Digestive glands: structure and function
Will you be able to complete this task: "List the human digestive glands"?If you doubt the exact answer, then our article is just for you.
Classification of glands
Glands are special organs that release biologically active substances - enzymes. They are biological catalysts that accelerate the process of chemical reactions, but are not part of its products. They are also called secrets.
There are glands of internal, external and mixed secretion. The first secrete secrets in the blood. For example, the pituitary gland, which is located in the base of the brain, synthesizes growth hormone that regulates this process. And the adrenal glands secrete adrenaline. This substance helps the body cope with stressful situations, mobilizing all its forces. The pancreas is mixed. It produces hormones that enter both the bloodstream and directly into the cavity of the internal organs( in particular, the stomach).
Such digestive glands, as salivary and liver, belong to the glands of external secretion. In the human body, they also include teary, dairy, sweat, and others.
Human digestive glands
These organs secrete enzymes that break down complex organic substances into simple ones that can be digested by the digestive system. Passing through the tract, the proteins break down to amino acids, complex carbohydrates - to simple, lipids - to fatty acids and glycerin. This process can not be carried out by mechanical processing of food with the help of teeth. This can only make the digestive glands. Let's consider the mechanism of their action in more detail.
The first digestive glands in their location in the tract are salivary glands. A person has three pairs: parotid, submandibular, sublingual. If food gets into the mouth or even when it enters the mouth, saliva starts to form. It is a colorless mucus-sticky liquid. It consists of water, enzymes and mucus - mucin. Saliva has a slightly alkaline reaction. Enzyme lysozyme is capable of neutralizing pathogenic microorganisms and healing the wounds of the oral mucosa. Amylase and maltase break down complex carbohydrates into simple carbohydrates. It's easy to check. Put a piece of bread in the mouth and in a short time it will turn into a crumb that can be easily swallowed. Slime( mucin) envelops and moistens slices of food.
Chewed and partially split food with throat cuts along the esophagus enters the stomach, where it undergoes further exposure.
Digestive glands of stomach
In the most expanded part of the digestive tract, the glandular mucosa secretes a special substance - gastric juice - into its cavity. It is also a clear liquid, but with an acidic medium. The composition of gastric juice includes mucin, enzymes amylase and maltase, which break down proteins and lipids, and hydrochloric acid. The latter stimulates the motor activity of the stomach, detoxifies pathogenic bacteria, stops putrefactive processes.
Different foods are in the human stomach for a certain time. Carbohydrate - about four hours, protein and fat - from six to eight. The fluids do not linger in the stomach, except milk, which turns here into curd.
This is the only digestive gland that is mixed. It is located under the stomach, which determines its name. In the duodenum, it produces digestive juice. This is the external secretion of the pancreas. Directly in the blood, it releases hormones insulin and glucagon, regulating carbohydrate metabolism in the human body. In this case, the body functions as an internal secretion gland.
The digestive glands also perform a secretory, protective, synthetic and metabolic function. And all this thanks to the liver. This is the largest digestive gland. Bile is constantly formed in its ducts. This bitter liquid is greenish-yellow in color. It consists of water, bile acids and their salts, as well as enzymes. The liver secretes its secret into the duodenum, in which the final cleavage( emulsification) of fats and disinfection of substances harmful to the body takes place.
Since the cleavage of polysaccharides begins already in the oral cavity, carbohydrate food is the most easily digestible. However, everyone can confirm that after a vegetable salad, the feeling of hunger comes very quickly. Nutritionists are advised to use protein foods. It is energetically more valuable, and the process of its splitting and digestion lasts much longer. Remember that the food must necessarily be balanced.
And now you list the digestive glands? What are their functions? We think that yes.