How is food absorbed into the body by the villi in the small intestine? | Socratic
Each villus transports nutrients to a network of capillaries and fine lymphatic vessels The small intestine is the part of the gastrointestinal tract between the. It is the primary site for nutrient absorption into the blood stream after being digested into small molecules with enzymes. Although these villi do not aid in the digestion of nutrients, they do help with nutrient absorption.
The first movement was segmentation, and it was the rhythmic contraction of the circular muscles of the wall of the small intestine - almost like the wall is being pinched. The second movement was pendular movements, which were caused by the rhythmic contraction of the longitudinal muscles - almost like a Slinky being stretched and contracted. As these different muscles contract and relax, your small intestine goes through a slew of gyrations which mix the chyme with the digestive juices and bring particles of food into contact with the small intestine wall.
Within the wall, we see a number of special modifications that allow for maximum nutrient absorption. Microvilli Microvilli are hairs that aid in absorption of nutrients. Nearly all of the nutrients you take in through your mouth are absorbed through the wall of the small intestine. This is no surprise when you take a look at the surface of the small intestine wall and notice all of the special modifications that are designed to increase nutrient absorption.
We had previously learned that the mucosa is the lining of the digestive tract, and it consists of simple columnar epithelial cells. In the small intestine, these cells contain microvilli, which are tiny hair-like projections that increase nutrient absorption.
These projections increase the surface area of the small intestine allowing more area for nutrients to be absorbed. Microvilli are microscopic and can only be seen with a very powerful microscope, but they give the cell surface a fuzzy appearance because there are so many of them.
Most all of the absorption which occurs in your body takes place in the small intestine through the action of the villi. It is not difficult to see then how vital these body structures are. Supporting Role So then, what is the job of villi other than digestion and absorption? The cells of the villi synthesize some enzymes which are destroyed by the acidic environment of the stomach to continue the digestive process.
These enzymes initiate a series of chemical reactions which will break down nutrients into usable forms. Celiac Disease and Villi Celiac disease directly impacts the role of the villi in digestion and absorption. This autoimmune disease causes your body to damage the villi whenever you eat foods containing gluten. If villi are damaged, their ability to perform properly is impaired.
The effects are two-fold. First, damage or destruction of the villi decreases the amount of surface area in your intestine available for absorption.
Second, rather than capturing valuable nutrients from your food, they are excreted, increasing your risk of malnutrition as well as vitamin and mineral deficiencies. This physical damage may be evident if your doctor performs a biopsy of the small intestine in order to confirm the diagnosis of celiac disease. Over time, the effects of celiac disease increase due to the decreased efficiency of the small intestine and damage to the villi.
This gives the stomach a pH of 1 to 2. This acid kills many bacteria, loosens food, converts pepsinogen into pepsin, and denatures salivary amylase. When this acid is overproduced it sometimes rises up into the oesophagus. Neutralising the acid with a base such as Rennies can control this condition. As the stomach wall contracts the food is churned and thus digested mechanically.
The Importance of Villi and the Small Intestine to the Digestion of Nutrients
The food becomes a thick milky mixture called chyme. This chyme will leave the stomach and go into the small intestine. To do so, it goes through the pyloric sphincter.
The cells of the stomach are replaced very rapidly. A million are produced per minute. In this way, damaged stomach cells are constantly being replaced. If the defence mechanisms to stop self-digestion of the stomach fail, then peptic ulcers of the stomach form.
These cause bleeding and may dissolve the stomach lining all the way through the stomach wall. It is now called a perforated ulcer. This is very dangerous as bacteria may travel through the ulcer and into the body cavity. In some cases it can cause death. The Small Intestine The small intestine is where the food is absorbed into the blood to be taken to the body cells.
The small intestine is about 6 metres long. It is made up of 3 parts. The duodenum, jejunum, and ileum. The duodenum- The main function of the duodenum is to finish the digestive process. The cells lining the duodenum produce digestive enzymes. Also, products from the pancreas and the liver enter the duodenum to do their work.
The lining of the small intestine consists of many folds called villi. Each villus has about microvilli.
These foldings and microvilli increase the surface area of the small intestine for increased digestion or absorption.
Intestinal glands are located between the villi. These glands produce numerous enzymes, which are collectively called intestinal juices. The intestinal gland is at the arrow, which is at the base of a villus: The Pancreas The Pancreas secretes pancreatic juice for the digestive system.
The salt sodium hydrogen carbonate which neutralises chyme in the stomach. Amylase which changes starch to maltose B.
Lipase which changes lipids to fatty acids and glycerol. These enzymes enter the and do their digestive work at the duodenum. They enter the duodenum through the pancreatic duct. The Liver There are many functions of the liver. Some of the most important are: The production of bile 2. Detoxifying the body, i.
How Do Nutrients Pass From the Villi to the Bloodstream? - Woman
Breaking down excess amino acids to form urea 4. Converting glucose to glycogen for storage 5. Converting excess carbohydrates to fats 6.
Storing minerals such as Iron, Copper, and Zinc. Making plasma proteins such as fibrinogen which is used in blood clotting 9. Making cholesterol which is used to form many hormones Producing heat for the blood and body Bile Bile is a yellow-green liquid that is produced in the liver and stored in the gall bladder.
Bile enters the duodenum through the bile duct. Bile has the following functions: