Chapter 3: From Tasting to Digesting
चखने से पचने तक (पाचन तंत्र एवं डॉ. बोमोंट का प्रयोग)
Don't Let a 20-Minute Bubbling Delay Cost You CTET Qualification
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- Tongue taste zones: Sweet (front tip), Salty & Sour (sides), Bitter (back).
- Stomach temperature & digestion: Dr. William Beaumont conducted digestion experiments on Alexis St. Martin (1822); internal stomach temperature is approximately 30°C.
- Gastric juice is acidic in nature; excessive acidity causes heartburn/indigestion.
- Digestion time comparison: Food digests significantly faster inside the natural stomach than in a test tube with extracted digestive juices.
- ORS (Oral Rehydration Solution): Mixture of boiled water, salt, and sugar given during vomiting/diarrhea to prevent dehydration.
- Glucose drip: Administered intravenously to provide immediate strength without needing oral digestion.
- Trap: CBSE states food digests faster in a glass test tube than in the stomach. Correct: Food digests much faster inside the warm, churning stomach (approx 30°C).
- Trap: CBSE states gastric juices in the stomach are alkaline or neutral. Correct: Stomach gastric juice is acidic.
NCERT Core Facts: Digestion & Dr. Beaumont's Historic Experiments
Chapter 3 connects human sensory taste with biological digestion through the real-life medical story of soldier Alexis St. Martin and army doctor Dr. William Beaumont in 1822.
1. The Human Tongue & Taste Buds
- The human tongue has thousands of tiny sensory bumps (taste buds) that identify primary taste profiles:
- Sweet: Detected predominantly at the front tip of the tongue.
- Salty and Sour: Detected predominantly along the front sides and middle sides of the tongue.
- Bitter: Detected predominantly at the back of the tongue.
- Digestion begins in the mouth: Saliva contains enzymes that break down complex starch into simple sugars (tested by chewing plain boiled rice for 30–32 bites until it tastes sweet).
2. Dr. Beaumont's Stomach Window Experiment (1822)
In 1822, soldier Alexis St. Martin was accidentally shot in the stomach. Doctor William Beaumont treated the wound, which healed leaving a permanent open hole covered only by a loose flap of skin. Dr. Beaumont used this window to observe live digestion for 9 years:
Key Scientific Findings:
- 1.Stomach Temperature: The natural temperature inside the stomach is approximately 30°C.
- 2.Acidic Nature: Gastric juices in the stomach are acidic in nature. When a person does not eat properly or feels stressed, excess acid causes acidity and burning sensation.
- 3.Churning Motion: The stomach physically churns and mixes food to accelerate chemical breakdown.
- 4.Stomach vs. Glass Test Tube Digestion Rate:
- Food digests substantially faster inside the living stomach than inside an artificial glass tube containing identical gastric juices outside the body.
| Food Item | Digestion Time Inside Stomach | Digestion Time Outside in Glass Tube |
|---|---|---|
| Unboiled Milk | 2 hours 15 minutes | 4 hours 45 minutes |
| Boiled Milk | 2 hours 00 minutes | 4 hours 15 minutes |
| Full Boiled Egg | 3 hours 30 minutes | 8 hours 00 minutes |
| Raw Egg (Beaten) | 2 hours 00 minutes | 4 hours 15 minutes |
| Raw Egg | 1 hour 30 minutes | 4 hours 00 minutes |
3. Dehydration, ORS & Kalahandi Rice Poverty
- ORS (Oral Rehydration Solution): When a child suffers from vomiting and loose motions, water and essential mineral salts are rapidly lost. ORS is prepared by mixing a pinch of salt and a spoonful of sugar in cooled boiled water.
- Kalahandi District (Odisha): NCERT highlights Kalahandi as one of India's richest rice-producing regions, yet severe poverty, famine, and child hunger persist due to unfair distribution systems.
Test Your Mastery: From Tasting to Digesting
Authentic CBSE exam questions tested directly from this NCERT chapter.
Which of the following statements about digestion inside the human stomach is correct as per NCERT Class 5 EVS?
एनसीईआरटी कक्षा 5 ईवीएस के अनुसार मानव आमाशय (पेट) के अंदर पाचन के संबंध में कौन सा कथन सही है?
Which part of India is highlighted in NCERT Class 5 EVS as a major rice-growing region that still experiences acute poverty and starvation?
एनसीईआरटी कक्षा 5 ईवीएस में भारत के किस क्षेत्र का उल्लेख किया गया है जहाँ अत्यधिक चावल उत्पादन के बावजूद भुखमरी रहती है?
What is the normal temperature inside the human stomach according to NCERT Class 5 EVS?
According to Dr. Beaumont's experiments documented in NCERT Class 5 EVS Chapter 3, the temperature inside the stomach is approximately 30°C, and gastric juices are acidic.
Where did Dr. William Beaumont conduct his famous digestive experiments in 1822?
Dr. Beaumont conducted his experiments on a wounded soldier named Alexis St. Martin, observing how food digests faster inside the stomach than outside in a test tube.