DIGESTION

OVERVIEWI. Process of digestion

II. Trip through the Digestive System

III. Problems of the digestive system

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I. Process of Digestion

A) Breakdown of food:

• Food is broken down by the digestive system.

• Digestion changes food into a usable form the cells can use.

Where does the digestive system start and end?

• Mouth• Pharynx• esophagus • stomach • small intestine • large intestine (also called the colon)• rectum• anus

• Food is changed into a usable food by some type of chemical

• Enzymes help speed up the changing of food into a usable form

What is the digestive What is the digestive system?system?

• made up of the digestive tract—a series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food

Enzymes help speed up the changing of food into a usable form• Fats, proteins and

carbs must be broken down by enzymes

• Vitamins, Minerals and water do not have to be broken down.

II. Trip through the Digestive System

1. Mouth 2. Esophagus3. Stomach 4. Small Intestine

- pancreas- liver- gallbladder

5. Large intestine 6. AnusOrgan Chart• SNEAK PEEK

1. Mouth: 1. Mouth: • Where food enters• Time spent: Few minutes• Production of saliva is the first step in

digestion (sometimes before you even start eating)

• Tongue moves it around and the saliva produced coats and lubricates the food for easier chewing and swallowing.

• Teeth cause only a mechanical change. • Saliva also contains an enzyme called

amylase – chemically break down certain

carbohydrates

Chemical change in the mouth: amylase

• Contained in saliva (salivary glands)

• Breaks down sugar and starches (carbs) into smaller components

Video

2. Pharynx2. Pharynx• Tube connecting mouth

to the esophagus• As you swallow the

epiglottis covers the windpipe so food does not go down the wrong tube.

• Lasts a few seconds• No digestion occurs

here

3. Esophagus• Tube connecting mouth

to stomach• Few seconds• No digestion occurs

here• Peristalsis (muscle

contractions) send the food down the tube until it reaches the sphincter (start of the stomach)

• Esophagus video

4. Into the Stomach 4. Into the Stomach • As food approaches, the sphincter valve

opens causing food to go into the stomach.

• Time spent: 4 hours

• Physical change: mixes and churns the food

• Chemical change: 2 enzymes - Pepsin and Rennin

• Acid that breaks down food

and bacteria

• Stores and processes food.

Physical change in the stomach

• Hydrochloric acid helps break the food down into smaller pieces

• Has a pH of 1

• Mixes and turns food to break into smaller pieces

Chemical change in the stomach

• Pepsin: breaks down protein

• Rennin: enzyme that turns milk into cheese

• Let’s view the stomach!

5. Through the Small Intestine5. Through the Small Intestine• Most chemical digestion and

absorption occurs here!

• 18-39 feet long on average... That's 4 -5 x's longer than you!

• The small intestine itself does not make enzymes, but 3 other organs not in the digestive tract deliver enzymes to the small intestine

• All 3 nutrients are digested via 3 other organs

• Time: 12 hours to digest and absorb

Three parts to the Small Intestine:Three parts to the Small Intestine:1. DuodenumDuodenum

– Located at the junction of the stomach and the small intestine– Receives bile from the

gallbladder, and other digestive enzymes from

the pancreas

― Bulk of the digestion of proteins, fats and carbohydrates takes place in the duodenum before the material travels further into the small intestine

2. 2. JejunumJejunum•coiled mid-section of the small intestine

3. Ileum 3. Ileum •final portion of the small intestine, which leads into the large intestine

•contain very small finger-like bumbumps called 'villi‘, which improves the small intestine's ability to absorb nutrients.

Three parts to the Small Intestine:Three parts to the Small Intestine:

The PancreasThe Pancreas• The pancreas

produces 3 enzymes• Lipase: breaks down

fats• Protease: Breaks

down protein• Amylase: Breaks

down carbs• Delivers these

enzymes to small intestine through the pancreatic duct

• pancreas is a small flat organ (about 18-25 cm long) that is located behind the stomach and sits close to the duodenum

The Liver:The Liver:• Largest organ of the body

(except the skin)

• Physical change:

Makes bile:

• BILE: Green, smelly liquid• Breaks fats into smaller fat

droplets• Delivers the bile to the

gallbladder for storage• Located in the upper

abdomen to the right of the stomach, below diaphragm

• liver is the body's 'detoxifier‘

• Ammonia - a toxic

product arising from the digestion of proteins, is converted into the less toxic 'urea' by the liver and then transferred to the kidneys

The GallBladderThe GallBladder

• Stores Bile (physical change)

• Delivers the bile when needed to the small intestine via the Hepatic Duct

• If the bile hardens it forms gallstones.

• small (10 cm long) pear-shaped organ that is located near the duodenum and the liver.

How are nutrients absorbed? How are nutrients absorbed? • Absorption: movement of chemicals into or out of an

organ

• Has villi on the inside that have blood vessels that carry nutrients throughout the body

• Villi increase the intestinal surface area • More surface =more absorption

6. Large intestine 6. Large intestine • Once in the large intestine:

digestion is already complete. • Large intestine only does

physical changes: removes water from undigested food and begins to produce feces.

• Time: 4 hours

• 3 parts: Ascending (up)

Transverse (across)

Descending (down)• Also contains: caecum,

appendix, colon and rectum

• Caecum – first part of the large intestine– accepts and stores processed material from the

small intestine and moves it towards the colon • Appendix

– has no known function and is thought to be a remnant from a previous time in human evolution.

• Colon – Shaped like an inverted 'U' – has four sections – mixture of fiber, small amounts of water, and

vitamins, etc, mixes with mucus and with bacteria that live in the large intestine to form feces.

• Rectum– rectum is the final part of the large intestine. – where stool (feces) is stored before being passed

as a bowel motion.

7. Anus• Where waste is excreted:

• opening through which stools/feces (ie, the waste products of digestion) pass out of the rectum and are eliminated from the body

• nervous system triggers the urge to pass stools.

• surrounded by very strong sphincter muscles contract and expand to open the anus and allow stools to pass

Problems of Digestive System-Heartburn

• Acid moves into the esophagus

• Caused by eating too much food

• Many people get acid reflux disease

• Take an antacid such as rolaids, tums, pepto-bismol

Problems Of Digestive System-Gallstones

• Bile stores up and hardens either in the liver or the gallbladder

• Block pathways for digestion

• have to have them surgically removed

Problems of Digestive SystemULCERS

• Sore or hole on inside the stomach or small intestine

• Caused by too much HCl & pepsin being produced

• Enzymes eat away at stomach lining • Causes burning sensation in stomach• Stress can bring on an ulcer or it is just natural

production of too much acid• Prescribed medicine for extreme cases• Minor cases can uses Pepsid AC

Problems of Digestive System-Appendicitis

• Swelled appendix• Bacteria builds up

from stuck food• Causes severe pain

on lower right side of body

• Appendectomy – the removal of the appendix

Problems of Digestive SystemConstipation

• Too much water is absorbed by the large intestine

• Can be a virus or something one eats

• Over the counter medicines usually take care of the problem

• Pepto-bismol, eating more roughage (lettuce), etc.

Problems of Digestive System Diarrhea

• Not enough water is absorbed by the large intestine

• Runny stools

• Caused by bacteria or virus or something one ate

• Over the counter medicines such as pepto-bismol will help