MCAT Basics (from MedSchoolCoach) Common Hormone Axes
Apr 22, 2025
Dive deep into the intricate world of hormone axes! Discover how the HPA axis manages our stress response with cortisol and CRH, while the HPG axis controls crucial reproductive hormones like testosterone and estrogen. Unravel the mysteries of the RAAS system, responsible for blood pressure regulation and electrolyte balance. Each segment provides a captivating look at how these hormonal interactions influence our physiology, making complex concepts accessible and engaging.
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Hypothalamus Looks Like Monkey Bread
- Sam likens the hypothalamus to monkey bread to illustrate clustered nuclei that secrete different hormones.
- The metaphor emphasizes how separate nuclei perform distinct endocrine functions within one structure.
How Cortisol Acts And Regulates
- Steroid hormones like cortisol need carrier proteins and bind nuclear receptors to alter gene transcription.
- Cortisol feeds back on hypothalamus and pituitary to reduce CRH and ACTH secretion.
HPG Axis Controls Reproduction
- The HPG axis uses pulsatile GnRH to stimulate LH and FSH from the anterior pituitary.
- LH and FSH drive sex steroid production and gametogenesis, with sex steroids providing negative feedback to the hypothalamus.