Overview of the Endocrine System

Aug 17, 2024

Unit 7: Endocrine System

Lecture Overview

  • Objectives: Refer to the objectives listed in your course outline.
  • Textbook Chapters: Relevant chapters are 30-35.

Introduction to the Endocrine System

  • Function:
    • Controls and regulates metabolic functions.
    • Regulates growth, chemical reactions, and physiological stability.
    • Glands secrete hormones that target specific cells.
    • Hormones are receptor-specific, causing specific physiological responses.

Hormones

  • Natural Substances: Secreted by glands, causing physiological effects on cells.
    • Highly specific to target sites depending on the hormone.

Negative Feedback System

  • Concept:
    • A system where the production of one hormone is controlled by the level of a second hormone.
    • Example: Gland X secretes Hormone X, triggering Gland Y to release Hormone Y.
    • If Hormone Y levels are too high, production of Hormone X is reduced to decrease Hormone Y.

Pituitary Gland

  • Location & Structure:

    • Includes anterior and posterior sections.
    • Previously considered the "master gland."

  • Control by Hypothalamus:

    • Hypothalamus regulates temperature, fluid volume, growth, and more.
    • Releases inhibitory hormones from anterior pituitary and nerve signals from posterior pituitary.

Anterior Pituitary Hormones

  • Releasing Hormones:

    • Examples:
      • Growth Hormone (GH)
      • Thyroid Stimulating Hormone (TSH)
      • Prolactin (affects lactogenesis and breast growth)

  • Inhibiting Hormones:

    • Somatostatin: Inhibits GH and TSH.
    • Dopamine: Produced in hypothalamus, inhibits prolactin.

Posterior Pituitary Hormones

  • Antidiuretic Hormone (ADH):

    • Produced in hypothalamus, stored in posterior pituitary.
    • Increases water absorption, concentrates urine, and causes vasoconstriction.
    • Helps maintain blood pressure.

  • Oxytocin:

    • Targets mammary glands and uterus.
    • Stimulates milk ejection and uterine contraction.
    • Used during childbirth to facilitate delivery.

For further understanding, refer to your textbook and class notes, especially on pages 473-474, and table 30.1 for detailed hormone information. Understanding these concepts will be important for grasping drug-specific effects later in the unit.