 Hello, last class we have seen what are the various salivary glands, what are the type of enzymes that are produced, I mean in the stomach up to stomach we have seen and what are the spingters, what is the peristallitic movement and let us continue with the digestion absorption of nutrients. So, after the stomach is the food goes into the small intestine. So, after the digestion of all the digestion of proteins, fat and carbohydrate is performed in the small intestine. So, the small intestine is divided into three parts, we have the deodenum which is the first 10 to 12 inches, then we have the jejunum which is 4 feet in length and followed by the helium which is 5 feet in length. So, nutrient digestion in the small intestine occurs because of the enzyme that is secretin which is released upon the, at the moment the food enters into the small intestine, secretin is secreted and this stimulates the release of the bicarbonate which is produced by the pancreas and required to change the acidity, I mean the pH of the contents in the small intestine. So, this bicarbonate it neutralizes the chi and neutralization is very important because the enzymes in the small intestine they need a neutral environment, they cannot work with acidic environment. Now, pancreatic juices and the secretions from the intestinal wall, they contain a variety of digestive enzymes which helps to digest the fat, carbohydrates and proteins. Bile is released from the gallbladder upon the appearance of fat into the small intestine. The moment the food starts from the stomach and enters the small intestine, if the food is fatty food then bile is released then this acts as an emulsifier and without it the lipid will not come into contact with the pancreatic lipase, lipase is the one enzyme which digest the fat. So, fats would not be digested properly if bile does not get released. So, with the pancreatic and the intestinal enzymes working together the digestion creates smaller compounds of protein fat and carbohydrate that is comes down to its functional units like the glucose, amino acids and fatty acids which can be easily absorbed. Now, minerals, vitamins and cholesterol are not broken down and they are generally absorbed unchanged. Now, nutrient absorption in small intestines, we have seen the digestion now the absorption. Most absorption occurs almost 90 percent of the absorption of all the nutrients occurs in small intestine. So, it provides a surface area that is equivalent to a tennis court if you open these small intestine and put it across the length the area is such large for absorption. So, nutrients are trapped in the folds of the intestinal wall they have a lining like this which are called as villi. So, these nutrients are trapped in the folds and absorbed through these microvilli. So, each villus contains blood vessels and lymph vessels which help in transporting the nutrients. Now, what are soluble nutrients are absorbed directly into the bloodstream whereas, fat soluble compounds they are absorbed into the lymph the entire fat and the fat soluble nutrients are absorbed through the lymph tract and then they enter into the blood they do not enter into the blood directly. So, these are the lymph nodes all the yellow part of the figure that shows the lymph lymphatic glands from through which the fat is absorbed and finally, here it joins the thoracic duct into the bloodstream. Now, deodenum and the upper jejunum the most of the minerals except sodium chloride and potassium are absorbed in the upper part of the small intestine that is the deodenum and the jejunum. Jejunum and upper helium you have the carbohydrates amino acids and water soluble vitamins getting absorbed into the bloodstream. And jejunum from the part of the jejunum lipids and fat soluble vitamins absorb here I if you remember I told you vitamin B12 is absorbed only in the stomach, but here again I am talking about vitamin B12 that means, this vitamin B12 is synthesized by the bacteria that are present in the intestine and this is not absorbed here, but it is only present. The large intestine it is the last 5 feet long and includes cecum, colon, rectum and anal canal very little digestion occurs in the large intestine there is no digestion actually in the large intestine. So, large population of bacteria that are present in the large intestine digest very small amounts of fiber and release very little amount of energy. So, bacterial activity it helps in synthesizing vitamin K, vitamin B12, thiamine, ribofluene but in and some of the gases. So, here you can see the large intestine the parts of the large the cecum the colon and the rectum. So, the main function of the large intestine is to absorb water sodium chloride potassium and vitamin K and bacteria whatever residue is left over and digested a few of them especially the fiber is digested by the bacteria that are present in the large intestine. Now, nutrient absorption I told you very little absorption of a nutrient sucker then mainly the absorption of water sodium potassium and chloride and the vitamin K that is produced are absorbed, but it does not absorb only synthesizes, but does not absorb vitamin B12. So, whatever is synthesized in the B12 large intestine is not of much use in the large intestine. Now, there are healthy bacteria that are produced in the large intestine and the intestinal tract you have the probiotics. Biotics are the live organisms that are present in the they are mostly bacteria and they are similar to the bacteria that are present in the human gut. So, now we ask the people to take curds which have probiotics in them. So, these are now available to the consumers in the form of dietary supplements and also in the form of foods. So, these probiotics are healthy and beneficial bacteria that are present in the intestine. So, you should always look for live and active cultures when you purchase probiotic food. So, good bacteria most oftenly comes in two forms the probiotics mainly they are lactobacillus and biphidobacterium and whatever fermented foods we prepare. So, you prepare some batter and leave it for fermentation most of it it develops lactobacillus and biphidobacterium that is why the fermented foods are very good for health. Now, the enzymes that are involved in digestion you have in the form of see in the mouth you produce the saliva which is slightly alkaline and it acts on starch then the enzyme that is produced is salivary amylase and it breaks down the starch into maltose and textrose. So, after breaking down then it reaches the stomach where the acidity is 1 to 2 pH. The enzymes that are produced are renin and pepsin which renin is present only in children which digest the milk protein whereas pepsin digest the other proteins and coagulated proteins and then it breaks them to coagulated proteins and polypeptides. Then the food enters the deodinum the first part of the intestine which again the media is alkaline and it acts on starch polypeptides which are got from the stomach and emulsified fats. Then the pancreatic amylase, trypsin and lipase are produced by the pancreas which also enter into the deodinum and they result in maltose, dipeptides and fatty acids and glycerol. The fatty acids the fat digestion is over. Then the food reaches the ilium the intestinal large part of the intestine where the pH is again neutral and it acts on the maltose, lactose, sucrose, dipeptides and emulsified fats which are I mean pushed into the small intestine the indium part and by the enzymes maltase, lactase, sucrose, peptidase and lipase they act on these substrates and final products that are produced are glucose, see glucose and galactose again this galactose is converted into glucose and glucose and tructose which again is converted into glucose then amino acids from the proteins fatty acids and glycerol from the fats. This is the in brief the enzymes that are involved in the digestion of the food that is eaten and which is converted into simpler form you can see how they are broken down from each stage to the final stage when it comes to the ilium and get absorbed. So we have seen the digestion absorption and utilization of nutrients throughout the gastrointestinal tract and with this we complete the digestion part of the food. Thank you.