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2.08 understand the_functions_and_disorders_of_the_digestive_system
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2.08 understand the_functions_and_disorders_of_the_digestive_system

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  • Food enters the digestive tract through the mouth. Food is broken down by the teeth and mixed with saliva. Saliva contains salivary amylase which converts starches in carbohydrates into simple sugars. EXPERIMENT : when you put a cracker in your mouth for a few minutes, it will have no taste because it is being broken down into glucose (simple sugar). Saliva is affected by the nervous system; just thinking of food will make our mouth water or the opposite can occur- a dry mouth when we are frightened or nervous.
  • For food to be tasted, it must be in a solution (saliva). The solution passes through the taste bud openings which stimulates the nerve endings in the taste cells. The sensation of taste is coupled with the sense of smell. When we experience an odor, it stimulates the olfactory nerve endings in the upper part of the nasal cavity. We may confuse the odor of a food with its flavor when it is stimulated simultaneously in the mouth. Bad cold, the mucous covers the olfactory nerve endings
  • Mastication is the mechanical breakdown of food by the act of chewing. Food is mechanically digested by the cutting, ripping, and grinding action of the teeth incisors (sharp for biting) canines (pointed for tearing) Premolars (bicuspids) for grinding molars (ridges for crushing and grinding).
  • The parotid duct carries its secretions (salivary amylase) into the mouth. It opens upon the inner surface if the cheeks, opposite the second molar of the upper jaw. The Submandibular duct opens upon the anterior base of the tongue. Its secretions include mucous and salivary amylase. The sublingual gland secretes mostly mucous.
  • Uvula protects food and liquid from entering the nasal cavity when swallowing.
  • Food leaves the mouth and travels to the pharynx. This is the passageway from both food and air Swallowing is a complex process involving the constrictor muscles of the pharynx. It begins as a voluntary process and changes into an involuntary process as food enters the esophagus. When we swallow, the tip of our tongue slightly arches and moves backward and upward. This action forces the food against the hard palate. At the same time, the soft palate and the uvula shut off the opening of the nasopharynx. The constrictor muscles of the pharynx contract which pushes food into the upper part of the esophagus. At the same time, other muscles in the pharynx raise the larynx causing the epiglottis to cover the trachea (windpipe) to prevent food from entering it. The act of swallowing is voluntary. However, as a bolus of food passes over the posterior part of the tongue and stimulates receptors in the walls of the pharynx, swallowing becomes an involuntary reflex reaction. Place your finger on your neck when you swallow, you can feel the larynx move upward.
  • Food is pushed through the esophagus by peristalsis (rythmic involunatry muscular contractions)
  • When food reaches the stomach, the cardiac sphincter relaxes and allows the food to enter. 2 to 3 quarts of digestive juices are produced each day (gurgling noises). When food enters, gastric juices are released and begin to work on the proteins in the food. Salivary amylase continues to work in the stomach. The action of gastric juices is helped by the churning of the stomach walls. The food is now in a semi-liquid form called chyme. The chyme leaves the stomach through the pyloric sphincter which acts as a gatekeeper. This action allows for small squirts of chyme to be released into the duodenum from time to time. Food takes 2 to 4 hours to leave the stomach. Food moves through the stomach by means of peristalsis. Vomiting occurs because of reverse peristalsis. The only substance that is actually absorbed in the stomach is alcohol and some medications.
  • The stomach mucosa contains millions of gastric glands which secrete gastric juices necessary for digestion. Enteroendocrine glands secrete gastrin which in turn stimulates cells to produce hydrochloric acid (HCL) and pepsinogen Parietal cells produce HCL which converts pepsinogen into pepsin and destroys bacteria and microorganisms that enter the stomach. It is the body’s natural sterilizer. Also produce intrinsic factor- element necessary for the absorption of Vitamin B12. Chief type cells produce pepsinogen which converts to pepsin. The enzyme pepsin breaks down protein into smaller pieces called protease and peptone. Mucus cells secrete alkaline mucous which helps neutralize the effects of HCL and other digestive juices. Mucous cells in the stomach replace themselves every 3-5 days. The pH in the stomach ranges from 0-7 depending on the type of food in the stomach. Rennin is found in infants and children but NOT in adults. It prepares milk proteins for digestion by other enzymes.
