Class 10 Biology: Life Processes – Nutrition in Human Beings Explained
Class 10th biology: Life Processes
In our previous article, we explored the different modes of nutrition and how simple organisms like Amoeba take in food. However, complex multicellular organisms like humans require a highly specialized system to break down and absorb nutrients.
In this post, we will look into Nutrition in Human Beings and understand how the human digestive system works step-by-step.
1. The Human Digestive System (Alimentary Canal)
Humans follow the Holozoic mode of nutrition, which involves taking in solid food, digesting it internally, and absorbing the nutrients.The process takes place in a long, continuous tube extending from the mouth to the anus, known as the Alimentary Canal. This canal is about 9 meters long and is supported by various digestive glands.
2. The 5 Steps of Nutrition in Humans
Just like Amoeba, human nutrition is completed in five distinct stages:I. Ingestion
Ingestion means taking food into the body. In humans, this is done through the Mouth.• Teeth: Cut, chew, and grind the food into smaller pieces (Mechanical digestion).
• Tongue: Helps in tasting and mixing the food thoroughly with saliva.
• Salivary Glands: Secrete Saliva, which contains an enzyme called Salivary Amylase. This enzyme breaks down complex starch into simple sugar (maltose).
II. Digestion
Human Digestive System
After being swallowed, the food moves down through a food pipe called the Oesophagus (Esophagus).
What is Peristaltic Movement? The walls of the food pipe gently contract and relax in a rhythmic manner to push the food forward into the stomach. This movement is called peristalsis.
A. In the Stomach
The stomach is a large, J-shaped muscular organ. Its muscular walls churn the food with Gastric Juice secreted by the gastric glands. Gastric juice contains:
• Hydrochloric Acid (HCl): Creates an acidic medium necessary for the action of pepsin and kills harmful bacteria entering with food.
• Pepsin: A protein-digesting enzyme that breaks down proteins into smaller molecules.
• Mucus: Protects the inner lining of the stomach from the corrosive action of the acid.
B. In the Small Intestine
The small intestine is the longest part of the alimentary canal. It is the site of the complete digestion of carbohydrates, proteins, and fats. It receives secretions from two major glands:
• Liver: Secretes Bile Juice, which is stored in the gall bladder. Bile makes the food alkaline for pancreatic enzymes to work and breaks large fat globules into tiny droplets (Emulsification of fats).
• Pancreas: Secretes Pancreatic Juice, which contains enzymes like Trypsin (for digesting proteins) and Lipase (for breaking down emulsified fats).
Finally, Intestinal Juice converts:
• Carbohydrates \rightarrow Glucose
• Proteins \rightarrow Amino Acids
• Fats \rightarrow Fatty Acids and Glycerol
3. Absorption
Once the food is completely broken down, it needs to enter the bloodstream. This happens in the walls of the small intestine.The inner lining of the small intestine has millions of tiny, finger-like projections called Villi.
• Function of Villi: They drastically increase the surface area for rapid absorption of digested food.
• Villi are richly supplied with blood vessels, which carry the absorbed food to every cell of the body.
4. Assimilation
The blood delivers the absorbed nutrients to all body cells. The cells utilize this food to:• Derive energy through cellular respiration.
• Build new tissues and repair old, damaged cells.
5. Egestion
The unabsorbed and undigested food material is sent into the Large Intestine.• Here, more villi absorb water from this residue material.
• The remaining solid waste is then removed from the body through the Anus, a process regulated by the anal sphincter.
Summary Diagram: Path of Food in Humans
Conclusion
The human digestive system is a marvel of biological engineering, turning the food we eat into energy and cellular building blocks. Mastering this topic is essential for your Class 10 board exams. In our next blog post, we will shift our focus to the next vital life process: Respiration.
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