Download Digestive System

Digestive System
1.
Objectives
What are the nutrients that the body uses
2. What is the purpose of digestion
3. Organs of the Digestive System
Nutrients of the Body
• Carbohydrates – Provide energy for the
body
– Fiber – helps food move through your
digestive tract
– Starch – Complex carbohydrate
– Sugar – Simple carbohydrate. It is the
building block of all carbohydrates
Fats
• Provides energy for the body when
carbohydrates are not available
– Fatty acids and glycerol – building blocks of
fats
– Saturated – from animals mainly
– Unsaturated – from plants mainly
Proteins
• Provides energy for the body when fats
and carbohydrates are not available.
• Used to build and repair the body
– Amino acids – building blocks of proteins
Minerals, Vitamins, Water
• Minerals -- Helps your body function
properly (ex. Keeps muscle, bones, nerves
healthy)
• Vitamins – needed for chemical reaction to
occur in the body (ex. Aids in blood
clotting)
• Water – chemical reactions of the body
take place in water.
Digestive System
• Purpose of the digestive system is to fuel the
body with energy from nutrients.
• Types of Digestion
– Mechanical – physical action of breaking food down
into smaller pieces (done in mouth and stomach)
– Chemical – food is broken down
into the essential nutrients the body can
use with the help of chemicals such as
enzymes
“Lock and Key” System
=
+
carbohydrate
enzyme
Sugars
“Lock and Key” System
• Enzymes
– Chemicals that help bread down substances (foods)
– Often end in “ase”
• Examples:
– Amylase  carbohydrates
– Protease  proteins
– Lipase  fats (lipids)
Mouth
Tongue
Esophagus
Liver
Gall bladder
Large Intestine
Stomach
Pancreas
Small Intestine
Rectum
Anus
Organs of the Digestive System
• Mouth
– Food is mechanically disgested with the help of the
teeth and tongue
– Food is chemically digested with the help of saliva
and the enzyme amlyase
• Saliva breaks down carbohydrates into sugars
• Salivary glands – secretes saliva into the mouth
– Food doesn’t enter the salivary glands
– Chyme is the name of the chewed food in your mouth
Esophagus and Stomach
• Esophagus – transports food to the
stomach. Smooth muscles push food
through the digestive tract, this is known
as peristalsis
• Stomach – produces gastric juice. A layer
of mucus protects the stomach lining from
gastic juice. Churns food with strong
muscles
– Gastric juice breaks down proteins into amino
acids
Liver and Gall Bladder
• Liver – produces bile
– Bile chemically digests food in the small
intestine.
– Food doesn’t enter the liver
– Bile breaks down fats into fatty acids
• Gall Bladder – small sac
underneath the liver which
stores bile.
– Food doesn’t enter the liver
Pancreas
• Known as the “super gland”
• Produces pancreatic juice. It chemically
digests food in the small intestine
• Food doesn’t enter the pancreas
• Pancreatic juice breaks down
carbohydrates, fats, and proteins
Small Intestine
• The most important digesting organ (22-24ft
long)
• Bile and pancreatic juice digest food in the small
intestine
• The small intestine produces intestinal juice
• Intestinal juice breaks down carbohydrates and
protein
• Most nutrients digested are absorbed in the
lining of the small intestine (villi)
Villi
• Fingerlike projections
inside the small
intestine
• Increase the surface
area for the absorption
of nutrients
• Absorption =
mechanical digestion
Large Intestine
• Water is absorbed in the large intestine (34 ft long)
• Waste products are collected in the large
intestine (feces) and are stored in the
rectum
• Wastes are expelled from the body
through the anus
• No digestion occurs here