Key Points
Key Points: Introduction of Chemical Coordination and Integration
- The neural system provides rapid, point-to-point coordination among organs.
- Neural coordination is fast but short-lived.
- Nerve fibres do not innervate all body cells.
- Cellular functions require continuous regulation.
- Hormones provide special coordination and integration.
- Neural and endocrine systems jointly regulate physiological functions.
Key Points: Testis
- Location & Function - Testes are in the scrotal sac; act as both sex organs (sperm) and endocrine glands (hormones).
- Structure - Made of seminiferous tubules + stromal/interstitial tissue.
- Leydig Cells - Produce testosterone, which matures male accessory organs (epididymis, prostate, etc.).
- Androgen Functions - Control spermatogenesis, muscle/hair growth, low voice pitch, and libido (via CNS).
- Metabolic Effect - Androgens have anabolic effects on protein and carbohydrate metabolism.
Key Points: Ovary
- Location & Function - Pair of ovaries in the abdomen; produce one ovum/cycle + secrete estrogen & progesterone.
- Structure - Made of ovarian follicles + stromal tissue; follicles secrete estrogen.
- Corpus Luteum - After ovulation, the ruptured follicle becomes the corpus luteum, which secretes progesterone.
- Estrogen Functions - Develops female sex organs, ovarian follicles, a high-pitched voice, and regulates sexual behaviour.
- Progesterone Functions - Supports pregnancy; stimulates alveoli formation and milk secretion in mammary glands.
Key Points: Hormones of Heart, Kidney and Gastrointestinal Tract
- Some non-endocrine tissues also secrete hormones (e.g., heart, kidney, gastrointestinal tract).
- The heart secretes Atrial Natriuretic Factor (ANF), which reduces blood pressure by dilating blood vessels.
- ANF is released when blood pressure increases, helping to bring it back to normal.
- Kidneys (juxtaglomerular cells) secrete erythropoietin, which stimulates RBC formation.
- The gastrointestinal tract secretes hormones that regulate digestion.
- Gastrin → stimulates secretion of HCl and pepsinogen.
- Secretin, CCK, and GIP → regulate pancreatic secretion, bile release, and inhibit gastric activity.
