The Digestive System Chapter 15, pages 422-428

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The Digestive SystemChapter 15, pages 422-428
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Digestion

• Digestion is the breaking down of food into
  simpler substances to be carried in the blood to
  the body cells
• Mechanical Process involves the chewing,
  mashing, and breaking food into smaller pieces
• Chemical Process involves changing food into
  simpler substances

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Function of the Digestive System

• Digestion the mechanical and chemical breakdown
  of food for use by the bodys cells
• Absorption the passage of digested food from
  the digestive tract into the circulatory system.

• Elimination the expulsion of undigested food or
  body wastes.

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Function of the Digestive System

• Food is moved through the digestive system by a
  process called peristalsis, which are a series of
  involuntary muscle contractions.

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Structures of the Digestive System

• The Teeth the primary function of teeth is to
  break the food into smaller pieces through
  mastication (chewing) to prepare the food to be
  swallowed.

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Structures of the Digestive System

• The Salivary Glands they are activated by the
  aroma of food.
• They secrete saliva which is a watery solution
  containing an enzyme that starts the digestion of
  carbohydrates by converting them into a soluble
  form of sugar

• It also lubricates your food making it easier to
  swallow.

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Structures of the Digestive System

• The Tongue forms the food into a ball (bolus)
  to prepare for swallowing and muscle contractions
  force the food into the pharynx (throat)

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Structures of the Digestive System

• The uvula a small, muscular flap of tissue
  suspended at the back of the mouth which closes
  over the opening of the nasal passages.

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Structures of the Digestive System

• The Epiglottis the flap of tissue that covers
  the trachea which closes to keep food from
  entering into the respiratory system.

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Structures of the Digestive System

• The Esophagus a 10 inch long, muscular tube
  that extends from the pharynx to the stomach. It
  is situated behind the trachea and the heart.
• Solid food takes about 9 seconds to travel
  through the esophagus.

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Structures of the Digestive System

• Sphincter Muscles a series of circular muscles,
  located along the digestive tract which prevents
  food from backing up as it moves through the
  digestive process.
• When relaxed, it forms an opening, and when
  contracted, it closes the opening.

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Structures of the Digestive System

• The Stomach A hollow, flexible, saclike organ,
  which is enclosed in three sets of muscles
  (longitudinal, circular, and oblique), which
  moves the stomach in different directions.

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Structures of the Digestive System

• This action produces rhythmic contractions that
  churn the food and gastric juices together to
  produce chyme ( a creamy, fluid mixture of food
  and gastric juices).
• Peristalsis moves the chyme into the small
  intestine.

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Structures of the Digestive System

• Gastric Juices
• Pepsin an enzyme that breaks down protein
• Hydrochloric Acid the hydrochloric acid is
  strong enough to dissolve metal, but your stomach
  lining is protected by mucus

• Despite the stomachs protective mucus, 500,000
  cells of the lining are destroyed every minute
  and must be replaced.
• Your entire stomach lining is replaced every
  three days.

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Structures of the Digestive System

• Small Intestine consists of three parts
  (duodenum, jejunum, and the ileum)
• It is 20-23 feet in length and 1 inch in diameter
• It is where the major part of digestion and
  absorption occurs.

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Structures of the Digestive System

• Chyme is moved through the small intestine at a
  relatively slow rate of approximately 3-5 hours.
• Chyme that enters includes partially digested
  carbohydrates, proteins, and undigested fat.

• Intestinal juices produced by glands in the small
  intestine, along with secretions from the liver
  and pancreas, complete the chemical breakdown of
  all food.

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Structures of the Digestive System

• The small intestine is lined with millions of
  fingerlike projections called villi.
• Villi absorb digested food particles where it
  enters the capillaries of the villi into the
  bloodstream to be carried throughout the body.

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Structures of the Digestive System

• Unabsorbed material leaves the small intestine in
  the form of liquid and fiber into the large
  intestine.

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Structures of the Digestive System

• The Large Intestine (Colon) a 5-6 foot and 2 ½
  inch organ that forms the lowest part of the
  digestive system.
• Movement of undigested food materials through the
  large intestine is very slow.
• The main functions are to absorb water and
  eliminate undigested food.

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Structures of the Digestive System

• As unabsorbed material from the small intestine
  passes through the large intestine, water,
  vitamins, and mineral salts are absorbed into the
  bloodstream to help maintain the water balance in
  your body.

• Many harmless bacteria live in your large
  intestine to change the consistency of undigested
  food to a semisolid waste (feces), which pass
  from your body through the anus and are excreted
  as a bowel movement.

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Organs that Aid Digestion

• The Liver the second largest organ in your body
  which functions as your bodys chemical factory
  and regulates the levels of most of the main
  chemicals in your blood.

