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DIGESTIVE SYSTEM Chapter 3 The digestive system consist of the Alimentary Canal….a tube that stretches from the mouth to the anus … and three accessory.

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Presentation on theme: "DIGESTIVE SYSTEM Chapter 3 The digestive system consist of the Alimentary Canal….a tube that stretches from the mouth to the anus … and three accessory."— Presentation transcript:

1 DIGESTIVE SYSTEM Chapter 3 The digestive system consist of the Alimentary Canal….a tube that stretches from the mouth to the anus … and three accessory organs –Liver –Gall bladder –Pancreas The following image shoes entire system

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3 Alimentary Canal Structure The Alimentary canal is organized into 4 functional layers: Mucosa: Submucosa Muscularis Serosa

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5 Mucosa: This is the site of mucous production The mucous aids in transportation, protection and absorption of nutrients

6 Submucosa It lies directly under the mucosa and contains VANL (vein, artery, nerve and lymphatic supply) It might also contain specialty glands

7 Muscularis The muscularis is composed of two layers of smooth muscle Circular layer Longitudinal layer These two layers works together rhythmically to create peristalsis to move food along.

8 Serosa The serosa is the most external layer It secretes a viscous fluid that helps to reduce friction so that our parts can slip/slide past each other

9 From the Beginning Lets start from the beginning (oral cavity) and work our way to the finish (anus)

10 The Oral Cavity

11 Structures for Study Labia Tongue Teeth Salivary glands Palate A lot of structures are found in the mouth…these are the ones we are going to examine

12 Labia (lips)

13 Function(s) The lips are a sensory organ that detect temperature….reduce the risk of burning In terms of digestion, labia also help to keep food in the mouth

14 Tongue Gustatory organ: taste Needed for food placement Needed for proper swallowing Library.thinkquest.org

15 Taste sweet salty bitter sour

16 Taste cont And for some reason power point would not let me add to the last slide Our fifth type of taste is umame (savory) and that occurs over the entire tongue Taste is regulated by the taste buds

17 Taste bud

18 Taste Buds They are embedded within the bumps on the tongues surface. They detect chemical concentrations The tip of the tongue detects sweet/salty Laterally it detects sour The rear of the tongue is bitter The entire tongue is umame (savory)

19 Library.thinkquest.org

20 Tongue Used for Swallowing

21 Teeth (Dentition) Our teeth allows us to be omnivores We have teeth for cutting, tearing and grinding This ability to be an omnivore is what has made us successful as a species Teeth are used for Mastication (chewing)

22 Tooth Development Primary Teeth (deciduous ) This is our first set….they erupt from 4-6 months and begin to fall out at 6-7 yrs We have 20 primary teet 4 central incisors 4 lateral incisors 4 cuspids 4 primary molars 4 secondary molars

23 Secondary Teeth (permanent) These are our adult teeth All of them should be in by of these 4 central incisors4 lateral incisors 4 cuspids8 bicuspids (premolars) 4 primary molars4 secondary molars 4 tertiary molars

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25 Salivary Glands Three groups –Parotid: Cheek area on top of Masseter muscle –Submandibular: found at the floor of the mouth –Sublingual: found at the floor of the mouth

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27 Function(s) of Salivary Glands Secrete slaiva Saliva is mixed with food to create a bolus Within saliva we find two prominent enzymes: –Salivary amylase: dissolves carbohydrates –Lingual Lipase: dissolves triglyverides

28 Enzymes In our bodies, enzymes are protein based chemicals that speed up chemical reaction rate and decrease activation energy. Because they are protein based, the can be denatured (change shape) and that disrupts function

29 Denaturing Enzymes can be denatured with changes in –pH: to much acid or base can change their shape –Temperature: Increases in temperature can destroy enzymes…e.g., high fever

30 Role of Enzymes In the digestive system, enzymes are utilized to reduce macronutrients into a more absorbable micronutrient Okay…..back to the oral cavity

31 Palate This is the roof of the mouth Divided into the hard and soft palate Functions to separate the oral and nasal cavities Cleft Palate is developmental dysfunction of the palate Please google some images of cleft palate

32 Pharynx

33 Divisions Nasopharynx: back of the nasal cavity Oropharynx: back of the throat Laryngopharynx: top of throat Pharynx functions as common passageway for respiratory and digestive systems

34 Esophagus Tube extending from laryngopharynx to the stomach First instance of sphincters in digestive systems

35 The Omentum The entire gut is covered by a fatty protective sheet called the Greater Omentum

36 Sphincters Sphincters are ring like structures that close tubes to controls flow

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38 Stomach

39 Stomach Cont The stomach is a j-shaped organ designed to hold 1 liter of food and fluid It is divided into 4 regions (see image): –Cardia –Fundus –Body –pylorus

40 Sphincters of Stomach Cardiac or Lower Esophageal Sphincter: prevents back flow of food from stomach to the esophagus Pyloric Sphincter: controls gastric (stomach) emptying

41 Gastric Pits The stomach is lined with gastric pits These pits increase surface area and contain specialty cells

42 Gastric Pit Cells Mucous cells: secrete huge amounts of protective mucous Parietal cells: secrete hydrochloric acid (HCl) and intrinsic factor…what are the functions of these chemicals? Chief cells: secrete pepsinogen and gastric lipase (function?) g- cells: secrete Gastrin ( function?)

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44 Function(s) of the Stomach The stomach takes the bolus from the mouth and mixes it with gastric juice to create chyme It allows absorbs some nutrients…water Food typically stays in the stomach for 1-3 hours Describe gastric bypass surgery

45 Small Intestines

46 Divisions of the Small Intestines Duodenum: first 15 or so inches of the S.I. it is the where the accessory organs enter the digestive system. It is the workhorse of the gut Jejunum: middle third. Site of nutrient absorption Ileum: the end of the S.I. get huge production of mucous in this division…and some absorption

47 Mesentary

48 The mesentary anchors the small intestines to the body. It holds a lot of VANL suppy for the digestive system

49 Accessory Organs Liver Gall bladder Pancreas

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51 Liver Divided into 4 lobes and is anchored back to the diaphragm via the Falciform Ligament

52 Functions Produces bile Metabolizes micronutrients Detoxifies the blood Stores nutrients Destroys old red blood cells

53 Gallbadder Small sac that sits underneath the liver It stores and concentrates bile It secretes bile via the common bile duct into the duodenum

54 Bile Is a cholesterol based product that emulsifies dietary fat It breaks fat down into micelles so that the fat can be suspended in water and has more surface area for enzymes to act upon it

55 Pancreas Functions as an exocrine and endocrine gland

56 Exocrine Gland Secrete their product through a duct to the outside of the body or into a hollow organ The pancreas secretes digestive enzymes and sodium bicarbonate into the duodenum via the pancreatic and common bile duct

57 Endocrine Gland Secretions are released into the bloodstream and travel to a target cell, tissue or organ The pancreas secretes the hormones insulin, glucagon and a few others will we not explore

58 Accessory Organ Secretions

59 Large Intestines

60 Approximately 3 feet in length Function to transport waste and remove water from waste

61 Large Intestines Divisions Cecum Appendix Ascending colon Transverse colon Descending colon Sigmoid colon Rectum Anus

62 Sphincters of the Large Intestines Ileocecal Valve: between the ileum and cecum Internal Anal Sphincter: under involuntary control. External Anal Sphincter: develops voluntary control at approximately 18 months of age

63 Summary of Digestive Fluid Production and Secretion

64 Digestive Pathologies for Study Peptic ulcer IBS GERD Crohns Disease Celiac Disease Diverticulosis Please learn each of these disorders


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