Hormones and the Endocrine System

Introduction

• Hormones are critical in regulating various bodily functions.
• There are over 50 hormones produced by the body.
• Key functions include:
  • Growth and development
  • Mood regulation
  • Sleep, hunger, reproduction, metabolism
  • Homeostasis (body balance)

Major Endocrine Glands

• Glands in the Brain:
  • Hypothalamus
  • Pituitary Gland:
    • Divided into anterior and posterior lobes.
  • Pineal Gland

Anterior Pituitary Gland

• Produces several key hormones:
  • Growth Hormone (GH): Influences growth of organs, bones, and cartilage.
  • Prolactin: Responsible for lactation and breast development.
  • Thyroid-Stimulating Hormone (TSH): Stimulates thyroid hormone production.
  • Adrenocorticotropic Hormone (ACTH): Stimulates adrenal glands.
  • Follicle-Stimulating Hormone (FSH): Regulates sexual development and reproduction.
  • Luteinizing Hormone (LH): Complements FSH in sexual reproduction.
• Hypothalamus commands the anterior pituitary via hormonal signals.

Posterior Pituitary Gland

• Secretes:
  • Anti-Diuretic Hormone (ADH or Vasopressin): Regulates blood pressure and water balance.
  • Oxytocin: Stimulates uterine contractions during childbirth and is linked to emotional bonding.
• Hormones are produced in the hypothalamus and stored in the posterior pituitary.

Pineal Gland

• Produces Melatonin: Regulates sleep-wake cycles in response to light conditions.

Thyroid Gland

• Largest true endocrine gland, shaped like a butterfly.
• Produces Thyroxine (T4): Increases metabolism.
• T4 converts to Triiodothyronine (T3): More active form in cells.
• Iodine is essential for T4 and T3 production (obtained through diet).
• Produces Calcitonin: Decreases blood calcium levels.

Parathyroid Glands

• Produce Parathyroid Hormone (PTH): Increases blood calcium levels.
• Important for bone health, muscle contraction, and blood clotting.

Pancreas

• Regulates blood glucose levels through:
  • Insulin: Lowers blood glucose by enabling cell absorption.
  • Glucagon: Raises blood glucose by signaling liver to release stored glucose.
• Linked to diabetes (Type 1 and Type 2).

Adrenal Glands

• Divided into:
  • Adrenal Cortex:
    • Produces glucocorticoids (e.g., Cortisol): Regulates metabolism and immune function.
    • Mineralocorticoids (e.g., Aldosterone): Regulate minerals and blood pressure.
  • Adrenal Medulla:
    • Produces adrenaline and noradrenaline: Triggers fight-or-flight response.

Gonads

• Testes (males) and ovaries (females) produce:
  • Estrogen, Progesterone, Testosterone: Control sexual development and reproductive functions.
• Hormonal levels vary between genders; both sexes produce all three hormones.

Interconnectedness of Hormones

• Hormones interact significantly:
  • Insulin, cortisol, thyroid hormone, and growth hormone all regulate glucose metabolism.
  • Hormone interactions affect calcium and blood pressure regulation.
• The nervous system and environment also influence hormonal activity.

Conclusion

• Hormonal balance is crucial for overall health and functioning.
• Hormones are continuously active, affecting the body beyond just adolescence.