Homeostasis: Endocrine System and Hormonal Communication

Introduction

• Topic: Homeostasis
• Focus: Endocrine system and hormones

Hormonal Communication

• Nervous System
  • Fast communication but energy-expensive
  • Transfers messages (e.g., brain to muscles, heart)
• Endocrine System
  • Communicates via hormones
  • Slower but less energy-intensive
  • Involves glands that produce and release hormones
  • Previously covered topics: glucose homeostasis, ADH and water balance

Glands

• Definition: Groups of cells producing and secreting substances
• Exocrine Glands: Have ducts
• Endocrine Glands: Secrete hormones directly into the bloodstream (no ducts)
• Hormones bind to specific cells with receptors for activation

Major Endocrine Glands

• Pineal gland
• Pituitary gland
• Hypothalamus
• Thyroid and parathyroid glands
• Thymus (immune system)
• Pancreas (insulin and glucagon)
• Adrenal glands
• Testes (males: testosterone)
• Ovaries (females)
• Placenta (during pregnancy)

Types of Hormones

• Hormones: Cell signaling molecules
• Classification:
  • Water-Soluble Hormones
    • Typically peptide hormones (e.g., ADH, insulin, glucagon)
    • Do not penetrate cell membranes
    • Bind to cell receptors, causing signaling cascades
  • Lipid-Soluble Hormones
    • Typically steroid hormones
    • Can penetrate cell membranes (lipid soluble)
    • Act inside the cell, often affecting genes and protein production

Hormones Chart

• Endocrine system hormones and their functions
• Important for understanding actions and mechanisms

Conclusion

• Next lecture: Homeostasis of the menstrual cycle