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Organs that Aid Digestion

• It clears the blood of drugs and poisonous
  substances by absorbing the substances and
  changing their chemical structure (making them
  water soluble).

• It then excretes them in bile (a yellowish-green,
  bitter fluid important in the breakdown of fats)
  through the hepatic duct to the gallbladder where
  it is stored.

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Organs that Aid Digestion

• The gallbladder a small pear-shaped sac about
  3-4 inches long and located under the liver.
• The neck of the gallbadder forms a duct (bile
  duct) leading to the duodenum

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Organs that Aid Digestion

• The gallbladder stores bile until food moves into
  the duodenum.
• A hormone produced in the small intestine then
  stimulates the release of the bile to break down
  fats contained in the food.

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Organs that Aid Digestion

• The pancreas as part of the endocrine system,
  the pancreas produce the hormone insulin.

• As part of the digestive system, the pancreas
  produces 3 digestive enzymes
• Trypsin which digests proteins.
• Amylase which digests carbohydrates.
• Lipase which digests fat

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Care and Problems of the Digestive System
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Lifestyle Habits

• Follow a well-balanced diet that includes a
  variety of foods that are low in fat and high in
  fiber.
• Eat slowly and chew your food thoroughly
• Do not wash your food down with liquid. Wait
  until you are finished chewing, swallow, and then
  take a sip of liquid.

• Drink at least eight 8-oz. glasses of water each
  day to help your digestive system function
  properly.
• Avoid using food as a way of dealing with your
  emotions. Instead, take a walk or write in a
  journal when you are stressed.

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Functional Digestive System Problems
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Indigestion

• A burning discomfort in the upper abdomen. It is
  a feeling of fullness, sometimes accompanied by
  gas and nausea.
• It can be caused from eating too much food,
  eating too quickly, and eating foods that are
  spicy and high in fat.

• Stomach disorders and stress can contribute to
  indigestion.

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Heartburn

• A burning sensation in the center of the chest
  that may rise from the bottom, or tip, of the
  breastbone up to the throat.

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Heartburn

• It results from acid reflux, or a backflow of
  stomach acid into the esophagus.
• As the acid enters the esophagus, it irritates
  the tissues causing a burning feeling

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Heartburn

• Heartburn can also be a symptom of a hiatal
  hernia, a condition in which part of the stomach
  pushes through an opening in the diaphragm.

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Heartburn

• Because frequent or prolonged heartburn can be an
  indication of more serious digestive disorders,
  it is important to discuss the symptoms with a
  medical professional

• They may recommend the use of an antacid or
  prescribe medications to help relieve symptoms.

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Gas

• Although a certain amount of gas in the stomach
  and intestines produced from the breakdown of
  food is normal, excessive gas can result in
  cramps or an uncomfortable feeling of fullness in
  the stomach.

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Gas

• Most foods that contain carbohydrates or complex
  sugars, such as beans, cabbage, broccoli, onions,
  and starches, can cause gas.
• Fats and proteins produce less gas than
  carbohydrates.

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Nausea

• A feeling of distress, fullness, and weakness
  that often precedes vomiting.
• Motion sickness, pathogens (germs), some
  medications, and dehydration can cause nausea.

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Nausea

• Vomiting is a reflex response that provides a
  built-in protection if you swallow a foreign
  substance.
• Powerful contractions of the abdominal muscles
  compress the stomach, while the esophageal
  sphincter relaxes to allow the contents of the
  stomach to exit

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Diarrhea

• A frequent passage of watery feces.
• When digested food passes too quickly through the
  large intestine, water cannot be absorbed and
  diarrhea results.

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Diarrhea

• Diarrhea may result from changes in eating style,
  overeating, emotional turmoil, or nutritional
  deficiencies.
• Bacterial or viral infections, and certain
  medications can also cause diarrhea.

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Diarrhea

• One of the greatest concerns about diarrhea,
  especially in young infants and young children is
  dehydration.
• To avoid dehydration, drink plenty of fluids.
• Fluids containing electrolytes help maintain the
  bodys fluid and chemical balance

• Medical attention should be sought if symptoms
  persist for more than 48 hours.

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Constipation

• A condition in which the feces become dry and
  hard and bowel movements are difficult.
• Constipation can be caused by not drinking enough
  water or not consuming enough fiber to move
  wastes through the digestive system.

• Some medications can also cause constipation.

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Constipation

• Following a diet that includes fruits and
  vegetables, drinking at least eight 8 oz. glasses
  of water each day, and getting regular physical
  activity are the best ways to avoid constipation.

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Structural Digestive System Problems
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Gallstones

• Gallstones are formed when cholesterol in bile
  crystallizes and blocks the bile duct between the
  duodenum of the small intestine and the
  gallbladder

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Gallstones

• Symptoms include pain in the upper right portion
  of the abdomen, nausea, vomiting, and fever.

