com) 26 The physical break down of food into smaller pieces. Purpose: to increase surface area, which increases reaction rates.
- 28. M.Bregar (mbregar@gmail.com) 28 Ingestion takes place once food enters into the mouth.
- 30. M.Bregar (mbregar@gmail.com) 30 Many organisms use teeth to masticate food with the purpose of increasing surface area.
- 31. M.Bregar (mbregar@gmail.com) 31 There are different types of teeth…
- 32. M.Bregar (mbregar@gmail.com) 32 Types of teeth found in an organism are a reflection of diet.
- 33. M.Bregar (mbregar@gmail.com) 33 The classes of teeth are: Canine Molars Pre-Molars Incisors Functions?
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- 35. The release of saliva, begins chemical digestion. 35
- 36. M.Bregar (mbregar@gmail.com) 36 Saliva secretion is under the control of the autonomic nervous system. It is produced by the salivary gland.
- 37. M.Bregar (mbregar@gmail.com) 37 Produced by the salivary gland. Saliva is a mixture of water, mucus, saliva, enzymes, and antibacterial compounds Tissue involved?
- 38. M.Bregar (mbregar@gmail.com) 38 Main functions include: Chemical digestion of carbohydrates. Lubrication & Binding of Food into a Bolus Allows for tasting?
- 39. M.Bregar (mbregar@gmail.com) 39 Other functions, can include evaporative cooling and oral hygiene depending on species.
- 40. 40 Food Leaves The Mouth M.Bregar (mbregar@gmail.com)
- 41. 41 The tongue shapes the food into a bolus The bolus is pushed into the esophagus
- 42. M.Bregar (mbregar@gmail.com) 42 A muscular tube which connects the pharynx to the stomach.
- 43. M.Bregar (mbregar@gmail.com) 43 Made of smooth muscle. Peristalsis: the contraction of smooth muscle pushing food down into stomach. Voluntary or Involuntary?
- 44. 44 DIGESTION & THE STOMACH M.Bregar (mbregar@gmail.com)
- 45. M.Bregar (mbregar@gmail.com) 45 A muscular bag (3 layers) lined with epithelial cells. Mechanical Digestion takes place as the food is churned.
- 46. M.Bregar (mbregar@gmail.com) 46 Rugae allow the stomach to stretch…
- 47. M.Bregar (mbregar@gmail.com) 47 The stomach has the ability to stretch. Rugae Folds of stomach wall lining Allows for increase in stomach volume
- 48. M.Bregar (mbregar@gmail.com) 48 As the stomach fills, receptors send impulses to the brain to indicate “fullness”
- 49. M.Bregar (mbregar@gmail.com) 49 Gastric glands in the stomach wall release gastric juice, so the stomach contains: Protease enzymes are released for the chemical digestion of proteins Hydrochloric Acid: destroys bacteria, activates enzymes. The stomach is lined with protective mucus.
- 50. M.Bregar (mbregar@gmail.com) 50 The digested bolus is now called chyme, and is slowly released into the small intestine. The movement of chyme is regulated by sphincter muscles. Note: some absorption does occur
- 52. M.Bregar (mbregar@gmail.com) 52 The intestines are classified into the small intestine and large intestine.
- 53. M.Bregar (mbregar@gmail.com) 53 The small intestine continues digestion and begins the process of absorption. The liver & pancreas help maximize absorption.
- 54. M.Bregar (mbregar@gmail.com) 54 Has 3 separate sections, each with unique function, they are the: Duodenum, Jejunum, Ileum.
- 55. M.Bregar (mbregar@gmail.com) 55 Chemical breakdown of chyme continues with the release of secretions from the pancreas and liver.
- 57. M.Bregar (mbregar@gmail.com) 57 Secretions released include Bile Responsible for emulsifying lipids. Produced by the liver, stored in the gall bladder Pancreatic Juice An alkaline mixture secreted by the pancreas, consists of: Enzymes Bicarbonate
- 58. M.Bregar (mbregar@gmail.com) 58 Bile contains various chemicals which can lead to the formation of gallstones.
- 60. M.Bregar (mbregar@gmail.com) 60 2nd largest organ in the body, with many additional functions, including: Waste Blood Regulation Regulation
- 61. M.Bregar (mbregar@gmail.com) 61 A multifunctional organ involved in the digestive and endocrine systems.
- 62. M.Bregar (mbregar@gmail.com) 62 Specific functions include: Digestive System Secretions complete the digestion of protein, carbohydrates, and fats. Secretions neutralize stomach acid. Endocrine System Secretes hormones that control blood sugar levels. Glucagon Insulin Somatostatin
- 63. M.Bregar (mbregar@gmail.com) 63 The location of the majority of absorption. Absorption is the movement of nutrients into the circulatory system
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- 65. M.Bregar (mbregar@gmail.com) 65 Inner surface of the small intestine are built to maximize absorption, they contain villi.
