Question

The main steps of nutrition in humans are________, __________, __________, _________ and ________.

Answer 1

Hint: The nutrition in human starts with the uptake of food in the mouth, then it goes to stomach where hydrochloric acid break down the food and passed to small intestine where finger like projection villi is present and the last step of nutrition takes in colon and finally waste is removed from the body.

Complete answer:
- Ingestion
- The first step of nutrition where food is taken into mouth, chewed and swallowed.
- In mouth teeth tear, shred and grind food whereas enzymes in saliva break down food molecules such as protein and complex sugar.
- The tongue is muscle that pushes your food towards teeth to be mechanically processed and shapes in small rounded pieces to be swallowed and passed to the digestion process.
- Digestion
- For digestion food reaches to the stomach where it stays for two to six hours.
- Here the food is converted into chyme , a creamy liquid in the presence of hydrochloric acid and pepsin forms gastric juices helps in chemical digestion.
- Absorption
- The digestion is completed in the small intestine by the presence of bile juice which aids in the breakdown of large fat globules into smaller globules.
- The presence of villus in the small intestine increases the surface area for absorption which is rich supply of blood capillaries and allows transport of nutrients to the liver. - Assimilation
- The large intestine is responsible for assimilation where nutrients are taken from the blood and into the cells.
- Sugar are converted into glycogen and stored in the liver and is carried out through bloodstream.
- Egestion
- The elimination of indigestible food or faeces from the body is termed as egestion or defection.
- The colon absorbs water whereas rectum stores faces before being expelled through anus.

Additional information:
- As both food and air go through the pharynx so, a flap of tissue called epiglottis covers the larynx to prevent food from travelling into lungs.
- Muscular contractions in the stomach known as peristalsis aid in mechanical digestion.
- The wall of ileum has an intestinal gland that produces intestinal juice consisting of peptidase, lipase, maltase, sucrase and lactase enzymes.
- Caecum and appendix are vestigial in humans whereas in herbivores they are large in size consisting of bacteria that produce cellulase to digest cellulose.
So, the correct answer is, ‘ingestion, digestion, absorption, assimilation and egestion.’


Note:
- Salivary glands help with digestion, lubrication and moistening of food by secreting enzyme filled saliva to help break down food.
- Fats are brought to the liver to be oxidised or stored and amino acids are converted into protoplasm and it repairs parts or tissues of the body.