Anatomy and Physiology The Digestive System

1
Anatomy and PhysiologyThe Digestive System

• Community Education
• Mr. Kestner

2
Digestive System

• The digestive system, also known as the
  gastrointestinal system, is responsible for the
  physical and chemical breakdown of food
• Breakdown is necessary so food can be taken into
  bloodstream and used by body cells and tissues
• System consists of alimentary canal and accessory
  organs

3
Food Breakdown

• Ingestion
• Taking of food into the body
• Peristalsis
• Physical movement along the tract
• Digestion
• Mechanical and chemical breakdown of food
• Absorption
• Passage of food from digestive tract into body
• Defecation
• Elimination of indigestible substances from body

4
Alimentary Canal

• A long, muscular tube that begins at the mouth
  and includes the mouth (oral cavity), pharynx,
  esophagus, stomach, small intestine, large
  intestine, and anus
• Accessory Organs
• Accessory organs are the salivary glands, tongue,
  teeth, liver, gallbladder, and pancreas

5
Parts of the Alimentary Canal

• The mouth, also called the buccal cavity,
  receives food as it enters body
• While food is in mouth, it is
• Tasted
• Broken down physically by teeth
• Lubricated and partially digested by saliva
• And swallowed

6
Parts of the Alimentary Canal

• The teeth are special structures in mouth that
  physically break down food by chewing and
  grinding
• Process is called mastication
• The tongue is a muscular organ that contains
  special receptors, called taste buds
• Taste buds allow a person to taste sweet, salt,
  sour, and bitter sensations
• The tongue also aids in chewing and swallowing
  foods

7
Parts of the Alimentary Canal

• The hard palate is the bony structure that forms
  the roof of the mouth and separates the mouth
  from the nasal cavities
• Behind the hard palate is the soft palate, which
  separates the mouth from the nasopharynx
• The uvula, a cone-shaped muscular structure,
  hangs from the middle of the soft palate and
  prevents food from entering the nasopharynx
  during swallowing

8
Parts of the Alimentary Canal

• Three pairs of salivary glands
• Parotid (cheek/jaw)
• Sublingual (beneath tongue)
• Submandibular (chin/neck)
• They produce a liquid called saliva
• Saliva lubricates mouth during speech and chewing
  and moistens food so it can be swallowed easily
• Also contains enzyme called salivary amylase
• Salivary amylase begins chemical breakdown of
  complex carbohydrates, or starches, into sugars
  that can be taken into the body

9
Parts of the Alimentary Canal

• After food is chewed and mixed with saliva, it is
  called a bolus
• When bolus is swallowed, it enters the pharynx
  (throat)
• Pharynx is a tube that carries both air
  (to trachea) and food (to esophagus)
• When a bolus is being swallowed, muscle action
  causes epiglottis to close over larynx

10
Parts of the Alimentary Canal

• The esophagus is the muscular tube dorsal to the
  trachea
• It receives bolus form pharynx and carries it to
  stomach
• Esophagus, and remaining part of alimentary
  canal, relies on rhythmic, wavelike, involuntary
  movement of its muscles
• Called peristalsis, it moves food in forward
  direction

11
Parts of the Alimentary Canal

• The stomach is an enlarged part of alimentary
  canal and receives food from esophagus
• Mucous membrane lining stomach contains folds
  called rugae
• Folds disappear as stomach fills with food
• Two sphincters at stomach ends called
• Cardiac sphincter
• Pyloric sphincter

12
Parts of the Alimentary Canal

• Cardiac sphincter
• Circular muscle between esophagus and stomach
• Closes after food enters stomach
• Prevents food from going back into esophagus
• Pyloric sphincter
• Circular muscle between stomach and small
  intestine
• Keeps food in stomach until food is ready to
  enter intestine
• Food usually remains in stomach approx. 1-4 hours

13
Parts of the Alimentary Canal

• During time food is in stomach, it is converted
  into a semifluid material, called chyme
• Chyme is from gastric juices produced by glands
  in stomach mixed with bolus
• Gastric juices contain HCL and Pepsinogen
• HCL kills bacteria, facilitates Fe absorption,
  and activates the enzyme pepsin (which starts
  protein digestion)