  • In the small intestine, the process of digestion is completed and absorption begins. The pancreas and the gallbladder release enzymes into the small intestines. Intestinal juices secreted by the cells of the small intestines include maltase (maltose to glucose), lactase (lactose into glucose and galactose), and sucrase (sucrose into glucose and fructose) which change starch into glucose. Peptidase changes protease and peptone into amino acids. Steapsin changes fat into fatty acids and glycerol. Carbohydrates->starch->glucose Protein-> amino acids Fats-> fatty acids and glycerol This end products are now ready for absorption in the small intestines. Absorption is possible because the lining of the small intestine is not smooth. It is covered with millions of projections called villi. Each villa contain a network of blood and lymph capillaries. The digested portion of the food passes through the villi into the bloodstream and lacteals and on to the body cells. The undigested portions pass on to the large intestine.
  • Pancreatic juices neutralize the acidic chyme and completes the digestion of carbohydrates, fats, and proteins Protease – proteins into peptones and amino acids Amylase- starch into maltose Lipase- fats into fatty acids and glycerol Nucleases- nucleic acids (DNA/RNA) nucleotides
  • 1-Manufacture bile- a yellow green fluid which is necessary for the digestion of fat The hepatic duct from the liver joins the cystic duct from the gallbladder to form the Common Bile Duct. The common bile duct carries the bile into the duodenum. 2- Produce and store glucose in the form of glycogen 3- Detoxify alcohol, drugs, and other harmful substances 4- Manufacture blood proteins such as fibrinogen, prothrombin, albumin, and globulin. 5- Prepare urea (the waste product of protein metabolism and from the breakdown of amino acids 6- Store vitamin A,D, and B complex 7- Breakdown hormones no longer useful to the body 8- Remove worn out red blood cells from circulation and the recycle the iron content
  • Function- store bile The gallbladder releases bile into the small intestines. Bile emulsifies fat to prepare it for digestion by the pancreatic and intestinal juices.
  • The intestinal chyme is emptied from the ileum to the side wall of the large intestine through the ileocecal valve. This valve permits passage of the chyme and prevents the backflow of chyme into the ileum. The secretion of colon mucosa is large amounts of mucous. This mucous lubricates the passage of fecal material. The main functions of the colon is 1- water absorption- lg quanities of water is absorbed back into the bloodstream. Water is drawn from the undgested food and indigestable materials that pass through the colon. Aslo vitamin B complex and K is absorbed in the colon 2- bacterial action- the lining of colon accumulates bacteria from hours after we are born. This bacteria population (flora) act upon indigested food remains, turning them into acids, amines, gases, and other waste products. Also responsible for the formation of B complex vitamins and vitamin K. 3- fecal formation- due to water absorption and bacterial action the liquid waste material is converted into a semisolid form called feces. Feces contains waste products from the blood, acids, amines, inorganic salts, gases (ammonia, carbon dioxide, hydrogen, sulfide and methane) <- THIS IS WHY OUR STOOL HAS A FOUL ODOR , mucous, and cellulose. 4- gas formation- most people produce 1-3 pints of gas each day and pass it through the rectum (flatulence). Gas is produced by swallowing air and the normal breakdown of food. The smell comes from the bacteria in the large intestine. 5- defecation - approx every 12 hours the fecal material moves into the lower colon and rectum by means of a series of long contractions (mass peristalsis). Varies from three a day to three a week. When the rectum becomes distended with an accumulation of feces, the defecation reflex is triggered. Nerve endings in the rectum are stimulates and a nerve impulse id transmitted to the spinal cord. From the spinal cord, nerve impulses are sent to the colon, rectum and internal anal sphincter. This causes the colon and rectum to contract and the internal sphincter will relax resulting in the emptying of the bowels (bowel movement). The purpose of these functions are to regulate the body’s water balance while storing and excreting waste products of digestion.
  • Cavities If the enamel wears down on the surface of the tooth, bacteria can enter and a cavity will form Preventative measures- brushing, flossing and using mouth wash
  • Inflammation of the gallbladder Gallstones= cholelithiasis Pain and digestive disorders. The doctor may even be able feel the swollen gallbladder. Smaller ones are passed with undigested food. Larger ones need to be surgically removed
  • Cleft palate can be on one or both sides of the roof of the mouth. It may go the full length of the palate. Some complications include: Failure to gain weight Feeding problems Flow of milk through nasal passages during feeding Poor growth Repeated ear infections Speech difficulties Tx: A cleft palate is usually closed within the first year of life so that the child's speech develops normally. Sometimes a prosthetic device is temporarily used to close the palate so the baby can feed and grow until surgery can be done. Continued follow-up may be needed with speech therapists and orthodontists.
