🌟 Human Endocrine System 🌟

The endocrine system includes glands and tissues that make hormones to control body functions. Major glands are:

🧠 1. Hypothalamus

  • Location: Base of the brain
  • Hormones: Releasing hormones (start pituitary hormones) & Inhibiting hormones (stop pituitary hormones).
  • Example: GnRH tells the pituitary to make gonadotrophins.
  • Fun fact: Uses blood vessels to send hormones to the pituitary! 💉

⚖️ 2. Pituitary Gland

  • Location: Attached to the hypothalamus by a stalk.
  • Two parts:
    • Anterior Pituitary makes:
      • Growth Hormone (GH) → Controls growth (too much = gigantism; too little = dwarfism).
      • Prolactin (PRL) → Makes milk in breasts.
      • TSH → Tells thyroid to work.
      • ACTH → Tells adrenal glands to make stress hormones.
      • LH & FSH → Control ovaries/testes (called gonadotrophins).
    • Posterior Pituitary stores:
      • Oxytocin → Contracts uterus during childbirth 🤰 and releases milk.
      • Vasopressin (ADH) → Saves water in kidneys. Low ADH causes Diabetes Insipidus (lots of pee! 💦).

🌙 3. Pineal Gland

  • Location: Back of the brain.
  • Hormone: Melatonin → Controls sleep-wake cycles 😴 and body rhythms.

🦋 4. Thyroid Gland

  • Location: Neck (around windpipe).
  • Hormones: Thyroxine (\(T_4\)) & Triiodothyronine (\(T_3\)) → Control metabolism, energy, and growth.
  • Problems:
    • Low iodine → Goiter (swollen neck) or Cretinism (stunted growth in babies).
    • Too much hormone → Hyperthyroidism (weight loss, fast heartbeat). Includes Graves’ disease (bulging eyes 👀).

🦴 5. Parathyroid Gland

  • Location: Back of thyroid (4 tiny glands!).
  • Hormone: Parathyroid hormone (PTH) → Raises blood calcium by breaking bone, saving calcium in kidneys, and absorbing calcium from food. 💀

🛡️ 6. Thymus

  • Location: Chest (between lungs).
  • Hormone: Thymosins → Help make infection-fighting T-cells. Weakens as we age 👴.

😰 7. Adrenal Gland

  • Location: On top of kidneys.
  • Two parts:
    • Adrenal Medulla (center):
      • Makes adrenaline & noradrenaline → “Fight or flight” hormones! ⚡ (Increase heart rate, blood sugar, alertness).
    • Adrenal Cortex (outer layer):
      • Cortisol → Manages stress, blood sugar, and fights inflammation.
      • Aldosterone → Saves salt & water in kidneys.
      • Too little cortisol → Addison’s disease (weakness, tiredness).

🍬 8. Pancreas

  • Location: Belly (behind stomach).
  • Hormones from Islets of Langerhans:
    • Glucagon (from α-cells) → Raises blood sugar by breaking glycogen.
    • Insulin (from β-cells) → Lowers blood sugar by helping cells absorb glucose.
    • Balance upset → Diabetes Mellitus (high blood sugar, pee has glucose).

👨 9. Testis (Males)

  • Hormone: Testosterone → Deep voice, muscles 💪, sperm production, body hair.

👩 10. Ovary (Females)

  • Hormones:
    • Estrogen → Grows breasts, regulates periods, female features.
    • Progesterone → Prepares uterus for pregnancy 🤰 & helps make milk.

❤️ 11. Bonus Hormones from Other Organs!

  • Heart: ANF → Lowers blood pressure.
  • Kidneys: Erythropoietin → Makes red blood cells.
  • Gut: Gastrin (digests food), Secretin (neutralizes acid), CCK (releases bile), GIP (stops stomach activity).

🔑 How Hormones Work

  • Hormones attach to special “receptors” (like locks 🔒) on target cells.
  • This turns on signals inside the cell to change how it works!

🎯 NEET Super-Shortlist 🎯

  1. Pituitary Disorders: Gigantism (too much GH) vs. Dwarfism (too little GH).
  2. Thyroid Issues: Goiter (iodine lack), Cretinism (baby hypothyroidism), Graves’ disease (hyperthyroidism + bulging eyes).
  3. Pancreas & Diabetes: Insulin (↓ sugar) vs. Glucagon (↑ sugar). Diabetes = high blood sugar + sugar in urine.
  4. Adrenal Hormones: Cortisol (stress) & Aldosterone (salt balance). Addison’s = low cortisol.
  5. Calcium Control: PTH (↑ calcium) vs. Thyrocalcitonin (↓ calcium).

You’ve got this! 💪 Study these, and you’ll ace it! 🎉