Renal Physiology Lecture 2: Fluid Dynamics & Electrolyte Balance

Question 1

Fluid and electrolyte intake must equal _______?

Answer 1

output

• fluid and electrolyte intake is variable
  
  • balance required to establish homeostasis → mostly by kidneys
• Water intake mostly by ingestion → consume approx. 2 L/ day
  
  • also intravenous infusion
  • Fluid losses: sweat feces, respiration

Question 2

What does water and sodium determine?

Answer 2

• ECF
• plasma osmolarity

Question 3

What is ECF

Answer 3

extracellular fluid

Question 4

Why are electrolytes precisely regulated?

Answer 4

protect cellular functions

• disruption can be life threatening
• Can disturb body pH levels

Question 5

What is total body water divided into?

Answer 5

• ICF: intracellular fluid (⅔ of TBW)
• ECF: extracellular fluid (⅓ of TBW)
  
  • comprised of interstitial fluid (bathes cells) and plasma (non-cellular portion)

Question 6

What body fluid is tightly regulating?q

Answer 6

ECF

• Cell membranes highly permeable to water
  
  • if ECF osmolarity fluctuated, so would cell volume

Question 7

What role do the kidneys have in water and electrolyte balance?

Answer 7

Kidneys regulate water and salt balance which controls blood volume

• changes in blood volume elicit changes in blood pressure