Human Body: Digestion, Respiration, Circulation and Excretion
Human Body: Digestion, Respiration, Circulation and Excretion
Four life processes keep the body running: digestion breaks down food, respiration releases energy, circulation carries materials, and excretion removes waste. NTPC asks which enzyme acts where, the role of the liver and bile, the products of anaerobic respiration, blood groups and the working unit of the kidney.
1. Digestive System
| Organ | Secretion and action |
|---|---|
| Mouth | Saliva with salivary amylase (ptyalin): starch to maltose |
| Stomach | Hydrochloric acid kills germs and activates pepsin; pepsin digests protein |
| Liver | Largest gland; makes bile, which emulsifies fats (bile has no enzyme) |
| Gall bladder | Stores bile |
| Pancreas | Pancreatic juice: trypsin (protein), lipase (fat), amylase (starch) |
| Small intestine | Longest part of the gut; completes digestion; villi absorb food |
| Large intestine | Absorbs water |
2. Respiration and Circulation
| Item | Fact |
|---|---|
| Aerobic respiration | Glucose + oxygen gives CO₂, water and much energy, in mitochondria |
| Anaerobic in muscles | Glucose gives lactic acid; causes cramps |
| Anaerobic in yeast | Glucose gives ethanol and CO₂ (fermentation) |
| Gas exchange | In alveoli of the lungs |
| Breathing muscle | Diaphragm |
| Heart | Four chambers; right side pumps blood to the lungs, left side to the body |
| Arteries and veins | Arteries carry blood away from the heart; veins bring it back |
| Exceptions | Pulmonary artery carries deoxygenated blood; pulmonary vein carries oxygenated blood |
| Normal blood pressure | About 120/80 mm Hg |
| Red blood cells | Carry oxygen with haemoglobin; made in bone marrow; life about 120 days |
| White blood cells | Fight infection |
| Platelets | Help clotting |
| Blood group | Can donate to | Can receive from |
|---|---|---|
| O negative | Everyone (universal donor) | O negative only |
| AB positive | AB positive only | Everyone (universal recipient) |
ABO blood groups were discovered by Karl Landsteiner; the Rh factor is named after the rhesus monkey
3. Excretion
| Item | Fact |
|---|---|
| Kidney's working unit | Nephron (about a million per kidney) |
| Filtration site | Glomerulus inside Bowman's capsule |
| Main nitrogenous waste in humans | Urea, made in the liver |
| Dialysis | Artificial kidney for kidney failure |
✗ Bile contains enzymes that digest fat | ✓ Bile has no enzymes; it emulsifies fat so that lipase can act
✗ All arteries carry oxygenated blood | ✓ The pulmonary artery carries deoxygenated blood to the lungs
हिंदी नोट: यकृत सबसे बड़ी ग्रंथि है और पित्त बनाता है, जो वसा का पायसीकरण करता है। मांसपेशियों में अवायवीय श्वसन से लैक्टिक अम्ल बनता है। O नेगेटिव सर्वदाता और AB पॉज़िटिव सर्वग्राही रक्त समूह है। वृक्क की कार्यात्मक इकाई नेफ्रॉन है।
Exam Pointer: No NTPC shift was verified for these patterns in this run; they are tagged syllabus-based. Bile, blood-group and nephron questions found online came from other RRB and SSC papers.
Pariksha Pattern: Every Way NTPC Asks This Topic
Pattern 1: Digestive enzymes and organs
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Which is the largest gland in the human body?
The liver.
Answer: Liver
EXAMATLAS LEVEL
Q. Match the secretion with its action: pepsin, bile, salivary amylase, trypsin.
Pepsin digests proteins in the stomach. Bile emulsifies fats. Salivary amylase turns starch into maltose in the mouth. Trypsin, from the pancreas, digests proteins in the small intestine.
Answer: Protein; fat emulsification; starch; protein
Pattern 2: Aerobic and anaerobic respiration
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Which substance builds up in muscles during heavy exercise and causes cramps?
Lactic acid, from anaerobic respiration when oxygen runs short.
Answer: Lactic acid
EXAMATLAS LEVEL
Q. What does yeast produce in anaerobic respiration, and where in the cell does aerobic respiration finish? Where does gas exchange happen in the lungs?
Yeast produces ethanol and carbon dioxide. Aerobic respiration is completed in the mitochondria. Gas exchange happens in the alveoli.
Answer: Ethanol and CO₂; mitochondria; alveoli
Pattern 3: Heart, blood and blood groups
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Which blood group is called the universal donor?
O negative, because its red cells carry no A, B or Rh antigens.
Answer: O negative
EXAMATLAS LEVEL
Q. Which vessel carries deoxygenated blood from the heart to the lungs, which blood cells help clotting, and who discovered blood groups?
The pulmonary artery. Platelets help clotting. Karl Landsteiner discovered the ABO blood groups.
Answer: Pulmonary artery; platelets; Karl Landsteiner
Pattern 4: Kidney and excretion
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. What is the structural and functional unit of the kidney?
The nephron.
Answer: Nephron
EXAMATLAS LEVEL
Q. In which organ is urea made, where is blood filtered in the nephron, and what treatment replaces kidney function in kidney failure?
Urea is made in the liver. Blood is filtered in the glomerulus inside Bowman's capsule. Dialysis does the kidney's job artificially.
Answer: Liver; glomerulus; dialysis
60-Second Revision
- Liver largest gland, bile emulsifies fat; pepsin stomach; trypsin and lipase pancreas.
- Anaerobic: lactic acid in muscles, ethanol and CO₂ in yeast.
- O negative universal donor; AB positive universal recipient; Landsteiner.
- Nephron, glomerulus, urea from liver, dialysis.