1
,From mouth into bloodstream.
* Pentose phosphate pathway
* Glycolytic pathway
2
,Carbohydrates are examples of macronutrients. These nutrients deliver energy/fuel to the
body. The body needs these in large amounts.
Carbohydrates (sugar chains) can be divided into sugars and starches. Sugars are mono- and
disacccharides while starches are polysaccharides.
Another exmample of polysaccharides are dietary fibers, these are non-digestible
carbohydrates which go intact through the intestinal system
and help to remove waste out of the body.
The main function of carbohydrates is to provide energy to the body. It can be stored in liver
and muscles if the energy is not used.
3
,The digestive system in regards to carbohydrates consists of the following organs:
mouth/oral cavity, stomach, pancreas, small intestine and large intestine (colon).
When carbohydrates are digested they will be converted into mono-sacharides. The 3
major sources that consist in the normal human diet are sucrose (disaccharide),
lactose (disaccharide found in milk) and starches (polysaccharide).
The digestion of carbohydrates start in the mouth, here the food is chewed and
mixed with saliva. Saliva contains the digestive enzyme ptyalin (alfa-amylase) which is
secreted mainly by the parotid glands. This enzyme hydrolyzes starch into the
disaccharide maltose and other small polymers of glucose. After it is mixed with
salivary amylase and other salivary juices, it is swallowed and passes through the
esophagus. The mixture enters the stomach where it is known as chyme.
When the food becomes mixed with the stomach secretions the activity of salivary
amylase is blocked by acid of the gastric secretions. After being in the stomach, the
chyme enters the beginning part of the small intestine (duodenum) and a bicarbonate
solution is secreted from your pancreas that buffers the acidic food mixture coming
from your stomach.
Then the pancreas secretes the enzyme amylase that is almost identical in function
with the salivary amylase, only several times as powerful. This enzyme breaks the
polysaccharides down into a disaccharide. The small intestine contains enterocytes
4
,that produce several enzymes called lactase, sucrase and maltase, these break down
the disaccharides into monosaccharides. They are capable of spliiting the
disaccharides lactose, sucrose and maltose.
Lactose splits into a molecule of galactose and one of glucose.
Sucrose splits into a molecule of fructose andone of glucose.
Maltose and other small glucose polymers all split into multiple molecules of glucose.
Thus, the final products of carbohydrate digestion are all monosaccharides. These are
all water soluble and are absorbed into the portal blood immediately.
Carbohydrates that weren’t digested and absorbed by the small intestine reach the
colon where they are partly broken down by intestinal bacteria. Fiber, which can’t be
digested like other carbohydrates, is excreted with feces or partly digested by the
intestinal bacteria.
4
, Overview
5
,From mouth into bloodstream.
* Pentose phosphate pathway
* Glycolytic pathway
2
,Carbohydrates are examples of macronutrients. These nutrients deliver energy/fuel to the
body. The body needs these in large amounts.
Carbohydrates (sugar chains) can be divided into sugars and starches. Sugars are mono- and
disacccharides while starches are polysaccharides.
Another exmample of polysaccharides are dietary fibers, these are non-digestible
carbohydrates which go intact through the intestinal system
and help to remove waste out of the body.
The main function of carbohydrates is to provide energy to the body. It can be stored in liver
and muscles if the energy is not used.
3
,The digestive system in regards to carbohydrates consists of the following organs:
mouth/oral cavity, stomach, pancreas, small intestine and large intestine (colon).
When carbohydrates are digested they will be converted into mono-sacharides. The 3
major sources that consist in the normal human diet are sucrose (disaccharide),
lactose (disaccharide found in milk) and starches (polysaccharide).
The digestion of carbohydrates start in the mouth, here the food is chewed and
mixed with saliva. Saliva contains the digestive enzyme ptyalin (alfa-amylase) which is
secreted mainly by the parotid glands. This enzyme hydrolyzes starch into the
disaccharide maltose and other small polymers of glucose. After it is mixed with
salivary amylase and other salivary juices, it is swallowed and passes through the
esophagus. The mixture enters the stomach where it is known as chyme.
When the food becomes mixed with the stomach secretions the activity of salivary
amylase is blocked by acid of the gastric secretions. After being in the stomach, the
chyme enters the beginning part of the small intestine (duodenum) and a bicarbonate
solution is secreted from your pancreas that buffers the acidic food mixture coming
from your stomach.
Then the pancreas secretes the enzyme amylase that is almost identical in function
with the salivary amylase, only several times as powerful. This enzyme breaks the
polysaccharides down into a disaccharide. The small intestine contains enterocytes
4
,that produce several enzymes called lactase, sucrase and maltase, these break down
the disaccharides into monosaccharides. They are capable of spliiting the
disaccharides lactose, sucrose and maltose.
Lactose splits into a molecule of galactose and one of glucose.
Sucrose splits into a molecule of fructose andone of glucose.
Maltose and other small glucose polymers all split into multiple molecules of glucose.
Thus, the final products of carbohydrate digestion are all monosaccharides. These are
all water soluble and are absorbed into the portal blood immediately.
Carbohydrates that weren’t digested and absorbed by the small intestine reach the
colon where they are partly broken down by intestinal bacteria. Fiber, which can’t be
digested like other carbohydrates, is excreted with feces or partly digested by the
intestinal bacteria.
4
, Overview
5