14
Parts of the Alimentary Canal

• When food, in form of chyme, leaves stomach, it
  enters the small intestine
• The small intestine is a coiled section of
  alimentary canal
• Approximately 20 feet in length and one inch in
  diameter
• Divided into three sections
• Duodenum
• Jejunum
• Ileum

15
Parts of the Alimentary Canal

• The duodenum is the first nine to ten inches of
  the small intestine
• Bile (from gallbladder and liver) and pancreatic
  juice (from pancreas) enter this section through
  ducts, or tubes
• The jejunum is approximately eight feet in length
  and forms middle section
• The ileum is the final 12 feet of small
  intestine, and connects with large intestine at
  the cecum

16
Parts of the Alimentary Canal

• Process of digestion is completed while food is
  in small intestine
• Products of digestion are absorbed into
  bloodstream for use by body cells
• Intestinal juices produced by small intestine
  contain enzymes maltase, sucrase, and lactase,
  which break down sugars into simpler forms

17
Parts of the Alimentary Canal

• Intestinal juices contain enzymes known as
  peptidases, which complete the digestion of
  proteins
• Juices also contain steapsin, which aids in the
  digestion of fat
• Bile from liver and gallbladder emulsifies
  (physically breaks down) fats
• Enzymes from pancrease, like amylase (for sugars)
  and lipase (for fats) also aid in breakdown

18
Parts of the Alimentary Canal

• After food has been digested, it is absorbed into
  bloodstream
• Walls of small intestine are lined with
  fingerlike projections called villi
• The villi contain blood capillaries and lacteals

19
Parts of the Alimentary Canal

• Capillaries absorb digested nutrients and carry
  them to liver, where they are either stored or
  released into circulation for use by body cells
• Lacteals absorb most of digested fats and carry
  them to thoracic duct in lymphatic system, which
  releases them into circulation
• When food has completed its passage through small
  intestine, only wastes, indigestible materials,
  and excess water remain

20
Parts of the Alimentary Canal

• The large intestine is the final section of the
  alimentary canal
• It is approximately five feet in length and
  two-and-a-half inches in diameter
• Functions include
• Absorption of H2O and any remaining nutrients
• Storage of indigestible materials before
  eliminated
• Synthesis (formation) and absorption of some
  B-complex vitamins and vitamin K by bacteria
  present
• Transportation of waste products out of body

21
Parts of the Alimentary Canal

• The large intestine is divided into a series of
  connected sections
• The cecum is the first section, attached to small
  intestine contains a small projection called
  the vermiform appendix
• Next section is the colon with several divisions
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon

22
Parts of the Alimentary Canal

• The rectum is the final six to eight inches of
  the large intestine and is a storage area for
  indigestibles and wastes
• It has a narrow canal, called the anal canal,
  which opens at a hole, called the anus
• Fecal material, or stool, the final waste product
  of the digestive process, is expelled through
  this opening

23
Accessory Organs

• The liver
• Largest gland in the body
• Located under diaphragm in RUQ of abdomen
• Secretes bile
• Used to emulsify fats and
• Makes fats water soluble necessary for
  absorption
• Stores sugar in form of glycogen
• Glycogen converts to glucose and released into
  bloodstream when additional blood sugar is needed
• Stores Fe and certain vitamins
• Produces heparin, which prevents clotting of
  blood
• Produces proteins such as fibrinogen and
  prothrombin
• Produces cholesterol
• Detoxifies substances such as alcohol and
  pesticides, and destroys bacteria taken into
  blood from intestine

24
Accessory Organs

• The gallbladder
• Small, muscular sac located under liver and
  attached to it by connective tissue
• Stores and concentrates bile, received from liver
• When bile is needed to emulsify fats in digestive
  tract, the gallbladder contracts and pushes bile
  through common bile duct into duodenum

25
Accessory Organs

• The pancreas
• A glandular organ located behind stomach
• Produces pancreatic juices containing enzymes to
  digest food
• Juices enter duodenum through pancreatic duct
• Enzymes in juices break down sugars, proteins,
  and fats
• Produces insulin, secreted into bloodstream
• Regulates metabolism (or burning) of
  carbohydrates to convert glucose (blood sugar)
  into energy

26
Diseases/Abnormal Conditions

• Appendicitis
• Acute inflammation of appendix
• Usually resulting from obstruction and infection
• Symptoms include
• Generalized abd pain, later localizes at RLQ
• Nausea and vomiting
• Mild fever
• Elevated white blood count
• Treatment
• Appendectomy
• If appendix ruptures, infectious material will
  spill into peritoneal cavity causing peritonitis,
  a serious condition

