HUMAN DIGESTIVE SYSTEM

Do you remember that food is needed by the body to supply energy? Food is processed in the body through four stages, namely: ingestion (the process of putting food into the mouth), digestion (digestion), absorption (absorption), and defecation (expenditure).

When food enters the mouth, the digestive process begins. Digestion is the process of breaking down food into small molecules so that it can be absorbed by the body through the blood vessels. Next, food molecules from the blood enter the cells, crossing the cell membrane. Molecules that are not used and needed by the body will be removed from the body through the excretory system such as sweat and urine. Undigested food in the form of feces will be excreted through the anus, this process is called defecation.

Digestion of food is divided into two types, namely mechanical digestion and chemical digestion. Mechanical digestion occurs when food is chewed, mixed, and kneaded. Mechanical digestion, for example, occurs in the mouth when food is crushed by the teeth. In chemical digestion, chemical reactions occur that break down large molecules of food into smaller molecules. Chemical digestion in the digestive process is usually carried out and assisted by digestive enzymes, such as amylase in the mouth.

 

 

 

1. Main Digestive Organs

The human digestive system consists of the main organs in the form of the digestive tract and accessory (additional) organs. The digestive tract is a channel through which food materials start from the mouth, esophagus, stomach, small intestine, large intestine, rectum, and ends at the anus.

 

 

The tongue, teeth, salivary glands (salivary glands), liver, gallbladder, and pancreas are accessory organs that aid in mechanical and chemical digestion.

The digestive glands are accessory organs that secrete enzymes to help digest food. For more details, you will learn about the digestive system which includes the digestive tract and accessory organs, including the following.

a. Mouth

Do you remember that ingestion takes place in the mouth?

 

 

 

Inside the mouth, there are teeth, tongue, and salivary glands (saliva). Saliva contains mucous or mucus, compounds that function as anti-bacterial, and the enzyme amylase or known as ptyalin enzyme. This enzyme will break down starch molecules into maltose molecules. In the mouth occurs mechanical and chemical digestion of food.

 

 

b. Esophagus (Esophagus)

After passing through the oral cavity, food in the form of a bolus will enter the pharynx (pharynx). The pharynx is a tube that extends from the back of the oral cavity to the surface of the esophagus (esophagus). At the base of the pharynx is a respiratory valve called the epiglottis. Epiglottis serves to close the end of the respiratory tract (larynx) so that food does not enter the respiratory tract.

After passing through the pharynx, the bolus goes to the esophagus (gullet). The muscles of the esophagus contract causing a squeezing motion that pushes the bolus into the stomach. This esophageal muscle movement is called peristalsis.

 

 

 

c. Stomach

After the esophagus, the food enters the stomach.

 

 

In the stomach, mechanical and chemical digestion occurs. Mechanically the gastric muscles contract to churn the bolus. The bolus is chemically mixed with gastric juice.

Gastric juice contains, hydrochloric acid (HCl), the enzyme pepsin, and the enzyme renin. HCl functions to make the space in the stomach acidic (pH 1-3) so that it can kill germs that enter with food. The pepsin enzyme will hydrolyze (break down) protein into peptone (a mixture of polypeptides and amino acids). The renin enzyme will precipitate the casein protein found in milk. After going through the digestive process for 2-4 hours in the stomach, the bolus becomes a yellowish material called chyme (intestinal porridge). Kimus will enter little by little into the duodenum. This arrangement is aided by the presence of sphincters, which are muscles arranged in a circle between the stomach and duodenum.

d. Small intestine

 

 

 

The small intestine is about 8.25 meters long. The small intestine consists of three parts, namely, the 12 finger intestine (duodenum) with a length of about 0.25 meters, the middle intestine (jejunum) with a length of about 7 meters, and the absorption intestine (ileum) with a length of about 1 meter. In the small intestine, chemical digestion occurs only.

In the duodenum there is a duct that is connected to the duodenum, bile and pancreas. Pancreatic juice contains the enzymes lipase, amylase, and trypsin. Lipase enzymes will digest fats into fatty acids and glycerol. Amylase will digest starch into maltose. Trypsin will digest proteins into polypeptides. Bile sap produced by the liver will emulsify fat, which makes fat soluble in water.

