Digestive system The digestive system begins breaking down food through mechanical and chemical digestion. After digested molecules are absorbed into the body and enter the blood stream. Any food not digested is eliminated as solid waste.
Stomach The stomach is an organ of digestion. It has a saclike shape and is located between the esophagus and the intestines. The human stomach is a muscular, elastic, pear-shaped bag, lying crosswise in the abdominal cavity beneath the diaphragm. It changes size and shape according to is position of the body and the amount of food inside. The stomach is about 12 inches (30.5 cm) long and is 6 inches. (15.2 cm) wide at its widest point. The stomach's capacity is about 1 qt (0.94 liters) in an adult.
Stomach cont…. Food enters the stomach from the esophagus. The connection between the stomach and the esophagus is called the cardiac sphincter. Once the food enters the stomach, gastric juices are used to break down the food. Some substances are absorbed muscle lining of the stomach. The stomach is composed of five layers. Starting from the inside and working our way out, the innermost layer is called the mucosa. Stomach acid and digestive juices are made in the mucosa layer. The next layer is called the submucosa. The submucosa is surrounded by the muscularis, a layer of muscle that moves and mixes the stomach contents. The next two layers, the subserosa and the serosa are the wrapping for the stomach. The serosa is the outermost layer of the stomach.
Pancreas The pancreas is a glandular organ that secretes digestive enzymes and hormones. In humans, the pancreas is a yellowish organ about 7 inches (17.8 cm) long and 1.5 inches. (3.8 cm) wide. The pancreas lies beneath the stomach and is connected to the small intestine at the duodenum
Pancreas cont…. The pancreas contains enzyme producing cells that secrete two hormones. The two hormones are insulin and glucagon. Insulin and glucagon are secreted directly into the bloodstream, and together, they regulate the level of glucose in the blood. The pancreas produces the body's most important enzymes. The enzymes are designed to digest foods and break down starches. If the pancreas is not working properly to neutralize chyme and break down proteins, fats and starch, starvation may occur.
liver The liver is the largest glandular organ of the body. It weighs about 3 lb (1.36 kg). It is reddish brown in color and is divided into four lobes of unequal size and shape. The liver lies on the right side of the abdominal cavity beneath the diaphragm. Liver tissue is composed of thousands of lobules, and each lobule is made up of hepatic cells, the basic metabolic cells of the liver.
Liver cont… The liver has many functions. Some of the functions are: to produce substances that break down fats, convert glucose to glycogen, produce urea (the main substance of urine), make certain amino acids. The liver is also responsible for producing cholesterol. It produces about 80% of the cholesterol in your body.
The small intestine The small intestine is the portal for absorption of virtually all nutrients into blood. Accomplishing this transport entails breaking down large supramolecular aggregates into small molecules that can be transported across the epithelium. By the time ingesta reaches the small intestine, foodstuffs have been mechanically broken down and reduced to a liquid by mastication and grinding in the stomach. The final stages of digestion occur on the surface of the small intestinal epithelium.