Chemical Coordination and Integration
வேதி ஒருங்கிணைப்பும் இணைவாக்கமும்
- 1Endocrine Glands and Hormones
Hormones are non-nutrient chemicals that act as intercellular messengers in trace amounts. Most NEET matching questions in this chapter are just gland → hormone → disorder triplets — learn them as sets.
- 2Hypothalamus and Pituitary Gland
The posterior pituitary makes nothing. It only stores and releases oxytocin and vasopressin that the hypothalamus makes — that is why it is not a 'true' endocrine gland.
- 3Pineal, Thyroid, Parathyroid and Thymus
PTH raises blood calcium; calcitonin (from the thyroid) lowers it. So a statement saying 'PTH decreases Ca2+ in blood' is false — and that is NEET's favourite trap here.
- 4Adrenal Gland
Adrenaline is the 'fight or flight' hormone and it boosts glycogen breakdown; aldosterone handles salt and water, not sugar. When NEET asks which hormone is NOT involved in sugar metabolism, the answer is aldosterone.
- 5Pancreas and Blood Glucose
Glucagon raises blood sugar (hyperglycaemic); insulin lowers it (hypoglycaemic). Mixing up these two words in an option is the most common way students lose this question.
- 6Testis and Ovary
Relaxin and inhibin are not antagonists — they act on completely different targets. NEET's 'NOT antagonistic' question is built around exactly this pair.
- 7Hormones of Heart, Kidney and Gastrointestinal Tract
Erythropoietin comes from the juxtaglomerular cells of the kidney, not from the bone marrow it acts on. And ANF comes from the heart's atrial wall. Organs that are not 'glands' still make hormones.
- 8Mechanism of Hormone Action
Steroid hormones cross the membrane and bind receptors inside the cell to switch genes on or off; protein and amine hormones stay outside and use second messengers like cyclic AMP. That one split answers every mechanism question.