UEQ: What happens to your food after you eat

it?

WarmUP: What are the major organs of the digestive system?

The Digestive System

Digestion

Function: Breakdown of food into a useable form that your 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

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 System1. Mouth

2. Esophagus

3. Stomach

4. Small Intestine

- pancreas

- liver

- gallbladder

5. Large intestine

6. Anus

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 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

MOUTHMOUTH• Where digestion starts

• Primary parts:

– Lips: Sensory organ to judge texture and temp.

– Cheeks

– Tongue: Harbors the taste buds and mixes food.

– Palate

– teeth

Taste bud Taste bud locationlocation.

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 (just swallowing)

3. Esophagus• Tube connecting

pharynx 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

Motor function of Digestive Tract

Mixing movements: when smooth muscles contract rhythmically

-ex: when stomach is full, waves of Propelling movements/Peristalsis: push contents through the system

http://vimeo.com/2595338

4. Into the Stomach 4. Into the Stomach • Next stop: the stomach!

• Time spent: 4 hours

• Physical change: mixes and churns the food

• Chemical change: – Gastric juices: 2 enzymes - Pepsin and Rennin– Acid that breaks down food

and bacteria

• Function: Stores and processes food.

Chemical change in the stomach

• Pepsin: breaks down protein

• Rennin: enzyme that turns milk into cheese (breaks down dairy)

• Let’s view the stomach!

5. Through the Small Intestine5. Through the Small Intestine• Most digestion and absorption of

nutrients into bloodstream occurs here!

• 18-39 feet long on average...

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

• Time: 12 hours to digest and absorb

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

• pancreas is a small flat organ that is located behind the stomach and start of small intestine

The Liver:The Liver:

• Largest organ of the body (except the skin)

• Makes bile:

• BILE:BILE: Green, smelly liquid

Breaks fats into smaller fat

droplets• Delivers the bile to the

gallbladder for storage

• liver is the body's 'detoxifier‘

• Plays a role with

the kidney in the urinary system too.

The GallBladderThe GallBladder

• Stores Bile

• Delivers the bile when needed to the small intestine

• If the bile hardens it forms gallstones.

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

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

of an organ by diffusion, facilitated or active transport

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

How the organs all work together:

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

digestion is already complete. • Large intestine only removes

water from undigested food and begins to produce feces.

• Time: 4 hours

• 3 parts: Ascending (up)

Transverse (across)

Descending (down)• Also contains: cecum,

appendix, colon and rectum

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• Lower esophageal sphincter opens too often or

does not close tight enough, stomach acid can reflux, or seep, into the esophagus and cause the burning sensation.

• Caused by eating too much food

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

Gallstones

• Block pathways for digestion

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

• have to have them surgically removed

ULCERS• Sore or hole on inside the stomach or small

intestine causes a burning feeling. • Enzymes eat away at stomach lining • 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

Appendicitis

• Swelled appendix• Causes severe pain on

lower right side of body• Bacteria builds up from

stuck food• Appendectomy – the

removal of the appendix

Constipation• 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

• Milk of Magnesia, eating more roughage (lettuce), prescription medications.

• Not enough water is absorbed by the large intestine causing runny stools

• Caused by bacteria or virus or something one ate

• Some people have diarrhea often as part of irritable bowel syndrome or other chronic diseases of the large intestine.

• Over the counter medicines such as Pepto-Bismol, Imodium A-D, and Kaopectate

Diarrhrea