Digestion of food continues in the jejunum. In this section the last digestion occurs before food substances are absorbed. Nutrients after passing through the jejunum into a form that is ready to be absorbed.

Absorption of nutrients occurs in the ileum. Glucose, water-soluble vitamins, amino acids, and minerals after being absorbed by the villi of the small intestine will be carried by the blood to the liver and circulated throughout the body. Glucose in the liver is then stored in the form of glycogen. Fatty acids, glycerol, and fat-soluble vitamins after being absorbed by the villi of the small intestine will be carried by lymph vessels to the liver, where they are stored in fatty tissue.

The structure of the human intestine has folds, both external and internal, which serve to widen the absorption area.

 

 

 

The wider the surface area of ​​the interior of the intestine, the more villi there are, which will cause the absorption process that occurs to be more effective. Glory to God who has designed the structure of the small intestine like that. Imagine if the intestinal structure is flat, then the absorption is also ineffective and takes a very long time, as a result we will lack the supply of nutrients.

d. Colon

The large intestine or colon has a length of ± 1 meter and consists of an ascending (upward) colon, a transverse (flat) colon, and a descending (descending) colon and ends at the anus. Between the small intestine and the large intestine is the appendix (cecum).

 

 

 

 

At the end of the cecum there is a small protrusion called the appendix which contains a mass of white blood cells that play a role in immunity. Food materials that reach the large intestine can be said to be waste substances. Wastes remain in the large intestine for 1 to 4 days. The residue consists of large amounts of water and indigestible food materials, such as cellulose.

The large intestine functions to regulate the water content of leftover food. If the water content in the leftover food is too much, then the colon wall will absorb the excess water. On the other hand, if the leftover food lacks water, the colon wall will expel water and send it to the rest of the food. In the large intestine there are lots of Escherichia coli bacteria that help decompose the remnants of the food. Escherichia coli bacteria are able to form vitamins K and B12.

The rest of the food that is not used by the body along with smelly gases is called feces and is excreted through the anus. After you know the digestive organs and how the digestive process occurs in them.

 2. Additional Digestive Organs

 The human digestive process does not only consist of the digestive tract, but also contains additional digestive organs in the form of digestive glands. The digestive glands help digest food by producing enzymes that are used in the chemical digestion of food. There are three additional digestive organs, namely the liver, gallbladder, and pancreas.

 

 

 

a. Heart

The liver is the largest gland in the body, located on the right side of the abdominal cavity below the diaphragm. The liver plays a role in the detoxification process. When the blood contains several substances that are harmful and toxic, the liver will neutralize these toxins so that they are not harmful to the body.

The liver is a storage organ. The liver will remove iron (Fe) and vitamins A, D, E, K, and B12 from the blood and store them. The liver also plays a role in maintaining the balance of blood glucose levels. When blood glucose levels are low, the liver releases glucose by breaking down glycogen. In fact, if needed, the liver will convert glycerol, fatty acids, and amino acids into glucose. In addition, the liver also regulates cholesterol levels in the blood. Cholesterol will be converted into colic acid (cholic acid) which serves to emulsify fat. Liver cells secrete a sap containing cholesterol, colic acid, bile salts, lecithin, bilirubin, and electrolytes. This sap is called bile sap.

 b. Gall bladder

The gallbladder is an organ under the liver. This sac will store bile produced by the liver. Bile sap is greenish yellow because it contains the pigment bilirubin. Bilirubin is a pigment formed from the breakdown of hemoglobin. Bile sap will be released into the small intestine and play a role in emulsifying fat. Thus, fat will be broken down into small granules so that it is more easily digested by digestive enzymes and continues the breakdown process until it can be absorbed by the body.

c. Pancreas

 The pancreas is an organ that is behind the stomach behind the stomach. The cells in the pancreas will produce pancreatic juice, which will enter the duodenum through the pancreatic duct. Pancreatic juice contains sodium bicarbonate (NaHCO3) and digestive enzymes that play a role in the breakdown of carbohydrates, proteins, and fats. The pancreas is also an endocrine gland that produces the hormone insulin.

This insulin hormone functions to regulate the process of converting glucose in the blood into glycogen which is stored in the liver. The presence of the hormone insulin is what controls the balance of the amount of glucose in the blood. If there is a disturbance in insulin production, it can lead to diabetes.