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)