  • Chronic progressive inflammatory disease of the liver characterized by the replacement of normal tissue with fibrous connective tissue. 75% of cases are caused by excessive alcohol consumption. Also viral hepatitis can cause cirrhosis. Symptoms : Exhaustion Fatigue Nausea Weakness Weight loss Itchy skin Abdominal pain Complications include: edema and acities, bruising and bleeding, jaundice, gallstones, toxins in the blood and brain, sensitivity to medications, enlarged blood vessels in the esophagus and stomach. Damage can not be reversed but tx can delay or reduce complications. Transplant may be necessary
  • Constipation is a condition in which defecation is delayed and the colon absorbs excessive water from the feces, rendering them dry and hard. Caused also by emotions such as anxiety, fear, or fright, medications, and poor diet. Tx: proper diet to include cereals, fruits, and vegetables, drinking plenty of fluids, getting enough exercise, having regular bowel habits, and avoiding stress as much as possible.
  • Loose watery and frequent bowel movements Caused by an irritation of the colon’s lining by bacteria, medication, poor diet, nervousness, toxic substances or irritants in food. Excessive diarrhea can cause dehydration and electrolyte imbalance.
  • Inflammation of the mucous membrane lining of the stomach and intestinal tract. A common cause us a virus which causes diarrhea and vomiting for 24-36 hours.
  • GERD is a disorder that affects the sphincter muscle connecting the esophagus with the stomach . The sphincter is weak it relaxes inappropriately which allows the contents of the stomach to flow make up into the esophagus. This will also cause heartburn- acid indigestion resulting from the backflow of gastric juice into the lower esophagus. Tx: medications and possible surgery
  • An inflammation of the liver Symptoms are fever, nausea, anorexia, ascities and jaundice (the yellowing of the whites of the eyes) A- Virus Hep A (HAV) spread through contaminated water and food B- Virus Hep B (HBV) spread through contaminated blood and body fluids including fecal material. Treated with anti-viral drugs. Vaccine available C -Viral Hep C (HCV) spread through contaminated blood. Treated with anti-viral drugs D - (HDV) is a coinfection with HBV E - (HEV) is spread through intestinal excretions
  • Effects about 1 million Americans. This is a result of a peristalsis disorder with no known cause. The most common symptom is diarrhea. Other symptoms are vomiting, abdominal cramping, blood in the stool, weight loss, and fatigue. Drug therapy including anti-inflammatory drugs and antibiotics. Also diet modifications, high fluid intake, and reduction and management of stress. Surgery may be necessary.
  • A sore or lesion that forms in the mucousal lining of the stomach or duodenum where acidand pepsin are present. Most are caused by a bacteria called H Pylori (helicobacter pylori). Another cause is the use of NSAIDs (Motrin, Aleve). Most common symptom is a burning pain in the abdomen between the sternum and the navel. Pain occurs between meals and in the early hours of the morning. Might be relieved by eating or taking an antacid. Tx includes H2 blockers- the medicine reduces the amount of acid the stomach produces by blocking histamine. Medications to reduce the stomach acid production, protecting the mucous lining and also life style changes.
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  • Transcript

    • 1. 2.08 Understand the functions and disorders of the digestive system Essential questions What are the functions of the digestive system? How do the functions of chemical and physical digestion interrelate? What are the common disorders of the digestive system? How are disorders of the digestive system treated? How do you relate the body’s use of nutrients to the digestive system? 2.08 Understand the functions and disorders of the digestive system 2
    • 2. Understand the functions of the digestive system 2.08 Understand the functions and disorders of the digestive system 3
    • 3. Functions of the digestive systemMouth (buccal / oral cavity) What digestive system functions occur in the mouth? 2.08 Understand the functions and disorders of the digestive system 4
    • 4. Functions of the digestive systemTongueWhat is thedigestive systemfunction of thetongue? 2.08 Understand the functions and disorders of the digestive system 5
    • 5. Functions of the digestive system TeethMastication 2.08 Understand the functions and disorders of the digestive system 6
    • 6. Functions of the digestive system Salivary glands 2.08 Understand the functions and disorders of the digestive system 7
    • 7. Functions of the digestive system Palate Uvula 2.08 Understand the functions and disorders of the digestive system 8
    • 8. Functions of the digestive systemPharynx  What does the pharynx do? 2.08 Understand the functions and disorders of the digestive system 9
    • 9. Functions of the digestive systemEsophagus What does the esophagus do? 2.08 Understand the functions and disorders of the digestive system 10
