Endocrine Glands and Hormones
~7 min read
- Endocrine system: Ductless glands secreting hormones directly into blood.
- Master gland: Pituitary — controls other endocrine glands.
- Key hormones: Insulin (pancreas), thyroxine (thyroid), adrenaline (adrenal), oxytocin (pituitary).
Hormones regulate metabolism, growth, reproduction and stress response. CDS/OTA tests gland-hormone pairs and deficiency/excess effects.
Major Endocrine Glands
| Gland | Hormone | Main function | Disorder if deficient |
|---|---|---|---|
| Pituitary (anterior) | Growth Hormone (GH) | Body growth | Dwarfism (deficit); Gigantism/Acromegaly (excess) |
| Pituitary (anterior) | TSH | Stimulates thyroid | — |
| Pituitary (posterior) | Oxytocin | Childbirth, milk ejection | — |
| Thyroid | Thyroxine (T₄) | Regulates metabolic rate | Goitre, cretinism (needs iodine) |
| Parathyroid | Parathormone | Calcium balance | Tetany |
| Pancreas (islets) | Insulin | Lowers blood glucose | Diabetes mellitus (Type 1) |
| Adrenal | Adrenaline, Cortisol | Fight-or-flight, stress | Addison's disease |
| Testis | Testosterone | Male secondary characters | — |
| Ovary | Oestrogen, Progesterone | Female cycle | — |
Chemical Nature of Hormones
- Peptide hormones (chains of amino acids): insulin, oxytocin, growth hormone, corticotropin (ACTH).
- Steroid hormones: testosterone, oestrogen, cortisone, cortisol — synthesised from cholesterol in smooth ER.
- Amino-acid derived: thyroxine (contains iodine), adrenaline.
- Cobalt is associated with haemoglobin formation (as part of vitamin B₁₂), not hormones.
- Insulin enables cells to take up glucose from blood — its deficiency causes diabetes mellitus.
Unique Points
- Pituitary is called the master gland because its hormones (TSH, ACTH, FSH/LH, GH) regulate most other endocrine glands.
- Most endocrine glands occur in pairs (adrenal, testis, ovary). The pituitary is the major unpaired gland.
- Iodine is essential for thyroid to synthesise thyroxine. Iodised salt prevents goitre.
CDS/OTA PYQ Examples
Q: Which hormone contains peptide chain?
(a) Oxytocin (b) Corticotropin (c) Insulin (d) Cortisone
Answer: (a/b/c) Oxytocin, Corticotropin (ACTH) and Insulin are all peptide hormones; Cortisone is a steroid. Original answer keyed to peptide hormone. [CDS-I 2016]
Q: Which hormone is essential for uptake of glucose by cells?
(a) GH (b) TSH (c) Insulin (d) Cortisol
Answer: (c) Insulin — facilitates GLUT-4 transporter on cells. [CDS-II 2016]
Q: Which endocrine gland is NOT found in pair in humans?
(a) Adrenal (b) Pituitary (c) Testis (d) Ovary
Answer: (b) Pituitary — single midline gland. [CDS-I 2020]
Q: Which is essential for thyroid to make thyroxin?
(a) NaCl (b) KCl (c) Cholesterol (d) Iodine
Answer: (d) Iodine. [CDS-I 2023]
Q: Cobalt is associated with:
(a) growth hormone (b) insulin (c) hemoglobin (d) intestinal enzymes
Answer: (c) Hemoglobin / vitamin B₁₂. [CDS-II 2015]
Drill Endocrine Glands and Hormones for CDS/OTA
CDS/OTA-pattern items on Endocrine Glands and Hormones with answer keys and explanations.
Start Free Mock TestFrequently Asked Questions
What is the difference between endocrine and exocrine glands?
Endocrine glands are ductless and pour hormones directly into the blood (thyroid, pituitary). Exocrine glands have ducts and release secretions onto a surface or into a cavity (salivary, sweat).
Why is the pituitary called the master gland?
Its hormones (TSH, ACTH, FSH, LH, GH) regulate most other endocrine glands — thyroid, adrenal cortex, gonads — and growth. But the hypothalamus controls the pituitary itself.
What causes diabetes mellitus?
Type 1: pancreatic β-cells destroyed (autoimmune), little or no insulin. Type 2: cells become resistant to insulin. Both raise blood glucose.