The Digestive System

3 Functions of the digestive system DIGESTION ABSORPTION ELIMINATION

Digestion Starts in the mouth Ends in the anus Food can be broken down mechanically (chewing) and chemically (with enzymes) to be digested (broken down).

Absorption Digested food enters into the bloodstream through the walls of the small intestine. Cells burn the energy (sugar, fatty acids, and amino acids) in the presence of oxygen to release stored energy within the food.

Elimination The digestive system eliminates materials that cannot be used in the body via elimination. The large intestine concentrates these solid wastes, called FECES, and finally the waste passes out of the body through the anus.

Inside the Oral Cavity The gastrointestinal tract (GI tract) begins with the oral cavity. Oral (or/o = pertaining to the mouth) The cheeks form the walls of the oval shaped oral cavity, and the lips surround the opening of the cavity. The hard palate form the anterior portion of the roof of the mouth. The soft palate consists of the muscular membrane that lies posterior to it.

The Oral Cavity

The uvula is the small tissue projection that hangs from the soft palate (hangy ball) The uvula helps with the production of the sounds of speech. The tongue covers the floor of the oral cavity, aids in moving the food during mastication (chewing) and deglutition (swallowing). Ruage are the bumps on the top of the hard palate.

The Oral Cavity Papillae, small raised bumps on the tongue, contains taste buds. Taste buds are sensitive to food chemicals and allow discrimination of different tastes as the food moves across the tongue.

Papillae Some people think that every bump on their tongue is, itself, a taste bud, but that is NOT true. –Each papillae has many taste buds within it. –In addition, we have taste buds that are not even on our tongues. –Some taste buds are found in our throats, cheeks, and on the roof of our mouths.

Papillae

Taste Regions

The Oral Cavity The gums are fleshy tissue that surrounds the sockets of the teeth. The adult human has 32 teeth (16 permanent teeth top/16 bottom arch). Central incisor (1) Lateral incisor (2) Canine (3) First premolar (4) Second premolar (5) First molar (7) Third Molar (wisdom tooth) (8)

Salivary Glands 3 pairs of salivary glands in the oral cavity Produce saliva, that contain digestive enzymes. Narrow ducts carry saliva into the oral cavity.

The Oral Cavity Together the teeth and saliva breakdown food in the oral cavity.

Components of the Digestive System Mouth Esophagus Stomach Small Intestine Large Intestine Gall bladder Liver Pancreas

Esophagus The esophagus is a muscular tube that connects your mouth to your stomach. It measures 9-10 inches from the end of the pharynx (throat) to the stomach. Peristalsis is the involuntary, progressive, rhythmic contraction of muscles in the walls of the esophagus (and other gastrointestinal organs) propelling a bolus (mass of food) toward the stomach.

Stomach The stomach is an organ often described as a stretchy bag that holds your food after you eat The stomach helps to break food into smaller pieces so your body can use it for energy and nutrition

Stomach Esophagus

The Stomach 3 parts: Fundus (upper portion) Body (middle section) Antrum (lower portion) FUNDUS BODY ANTRUM

Inside the Stomach The lining of the stomach contains digestive glands that produce the enzyme pepsin (to begin digestion of proteins) and hydrochloric acid. Food remains in the stomach for 1 to 4 hrs (or longer), depending on the type/amount of food eaten.

Sphincters Spincters are rings of muscles that control the opening and closing of the stomach The lower esophageal sphincter relaxes and contracts to move food from the esophagus to the stomach. The pyloric sphincter allows food to move from the stomach to the intestine.

Small Intestine Facts It is a tube that is 20 feet long. The small intestine continues and completes the digestion food. Food stays in your small intestine for 4 to 8 hours.

Small Intestine

The small intestine measures about 7m or 20 feet from the pyloric sphincter to the first part of the large intestine. 3 parts of the small intestine: 1. DUODENUM 2. JEJENUM 3. ILEUM

The Small Intestine The small intestine is lined with villi, tiny microscopic projections. There are very small blood vessels in the villi that absorb the digested nutrients into the bloodstream and lymph vessels.

Duodenum The duodenum is the first portion of the small intestine. It is a very important area dure to the fact that three things occur here: –Receives food from the stomach –Bile from the gallbladder –Pancreatic juice from the pancreas Enzymes and bile help digest food before it passes to the second part of the small intestine.

Large Intestine Facts A tube that is 1.5 m long Receives waste materials from the small intestine Waste products remain for 10 to 12 hours

Large Intestine

The appendix hangs from the large intestine where it meets the small intestine. The appendix has no clear function but can become inflamed and infected when clogged or blocked. Thought to be involved with breakdown of plants during primitive life.

Large Intestine Sections

The Large Intestine The main function of the large intestine is the absorption of water from the waste material, allowing the body to expel solid feces (stools). Defecation is the expulsion or passage of feces from the body through the anus. Diarrhea, or watery stools, results from reduced water absorption into the bloodstream through the walls of the large intestine.

Gall Bladder Facts Storage tank for bile (a greenish-yellow liquid) that helps your body break down and use fats Located under your liver and is shaped like a pear After you eat the gallbladder contracts, forcing the bile into the common bile duct.

Gall Bladder

Functions of the Liver 1.Maintain proper sugar levels (glucose) 2.Manufacture blood proteins (blood clotting) 3.Releasing bilirubin, a pigment in bile 4.Remove poisons (toxins) from the blood.

Liver

Jaundice Jaundice is a yellowish discoloration of the skin, whites of the eyes, and mucous membranes. Jaundice occurs when bilirubin can’t leave the body.

Pancreas The function of the pancreas in the digestive system is to help digest food by producing enzymes that break down carbohydrates, fats and proteins.

Hernia A hernia is the protrusion of an organ through a wall that normally contains it. There are many different types of hernias and several involve organs in the digestive system. An inguinal hernia, for example, is when part of the intestine protrude through the abdominal wall. It appears as a bulge in the skin and can be very painful.

Hiatal Hernia A hiatal hernia occurs when the upper part of the stomach protrudes upward through the diaphragm.

Heartburn Has nothing to do with the heart - it is a digestive problem Heartburn is a pain behind the breast bone, often described as ‘burning’ in quality. Acid is present in the stomach to digest food. Heartburn occurs when small amounts of this acid rise up into the esophagus - the tube which carries food from the mouth to the stomach. This is called acid reflux.