The Digestive System

Introduction to the Digestive System In this section, we discuss the body’s processing of food. This process prepares nutrients so that they can be used by each cell Body cells cannot absorb nutrients from food. Food must be changed into a substance into that body cells can use This process is called digestion Once digestion occurs, nutrients move into the bloodstream and waste moves out. This is called absorption.

Digestive System The digestive system is a very long muscular tube that begins at the mouth and ends at the anus. (Alimentary Canal) This is made up of many parts, including: Mouth Salivary glands Pharynx Epiglottis Esophagus Cardiac Sphincter Stomach Pyloric Sphincter Small Intestine Large intestine Rectum Anus

Digestive System Mouth- where food enters Salivary glands- located under the tongue near the jawbone and at the back of the throat Produce a secretion that dissolves food and coats with a mucus that allow it to pass through the esophagus easily Amylase- breaks down carbohydrates When food leaves the mouth it is in the form of bolus (soft rounded ball of chewed food)

Figure 13.21

Digestive System Pharynx- passageway for food Epiglottis- flap that covers the trachea when food or water is swallowed Esophagus- receives food and water from pharynx Cardiac sphincter- a ring of muscle fibers located where the esophagus and stomach join. This keeps stomach contents from moving into the esophagus

Digestive System Stomach- an enlarged part of the alimentary canal that receives food and water from the esophagus. Holds food until digestive juices have broken down the food particles into chyme (creamy semifluid mixture of food and digestive juices) Pyloric sphincter- ring-like muscle found at the far end of the stomach. This is to keep the food in the stomach long enough to become chyme. Small intestine- attached to the stomach at the pyloric sphincter. About 20ft long Part of the alimentary canal where most absorption takes place Contain projections called villi (absorbs nutrients)

Digestive System Large intestine- attached to the small intestine and receives food substances that are of little value to the body. It absorbs water, mineral salts, and vitamins. Discharges a mucus to aid in the movement of feces. Rectum- part of the large intestine. Last 6-8 inches of the alimentary canal. Serves as a storage for feces Anus- part of the large intestine The end of the alimentary canal Where fecal material is evacuated Closure of anus is controlled by the sphincter muscle

Figure 13.22

Digestive System The Accessory Structures assist in the process of digestion Liver Gallbladder Pancreas

Digestive System Liver- the largest gland in the body Has many functions Production of bile Removal of poisons that have been absorbed in the small intestine Storage of vitamins Production of heparin (prevents blood from clotting) Production of antibodies, which act against infection and foreign matter

Digestive System Gallbladder- a muscular sac Stores bile that the liver produces When chyme reaches the duodenum, the gallbladder squeezes bile into the duodenum to aid in chemical breakdown of the chyme

Digestive System Pancreas- produces pancreatic juices that also aid in the chemical breakdown of food Manufactures insulin which regulates the amount of sugar used by tissues

Medical Terminology

Common Disorders of the Digestive System

Common Disorders of the Digestive System

Common Disorders of the Digestive System

Common Disorders of the Digestive System

Jobs and Professions Gastroenterologist Hepatologist Dietician Dietary Aide

Questions What is the alimentary canal? What are the five functions of the liver? What are the differences in the function between the small intestine and the large intestine? What are the accessory structures of the digestive system?

Sources Badasch, S. A., & Chesebro, D. S. (2011). Asepsis and Standard Precautions. In Health Science Fundamentals: Exploring Career Pathways (1st ed., Revised , pp. 370-376). Upper Saddle River, NJ: Pearson.