- 67. M.Bregar (mbregar@gmail.com) 67 Contain blood vessels and lacteals: Lacteals: Blood Vessels:
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- 69. M.Bregar (mbregar@gmail.com) 69 Final portion of the small intestine, absorption continues through villi. Leftovers (waste) are compacted, passing through the cecum into the large intestine.
- 70. M.Bregar (mbregar@gmail.com) 70 Main function is the absorption of water & electrolytes from the indigestible food. Vitamins: ___________ are absorbed. Mucus is secreted, binding the dehydrated waste into feces.
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- 73. M.Bregar (mbregar@gmail.com) 73 After approximately 50 hours, egestion occurs at which point defecation occurs. Waste materials are eliminated in the form of feces.
- 74. M.Bregar (mbregar@gmail.com) 74 Final portion of large intestine, which is a temporary storage area for feces. When full, the anal sphincter looses, allowing feces to pass through the anus exiting the body.
Hinweis der Redaktion
- The whole process can takes approximately 40-50 hours.
- Metabolism – the chemical reactions which take place in the body.Dietary minerals are generally trace elements, salts, or ions such as copper and iron. Some of these minerals are essential to human metabolism.Vitamins are organic compounds essential to the body. They usually act as coenzymes or cofactors for various proteins in the body.Water is an essential nutrient and is the solvent in which all the chemical reactions of life take place.
- Carbohydrates: simple sugars & complex sugars.
- Enzymes are
- Enzymes are
- Enzymes are
- For most enzymes the optimum temperature is about 30°C.Many are a lot lower, cold water fish will die at 30°C because their enzymes denature.A few bacteria have enzymes that can withstand very high temperatures up to 100°C.Most enzymes however are fully denatured at 70°C.
- Secretion of saliva is under control of the autonomic nervous system, which controls both the volume and type of saliva secreted. This is actually fairly interesting: a dog fed dry dog food produces saliva that is predominantly serous, while dogs on a meat diet secrete saliva with much more mucus. Parasympathetic stimulation from the brain, as was well demonstrated by Ivan Pavlov, results in greatly enhanced secretion, as well as increased blood flow to the salivary glands.
- Most animals have three major pairs of salivary glands that differ in the type of secretion they produce:parotid glands produce a serous, watery secretionsubmaxillary (mandibular) glands produce a mixed serous and mucous secretionsublingual glands secrete a saliva that is predominantly mucous in characterThe basis for different glands secreting saliva of differing composition can be seen by examining salivary glands histologically. Two basic types of acinar epithelial cells exist:serous cells, which secrete a watery fluid, essentially devoid of mucusmucous cells, which produce a very mucus-rich secretionAcini in the parotid glands are almost exclusively of the serous type, while those in the sublingual glands are predominantly mucus cells. In the submaxillary glands, it is common to observe acini composed of both serous and mucus epithelial cells.
- Lubrication and binding: the mucus in saliva is extremely effective in binding masticated food into a slippery bolus that (usually) slides easily through the esophagus without inflicting damage to the mucosa. Saliva also coats the oral cavity and esophagus, and food basically never directly touches the epithelial cells of those tissues.Solubilizes dry food: in order to be tasted, the molecules in food must be solubilized.Oral hygiene: The oral cavity is almost constantly flushed with saliva, which floats away food debris and keeps the mouth relatively clean. Flow of saliva diminishes considerably during sleep, allow populations of bacteria to build up in the mouth -- the result is dragon breath in the morning. Saliva also contains lysozyme, an enzyme that lyses many bacteria and prevents overgrowth of oral microbial populations.Initiates starch digestion: in most species, the serous acinar cells secrete an alpha-amylase which can begin to digest dietary starch into maltose. Amylase is not present, or present only in very small quantities, in the saliva of carnivores or cattle.Provides alkaline buffering and fluid: this is of great importance in ruminants, which have non-secretory forestomachs.Evaporative cooling: clearly of importance in dogs, which have very poorly developed sweat glands - look at a dog panting after a long run and this function will be clear.
- Evaporative CoolingAs the liquid forms a gas, the remaining liquid contains less energy (in other words, the molecules are moving more slowly), which means it is cooler. This can cool the skin and, therefore, the blood supply under the skin.By panting, dogs (and other animals such as gazelles and birds) use evaporative cooling to lower their body temperature. Some saliva on the tongue evaporates, while some cools. The saliva comes into contact with blood vessels in the tongue, which effectively cools the blood. This cooler blood then travels to cool organs.Oral HygieneRemoves food particles, keeps food from getting trapped and stuckContains antibacterial agents such as secretorylgA and lysosome LgA =Lysosome =
- Rugae or gastric foldsThe rugae allow the stomach to stretch, to increase volume.
- HypothalamusRegulates satiety Negative feed back system with use of nerves and hormones Stretching of stomach wall, sends signals to brain to taper off eatingHormone ghrelin triggers a hunger response, so this is decreased.OvereatingOccurs when your not paying attention to body signals, eating more than physically required.When your not enjoying food, your overeating (mechanical eating)Feeling sluggishFeeling bloated, stretched stomach.
