Physiological Feedback Mechanisms

Jun 21, 2024

Physiological Feedback Mechanisms

Overview

  • Feedback mechanisms: Essential for controlling molecular and physiological processes.
  • Two types: Positive feedback and Negative feedback.

Positive Feedback

  • Definition: A process that increases the rate of product formation.
  • Analogy: Domino or chain effect.
  • Process: One product stimulates the creation of another product, and so on.

Negative Feedback

  • Definition: A process that decreases the rate of product formation to prevent accumulation.
  • Importance: Prevents toxic buildup of products in the blood.
  • Mechanism: Inhibits the process that increases product formation.

Feedback Mechanisms in Female Physiology

  • Involves the hypothalamus, pituitary gland, and ovaries.
  • Four key hormones: Estrogen, GnRH (Gonadotropin Releasing Hormone), LH (Luteinizing Hormone), and Progesterone.

Hypothalamus

  • Master control gland of the endocrine system.
  • Signals the pituitary gland.

Pituitary Gland

  • Located in the brain.
  • Has two lobes:
    • Posterior lobe
    • Anterior lobe (focus of discussion)

Ovaries

  • Females have two ovaries located lower in the body.

Hormonal Feedback During the Menstrual Cycle

Positive Feedback Loop Before Ovulation

  1. Estrogen: Secreted in small amounts by the ovaries.
  2. GnRH: Released by the hypothalamus.
  3. LH: Released by the anterior pituitary.
  4. Cycle: Estrogen → GnRH → LH → More estrogen.

Result of Positive Feedback

  • Increased levels of GnRH and LH in the blood.
  • High levels of LH trigger a new response.

Negative Feedback to Control Hormone Levels

  1. Progesterone: Secreted by the corpus luteum after ovulation.
  2. Function: Inhibits production of GnRH and LH.
  3. Outcome: Prevents accumulation of hormones in the blood.

Homeostasis

  • Feedback mechanisms maintain balance in the body (homeostasis).
  • Prevents molecular and physiological processes from becoming imbalanced.
  • Ensures optimal functioning of the body.

Summary

  • Positive Feedback: Stimulates production of more products (e.g., Estrogen, GnRH, LH).
  • Negative Feedback: Inhibits further production to prevent excess (e.g., Progesterone's role post-ovulation).
  • Both mechanisms are crucial for maintaining physiological balance and health.