Download Small intestine and pancreas

Small Intestine
and
Pancreas
Small Intestine
Small Intestine:
-“small”= Small diameter (7m long)
- Main site for digestion and absorption
Duodenum:
Small Intestine
Small Intestine:
-“small”= Small diameter (7m long)
- Main site for digestion and absorption
Duodenum:
First 25-30cm of the small
Intestine. Where most of
the digestion occurs.
Small Intestine & the Pancreas
Moving food from stomach to small intestine:
Remember the food that comes from the
stomach is mixed with hydrochloric acid and
pepsin. = dangerous for small intestine
Solution:
-Release bicarbonate ions to neutralize acids
Controlling Bicarbonate Release
1) Stomach acid and food moves into the small
intestine
2) Prosecretin is converted to secretin by acid
Controlling Bicarbonate Release
1) Stomach acid and food moves into the small
intestine
2) Prosecretin is converted to secretin by acid
3) Secretin is absorbed into the bloodstream
4) As blood moves to pancreas the sectretin in
the blood causes the pancreas to release
bicarbonate into the small intestine
Controlling Bicarbonate Release
1) Stomach acid and food moves into the small
intestine
2) Prosecretin is converted to secretin by acid
3) Secretin is absorbed into the bloodstream
4) As blood moves to pancreas the sectretin in the
blood causes the pancreas to release
bicarbonate into the small intestine
5) Bicarbonate neutralizes the acid to protect the
walls of the small intestine
pH changes from 2  9
6) The new basic pH causes pepsin to become
inactive so it won’t digest the intestinal wall
Pancreas and the breakdown of food
Food: 3 main groups
-Protein
-Carbohydrates
-Lipids (fats)
Breakdown of Protein:
Remember at this point protein is only broken
down into short chains
Enterokinase: An enzyme in the small intestine
that activates trypsinogen converting it into
tripsin
Trypsin:
Erepsins (peptidases):
Breakdown of Protein:
Remember at this point protein is only broken
down into short chains
Enterokinase: An enzyme in the small intestine
that activates trypsinogen converting it into
tripsin
Trypsin: Breaks down the peptone chains into
shorter peptone chains
Erepsins (peptidases):
Breakdown of Protein:
Remember at this point protein is only broken
down into short chains
Enterokinase: An enzyme in the small intestine that
activates trypsinogen converting it into tripsin
Trypsin: Breaks down the peptone chains into
shorter peptone chains
Erepsins (peptidases): Break down the shorter
peptone chains into individual amino acids
Breakdown of Sugar (Carbohydrates)
Amylase (also released by salivary glands):
Released by the pancreas. Breaks down the
smaller sugar chains into disaccharides (di = 2.
Saccharide = sugar)
Disaccharase enzymes:
Breakdown of Sugar (Carbohydrates)
Amylase (also released by salivary glands):
Released by the pancreas. Breaks down the
smaller sugar chains into disaccharides (di = 2.
Saccharide = sugar)
Disaccharase enzymes: Break down
disaccharides into glucose and fructose
Eg. Maltase breaks down maltose into 2 glucose
molecules
Breakdown of Lipids (Fats)
Lipase: Lipid digesting enzymes released by the
pancreas.
Two types of Lipase
-Pancreatic lipase:
-Cholesterol lipase:
Breakdown of Lipids (Fats)
Lipase: Lipid digesting enzymes released by the
pancreas.
Two types of Lipase
-Pancreatic lipase: breaks down triglycerides
into fatty acids and glycerol
-Cholesterol lipase: breaks off one fatty acid and
converts it into cholesterol
Liver and Gall Bladder
Liver: Has three
functions related to
digestion
1) Create bile salts
2) Storage of nutrients
3) Breakdown of
toxins
Bile Salts
Location of Bile Salts: Formed in the liver and
collected in the Gall bladder where the excess
water is removed (becomes more
concentrated). They enter the duodenum via
the bile duct.
Controlling the release of Bile Salts
1) Fats present in the small intestine
2) Fats cause the release of Cholecystokinin
(CCK) a hormone.
Controlling the release of Bile Salts
1) Fats present in the small intestine
2) Fats cause the release of Cholecystokinin
(CCK) a hormone.
3) CCK moves into blood
4) Blood reaches gall bladder
5) Here CCK triggers the release of bile salts
from the gall bladder to the small intestine
Controlling the release of Bile Salts
1) Fats present in the small intestine
2) Fats cause the release of Cholecystokinin (CCK) a
hormone.
3) CCK moves into blood
4) Blood reaches gall bladder
5) Here CCK triggers the release of bile salts from
the gall bladder to the small intestine
6) Once in the small intestine the bile salts break
down the large fat droplets into smaller drops
(just like dish soap) = emulsification
7) This leaves a larger surface for pancreatic lipase
to get at the fat
Gallstones and jaundice
Liver as a Storage organ
Storage in Liver: Stores glycogen and vitamins
(A, B12, D)
Breakdown of Toxins: Breaks down harmful
substances into less harmful chemicals that
can be dissolved into blood and excreted in
urine. This process does damage liver tissue
Eg. alcohol
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j
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Problems with Detoxification
Problem with detoxification: The liver cells that
are damaged when they try to breakdown
toxins are replaced by connective tissue and
fat.
= Erode the liver you lose the cells that perform
functions needed by the body
This leads to Cirrhosis
Diagnostic Questions
• Symptom: