• The human digestive system is a set of organs that function to convert food into basic nutrients to provide energy throughout the body.
• Human beings require various nutrients, proteins and vitamins which are met through digestion.
As soon as saliva mixes with the chewing of food, the process of digestion begins. The entire process of digestion passes through five stages.
1. Ingestion
2. Digestion
3. Absorption
4. Assimilation
5. Defecation
Ingestion
The process of ingesting and absorbing food, drink or any other substance through the mouth is known as ingestion. Digestion
• Digestion is the process through which large insoluble and non-absorbable food particles are broken down into smaller water-soluble and absorbable particles that are eventually absorbed by the blood plasma.
• The process of digestion starts from the mouth. Where the salivary gland secretes saliva from the mouth, in which two types of enzymes are found. Tylin and Maltese . • It is acidic with a pH of 6.8.
• The food reaches the stomach through the tube or esophagus. stomach digestion (Digestion in Stomach)
• Food stays in the stomach for about 4 hours. • The pH value of the stomach ranges from 1.5 to 2.5 .
• In the highly acidic environment of the stomach, there are gastric glands which secrete gastric juice, which is a light yellow colored acidic fluid.
• Hydrochloric acid helps in acidifying the food, which stops the action of tyalin in saliva. Digestion in the pancreas (Digestion in Duodenum)
• As soon as the food reaches the stomach, the bile juice coming out of the liver comes and meets it.
• The main function of bile juice is to convert acidic food into alkaline as they are alkaline in nature .
• This pancreatic juice comes from the pancreas and is found in food and contains the following three types of enzymes.
1. Trypsin
2. Amylase
3. Lipase.
4. Maltage
5. Lactase Absorption
• The remaining food is absorbed by the blood plasma in a process known as absorption.
• Absorption The use of food by the body or the movement of digested particles, which is used, is called assimilation.
read also Newton’s Laws of Motion
• This is the final act of digestion.
• It is also known as bowel movement. The undigested food reaches from the smallest to the large intestine. Where bacteria convert it into feces which is passed out through the anus. Liver
• It is the largest gland in the human body. • Its weight varies from 1.2 kg to 2 kg.
• Bile is produced only by the liver.
• This bile accelerates the action of enzymes present in the intestine.
• The liver converts more and more amino acids into ammonia by reduction.
• This ammonia is further converted to urea by the Ornithine Cycle .
• Urea comes out of the body through the kidney .
• The liver converts some amount of protein into glucose during a carbohydrate deficiency.
• Fibrinogen is a protein produced by the liver that helps in blood clotting.
• A protein called heparin is produced in the liver which prevents blood from clotting inside the body.
• Dead RBCs are destroyed only by the liver.
• The liver stores small amounts of iron, copper and vitamins.
• It helps to regulate body temperature. The liver is an important clue in the investigation of the cause of death of a person killed by food poisoning . Gall Bladder
• The gallbladder is a pear-shaped sac in which bile from the liver is stored.
• Bile is a yellow-green colored alkaline liquid. Its pH value is 7.7 Pancreas
• It is the second largest gland in the human body .
• It functions simultaneously as an endocrine (ductless) and exocrine (ductal) type of gland.
• Pancreatic juice is known as pre-digestive juice because the enzymes it contains are able to preserve all three types of food, which are carbohydrates, fats, and proteins .
• It is an alkaline liquid with a pH of 7.5 to 8.5 . Insulin
• Insulin was discovered by Bentik and Best in 1921.
• Secreted by beta cells of the pancreas.
• Insulin is a type of hormone.
• It controls the process of making glycogen from glucose.
• Occurs in diabetes due to lack of insulin