DIGESTIVE SYSTEM

Digestive System – also known as gastrointestinal system

Function: Physical and chemical breakdown of food so it can be taken into the bloodstream and used by the body’s cells and tissues.

Digestive Systems consists of the Alimentary Canal and accessory organs:

Alimentary canal – long, muscular tube that includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.

Accessory organs – salivary glands, tongue, teeth, liver, gallbladder and pancreas

Parts of Alimentary Canal

Mouth - also called buccal cavity or oral cavity Food intake Tasted Broken down physically (teeth) Lubricated and partially digested by

saliva swallowed

Teeth

Teeth - physically break down food by mastication (chewing and grinding).

Tongue

Tongue – muscular organ containing special receptors called taste buds. Taste buds allow a person to taste sweet, sour, salty, bitter sensations

Aids in chewing and swallowing food.

Hard Palate

Bony structure that forms the roof of the mouth and separates the mouth from the nasal cavities

http://www.youtube.com/watch?v=KIPL52wGu0Q

Soft Palate

Separates the mouth from the nasopharynx

Uvula – cone shaped muscular structure that hangs from the middle of the soft palate Function of uvula – to prevent food from

entering nasopharynx during swallowing

Salivary Glands and Saliva 3 Pairs of Salivary Glands (parotid,

sublingual, submandibular) produce saliva. Saliva – lubricates mouth during speech

and chewing, and moistens food so it can be easily swallowed.

Saliva contains enzyme (a substance that speeds up a chemical reaction) called salivary amylase. This begins the chemical breakdown of carbohydrates, or starches, into sugars that can be taken into the body.

After food is chewed and mixed with saliva it forms a bolus.

When bolus swallowed – enters the pharynx

Pharynx

Pharynx is a tube that carries both air and food Carries air to the trachea (windpipe) Food to the esophagus When bolus is swallowed, muscle action

causes epiglottis to close over the larynx to prevent bolus from entering respiratory system and causes it to enter esophagus.

Esophagus

Esophagus – approx. 10 inch long muscular tube dorsal (behind) the trachea.

Receives bolus from mouth and carries it to the stomach

Food is moved in a forward direction through the alimentary canal by peristalsis

Peristalsis – rhythmic, wavelike, involuntary movements

http://www.youtube.com/watch?v=vItktDQo-mE

http://www.youtube.com/watch?v=8V6VsNkGfTQ

Stomach

J-shaped muscular organ that acts as a bag or sac to collect, churn, digest and store food.

Receives food from the esophagus Composed of 3 parts: fundus (upper region),

body (main portion), antrum (lower region). Mucous membrane lining of stomach contains

folds called rugae. Rugae disappear as the stomach fills with food and expands.

Stomach is about the size of your fist, but can expand to hold up to a quart of food.

Sphincters of Stomach

Stomach contains muscular valves called sphincters.

Sphincters control the flow of food in one direction only.

Cardiac sphincter (or lower esophageal sphincter) – circular muscle between esophagus and stomach. Closes after food enters stomach and prevents food from going back into esophagus. Prevents regurgitation.

Stomach Sphincters cont’d

Pyloric sphincter – located at lower end of stomach and controls passage of food into duodenum of small intestine.

Keeps food in stomach while being mixed with gastric juices that aid digestion until ready to be released into small intestine.

Food remains in stomach for 1-4 hours

Med Tip

When the pyloric sphincter becomes abnormally narrow, a condition called pyloric stenosis results in which food is unable to pass from the stomach to the small intestine. Emesis (vomiting) is the main symptom.

Chemical Digestion in Stomach While food is in stomach, chemical

digestion occurs. Gastric juices are produced by gastric glands in the stomach.

Gastric juices such as hydrochloric acid and enzymes are released to convert the food into a semifluid substance called chyme.

Functions of Gastric Juices Hydrochloric acid – kills bacteria,

facilitates iron absorption, actives the enzyme pepsin.

Enzymes in gastric juices – lipase helps break down fats and pepsin starts protein digestion.

In infants, the enzyme rennin is released to aid in the digestion of milk. Rennin is not present in adults.

g tube placement g tube feeding demonstration

Myth or Fact about your Stomach?

1. Myth or Fact: Digestion takes place primarily in the stomach.

Answer: Myth. The major part of the digestive process takes place in the small intestine. The stomach takes in the food, then churns it and breaks it into tiny particles called "chyme." The chyme are then released in small batches into the small intestine, where most digestion occurs, he says.Contrary to popular belief, foods do not digest in the order they are eaten. Everything lands in the stomach where it's all churned together, and when it's ready it's released into the small intestines together.

2. Myth or Fact: If you cut down on your food intake, you'll eventually shrink your stomach so you won't be as hungry

Answer: MythOnce you’re an adult, your stomach

remains the same size.

