📑 Topics on this page (Jump to Topic):
📌 1. Digestive & Respiratory Systems
- Digestion begins in the mouth: saliva has ptyalin (salivary amylase) — digests starch. The stomach has HCl and pepsin (proteins). Most digestion and absorption occur in the small intestine (villi).
- Liver — largest gland; makes bile (emulsifies fats; no enzymes), stored in gall bladder. Pancreas — mixed gland (trypsin, lipase, amylase + insulin).
- The large intestine mainly absorbs water. Adults have 32 teeth; milk teeth 20; hardest substance — enamel.
- Respiration: nose → pharynx → larynx → trachea → bronchi → alveoli — gas exchange. Normal breathing rate ~12–16/min (adult). The diaphragm is the main breathing muscle.
- Oxygen is carried mainly by haemoglobin; CO₂ mainly as bicarbonate. Anaerobic respiration in muscles produces lactic acid (fatigue).
📌 2. Circulatory System & Blood Groups
- The human heart is four-chambered (2 atria + 2 ventricles); William Harvey (1628) discovered blood circulation. Normal heartbeat ~72/min; blood pressure ~120/80 mm Hg (measured by sphygmomanometer).
- Arteries — heart to organs (oxygenated; exception: pulmonary artery); veins — organs to heart (exception: pulmonary vein carries oxygenated blood). The heartbeat starts at the SA node (pacemaker).
- ABO blood groups — Karl Landsteiner (1900–01); Rh factor — Landsteiner and Wiener (1940). O− universal donor, AB+ universal recipient.
| Blood group | Antigen on RBC | Antibody in plasma |
|---|---|---|
| A | A | b |
| B | B | a |
| AB | A and B | None |
| O | None | a and b |
📌 3. Excretory, Nervous, Endocrine & Skeletal Systems
- The unit of the kidney is the nephron (~1 million per kidney). Urine's yellow colour — urochrome. Humans mainly excrete urea (made in the liver).
- Brain: cerebrum — intelligence, memory, largest part; cerebellum — balance and coordination; medulla oblongata — involuntary actions like heartbeat, breathing. Reflex action — controlled by spinal cord.
| Gland | Hormone / fact |
|---|---|
| Pituitary | "Master gland"; growth hormone (deficiency — dwarfism, excess — gigantism) |
| Thyroid | Thyroxine (needs iodine); deficiency — goitre |
| Pancreas (islets of Langerhans) | Insulin (β-cells) — lowers blood sugar; deficiency — diabetes |
| Adrenal | Adrenaline — "fight or flight" hormone |
- Adults have 206 bones (newborn ~300). Longest — femur (thigh); smallest — stapes (middle ear). Largest organ — skin; largest internal gland — liver.
⚠️ Exam Traps:
- Bile contains no digestive enzyme.
- The pulmonary vein carries oxygenated blood.
- Universal donor is O−, universal recipient AB+.
📌 4. Practice MCQs
📝 Practice MCQs (prepared by SF Prep — not PYQs)
Q1. The largest gland in the human body is the: Practice
Correct answer: (B)
It produces bile.
It produces bile.
Q2. Most digestion and absorption of food occurs in the: Practice
Correct answer: (C)
Villi increase surface area.
Villi increase surface area.
Q3. The enzyme present in saliva is: Practice
Correct answer: (D)
Converts starch to maltose.
Converts starch to maltose.
Q4. The main function of bile is: Practice
Correct answer: (D)
Bile contains no enzymes.
Bile contains no enzymes.
Q5. Gas exchange in humans occurs in the: Practice
Correct answer: (A)
Thin walls and capillaries.
Thin walls and capillaries.
Q6. Blood circulation was discovered by: Practice
Correct answer: (C)
In 1628.
In 1628.
Q7. How many chambers does the human heart have? Practice
Correct answer: (B)
2 atria + 2 ventricles.
2 atria + 2 ventricles.
Q8. Which vein carries oxygenated blood? Practice
Correct answer: (C)
From lungs to heart.
From lungs to heart.
Q9. The "pacemaker" of the heart is the: Practice
Correct answer: (D)
Impulse starts at the sino-atrial node.
Impulse starts at the sino-atrial node.
Q10. ABO blood groups were discovered by: Practice
Correct answer: (A)
1900–01; Nobel Prize 1930.
1900–01; Nobel Prize 1930.
Q11. The universal donor blood group is: Practice
Correct answer: (B)
No A, B or Rh antigen on RBCs.
No A, B or Rh antigen on RBCs.
Q12. Antibodies in the plasma of blood group AB: Practice
Correct answer: (A)
Hence AB+ is the universal recipient.
Hence AB+ is the universal recipient.
Q13. The structural and functional unit of the kidney is the: Practice
Correct answer: (A)
~1 million per kidney.
~1 million per kidney.
Q14. The yellow colour of urine is due to: Practice
Correct answer: (D)
Pigment from haemoglobin breakdown.
Pigment from haemoglobin breakdown.
Q15. Body balance is maintained by the: Practice
Correct answer: (A)
Also muscular coordination.
Also muscular coordination.
Q16. The "master gland" is the: Practice
Correct answer: (C)
Controls other glands.
Controls other glands.
Q17. Insulin is secreted by: Practice
Correct answer: (D)
Islets of Langerhans; deficiency causes diabetes.
Islets of Langerhans; deficiency causes diabetes.
Q18. The "fight or flight" hormone is: Practice
Correct answer: (B)
From the adrenal medulla.
From the adrenal medulla.
Q19. The number of bones in an adult human is: Practice
Correct answer: (B)
Newborn ~300 (some fuse later).
Newborn ~300 (some fuse later).
Q20. The smallest bone in the human body is the: Practice
Correct answer: (C)
In the middle ear; longest is femur.
In the middle ear; longest is femur.