Download Small Intestine - Human Digestive System

Small Intestine
Proudly presented by:
- Jason Tan Tse How
- Teo Hong Soon
- Hoe Feng Yu
- Ahmad Tirmuzi
- Hazel Ong Li Ying
Structure Of Small Intestine
o Tube-like structure winds compactly back and forth within
the abdominal cavity for about 7 m
o Consist of #1 Duodenum
#2 Jejunum
#3 Ileum
o Have finger-like projections known as villi (increase surface
area for absorption of nutrients).
Function Of Small Intestine
o Small intestine breaks down the food mass into smaller
molecule, so that they can diffuse through the walls of the
intestine and absorbed by the bloodstream.
pH Level of Small Intestine
• between 8.0 to 8.5
• because the enzymes present in the small intestine work well at
a higher optimum pH level
Enzymes
6 types of enzymes that break down disaccharides into
monosaccharides:
• Sucrase breaks down sucrose into glucose and fructose
• Maltase breaks down maltose into glucose.
• Isomaltase, which breaks down maltose
• Lactase breaks down lactose into glucose and galactose
• Intestinal lipase breaks down fatty acids
Enzymes
• small intestine receives lipase, trypsin and amylase from the
pancreas
• transported from the pancreas to the duodenum through the
pancreatic duct
• Protein, fats and starch are broken down into smaller
molecules
Enzymes
• However, they are not fully broken down yet which causes
the enzymes of the small intestine to act upon them
• Enzymes include peptidase, which breaks down peptides into
amino acids and the enzyme maltase acts upon maltose
which produces glucose
Enzymes
• These molecules are absorbed by the villi in the small
intestine and according to they molecule they are either
absorbed by the lacteal or blood capillaries
Movement Of Food
o Food is being pushed down by the wave-like movement
of the muscular wall called peristalsis .
o As it is carried along, it is subject to the digestive action
of the secretions of the intestinal lining as well as to that
of bile and
Movement Of Food
• pancreatic juices which enter the upper intestine (duodenum)
from ducts leading from the liver and pancreas.
• Food continues to pass into the middle (jejunum) and end
(ileum) of the small intestines.
#1 Duodenum
oFirst part of the Small Intestine.
oMixed the food from the stomach with bile from the gall bladder
and digestive juices from the pancreas.
#2 Jejunum
oMiddle part of small intestine
oThe passive transport of sugar fructose and the active transport
of amino acids, small peptides, vitamins, and most glucose take
place here.
oThe villi in the jejunum are much longer than in the duodenum
or ileum
#3 Ileum
o Absorption
of vitamin B12 and bile salts and whatever
products of digestion that were not absorbed by the jejunum.
o Has an extremely large surface area both for the adsorption of
enzyme molecules and for the absorption of products of
digestion.
#3 Ileum
• Contain the protease and carbohydrase enzymes (gastrin,
secretin, cholecystokinin) responsible for the final stages of
protein and carbohydrate digestion
• The villi contain large numbers of capillaries which take the
amino acids and glucose produced by digestion to the hepatic
portal vein and the liver.
Picture of the Small Intestine
Picture of the Small Intestine
Picture of Villi
Illnesses of the Small Intestine
• Duodenal cancer is a cancer in the beginning section of the
small intestine.
• Relatively rare as compared to stomach cancer and colorectal
cancaer
Importance of the Small Intestine
The small intestine is very important to us because:
• Without the small intestine, food that we need will not be able
to be absorbed into the body
• food that we consume will not be digested completely without
the help of the small intestine
THE END