The Pituitary Gland: Often called the 'master gland,' it is located at the base of the brain and produces hormones that trigger other glands to release their own hormones.
Metabolic Control: The Thyroid produces thyroxine to regulate the rate of metabolism, while the Pancreas produces insulin to manage blood glucose levels.
Stress Response: The Adrenal glands produce adrenaline, which prepares the body for immediate physical action by increasing heart rate and diverting blood to muscles.
Reproductive Control: The Ovaries (in females) and Testes (in males) produce sex hormones like oestrogen and testosterone that drive the development of secondary sexual characteristics.
| Feature | Nervous System | Endocrine System |
|---|---|---|
| Transmission | Electrical impulses along neurones | Chemical hormones in the blood |
| Speed | Very rapid (milliseconds) | Slower (seconds to days) |
| Duration | Short-lived effect | Longer-lasting effect |
| Targeting | Precise (specific muscle/gland) | Widespread (multiple target organs) |
Identify the Source: Always memorize which gland produces which hormone. A common exam task is to match a specific physiological change (e.g., increased heart rate) to its source gland (Adrenal).
Check the Medium: Remember that hormones travel in the blood plasma, not the red blood cells or the nerves. This is a frequent point of confusion in multiple-choice questions.
Specificity is Key: If asked why a hormone doesn't affect every cell, the answer must mention specific, complementary receptors on the target cell membrane or inside the cell.
Feedback Loops: Be prepared to explain how one hormone can inhibit or stimulate another, such as how oestrogen levels influence the release of FSH and LH in the brain.
