Digestive System

KEY TERMS Alimentary Canal Anus Colon Digestive System Duodenum Esophagus Gallbladder Hard Palate Ileum Jejunum Large Intestine Liver Mouth Pancreas Peristalsis Pharynx Rectum Salivary Glands Small Intestine Soft Palate Stomach Teeth Vermiform Appendix Villi

Digestive System The digestive system (gastrointestinal system) is responsible for: The physical and chemical breakdown of food Absorption of nutrients Elimination of wastes The digestive system consists of: Alimentary canal Accessory organs

Alimentary Canal A long, muscular tube that begins at the mouth and includes the: Mouth Pharynx Esophagus Stomach Small intestine Large intestine Anus

Parts of Alimentary Canal Mouth – receives the food Teeth – help with the mastication of food Tongue – aids in chewing, swallowing, and tasting of food Hard palate – bony structure that is the roof of your mouth, separates the mouth from the nasal cavities Soft palate – separates the mouth from the nasopharynx, includes the uvula which helps to prevent food from entering the nasopharynx Salivary glands – produces salivary amylase which begins the chemical breakdown of carbohydrates into sugars

Poly want a cracker?? YUMMY!!!! A cracker is mostly a carbohydrate (starch) but if you leave it in your mouth long enough it will become a sugar. TRY IT!!!! Chew up an unsalted cracker but don’t swallow it! Keep the bolus (chewed up food) in your mouth for 1 minute… After you notice the sweet taste you may swallow! YUMMY!!!!

Parts of Alimentary Canal (cont.) Pharynx (throat) – carries both food and air (air to the trachea and food to the esophagus) Bolus (chewed food and saliva) enters the esophagus Epiglottis is closed over the larynx to prevent food from entering the respiratory tract Esophagus – muscular tube behind the trachea that carries the bolus to the stomach Like all parts of the alimentary canal, it relies on peristalsis (rhythmic, wavelike, involuntary movement of muscles) to move the food in a forward direction

Parts of Alimentary Canal (cont.) Stomach Receives the food from the esophagus Cardiac sphincter – muscle b/n the esophagus and stomach that closes after food enters Pyloric sphincter – muscle b/n the stomach and small intestine that keeps food in the stomach until it is time to move on Food remains in the stomach for 2-4 hours Food is converted into chyme (semifluid material) by gastric juices (hydrochloric acid and enzymes) Food is then ready to move to the small intestine

Parts of Alimentary Canal (cont.) Small intestine – accepts chyme from the stomach Coiled section that is approx 20 feet in length and 1 inch in diameter Divided into 3 sections: Duodenum (first 9-10 inches) – bile and pancreatic juices enter this section Jejunum (8 ft in length) – forms the middle section Ileum (final 12 ft) – connects with the large intestine at the cecum

Parts of Alimentary Canal (cont.) Small Intestine Process of digestion is completed here Products of digestion are absorbed into the bloodstream Bile from the liver and gallbladder physically breaks down fat Wall of small intestine is lined with villi (fingerlike projections) – absorb the digested nutrients and carry them to the liver Once food has completed its trek through the small intestine, only wastes, indigestible materials, and excess water remains

Parts of Alimentary Canal (cont.) Large Intestine Last part of the alimentary canal Approx 5 feet in length and 2 inches in diameter Functions: Absorption of water and any remaining nutrients Storage of waste before elimination Transportation of waste out of the alimentary canal

Parts of Alimentary Canal (cont.) Large Intestine Divided into a series of connected sections: Cecum - connected to the ileum of the small intestine (contains the appendix) Colon Ascending colon – continues up the right side of the body Transverse colon – extends across the abdomen Descending colon – extends down the left side of the body Sigmoid colon – S-shaped section that joins with the rectum

Parts of Alimentary Canal (cont.) Rectum – final 6-8 inches of the large intestine Storage area for indigestibles and wastes Has a narrow canal called the anal canal which opens at the anus Anus – fecal material is expelled through this opening

Accessory Organs Liver The largest gland in the body Located under the diaphragm in the upper right quadrant Secretes bile which breaks down fats and makes them water soluble Stores sugar in the form of glycogen, iron, and some vitamins Produces heparin (prevents clotting in the blood) Detoxifies substances such as alcohol and pesticides

Accessory Organs Gallbladder Small, muscular sac located under the liver and attached to it by connective tissue Stores and concentrates bile which is received from the liver Sends bile to the duodenum when needed

Accessory Organs Pancreas Glandular organ located behind the stomach Produces enzymes to digest food Produces insulin which regulates metabolism (converting glucose into energy)

Diseases and Abnormal Conditions Appendicitis Acute inflammation of the appendix Resulting from an obstruction and infection Symptoms – abdominal pain that localizes in the LRQ, nausea and vomiting, mild fever, and elevated WBC Rupture of the appendix is a serious condition (infection spills into the peritoneal cavity) Treatment - appendectomy

Diseases and Abnormal Conditions Cholecystitis Inflammation of the gallbladder Symptoms occur after eating fatty foods and include: indigestion, nausea and vomiting, pain that starts under the rib cage and radiates to the right shoulder Treatment: low-fat diet or a cholecystectomy Cirrhosis Chronic destruction of liver cells which leads to scar tissue Some causes include hepatitis and alcoholism Some common symptoms: liver enlargement, anemia, jaundice, and hematemesis

Diseases and Abnormal Conditions Constipation Causes include a diet low in fiber, dehydration, or extended laxative use Usually self-corrected with diet, hydration, and exercise Diarrhea Causes include infection, stress, and diet Treated by eliminating the infection and modifying diet Hemorroids Painful dilated veins in the rectum Causes include constipation, laxative abuse, or pregnancy Treatment includes a high fiber diet, increased fluid intake, or a hemorrhoidectomy

Diseases and Abnormal Conditions Diverticulitis Inflammation of the diverticula (sacs that form in the intestine as the mucosal lining pushes through the surrounding muscle) Occurs when fecal material or bacteria become trapped in the diverticula Symptoms include: abdominal pain, abdominal distention, low grade fever, nausea and vomiting Treatment includes antibiotics, pain medication, change in diet, or even surgery to remove the affected section of the colon

Diseases and Abnormal Conditions Gastroenteritis Inflammation of the mucous membrane that lines the stomach and intestinal tract Causes include food poisoning, infection, and toxins Symptoms include abdominal cramping, nausea, vomiting, fever, and diarrhea Treatment includes rest, antibiotics, and increased fluid intake