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Sodium - Physiology

In this course, we explain the basic physiology of sodium homeostasis in the human body. We explain the factors controlling the distribution of water between body compartments. You will learn how plasma osmolarity is regulated by ADH, thirst mechanisms and the renin-angiotensin-aldosterone system.

1.0 x AMA PRA Category 1 Credits™
Available on the Pro Plan



In this course, we teach you the basic physiology of sodium homeostasis in the human body. We begin by explaining the important concept of body fluid compartments and the factors controlling the distribution of water between these compartments. We explain the meaning of the terms plasma osmolarity and plasma osmolality and explain how they are related. We teach you how plasma osmolarity is regulated by ADH, thirst mechanisms and the renin-angiotensin-aldosterone system.


Planner and Author: Dr John Seery MB PhD

  • Consultant Physician at St. Vincent's University Hospital, Dublin, Ireland
  • Lecturer at the School of Medicine and Medical Science, University College Dublin, Ireland
  • Studied medicine at the University of Cambridge, United Kingdom
  • A Natural Sciences graduate of Trinity College Dublin, Ireland
  • PhD in Cell Biology from University College London, United Kingdom

Planner: Dr Karen Strahan PhD (University of Cambridge), Head of Editorial
Planner: Tommy O'Sullivan, CME Manager

Estimated Time to Complete

1.0 hours

Target Audience

  • Physicians
  • Nurses
  • Nurse Practitioners
  • Physician Assistants
  • Paramedics

Learning Objectives

Upon successful completion of this activity, you will be able to:

  • Explain the physiological processes underlying sodium homeostasis and extracellular fluid osmolarity in the human body
  • Interpret an abnormal plasma sodium concentration in terms of basic physiological principles.

Course Content

  • Introduction
  • Body Fluid Compartments
  • Osmolality/Osmolarity
  • Plasma Osmolality/Osmolarity
  • Effective Osmolality/Osmolarity
  • Sodium Homeostasis - Introduction
  • Sodium Homeostasis - ADH and Thirst
  • The Renin-Angiotensinogen-Aldosterone Axis
  • Quiz

Release date


Expiration date


Instructions for Participation

Participants must complete the online activity during the valid period as noted above.
Follow these steps:

  1. View videos in sequence
  2. Complete quiz
  3. Complete the activity evaluation form to provide feedback for continuing education purposes and for the development of future activities
  4. Download the Certificate of Completion

Relevant Financial Disclosures

Acadoodle adheres to the ACCME's Standards for Integrity and Independence in Accredited Continuing Education. Any individuals in a position to control the content of a CE activity, including faculty, planners, reviewers or others are required to disclose all relevant financial relationships with ineligible entities (commercial interests). All relevant conflicts of interest have been mitigated prior to the commencement of the activity.

Planners and faculty for this activity have no relevant financial relationships with commercial interests to disclose.


Ganong WF. (1983) Review of Medical Physiology. 11th Edition. Lange Medical Publications. Los Altos, California USA.

Bie P. Mechanisms of sodium balance: total body sodium, surrogate variables, and renal sodium excretion. Am J Physiol Regul Integr Comp Physiol. 2018;315(5):R945-62.

Kumar MA. Osmoregulation and osmoreceptors. J Postgrad Med. 1980;26:4-10.;year=1980;volume=26;issue=1;spage=4;epage=10;aulast=Kumar

Fitzsimons JT. Angiotensin, Thirst and Sodium Appetite. Physiol Rev. 1998;78(3):583-686.

ACCME Accreditation Statement

Acadoodle, Ltd is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

Credit Designation Statement

AMA Physician’s Recognition Award

Acadoodle, Ltd designates this enduring material activity for a maximum of 1.0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

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