3. Myth or Fact: Thin people have naturally smaller stomachs than people who are heavy.

Answer: Myth. While it may seem hard to believe, the size of the stomach does not correlate with weight or weight control. People who are naturally thin can have the same size or even larger stomachs than people who battle their weight throughout a lifetime. Weight has nothing to do with the size of the stomach. In fact, even people who have had stomach-reducing surgeries, making their tummy no larger than a walnut, can override the small size and still gain weight.

4. Myth or Fact: Exercises like sit-ups or abdominal crunches can reduce the size of your stomach

Answer: Myth. No exercise can change the size of an organ, but it can help burn the layers of fat that can accumulate on the outside of your body. Plus it can help tighten the muscles in the abdomen, the area of the body lying just south of the diaphragm, that houses the stomach and many other internal organs.

Interestingly, the part of your "belly fat" that can do you the most harm may actually be the fat you don't see. It resides in the "omentum," a kind of internal sheet that lies over and around your internal organs.

5. Myth or Fact: One way to reduce acid reflux is to lose as little as 2 to 3 pounds.

Answer: Fact. The less acid that flows back up into your esophagus, the fewer problems you will have clearing it. And believe it or not, losing just 2 pounds of weight from the abdominal area can make a difference -- and pregnancy is about the best example of this. As the baby grows and pushes against the internal organs, heartburn increases; but once the baby is born and the pressure is relieved, the heartburn is, too. In much the same way, losing even a little bit of belly fat can provide similar relief

6. Myth or Fact: Beans cause everyone to make excess gas, and there's nothing you can do about it.

Answer: Myth ... sort of! Beans are high in a kind of sugar that requires a certain enzyme to properly digest. Some people have more if it, some people less. And the less you have, the more gas that will be produced during digestion of beans. What can help: Studies show that over-the-counter products that add more of the enzyme needed to break down the sugar in beans as well as other traditionally gassy vegetables can help if taken before you eat. After the fact, you can reduce the gas that forms by taking a product containing simethicone, which is a true bubble buster, releasing the surface tension on gas bubbles that form as a result of eating foods that are hard to digest.

Small Intestine

Food in the form of chyme enters the small intestine.

Small intestine Coiled Approx. 20 feet long and 1 inch in

diameter Divided into 3 sections: duodenum,

jejunum, and ileum

Duodenum

First 10 inches of small intestine Bile from gallbladder and liver and

pancreatic juice from pancreas enter small intestine through ducts, or tubes.

Jejunum

Middle portion of small intestine About 8 feet long

Ileum

Last portion of small intestine 12 feet long and is the longest

portion of small intestine Joins the large intestine at the

ileocecal valve Ileocecal valve is a muscular valve

which prevents food from returning to the ileum

Attaches to cecum of large intestine

Digestive Process of Small Intestine

Process of digestion is completed in small intestine

Products of digestion absorbed into bloodstream for use by body’s cells

Walls of small intestine are lined with villi which contain blood capillaries and lacteals.

Blood capillaries carry digested nutrients to liver where they are stored or released to body cells

Lacteals absorb most digested fats into lymphatic system released to circulatory system

Large Intestine

Final section of alimentary canal Approx 5 feet and 2 inches in

diameter Only waste, indigestible materials,

and excess water go to large intestine

Functions of Large Intestine

Absorption of water and any remaining nutrients

Storage of indigestible material before eliminated by body

Synthesis (formation) and absorption of some B-complex vitamins and vitamin K

Transportation of waste products out

Sections of Large Intestine

Cecum Connected to ileum of SI Contains vermiform appendix

Colon Ascending colon Transverse colon Descending colon Sigmoid colon

Rectum Final 6-8 inches of LI Storage for indigestables and waste

Rectum – Anal Canal – Anus Fecal material (stool, waste, feces) -

the final waste product of digestion is expelled through this opening (bowel movement - BM)

Polypectomy colon cancer parasite in colon

colostomy care

Accessory Organs

Pancreas Gallbladder Liver

Liver

Largest gland in body Located in RUQ Function:

secretes bile which aids in digestion of fats

Stores sugar in form of glycogen Stores iron and vitamins Produces heparin – prevents blood

clotting Detoxifies substances such as alcohol,

pesticides, and destroys bacteria

Gallbladder

Small, muscular sac located under liver

Stores and concentrates bile which it receives from the liver

When the bile is needed to emulsify fats in the digestive tract, the gallbladder contracts and pushes the bile through the common bile duct and into the duodenum.

Pancreas

Glandular organ behind the stomach Produces pancreatic juices which

contain enzymes to digest food Juices enter duodenum through

pancreatic duct Amylase or amylopsin – sugar Trypsin and chymotrypsin – proteins Lipase and steapsin – fats

Pancreas

Produces insulin Insulin: Regulates the metabolism,

or burning of carbohydrates to convert glucose (sugar) to energy.

What happens to a hamburger?

You are getting ready to eat a hamburger which contains a buttered bread bun, a meat patty, and cheese.

What will happen to the hamburger at each stage of the digestive process: mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum