Download The Digestive System

Digestive and Excretory
Systems
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
it’s function.
3. Compare and contrast Nutrients,
Vitamins, and Minerals.
The Digestive System
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
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
The pathway that food follows?
mouth
pharynx
esophagus
stomach
small intestine
large intestine
rectum
anus
The Digestive Tract
1.
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)
2. Pharynx- The location where the GI tract and
the respiratory system crossover
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
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
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
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
Review
Nutrient Absorption
Nutrients
• Part of food that performs a function in the
body
– provides energy
– promote growth and development
– regulate metabolism
Polymers
Carbohydrates
Proteins
Lipids
Monomers
glucose
amino acids
free fatty acids
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
• ExamplesCalcium- Bones and muscle contraction
Phosphourous - Bone, phospholipids, ATP
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