Solid organs of the digestive system are the liver, pancreas, and gallbladder. However, the hollow and solid organs are not alone in the process of digesting food.

There are other areas of the body that assist and digestion. They include bacteria in the tract and parts of the nervous and circulatory systems. Food enters the mouth and passes to the anus through the hollow organs of the tract. Digestion happens when food moves through the tract. Muscles in the hollow organs contract and relax, moving like a wave that travels through the ocean. This moves food along. Peristalsis is the process of the movement of food through the tract. So, digestion begins in the mouth when you chew and ends in the large intestine 18 to 20 hours later. As food passes through the tract, it mixes and digestive juices, causing large molecules of food to break down into smaller molecules. Think of a can of tomato soup. When you open the can, it is a thick red blob. You have to add water to make the blob turn into the soup - this is similar to how the digestive juices break down the molecules into nutrients. Absorption of the smaller molecules, including carbohydrates, proteins, fats, vitamins, and minerals, happen through the walls of the small intestine and go into the bloodstream. 

Then, the circulatory system, specifically the Exo Slim blood, works to distribute these nutrients to the rest of the body. You eat until you're satisfied, and then you do not think about digestion again. But for the next 18 to 20 hours, your digestive system is doing its job. The food you ate travels throughout your body. Digestion: Mouth to Stomach Even before food enters your mouth, the digestion process begins. Think of your favorite food. You can almost taste it, right? Now you have the food placed in front of you, and what happens? You begin to salivate, or produce saliva in your mouth. This happens because the brain sends impulses through the nerves that control the salivary glands, telling them to prepare for a meal - so your body releases saliva. Then, you begin to eat the food. Your teeth tear and chop the food while the saliva moistens it for easier swallowing. Amylase is an important digestive enzyme in your saliva. It starts to break down some of the carbohydrates in the food even before it leaves your mouth. Swallowing then moves the food into your throat, also called the pharynx. From the throat, food travels down a muscular tube called the esophagus. Peristalsis then forces the food down through the esophagus to the stomach. At the end of the esophagus, there is a muscular ring, called a sphincter, that opens for food and then shuts. When the sphincter is closed, food or fluid cannot flow back up into the esophagus. 

The stomach muscles churn and mix the food and digestive juices, breaking it into much smaller, more digestible pieces. All of this takes place andout you even being aware of the muscles of the esophagus and stomach moving. Most substances in the food we eat require further digestion and must travel into the intestine before being absorbed. By the time food is ready to leave the stomach, it has been processed into chyme, a thick liquid consisting of gastric juices and partially digested food. This is then squirted down into the small intestine, where digestion of food continues so the body can absorb the nutrients into the bloodstream. When we last left Timmy, he was playing in his backyard pretending to be his favorite animal, a chameleon. Oh yeah, and he also ate a butterfly! We followed the path that the ingested butterfly took down Timmy's upper gastrointestinal tract, from his mouth, to his pharynx, down his esophagus, and through his stomach. Now let's continue on our journey through Timmy's digestive system as we follow the path that the food takes through the lower gastrointestinal tract. We know that liquefied food and gastric juice is released by the pyloric sphincter a little at a time from the stomach into the duodenum, which is the first section of small intestine where digesting food enters from the stomach. 

A lot of people think that this food is now digested into products that can be absorbed into the bloodstream, but that's not the case at all, because full digestion of the food still requires a lot more work. As soon as the liquefied food and gastric juice enters the duodenum, the acid and partially digested food stimulates the pancreas to secrete bicarbonate, water, and many different digestive enzymes, which flow into the duodenum to mix and the gastric juice. You may remember that bicarbonate is a base and that bases neutralize acids. So when the bicarbonate secreted by the pancreas mixes and the gastric juice, it neutralizes the acid. Meanwhile, digestive enzymes are secreted from the liver and pancreas as zymogens, which, you may remember, are inactive precursors of enzymes that require a change to be activated. These zymogens are activated by other enzymes in the duodenum and then start breaking carbohydrates into smaller sugars, and also breaking proteins into peptides and amino acids. Once the carbohydrate chains have been broken down into monosaccharides, they can be transported across the luminal membrane and into the epithelial cells of the small intestine. Likewise, proteins and peptides can't be absorbed by the small intestine. But once they are broken down into their component amino acids, these are easily transported into the epithelial cells. However, fats are a little more complicated. 

You see, fats, which are also called lipids, are hydrophobic. They repel water and clump together and other lipids, because when they clump together they have less interaction and the water. This means that they are insoluble. They won't go into solution and they aren't available for soluble digestive enzymes to break them down. Fortunately, our liver produces bile salts, which coat the lipids and keep them separated into tiny droplets that don't clump together. These tiny, coated droplets give the digestive enzymes enough surface area to gain access to the lipids and break them down. One such digestive enzyme is lipase, which is an enzyme that breaks lipids down into monoglycerides and fatty acids. These monoglycerides and fatty acids can then be absorbed by the small intestine. Although the liver produces bile, it is stored in the gall bladder, which then releases it into the duodenum when digestion is taking place. The human digestive system is a complex series of organs and glands that processes food. In order to use the food we eat as energy, our body has to break the food down into smaller molecules that it can process; it also has to excrete (or get rid of) waste. Most of the digestive organs (like the stomach and intestines) are tube-like and contain the food as it makes its way through the body. 

The digestive system is essentially a long, twisting tube that runs from the mouth to the anus, plus a few other organs (like the liver and pancreas) that produce or store digestive chemicals. Andout the digestive system, our bodies would not be able to get nutrients from the food we eat or get rid of the waste products that food makes and we would soon become ill! The small intestine is about 7 metres long, and about 2.5 centimetres in diameter. The surface area is around 250 square metres, or about the size of a tennis court! Some animals have stomachs and multiple compartments. (They're often mistakenly said to have multiple stomachs.) Cows, giraffes, deer and cattle have four-chambered stomachs, which help them digest their plant-based food. Some animals – including seahorses, lungfishes and platypuses The human digestive system is a complex series of organs and glands that processes food. In order to use the food we eat as energy, our body has to break the food down into smaller molecules that it can process; it also has to excrete (or get rid of) waste. Most of the digestive organs (like the stomach and intestines) are tube-like and contain the food as it makes its way through the body. 

The digestive system is essentially a long, twisting tube that runs from the mouth to the anus, plus a few other organs (like the liver and pancreas) that produce or store digestive chemicals. Andout the digestive system, our bodies would not be able to get nutrients from the food we eat or get rid of the waste products that food makes and we would soon become ill! The small intestine is about 7 metres long, and about 2.5 centimetres in diameter. The surface area is around 250 square metres, or about the size of a tennis court! Some animals have stomachs and multiple compartments. (They're often mistakenly said to have multiple stomachs.) Cows, giraffes, deer and cattle have four-chambered stomachs, which help them digest their plant-based food. Some animals – including seahorses, lungfishes and platypuses – have no stomach. Their food goes from the oesophagus straight to the intestines. We make 1 to 3 pints of saliva a day. It takes your mouth, oesophagus, stomach, small intestine, large intestine, gallbladder, pancreas and liver just to digest a glass of milk. An adult’s stomach can hold approximately 1.5 litres of material. Food stays in your stomach for 3 to 4 hours. Cells along the inner wall of the stomach secrete roughly 2 litres of hydrochloric acid (the powerful chemical commonly found in some cleaning supplies, including toilet-bowl cleaners!) each day, which helps kill bacteria and aids in digestion.