Post on 22-Dec-2015
Digestive SystemThe Gastrointestinal System
Digestive System
Alimentary CanalLong, muscular organ that includes the mouth (oral cavity), pharynx, esophagus, stomach, small intestine, large intestine & anus
Buccal Cavity Mouth – receives food
as it enters the body Teeth - Food in the
mouth is tasted, broken down physically by the teeth, digested, by saliva & swallowed
Mastication – Chewing & grinding of food by the teeth
Buccal Cavity Tongue – Muscular organ
with special receptors – taste buds
Hard Palate – bony structure that forms the roof of the mouth
Soft Palate – Separates the mouth from the nasopharynx
Uvula – hangs from the soft palate & keeps food from entering the nasopharynx during swallowing
Buccal Cavity 3 pairs of salivary glands Parotid Sublingual Submandibular Produce saliva to lubricates
the mouth during speech & chewing and moistens food so that it can be swallowed easily
Salivary Glands Saliva contains the
enzyme salivary amylase (ptyalin)
Begins the chemical breakdown of carbohydrates (starches), into sugars that can be used by the body
Bolus – food that has been chewed & mixed with saliva
Pharynx The Throat A tube that carries the air
to the trachea & food to the esophagus
When a bolus is being swallowed muscle action causes the epiglottis to close over the larynx, preventing the bolus from entering the respiratory tract causing it to enter the esophagus
Esophagus Muscular tube dorsal to
the trachea Receives the bolus from
the pharynx & carries it to the stomach
Relies on a rhythmic, wavelike involuntary movement of its muscles called peristalsis
Stomach Enlarged part of the
alimentary canal. Receives food from the
esophagus Rugae – folds inside the
stomach Cardiac Sphincter –
between esophagus & stomach
Pyloric sphincter – between stomach & small intestine
Stomach Food in stomach 1-4
hours Chyme – food is
converted into a semi-fluid material
Gastric Juices – contain hydrochloric acid & enzymes
Stomach Enzymes Hydrochloric Acid – kills
bacteria, facilitates iron absorption & activates the enzyme pepsin
Lipase – starts the chemical break down of fats
Pepsin starts protein digestion
Rennin aids in the digestion of milk (found only in children)
Small Intestine Coiled section of alimentary
canal 20 feet long Divided into the: duodenum (9-10 in.) jejunum (8
ft.) ileum (12 feet) Cecum – place that the small
intestine connects to the large intestine.
Ileocecal valves – separates the ileum & cecum
Small Intestine
Enzymes in the Small Intestine Duodenum – Bile (from
the gallbladder & liver) and pancreatic juice enter through ducts
Process of digestion is completed in the small intestine
The products of digestion are absorbed into the blood stream for use by body cells
Small Intestine Enzymes Maltase, sucrase & lactase break down sugars into simpler
forms Peptidases – completes the digestion of proteins Steapsin – aids in the digestion of fats Bile – from liver & gallbladder emulsifies fats
Pancreatic enzymes complete digestion Pancreatic amylase or amylopsin acts on sugars Trypsin and chymotrypsin act on proteins Lipase or steapsin acts on fats
Absorption After food is digested it is absorbed into the
bloodstream Walls of small intestine are lined with finger-
like projections called villi Villi contain blood capillaries & lacteals Blood capillaries absorb the nutrients & carry
them to the liver
Absorption
Large Intestine 5 ft. in length & 2 in. in
diameter Functions include:
absorption of water & remaining nutrients, storage of indigestible materials before elimination
Synthesis of some B complex vitamins & vitamin K
Transportation of waste products from the body
Large Intestine Cecum – first section
& is connected to the ileum of the small intestine. It contains a small projection called the veriform appendix
Large Intestine Colon has several
divisions: Ascending colon – up the
right side of body from the cecum to the lower part of the liver
Transverse Colon – Extends across the abdomen, below the liver & stomach and above the small intestine
Large Intestine Descending Colon – extends down the left
side of the body. Connects with the sigmoid colon
Sigmoid Colon, an S shaped section that joins the rectum
Rectum – final 6 – 8 in. of the large intestine & is a storage area for indigestible & waste
The narrow anal canal opens at a hole called the anus
Fecal material or stool, the final waste product is expelled
Liver
Liver Largest Gland Secretes Bile which emulsifies fats & makes them
water soluble Stores Sugar in the form of glycogen Stores Iron & Vitamins Produces heparin, fibrinogen, prothrombin &
Cholesteral Detoxifies substances Destroys bacteria taken into the blood from the
intestine
Liver Heparin: Prevents clotting Fibrinogen: Blood Protein aids in clotting Prothrombin: Blood Protein aids in clotting
Gallbladder Small, muscular sac
located under liver Stores & concentrates
bile Bile needed to emulsify
fats
Pancreas Glandular organ Produces pancreatic
juices & enzymes Produces insulin
Diseases Appendicitis – Acute inflammation or
infections of the appendix
Symptoms: RLQ abdominal pain, nausea/vomting, mild fever, elevated WBC.
Danger- peritonitis
Diseases Cholecystitis- inflammation of the
gallbladder, characterized by formation of cholelithiasis (gallstones, which are crystallized cholesterol, bile salts, and bile pigments)
Symptoms- pain under the rib cage radiating to the right shoulder, indigestion, n/v occurs after eating fatty meal.
continued Cholecystitis- if a gallstone blocks the bile
duct, it can rupture causing peritonitis
Treatment-low fat diet, lithotripsy, and possible cholecystectomy
Diseases Constipation-when fecal material stays in the
large intestine too long causing excessive reabsorption of water. Stool becomes hard, dry, and difficult to eliminate.
Causes- low fiber diet; chronic laxative use makes the bowel “lazy”
Treatment- high fiber diet; fluids, and exercise (avoid laxatives if possible)
Diseases Diarrhea- frequent water stools caused by
infection, stress, diet, irritated colon, or toxic substances. Can be dangerous in infants and small children.
Treatment is directed at eliminating the cause, modifying diet, and adequate fluids.
Diseases Diverticulitis- inflammation of the diverticula
(sacs) that form in the lining of the intestine. Occurs when fecal material or bacteria become trapped in the “sacs”. Can result in abscess or rupture and cause peritonitis.
Symptoms- abdominal pain, gas, abdominal distention, constipation, diarrhea
Treatment-antibx, pain med, surgery
Diseases Gastroenteritis- inflammation of the mucosal
membrane lining the GI tract.
Cause-food poisoning, infection, toxins
Symptoms- abdominal cramping, n/v, diarrhea
Treatment- replace fluids, rest, antibiotics, IV fluids if severe.
Diseases Hemorrhoids- painful dilated or varicose
veins of the rectum or anus.
Symptoms- pain, itching, bleeding
Treatment- high fiber diet, stool softeners, sitz baths, warm moist compresses.
If severe, hemorrhoidectomy.
Diseases Hepatitis- inflammation of the liver A- infectious hepatitis- transmitted in food or
water that has been contaminated by feces of an infected person. Most benign type.
B- transmitted by all body fluids including breast milk, saliva, and urine. (vaccine)
C- also transmitted through blood and body fluids but more likely to cause cirrhosis.
Hepatitis continued C-no vaccine Symptoms- fever, fatigue, anorexia, n/v,
mylagia, dark urine, clay colored stool, enlarged liver and jaundice.
Treatment- rest, diet high in protein and calories but low in fat. If severe, liver transplant.
Diseases Hernia- a rupture that occurs when an internal
organ pushes through a weakening or natural opening in a body wall.
hiatal hernia- when the stomach protrudes through the diaphragm into the chest cavity through the opening for the esophagus.
If a hernia cannot be reduced, then a herniorraphy is performed.
Diseases Ulcer – open sore on the lining of the
digestive tract. Peptic ulcers include stomach and duodenal ulcers.
Causes- H. pylori bacteria is most common cause (infection) by burrowing into the lining allowing gastric juices to create an ulcer.
Symptoms- burning pain, indigestion, melena, and hematemesis.
Ulcers cont. Treatment- bland diet, decreased stress,
avoiding irritants. Bismuth medications (pepto bismol is used) If H. Pylori is the cause, this is an infection that should be treated with antibiotics.
Diseases GERD (gastroesophageal reflux disease)-
occurs when stomach contents and acid leak back into the esophagus and there are visible signs of irritation to the lining of the esophagus. Many people have acid reflux, heartburn, and indigestion but that doesn’t mean they have GERD.
GERD cont. Symptoms- burning pain in your lower chest,
tasting acid in your mouth, throat. Treatment- dietary and lifestyle changes;
avoiding irritation to the esophagus (chocolate, peppermint, alcohol, fatty foods, coffee, citrus fruits and juices)