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The Digestive System
Daniel Condo
11th Grade Health
Functions of the Digestive System
1. Ingestion
2. Digestion
3. Movement/Propulsion
4. Absorption
5. Elimination
Order of Digestion
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Mouth
Pharynx
Esophagus
Stomach
Small Intestine
Large Intenstine
Rectum and Anus
Mouth
Functions: Ingestion, Digestion, and Movement
-Ingestion: - Taking in food and chewing
-Digestion: - Mechanical breakdown= Teeth (chewing)
- Chemical breakdown= Saliva (Enzymes)
-Movement: -Tongue pushes food to back of mouth
- Swallowing Reflex starts in mouth,
moving food into the Pharynx
Extra Credit Question
How many teeth are in your mouth?
Answer = 32
Pharynx
- Commonly known as the Throat
Functions: Movement
-Movement: - Swallowing Reflex
- Tongue blocks food from going back
into mouth
- Nasal passage is blocked off
- Larynx or Windpipe is blocked off
- Constrictor muscles move food to the
esophagus
Esophagus
Function: Movement
-Movement: - Upper Sphincter* opens allowing food in
from the Pharynx, then closes
- Peristalsis** moves the food down the
Esophagus
- Lower Sphincter opens to pass food into
the Stomach, then closes
*Sphincter = muscular opening
**Peristalsis = Involuntary , wave-like muscular movement
Stomach
Functions: Digestion, Absorption, Movement
-Digestion: - Mechanical breakdown occurs when
involuntary muscles of stomach churn food
with Gastric Juices (stomach acid)
- Chemical breakdown occurs when gastric
juices (including enzymes) separate food
into smaller molecules
- Lower Sphincter of Esophagus closes
when mixing to keep out gastric juices
Stomach cont.
-Absorption: - Now broken down into smaller molecules
some nutrients can be absorb by the
stomach wall
- Stomach wall (Rugae) unfolds allowing
more surface area for absorption
-Movement: -Sphincter opens at base of the stomach to
allow food (Chyme) into Small Intestine
- Peristalsis of stomach moves it into SI
Better Understanding of the Stomach
https://www.youtube.com/watch?v=URHBBE3R
KEs
Small Intestine
Functions: Digestion, Absorption, Movement
-Digestion: - Chyme is exposed to more enzymes from
ducts lining the SI
- Majority of digestion is done in the Small
Intestine; mainly chemically
- Nutrients are now broken down into easily
absorbable compounds
Small Intestine cont.
-Absorption: - SI is the longest section of the Digestive
System to maximize absorption
- Also takes the longest for food to travel to
again maximize absorption
- SI is lined with small finger-like
folds called Villi which absorb nutrients
while creating more surface area
-Movement: - SI is lined with two layers of muscle that
pass chyme into the Large Intestine
through peristalsis
Large Intestine
Functions: Absorption, Movement
-Absorption: - Large Intestine absorbs water and
electrolytes from remaining chyme
- LI also forms remaining chyme, which is
mainly waste, into feces
- Movement: - LI utilizing peristalsis to some extent
- Main movement is cause by large
muscular contractions 2-3 times a day
Rectum
Function: Elimination
-Elimination: - Main function of the rectum is store
feces until an appropriate time for
excretion
Anus
Function: Elimination
-Elimination: - Anus has 2 Sphincters
- Internal sphincter opens involuntary
and brings on the sensation of having to
“go”
- The External sphincter is controlled
voluntarily and allows to choose when
you “go”
What you need to know
• Functions of Digestive System
• Order of Digestion
• Main job of each organ