Digestive and Excretory Systems

1
Digestive and Excretory Systems
2
By the end of this unit, I should be able to

1. List and describe the sequence of organs in the
   gastrointestinal (G.I.) tract.
2. Describe how the general physiology of each organ
   in the G.I. tract aids in its function.
3. Compare and contrast Nutrients, Vitamins, and
   Minerals.

3
The Digestive System
4
The Digestive System

• A long hollow tube- called the
• Gastrointestinal Tract (GI Tract)
• Purpose to break down macromolecules into unit
  molecules that our body then absorbs

5
The Processes of Digestion

1. Ingestion- taking food in
2. Digestion- break down of food
3. Movement- from one segment of the tract to the
   next
4. Absorption- when nutrients cross the wall of the
   GI tract and enter the cells lining the tract and
   then enter into the blood stream.
5. Elimination- undigested molecules are removed

6
The pathway that food follows?
mouth pharynx esophagus stomach small intestine
large intestine rectum anus
7
The Digestive Tract

• Mouth-
• Teeth are well adapted for chewing many kinds of
  food
• Saliva - a mixture of water, mucus, and a
  digestive enzyme called salivary amylase
  (breaking down starches into sugars)

8

• 2. Pharynx- The location where the GI tract and
  the respiratory system crossover

9

• 3. Esophagus- long muscular tube that connects
  the pharynx with the stomach
• muscles in the Esophagus wall move food toward
  the Stomach. 
• Waves of muscular contractions called peristalsis
  move food through the digestive tract

10

• 4. Stomach- J shaped muscular organ that lies on
  the left side of the body beneath the diaphragm
• Stores food
• Stomach acid and gastric enzymes begin the
  breakdown of protein
• Pepsin- the enzyme that begins protein digestion

11

• 5. Small Intestine-
• Digests carbohydrates, fats, and completes the
  digestion of proteins.
• ABSORBS nutrients
• 6. Large Intestine-
• Absorb water to prevent dehydration
• Absorbs vitamins (B complex and K) produced by
  intestinal flora
• Forms and rids the body of feces through the anus

12
Accessory Organs

• Pancreas- secretes Pancreatic Fluid into the
  Small Intestine. 
• Lipase enzymes - break down fat molecules to free
  fatty acids, diglycerides, and monoglycerides
• Emulsification of fats- broken down into smaller
  droplets
• Liver- produces bile, destroys old blood cells,
  detoxifies blood, stores iron, and helps regulate
  blood cholesterol levels
• Bile- produced by liver and stored in the
  furthers the process of digestion
• Gall bladder- stores bile

13
Review
14
Nutrient Absorption
15
Nutrients

• Part of food that performs a function in the body
• provides energy
• promote growth and development
• regulate metabolism
• Polymers Monomers
• Carbohydrates glucose
• Proteins amino acids
• Lipids free fatty acids

16
Minerals

• Inorganic (nonliving) substance that occurs
  naturally in the ground
• Living organisms require them for parts of cells,
  body fluids and structural components of tissues
• Examples-
• Calcium- Bones and muscle contraction
• Phosphourous - Bone, phospholipids, ATP

17
Vitamins

• Organic compounds that the body uses for
  metabolic purposes, but is unable to produce
  enough on its own
• Many are co-enzymes (enzyme helpers)
• Examples Vitamin D, B, C