The Digestive System

1
The Digestive System

• -a one way tube through the body
• Topics
• Digestion and absorption
• The organs of the tube

2
Digestion

• Your digestive system digests two ways
• Chemically
• Acids and enzymes react with foods to release
  their nutrients
• Physically/Mechanically
• Food is smooshed, torn and broken down into
  smaller pieces to releases nutrients

3
Absorption

• After food has been digested
• Nutrients from food leave your digestive tract
• And are absorbed into your blood

4
Organs of the tubeMouth

• Mechanical digestion (physical breakdown)
• Teeth
• Chemical digestion (digestive enzymes)
• Saliva
• Under control of nervous system
• Contains
• lysozyme (antibacterial enzyme)
• Amylase (breaks down starch)

5
Esophagus

• Tube that pushes bolus from the mouth to the
  stomach
• bolus food clump
• The pushing is done by Peristalsis (click on word
  for animation)
• wave of muscle contractions
• Peristalsis pushes our food through the entire
  digestive system
• Heartburn is stomach acid burning the bottom of
  the esophagus

6
The Stomach

• Chemical Digestion
• Glands secrete mucus and hydrochloric acid
• Acid activates release of pepsin
• Ulcers
• Painful hole in stomach caused by excess acid or
  bacteria
• Mechanical digestion
• Stomach muscles churn to produce chyme
• Chyme is mushed up food in stomach

7
The Small Intestine

• Starts right after the stomach
• Many enzymes and chemicals break down food
• Enzymes and chemicals are injected from the
  pancreas and liver
• ABSORBS nutrients.
• Small intestine is lined w/villi (tiny
  projections) covered w/microvilli
• Peristalsis pushes bolus along to large intestine

8
The Pancreas

• Pancreas gland just below the stomach
• Neutralize stomach acid
• Releases baking soda
• Produces enzymes that break down macromolecules
• Produces insulin

9
The Liver

• Liver large organ just above the stomach
• Produces bile (breaks down fat)
• Also vital for removal of toxins from body

10
The Large Intestine

• Recovers water
• Forms and stores feces
• Microbial fermentation to digest indigestible
  foods (cellulose/wood)
• Pushes waste to rectum by peristalsis

11
The anus
Rectum

• The rectum holds feces until they leave the anus
• The anus is a sphincter muscle
• When you go 2 the sphincter relaxes
• When you hold it, the sphincter contracts
• Peristalsis pushes feces out of your body

Anus