SILVERTHORN
CHAPTER 20 – FLUID AND ELECTROLYTE BALANCE
FLUID AND ELECTROLYE HOMEOSTASIS
The body’s task is to maintain mass balance: what comes in must be excreted if the body does
not need it. The kidneys are the primary route for water loss and removal of many ions. Water and
Na+ are associated with ECF volume and osmolarity. Disturbances in K + balance can cause serious
problems with cardiac and muscle function by disrupting the membrane potential of excitable cells.
Ca2+ is involved in exocytosis, muscle contraction, bone formation and blood clotting. H+ and HCO3-
determine body pH.
ECF OSMOLARITY AFFECTS CELL VOLUME
If ECF osmolarity decreases as a result of excess water intake, water moves into the cell and
they swell. If ECF osmolarity increases, water moves out of the cells and they shrink. Many
cells have independent mechanisms for maintaining cell volume. Renal tubule cells are
constantly exposed to high ECF osmolarity, yet they remain normal cell volume. They
synthesize organic solutes as needed to make their intracellular osmolarity match that of the
medullary interstitial fluid. Other cells regulate by changing their ionic composition.
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller kipsten. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.15. You're not tied to anything after your purchase.