27
Diseases/Abnormal Conditions

• Cholecystitis
• Inflammation of the gallbladder
• When gallstones form from crystallized
  cholesterol, bile salts, and bile pigments, the
  condition is known as cholelithiasis
• Symptoms (frequently occur after eating fatty
  foods) include
• Indigestion
• Nausea and vomiting
• Pain that starts under the rib cage and radiates
  to the right shoulder
• Treatment
• Low-fat diet
• Lithotripsy (low shock waves used to shatter
  gallstones)
• Cholecystectomy
• If gallstone blocks bile ducts, gallbladder can
  rupture and cause peritonitis

28
Diseases/Abnormal Conditions

• Cirrhosis
• Chronic destruction of liver cells accompanied by
  formation of fibrous connective and scar tissue
• Causes include
• Hepatitis, bile duct disease, chemical toxins,
  and malnutrition associated with alcoholism
• Symptoms (vary and become more severe as disease
  progresses) include
• Hepatomegaly (enlarged liver), Anemia,
  Indigestion, Nausea and vomiting, Nosebleeds,
  Jaundice, and Ascites (accumulation of fluid in
  peritoneal cavity)
• When liver fails, disorientation, hallucinations,
  hepatic coma, and death occur
• Treatment
• Directed toward preventing further damage to
  liver
• Alcohol avoidance, proper nutrition, vitamin
  supplements, rest, infection prevention, and
  appropriate exercise are encouraged

29
Diseases/Abnormal Conditions

• Constipation
• When fecal material remains in colon too long,
  causing excessive reabsorption of water
• Feces, or stool, becomes hard, dry, and difficult
  to eliminate
• Causes include
• Poor bowel habits, chronic laxative use leading
  to a lazy bowel, diet low in fiber, and certain
  digestive diseases
• Treatment
• Usually corrected by a high fiber diet
• Adequate fluids
• Exercise
• Although laxatives are sometimes used to
  stimulate defecation, frequent laxative use may
  be habit froming and lead to chronic constipation

30
Diseases/Abnormal Conditions

• Diarrhea
• Condition characterized by frequent watery stools
• Can be extremely dangerous in infants and
  children because of the excessive fluid loss
• Causes include
• Infection, stress, diet, irritated colon, toxic
  substances
• Treatment
• Directed toward eliminating cause
• Providing adequate fluid intake
• Modifying diet

31
Diseases/Abnormal Conditions

• Diverticulitis
• Inflammation of the diverticula, pouches (or
  sacs) that form in the intestine as the mucosal
  lining pushes through the surrounding muscle
• Causes include
• Fecal matter and bacteria becoming trapped in the
  diverticula
• Can result in abscess or rupture leading to
  peritonitis
• Symptoms (vary depending on amount of
  inflammation) include
• Abd pain, irregular bowel movements, flatus,
  constipation or diarrhea, abd distention,
  low-grade fever, and nausea and vomiting
• Treatment
• Antibiotics, stool-softening medications, pain
  medications, and surgery to remove the affected
  section of the colon (in severe cases)

32
Diseases/Abnormal Conditions

• Gastroenteritis
• An inflammation of the mucous membrane that lines
  the stomach and intestinal tract
• Causes include
• Food poisoning, infection, and toxins
• Symptoms include
• Abd cramping, nausea, vomiting, fever and
  diarrhea
• Treatment
• Usual methods are rest and increased fluid intake
• Severe cases antibiotics, IV fluids, and
  medications to slow peristalsis may be used

33
Diseases/Abnormal Conditions

• Hemorrhoids
• Painful, dilated or varicose veins of the rectum
  and/or anus
• Causes include
• Straining to defecate, constipation, pressure
  during pregnancy, insufficient fluid intake,
  laxative abuse, and prolonged sitting or standing
• Symptoms include
• Pain, itching, and bleeding
• Treatment
• High-fiber diet increased fluid intake stool
  softeners sitz baths or warm, moist compresses
  and, in some cases, a hemorrhoidectomy