    • 10. Functions of the digestive systemStomach 2.08 Understand the functions and disorders of the digestive system 11
    • 11. Functions of the digestive systemGastric juices  Enteroendocrine glands  Parietal cells  Chief type cells  Mucus cells  Rennin 2.08 Understand the functions and disorders of the digestive system 12
    • 12. Functions of the digestive systemSmall Intestine 2.08 Understand the functions and disorders of the digestive system 13
    • 13. Functions of the digestive systemPancreas  What digestive enzymes are secreted by the pancreas? 2.08 Understand the functions and disorders of the digestive system 14
    • 14. Functions of the digestive system Liver1- Manufacture bile2- Produce and store glycogen3- Detoxify alcohol, drugs, andharmful substances4- Manufacture blood proteins5- Prepare urea6- Store vitamins7- Break down hormones8- Remove red blood cells andrecycle iron content 2.08 Understand the functions and disorders of the digestive system 15
    • 15. Functions of the digestive systemGallbladde r 2.08 Understand the functions and disorders of the digestive system 16
    • 16. Functions of the digestive systemLarge Intestine  What are the functions of the large intestines? 2.08 Understand the functions and disorders of the digestive system 17
    • 17. Functions of the digestive system Fecal transplant  Allows the bacteria from  Used to treat Clostridium the healthy stool to difficile that grows in repopulate the gut of the human intestines patient who has lost  Symptoms range from healthy bacteria in their persistent diarrhea to life- threatening inflammation of gut the colon to death 2.08 Understand the functions and disorders of the digestive system 18
    • 18. Functions of the digestive system 2.08 Understand the functions and disorders of the digestive system 19
    • 19. Disorders of the digestive system Anorexia  Anorexia nervosa  Decreased or poor  Eating disorder appetite characterized by refusal to eat  Symptom  Psychiatric disorder 2.08 Understand the functions and disorders of the digestive system 20
    • 20. Disorders of the digestive systemCaries  What is another name for caries?  What are caries? 2.08 Understand the functions and disorders of the digestive system 21
    • 21. Disorders of the digestive systemCholecystitis  What is it?  What are the symptoms?  How is it treated? Cholelithiasis (Gallstones) 2.08 Understand the functions and disorders of the digestive system 22
    • 22. Disorders of the digestive systemCleft palate  What is it?  How is it treated? 2.08 Understand the functions and disorders of the digestive system 23
    • 23. Disorders of the digestive systemCirrhosis  What is cirrhosis?  What are the symptoms? 2.08 Understand the functions and disorders of the digestive system 24
    • 24. Disorders of the digestive systemConstipation  What is constipation?  What are some causes? 2.08 Understand the functions and disorders of the digestive system 25
    • 25. Disorders of the digestive disordersDiarrhea  What is it?  What causes it? 2.08 Understand the functions and disorders of the digestive system 26
    • 26. Disorders of the digestive disorders GastroenteritisWhat is it?What causes it? 2.08 Understand the functions and disorders of the digestive system 27
    • 27. Disorders of the digestive systemGastroesophageal Reflux Disease (GERD) What is it? What causes it? 2.08 Understand the functions and disorders of the digestive system 28
    • 28. Disorders of the digestive systemHepatitis Hepatitis A Hepatitis B Hepatitis C Hepatitis D Hepatitis E 2.08 Understand the functions and disorders of the digestive system 29
    • 29. Disorders of the digestive systemIrritable bowel syndrome  What is it?  What causes it?  How is it treated? 2.08 Understand the functions and disorders of the digestive system 30
    • 30. Disorders of the digestive systemPeptic ulcer  What is it?  What causes it?  How is it treated? 2.08 Understand the functions and disorders of the digestive system 31
    • 31. Relevance of nutrition to the digestive system Healthy dietary habits help maintain homeostasis of body systems 2.08 Understand the functions and disorders of the digestive system 32
    • 32. Relevance of nutrition to the digestive system Vitamins  Electrolytes  Fat soluble  Calcium  Vitamins A, D, E, K  Chloride  Water soluble  Magnesium  Vitamins C, B  Phosphorus  Potassium  Sodium 2.08 Understand the functions and disorders of the digestive system 33
    • 33. 2.08 Understand the functions and disorders of the digestive system Essential questions What are the functions of the digestive system? How do the functions of chemical and physical digestion interrelate? What are the common disorders of the digestive system? How are disorders of the digestive system treated? How do you relate the body’s use of nutrients to the digestive system? 2.08 Understand the functions and disorders of the digestive system 34

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