chyme
Now we’ll close the pyloric sphincter and imagine some chyme in the stomach.
The sphincter opens briefly and lets some chyme into the duodenum.
Bile is secreted from the bile duct into the duodenum
large fat
particle
Partially digested food at this point contains some large fat particles. (pause)
We’ll show one here.
Bile physically breaks up larger fat
particles into smaller ones.
.
This process is called emulsification.
large fat
particle
Bile physically breaks up large fat particles into smaller ones.
Bile physically breaks up larger fat
particles into smaller ones.
.
This process is called emulsification.
large fat
particle
This process is called emulsification.
emulsification
large fat
particle
smaller
fat
particles
Here’s how it works…We see the large fat particle breaking up into smaller particles.
No chemical reactions occur during emulsion. This is a type of physical digestion.
Chyme changes colour
The presence of bile also causes the chyme to change colour during its time in the
duodenum
very large
surface area
Speeds up
the action of
enzymes
Looking at the small fat particles (pause), we see they have a very large combined surface area. (click) This
greatly speeds up the action of enzymes, which break down fats chemically.
Now, we’ll move back over here…
At the same time as bile is secreted, pancreatic juice also enters the duodenum from the pancreatic duct.
We’ll discuss what pancreatic juice does.
Functions of Pancreatic Juice
1. Bicarbonate ions (HCO3–) in pancreatic juice are basic, so they
neutralize the excess acid in the chyme.
2. Pancreatic juice contains enzymes which break down proteins
into amino acids.
3. Pancreatic juice contains enzymes which break down fats into
fatty acids and glycerol.
4. Pancreatic juice contains enzymes which break down
carbohydrates into simple sugars.
5. Amino acids, fatty acids, and simple sugars can be absorbed
into the bloodstream. This happens further down in the small
intestine.
Pancreatic juice is a complex mixture of bicarbonate ions and a number of enzymes. It is very important for
digestion in the duodenum of the small intestine. We’ll look at some of its main functions here.
Functions of Pancreatic Juice
1. Bicarbonate ions (HCO3–) in pancreatic juice are basic, so they
neutralize the excess acid in the chyme.
2. Pancreatic juice contains enzymes which break down proteins
into amino acids.
3. Pancreatic juice contains enzymes which break down fats into
fatty acids and glycerol.
4. Pancreatic juice contains enzymes which break down
carbohydrates into simple sugars.
5. Amino acids, fatty acids, and simple sugars can be absorbed
into the bloodstream. This happens further down in the small
intestine.
Chyme comes from the stomach, and is therefore highly acidic, containing many H + ions
Functions of Pancreatic Juice
1. Bicarbonate ions (HCO3–) in pancreatic juice are basic, so they
neutralize the excess acid in the chyme.
2. Pancreatic juice contains enzymes which break down proteins
into amino acids.
3. Pancreatic juice contains enzymes which break down fats into
fatty acids and glycerol.
4. Pancreatic juice contains enzymes which break down
carbohydrates into simple sugars.
5. Amino acids, fatty acids, and simple sugars can be absorbed
into the bloodstream. This happens further down in the small
intestine.
Bicarbonate ions in the pancreatic juice move into the duodenum.
Functions of Pancreatic Juice
1. Bicarbonate ions (HCO3–) in pancreatic juice are basic, so they
neutralize the excess acid in the chyme.
2. Pancreatic juice contains enzymes which break down proteins
into amino acids.
3. Pancreatic juice contains enzymes which break down fats into
fatty acids and glycerol.
4. Pancreatic juice contains enzymes which break down
carbohydrates into simple sugars.
5. Amino acids, fatty acids, and simple sugars can be absorbed
into the bloodstream. This happens further down in the small
intestine.
And they come in contact with the acid present,
Functions of Pancreatic Juice
1. Bicarbonate ions (HCO3–) in pancreatic juice are basic, so they
neutralize the excess acid in the chyme.
2. Pancreatic juice contains enzymes which break down proteins
into amino acids.
3. Pancreatic juice contains enzymes which break down fats into
fatty acids and glycerol.
4. Pancreatic juice contains enzymes which break down
carbohydrates into simple sugars.
5. Amino acids, fatty acids, and simple sugars can be absorbed
into the bloodstream. This happens further down in the small
intestine.
And neutralize it. Now the chyme is no longer acidic, and it will not harm the intestinal walls.
Functions of Pancreatic Juice
1. Bicarbonate ions (HCO3–) in pancreatic juice are basic, so they
neutralize the excess acid in the chyme.
2. Pancreatic juice contains enzymes which break down proteins
into amino acids.
3. Pancreatic juice contains enzymes which break down fats into
fatty acids and glycerol.
4. Pancreatic juice contains enzymes which break down
carbohydrates into simple sugars.
5. Amino acids, fatty acids, and simple sugars can be absorbed
into the bloodstream. This happens further down in the small
intestine.
So we’ll summarize here that bicarbonate ions coming in with pancreatic juice are basic
and therefore they neutralize excess acid in the chyme.