Download The Endocrine System

The Digestive System
A Closer Look
QOTD – Label Me!
Answers
1.
2.
3.
4.
5.
6.
7.
8.
Tongue
Esophagus
Stomach
Duodenum
Pancreas
ileum
Large Intestine
Rectum
Purpose:

To enable the absorption of the nutrients needed
for growth, maintenance and repair
Components of Digestion
Ingestion
= the taking in of nutrients
= enters by mouth
Digestion
= the breakdown of complex organic molecules into
smaller components by physical & chemical means
Mechanical – done by teeth, and stomach
Chemical – done by the mouth, stomach,
liver, gallbladder, pancreas, small & large intestine.
Break It Down Now!
Enzymes



Carbohydrases break down ________
Peptidases break down… ________
Lipases break down…
________
SEE HANDOUTS!
Absorption


The taking up of digested molecules into cells
Done by stomach, small intestine (villi), large
intestine
small intestine (villi)
Absorption





The Small Intestine is designed to have a
large surface area.
The inner membrane is folded like a fan
The entire surface is covered with villi (villus)
Each villus is covered with microvilli
Absorption involves diffusion and active
transport
Anatomy of a Villus
Proteins
Microvilli
Capillary
Lacteal
BEFORE
DIGESTION…
Starches
TOO BIG!!
AFTER DIGESTION…
SMALL ENOUGH!!
Lipids
Water
Minerals
TO BLOOD
Water soluble vitamins
(B, C)
Glucose
Amino Acids
Glycerol
TO LYMPH
Fatty Acids
Fat soluble vitamins (A,
D, E, K)
Elimination


The removal of waste from the body
Done by large intestine, rectum and anus
Control Mechanisms
Regulation through
feedback
 Done by hormones
(chemical messengers)
 Thermostat Example:
-Too hot, shuts down
-Too cold, starts furnace

Digestion of Fats


When fats enter the
duodenum, the
hormone CCK
(Cholecystokinia) is
released which causes
the gall bladder to
release bile.
Fats are emulsified
Acidic Chyme


When acidic chyme
enters the small
intestine, the hormone
secretin is released
which causes the
pancreas to release
bicarbonate ions.
The acid is then
neutralized!
Blood Glucose Levels




When glucose enters the
blood stream, the pancreas
releases Insulin.
Insulin stimulates the
storage of glucose
(as Glycogen, in the liver)
When blood glucose levels
drop too low, the pancreas
releases Glucagon.
Glucagon stimulates the
release of glucose (from
Liver) into the bloodstream
Blood Sugar Levels
Check out Page 270!
Digestive System Problems
1. Ulcer
 A sore wall of the
stomach (peptic) or
duodenum (duodenal)
 HCl creates a hole in
the mucous lining…acid
irritates muscles
 Caused by bacteria that
reduce amount of
mucous.
 Treated with antibiotics
Digestive System Problems
2. Cirrhosis of the Liver.
 Scar tissue in liver.
 Caused by excessive
alcohol consumption and/or
hepatitis virus.
 Results in jaundice (yellow
skin), nausea, pain, fluid in
abdomen
 Treatment…stop drinking!,
vitamins, transplant.
 Read Page 273!
Digestive System Problems
3. Inflammatory Bowel Disease
 Crohn’s Disease and
Ulcerative colitis
 Inflammation of the lining of
small or large intestine.
 Treatment: Drugs,
supplements or…
 Resection and Colostomy
 A stoma is created, and a
pouch collects the waste.
Digestive System Problems
4. Acid Reflux
•Stomach acid burns the
tissue of the esophagus
•Caused by a weak cardiac
sphincter
Digestive System Problems
5. Constipation
 Too much water is
removed from feces
 Usually because waste
is moving too
slowly…bunged up!
 Treatment: Eat fibre!
(cellulose), laxatives,
suppositories.
A CURE FOR CONSTIPATION?