Overview of the Endocrine System

Jun 19, 2024

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Overview of the Endocrine System

Introduction

  • Introduced by Eddie Watson from ICU Advantage
  • Series will cover various aspects and disorders of the endocrine system
  • Important topics:
    • Addison's vs. Cushing's
    • Hypoglycemia
    • Diabetes
    • DKA vs. HHS
    • DI vs. SIADH
    • Thyroid Storm vs. Myxedema Coma

Subscription and Engagement

  • Encourages viewers to subscribe for more educational content
  • Importance of likes and comments for support

Functions of the Endocrine System

  • Regulates body's internal environment
  • Uses endocrine glands (secrete hormones into the bloodstream) vs. exocrine glands (secrete hormones into ducts)
  • Works closely with the nervous system to regulate:
    • Growth
    • Reproduction
    • Sex differentiation
    • Metabolism
    • Fluid and electrolyte balance
    • Internal homeostasis
  • Nervous system releases neurotransmitters at synapses, reacts quickly
  • Endocrine system releases hormones into blood, reacts slowly

Hormones: Chemical Messengers

  • Hormones act on distant target cells
  • Three types:
    • Endocrine: into bloodstream
    • Paracrine: affect neighboring cells
    • Autocrine: affect the cell that secreted them
  • Specific receptors on target cells (lock-and-key model)
  • Two ways hormones bind:
    • On cell surface (secondary messengers)
    • Inside the cell (direct protein synthesis)
  • Depends on water (surface) or lipid (inside) solubility

Categories of Hormones

  1. Peptides (Protein Hormones)
    • Water soluble
    • Act on surface receptors
    • Examples: Vasopressin, Insulin, Growth Hormone
  2. Steroids
    • Lipid soluble
    • Act inside the cell
    • Examples: Aldosterone, Cortisol, Testosterone
  3. Amines
    • Amino acid derivatives
    • Can act on cell surface or inside
    • Examples: Epinephrine, Norepinephrine (surface), T3 and T4 (inside)

Feedback Mechanisms

  • Hormones regulated by feedback:
    • Positive Feedback: Rare
    • Negative Feedback: Common
  • Example: Thyroid Stimulating Hormone (TSH) > Thyroid (T3 & T4) > Inhibits further TSH release

Endocrine Glands: Anatomy and Physiology

Brain

  1. Hypothalamus
    • Control center
    • Link between nervous and endocrine systems
    • Passes signals to the pituitary
  2. Pituitary Gland
    • Master gland (anterior and posterior parts)
    • Anterior: TSH, LH, FSH, Prolactin, GH, ACTH
    • Posterior: ADH (Vasopressin), Oxytocin
  3. Pineal Gland
    • Produces melatonin (sleep regulation)

Thyroid and Parathyroid

  1. Thyroid Gland
    • Wraps around trachea
    • Produces T3 & T4 (metabolism, growth, blood pressure regulation)
  2. Parathyroid Glands
    • Usually four
    • Regulates calcium levels (muscle contraction, bone growth)

Other Glands

  1. Thymus
    • Maturation of T-cells
  2. Pancreas
    • Produces insulin and glucagon (blood sugar regulation)
  3. Adrenal Glands
    • On top of kidneys
    • Cortex: Steroids (Cortisol, Aldosterone)
    • Medulla: Catecholamines (Epinephrine, Norepinephrine)
  4. Gonads
    • Ovaries: Estrogen, Progesterone
    • Testes: Testosterone

Other Hormone-Producing Organs

  • Heart: ANP, BNP (blood pressure and volume regulation)
  • Kidneys: Erythropoietin (RBC production), Renin (aldosterone release)
  • Stomach/Intestines: Digestive hormones
  • Bones/Skin/Adipose Tissue: Leptin (fat regulation)

Conclusion

  • Comprehensive overview of endocrine system anatomy and physiology
  • Importance of understanding for future lessons on endocrine disorders
  • Encouragement to like and subscribe
  • Preview of next lesson on Addison’s vs. Cushing’s