Digestion System

Main Functions Digestion  Process of changing food into a substance body cells can accept Absorption  Transfer of nutrients into blood Elimination of waste Maintains proper amounts of water, electrolytes, nutrients

Structures and Functions Mouth  Teeth begin breakdown of food (mastication)  Forms a bolus for swallowing  Digestion begins here

Structures and Functions Saliva moistens food Salivary enzymes: ptyalin (amylase) break down starches to simpler sugars

Structures and Functions Uvula  Structure suspend from soft palate  Directs bolus down esophagus

Structures and Functions Esophagus  Tube like structure that carries food from mouth to stomach  Bolus moved by rhythmic wavelike motion called peristalsis  watch?v=o18UycWRsaA watch?v=o18UycWRsaA

Structures and Functions Stomach  Physical breakdown of food continues  Bolus + hydrochloric acid & enzymes = chyme  Esophogeal sphincter valve prevents chyme from flowing back into esophagus  Pyloric sphincter valve controls flow of chyme into intestines

Structures and Functions Small intestine  Lined with tiny projections called villi  Nutrients absorbed into blood or liver for storage

Structures and Functions Small intestine  Major divisions Duodenum  First 9-10 inches  Digestive enzymes and bile produced to complete digestion Jejunum  Middle section  8 feet long Ileum  Final 12 feet  Connects with large intestine by iliocecal sphincter

Structures and Functions Large intestine  Three major portions Ascending colon  Right side Transverse colon Descending colon  Left side

Structures and Functions Large intestine  Receives unusable food substances  Absorbs water, mineral salts, and vitamins  Secretes mucus to aid fecal movement

Structures and Functions Rectum  Last 6-8 inches Serves as fecal storage area Anus  Fecal material evacuated from body

Accessory Organs

Appendix a small, blind tube extending from large intestine at junction of small and large intestines. function is not understood.

Accessory Organs Liver  Produces bile to break up fats  Detoxifies and removes harmful substances  Stores fat soluble vitamins: D,A,K,E  Production of clotting factors  Production of antibodies  Production of cholesterol  Stores sugar in form of glycogen

Assessory Organs Gallbladder  Inferior to and attached to liver  Bile storage

Assessory Organs Pancreas  Posterior to stomach  Produces digestive enzymes  Produces hormone insulin for blood sugar balance

Pathology of the Digestive System

Conditions of the Digestive System Gastritis  Inflammation of the stomach lining Appendicitis  Inflammation of the appendix Hepatitis  Inflammation of the liver Cholecystitis  Inflammation of the gallbladder

Conditions of the Digestive System Constipation  Inability to have a bowel movement Diarrhea  Passage of frequent and watery stools Gastroesophageal reflux disease (GERD)  Esophageal sphincter does not close all the way  Frequent heartburn or chest pain

Conditions of the Digestive System Ulcers  Lesion on mucous membrane of stomach or duodenum  Ulcers formed by: Too much hydrochloric acid &/or pepsin Low production of mucus Bacterium called H. pylori

The End

Digestive System Word Bank Sublingual salivary glands Stomach Rectum Liver Parotid salivary glands Gallbladder Transverse colon Appendix Descending colon Duodenum Submaxillary salivary glands Pancreas Esophagus Ascending colon Jejunum Ileum