From Intake to Output

 The body cannot use food in its original form ◦ The pieces are too large ◦ Some foods, such as fats, cannot be absorbed by the bloodstream ◦ Overall foods are too complex for the body to use without being broken down first  The process of digestion is: ◦ Physical or mechanical – teeth, chewing, peristalsis ◦ Chemical – enzymes

 Alimentary canal ◦ An approximately 30-foot long tube running from the mouth to the anus ◦ Includes the mouth, throat, esophagus, stomach, small intestine, large intestine, and anus  Accessory organs ◦ Aid the digestive process by reducing food mechanically and chemically to a simple form that the body can use ◦ Includes the teeth, tongue, salivary glands, pancreas, liver, and gallbladder

 Mouth →  Pharynx →  Esophagus →  Stomach →  Small intestine →  Large intestine →  Rectum →  Anus

 Primary role – to help digest food by reducing its size through chewing (physical digestion)  Also aids in chemical digestion by mixing food with saliva, which contains enzymes  The mouth moves food to the back of the throat; called the pharynx  At this point a cartilaginous lid called the epiglottis closes over the larynx to keep food out of the trachea  Food passes through the pharynx into the esophagus

 A food delivery tube that descends through the mediastinum and the diaphragm into the stomach  Swallowing moves the food down the esophagus to the stomach  A sphincter muscle is located where the esophagus joins the stomach ◦ This muscle opens to allow food to enter the stomach ◦ It then closes to prevent the food and stomach acid from flowing back up the esophagus

 Primary role – Storage and to continue reducing the size of the food ◦ The stomach goes through contractions of its smooth muscles in order to grind food into smaller and smaller particles ◦ Acid, mucous, and enzymes are introduced in the stomach  The stomach moves the finer food particles to the pyloric region of the stomach, which pushes it to the small intestine

 A coiled tube about 22 feet long where a majority of the digestion takes place ◦ Broken into 3 sections  Duodenum  Jejunum  Ileum ◦ Coiled in order to increase its surface area  Provides more surface for glands to secrete enzymes for digestion  Lined with 4-5 million villi ◦ Finger-like projections that help to mix food with enzymes and to move it along to the large intestine

 Primary role – to absorb water and electrolytes or salts  A 5-foot tube similar to the small intestine ◦ Differs in that it has no villi and absorbs no nutrients  Has sections ◦ Ascending colon – goes up right side ◦ Transverse colon – goes across abdomen ◦ Descending colon – goes down the left side ◦ Sigmoid colon – end of large intestine; delivers leftovers to the rectum

 Last stop in the digestive pathway  Where all undigested food, known as feces, goes to be eliminated  The rectum contains 2 sphincter valves, known as the anus, that remain tightly closed except during defecation

 Body’s largest gland  Secretes bile to help the body digest fats  Also helps to filter toxic chemicals from the venous blood as it travels back to the heart  Spleen ◦ assists the liver by removing damaged blood cells

 Produces a fluid with 3 enzymes that breaks down food  Also secretes insulin ◦ Without insulin, sugar collects in the blood instead of reaching tissues, which causes diabetes

 Pear-shaped sac located on the underside of the liver (green)  Receives most of the liver’s bile and stores it until needed  Sends bile to the small intestine when needed to break down fatty foods

 Teeth – Grinds food into smaller, more manageable particles for digestion  Tongue – Contains glands that secrete enzymes and helps to move the food to the pharynx  Salivary glands – Secrete salivary amylase, the first enzyme involved in digestion ◦ Can’t taste food without this enzyme

 Fluids that come through the body must also be digested and filtered  The urinary system is responsible for filtering fluids and eliminating excess acids and salts  The body’s cells discharge all waste into the bloodstream  The blood carries the acids and salts to the kidneys for filtration  The kidneys filter the blood, then return the filtered fluid back to the bloodstream

 The kidneys continue to filter the leftover fluid and send it along to the ureter  The ureter is a long tube that descends to the urinary bladder  The bladder is a hollow muscular organ with a sphincter muscle on its lower section  Once the bladder fills, the body triggers the sphincter to relax and the liquid waste is eliminated as urine

 1. What is the pathway of digestion?  2. What are the organs of the alimentary canal?  3. What are the accessory organs of digestion?  4. What is physical digestion?  5. What is chemical digestion?  6. Why does the body need to go through digestion of food?

 7. Be able to define the following: ◦ Epiglottis ◦ Peristalsis ◦ Pyloric region ◦ Duodenum ◦ Jejunum ◦ Ileum ◦ Enzyme ◦ Gland ◦ Villi ◦ Pharynx

 8. Know the role of the following in digestion: ◦ Mouth, teeth, tongue ◦ Esophagus ◦ Stomach ◦ Small intestine ◦ Large intestine, including the 4 regions ◦ Rectum ◦ Liver ◦ Pancreas ◦ Gallbladder ◦ Kidneys