34
Diseases/Abnormal Conditions

• Hepatitis
• A viral inflammation of the liver
• Type A, HAV, or infectious hepatitis
• highly contagious
• transmitted in food or water contaminated by
  feces of infected person
• Vaccine is available to prevent HAV
• Type B, HBV, or serum hepatitis
• transmitted by blood and serum
• more serious than HAV and can lead to chronic
  hepatitis or cirrhosis of the liver
• Vaccine developed to prevent HBV is recommended
  for all health care workers
• Other strains of hepatitis virus identified
  include types C, D, and E

35
Diseases/Abnormal Conditions

• Symptoms of hepatitis include
• Fever, Anorexia (lack of appetite), Nausea,
  Vomiting, Fatigue, Dark-colored urine,
  Clay-colored stool, Enlarged liver, and Jaundice
• Treatment methods include
• Rest and a diet high in protein and calories and
  low in fat
• A liver transplant may be necessary if the liver
  is severely damaged

36
Diseases/Abnormal Conditions

• Hernia
• Or rupture, occurs when an internal organ pushes
  through a weakened area or natural opening in a
  body wall
• Hiatal Hernia
• When the stomach protrudes through the diaphragm
  and into the chest cavity through the opening for
  the esophagus
• Inguinal Hernia
• When a section of the small intestine protrudes
  through the inguinal rings of the lower abdominal
  wall
• Symptoms include
• Heartburn, stomach distention, chest pain, and
  difficult swallowing
• Treatment
• A bland diet, small frequent meals, staying
  upright after eating, and surgical repair
• If hernia cannot be reduced (pushed back in
  place) a herniorrhaphy is performed

37
Diseases/Abnormal Conditions

• Pancreatitis
• Inflammation of the pancreas
• Pancreatic enzymes begin to digest pancreas
  itself becomes necrotic, inflamed, and edematous
  If damage extends to blood vessels in pancreas,
  hemorrhage and shock occur
• Causes
• May be caused by excessive alcohol consumption or
  blockage of pancreatic ducts by gallstones
• Many cases are idiopathic, or of unknown cause
• Symptoms include
• Severe abd pain that radiates to back, nausea,
  vomiting, diaphoresis, and jaundice if swelling
  blocks the common bile duct
• Treatment depends on cause
• Cholecystectomy is performed if gallstones are
  cause
• Analgesics for pain and nutritional support are
  used if cause is alcoholism or idiopathic
• This type of pancreatitis has a poor prognosis
  and often results in death

38
Diseases/Abnormal Conditions

• Peritonitis
• Inflammation of the abdominal peritoneal cavity
• Usually occurs when a rupture in the intestine
  allows the intestine contents to enter the
  peritoneal cavity
• A ruptured appendix or gallbladder can cause this
  condition
• Symptoms include
• Abd pain and distention, fever, nausea and
  vomiting
• Treatment includes
• Antibiotics
• Surgical repair of damaged intestine (if
  necessary)

39
Diseases/Abnormal Conditions

• Ulcer
• An open sore on the lining of the digestive tract
• Peptic ulcers include gastric ulcers and duodenal
  ulcers
• Causes
• Major cause is bacterium Helicobacter pylori (H.
  pylori), that burrows into stomach membranes,
  allowing stomach acids and digestive juices to
  create an ulcer
• Symptoms include
• Burning pain, indigestion, hematemesis, and
  melena (dark, tarry stool)
• Usual treatment methods are
• Antacids, a bland diet, decreased stress, and
  avoidance of irritants such as alcohol, fried
  foods, tobacco and caffeine
• If H. pylori bacteria are present, treatment with
  antibiotics and Pepto-Bismol usually cures the
  condition
• Severe cases, surgery is performed to remove the
  affected area

40
Diseases/Abnormal Conditions

• Ulcerative colitis
• Severe inflammation of colon accompanied by
  formation of ulcers abscesses
• Thought to be caused by stress, food allergy, or
  autoimmune reaction
• Main symptom is diarrhea containing blood, pus,
  and mucous
• Other symptoms include wt. loss, weakness, abd
  pain, anemia, and anorexia
• Periods of remission and exacerbation are common
• Treatment
• Directed toward controlling inflammation,
  reducing stress, maintaining proper nutrition,
  and avoiding substances that aggravate condition
• In some cases, surgical removal of the affected
  colon and creation of a colostomy is necessary
• Artificial open in colon allows fecal material to
  be excreted through abd