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Gallstones

• Treatment includes taking medications that
  dissolve the stones or having the stones broken
  down by high-intensity ultrasound waves.

• Surgical removal of the stones and possibly the
  gallbladder itself is an option when symptoms are
  severe.

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Appendicitis

• An inflammation of the appendix, a tube about 3-4
  inches long that extends from the beginning
  portion of the large intestine.
• The appendix becomes swollen and inflamed if it
  is blocked or clogged by bacteria or other
  foreign matter that prevents the release of its
  secretions.

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Appendicitis

• Symptoms include pain in the lower right portion
  of the abdomen, fever, loss of appetite, nausea,
  and vomiting.
• The appendix may burst, spreading infection
  throughout the abdomen, making the condition
  extremely serious.

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Appendicitis

• Medical care is essential and treatment involves
  surgical removal of the appendix.

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Gastritis

• An inflammation of the mucous membrane that lines
  the stomach and is the most common disorder of
  the digestive system.

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Gastritis

• An increase in the production of stomach acid,
  the use of tobacco or alcohol, infections caused
  by bacteria or viruses, and medications such as
  aspirin can irritate the stomach lining.

• Symptoms include pain, indigestion, decreased
  appetite, nausea and vomiting.
• Treatment includes avoiding irritants and taking
  medications or antibiotics to eliminate
  infection.

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Lactose Intolerance

• Lactose, a type of sugar found in milk and other
  dairy products, is normally broken down by the
  enzyme lactase.
• People who are lactose intolerant do not produce
  enough lactase, so undigested lactose remains in
  the small intestine.

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Lactose Intolerance

• Bacteria in the digestive tract ferment ingested
  lactose, producing symptoms such as abdominal
  cramps, bloating, gas and diarrhea.
• Chewing lactase enzyme tablets can reduce
  symptoms.

• People who are lactose intolerant should choose
  alternate sources of calcium including dark green
  vegetables such as broccoli and kale, fortified
  soymilk, and yogurt with active cultures.

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Peptic Ulcer

• A sore in the lining of the digestive tract which
  can occur in the esophagus, stomach (gastric
  ulcer), or duodenum.
• They can be caused by regular use of
  anti-inflammatory drugs and by a bacterial
  infection caused by Helicobacter pylori (H.
  pylori)

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Peptic Ulcer

• Symptoms include nausea, vomiting, and abdominal
  pain that worsens when the stomach is empty.
• Ulcers can cause bleeding in the stomach, and
  without treatment, they may perforate, or break
  through the stomach wall.

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Peptic Ulcer

• Treatment includes medications that neutralize
  acid or eliminate infection and avoiding
  irritants such as aspirin, cigarette smoke, and
  alcohol.

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Colitis

• An inflammation of the colon caused by a virus,
  an amoeba, a bacterium such as the one that
  causes ulcers, or stress.

• Symptoms include diarrhea (usually with blood and
  mucus), abdominal pain, and sometimes fever.

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Hemorrhoids

• Swollen veins in the lower rectum and anus, as a
  result of increased pressure in the veins of the
  anus.
• They are most common in people with
  constipation, or who sit alot, pregnant women,
  and following childbirth

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Hemorrhoids

• Symptoms include itching, pain, and bleeding.
• Eating fiber-rich foods and getting regular
  exercise can help reduce the risk of developing
  hemorrhoids.
• They can be treated with a variety of
  over-the-counter medications.

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Cirrhosis

• Destruction of liver tissue, usually caused by
  prolonged and heavy alcohol use, resulting in a
  scarring of the liver tissue.
• Alcohol interferes with the livers ability to
  break down fats which blocks the flow of blood in
  liver cells.

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Cirrhosis

• Liver tissue is destroyed and replaced with
  useless scar tissue, preventing normal liver
  function.
• Cirrhosis can lead to liver failure and may cause
  death unless a liver transplant is performed.

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Crohns Disease

• A disease associated with problems of the immune
  system which causes inflammation of the lining of
  the digestive tract.
• Symptoms include diarrhea, weight loss, fever,
  and abdominal pain.

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Colon Cancer

• Cancer of the colon and rectum is the second
  leading cause of cancer deaths in the United
  States.
• This cancer usually develops in the lowest part
  of colon, near the rectum

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Colon Cancer

• As the cancer grows larger, it either blocks the
  colon or causes bleeding, often during
  elimination.
• Cancers of this type are usually slow to spread,
  so seeking early medical help greatly increases a
  persons chance for survival.

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Tooth Decay

• Tooth decay weakens a tooth and affects the way a
  person bites and chews food.
• Brushing and flossing daily is the best way to
  prevent tooth decay and to keep your teeth
  healthy.