digestive system. which organ of the digestive system does each picture represent? knife food...

Digestive System

Which organ of the digestive system does

each picture represent?

Knife Food Processor Garbage Disposal

• The function of the digestive system is to break down food so that it can be used as energy in your body.

• The system consists of a series of complex organs and glands (which excrete enzymes) that break down food into small usable particles.

Mechanical Digestion:

-food is broken down mechanically, with movement

Ex: Teeth

Chemical Digestion:

-food is broken down with a chemical or enzyme

Ex: Saliva

• Peristalsis- series of involuntary smooth muscle contractions along the walls of the digestive tract.

• Moves food through the digestive system.

Organs Involved:1. Mouth2. Esophagus (A)3. Stomach (C)4. Small Intestine (E)5. Large Intestine (F)

• Appendix• Pancreas (D)• Liver (K)• Gall Bladder (J)

Digestion begins in the mouth.

As you chew your food, two processes are occurring:

1. TEETH- your teeth begin mechanical digestion by breaking down food into smaller pieces.

2. SALIVA- this enzyme helps break down starches chemically

1

The mouth completes both mechanical and chemical digestion!

As you swallow, the food must pass several structures:

• Pharynx- Back of the throat opens into esophagus

• Epiglottis- flap of tissue that keeps chewed food from going down the trachea to the lungs. As you swallow, the epiglottis flops closed.

• Larynx- Vocal cords

• The esophagus is a long tube that runs from the mouth to the stomach.

• After being chewed and swallowed, the food ball (bolus) enters the esophagus.

2

• The food is deposited in the Stomach.

• The stomach is a large, sac-like organ made of muscle.

3

• The stomach churns food AND bathes it in gastric juice (acidic).

• Food remains in the stomach for 2-4 hours, turning into a thin liquid soup called chyme.

3

The stomach completes both mechanical and

chemical digestion!

• The liquid chyme is the transported to the small intestine.

• SI is a narrow muscular tube about 6 meters long, lined with villi.

4

• Bile and other enzymes are injected into the Small Intestine to further break down the food.

4

Is this mechanical or chemical digestion?

Food remains in the SI for 3-5 hours

Don’t forget the Bacteria!

• Villi- finger-like extensions that absorb nutrients

• Villus expand surface area of SI.

4

• The function of the SI is to absorb all usable nutrients.

• The villi are covered with capillaries which pick up the nutrients for ALL cells in the body.

4

Blood vessels pick up nutrients

from SI

What system works with Digestive?

• Anything (liquid or solid) that is not absorbed by the SI is sent to the Large Intestine.

• The colon absorbs most excess liquids.

5

Don’t forget the Bacteria!

• After about 18-24 hours…

• The END process- solid waste (feces) is stored in the rectum until it is excreted through the anus.

5

• The digestive system is also part of the

Excretory system!

Your meal’s entire journey through the Digestive System has taken between 24 and 33 hours.

Many organs play a role in the digestion of foods but never come in contact with food, we call these accessory organs.

Three such organs are:

– Liver– Gall Bladder– Pancreas

• Liver- large organ located above and in front of the stomach.

• It filters toxins from the blood and makes bile (breaks down fats).

• Gall Bladder- small, sac-like organ located near the SI.

• It stores and releases bile into the small intestine.

• Pancreas- an enzyme producing organ located below the stomach and above the intestines.

• Enzymes from the pancreas aid in digestion of carbohydrates, fats and proteins in the small intestine.