- gastric gland, any of the branched tubules in the inner lining of the stomach that secrete gastric juiceand protective mucus.There are three types of gastric glands, distinguished from one another by location and type of secretion. The cardiac gastric glands are located at the very beginning of the stomach; the intermediate, or true, gastric glands in the central stomach areas; and the pyloric glands in the terminal stomach portion. Both the cardiac and pyloric glands secrete mucus, which coats the stomach and protects it from self-digestion by helping to dilute acids and enzymes.Stomach EnzymesPepsin is the main gastric enzyme. It breaks proteins into smaller peptide fragmentsGelatinase, degrades type I and type V gelatin and type IV and V collagen, which are proteoglycans in meat.Gastric amylase degrades starch, but is of minor significance.Gastric lipase is a tributyrase by its biochemical activity, as it acts almost exclusively on tributyrin, a butter fat enzyme.Pepsin enzyme is secreted by gastric glandsRenin enzyme change the liquid milk to solidAcid: Hydrochloric acid is secreted from parietal cells into the lumen where it establishes an extremely acidic environment. This acid is important for activation of pepsinogen and inactivation of ingested microorganisms such as bacteria.
- The stomach does do some absorption too.Some medicines (i.e. aspirin), water and alcohol are all absorbed through the stomach.
- Intestines are 17 to 35 feet. Majority of that is small intestine.
- Shortest part of the intestine (15 inches in humans).Regulates release of chyme via hormones (secretin & cholecytokini)
- Bile a complex fluid containing water, electrolytes and bile acids, cholesterol, phospholipids and bilirubin. Up to 800ml is made by daily, by humans.Functions: bile acids / salts allow for the breakdown and absorption of fats, including fat-soluble vitamins. The bile can contain waste products (bilirubin) which is then eliminated with the feces.Bilirubin – waste product of catabolism of red blood cells.Pancreatic JuiceSecreted by the pancreasVarious enzymes (proteases, lipases, and amyliase) including trypsinogen, chymotrypsinogen, elastase, carboxypeptidase, pancreatic lipase, nucleasesand amylase.maltase cleaves maltose into two molecules of glucoselactase cleaves lactose into a glucose and a galactosesucrase cleaves sucrose into a glucose and a fructose
- Gallstones form when cholesterol and other things found in bile make stones. They can also form if the gallbladder does not empty as it should. People who are overweight or who are trying to lose weight quickly are more likely to get gallstones.Symptoms:-mild pain in the pit of your stomach or in the upper right part of your belly. Pain may spread to your right upper back or shoulderblade area. Sometimes the pain is more severe. It may be steady, or it may come and go. Or it may get worse when you eat.-May have fever and chills.
- There are two distinct sources that supply blood to the liver:Oxygenated blood flows in from the hepatic artery.Nutrient-rich blood flows in from the hepatic portal vein.The liver holds about 13 percent of the body's blood supply at any given moment. The liver consists of two main lobes, both of which are made up of thousands of lobules. These lobules are connected to small ducts that connect with larger ducts to ultimately form the hepatic duct. The hepatic duct transports bile produced by the liver cells to the gallbladder and duodenum (the first part of the small intestine).FunctionsBile production (carries waste, breaks down waste)Blood Regulation (remove waste, produces proteins for plasma, regulates blood clotting, regulate amino acid levels in blood)Waste Regulation (remove waste from blood, conversion of ammonia to urea waste product of protein digestion) Metabolic activity (glucose into glycogen, production of proteins/cholesterol for fat transportationProcessing of hemoglobin for use of its iron content (The liver stores iron.)
- Contains Islets of Langerhans, which are cells that release:Glucagonraises the level of glucose (sugar) in the bloodInsulin stimulates cells to use glucoseSomatostatinmay regulate the secretion of glucagons and insulin
- Lacteals:Vessels (capillary) of lymphatic systemAbsorbs fats, which form a milky substance referred to as chyle (lymph, fats, and fatty acids)Absorbs glycerol Lacteals merge into larger vessels At thoracic duct, chyle is dumped into blood stream.Liver takes overBlood VesselsAbsorb glucose and amino acids
- Can be about 2-4 m.Villi are shorter.Cecum is the beginning of the large intestine. Receives waste materials which will become fecal matter.Separated from the small intestine by the ileocecal valve
- Takes about 16-32 hours for passage through large intestine. About 1.5L of chyme passes through the valve.Vitamins are absorbed – K, B12, thiamine, and riboflavin K – important for blood clotting B12 - Thiamine - Riboflavin - Vitamins are made by colonic bacteria. Mucus also protects epethilial cells.
- Normal feces are roughly 75% water and 25% solids. The bulk of fecal solids are bacteria and undigested organic matter and fiber. The characteristic brown color of feces are due to stercobilin and urobinin, both of which are produced by bacterial degradation of bilirubin. Fecal odor results from gases produced by bacterial metabolism, including skatole, mercaptans, and hydrogen sulfide.