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Questions and Answers
What percentage of extracellular cations does sodium Na+ represent?
What percentage of extracellular cations does sodium Na+ represent?
What is the primary mechanism that prevents sodium Na+ from reaching equilibrium between the extracellular fluid and inside the cell?
What is the primary mechanism that prevents sodium Na+ from reaching equilibrium between the extracellular fluid and inside the cell?
How many sodium Na+ ions are moved out of the cell by the Na+,K+ ATPase ion pump?
How many sodium Na+ ions are moved out of the cell by the Na+,K+ ATPase ion pump?
What happens to water when sodium Na+ is actively removed from the cell?
What happens to water when sodium Na+ is actively removed from the cell?
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What is the normal plasma osmolality value approximated in mmol/L?
What is the normal plasma osmolality value approximated in mmol/L?
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Which of the following statements is true regarding potassium K+ compared to sodium Na+?
Which of the following statements is true regarding potassium K+ compared to sodium Na+?
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Flashcards
Sodium (Na+)
Sodium (Na+)
The most abundant cation found outside of cells (ECF), making up 90% of all extracellular cations.
Plasma Osmolality
Plasma Osmolality
A measure of the concentration of dissolved particles in a solution, primarily determined by sodium in the plasma.
Na+, K+ ATPase Pump
Na+, K+ ATPase Pump
A specialized protein pump embedded in cell membranes responsible for actively moving sodium and potassium ions across the cell membrane.
Potassium (K+)
Potassium (K+)
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Osmosis
Osmosis
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Homeostasis
Homeostasis
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Study Notes
Sodium (Na+) in Extracellular Fluid (ECF)
- Sodium (Na+) is the most abundant cation in the ECF, making up 90% of all extracellular cations.
- It significantly influences plasma osmolality.
- Normal plasma osmolality is approximately 295 mmol/L, with 270 mmol/L contributed by Na+ and associated anions.
- The concentration of Na+ is much higher outside cells compared to inside.
- Passive diffusion of Na+ across cell membranes would lead to equilibrium.
- Cells utilize active transport systems, like ATPase ion pumps, to maintain this concentration gradient.
Potassium (K+) in Intracellular Fluid
- Potassium (K+) is the major intracellular cation.
- Like Na+, K+ would eventually diffuse across the cell membrane to reach equilibrium.
- The Na+/K+ ATPase ion pump actively transports ions.
- This pump moves three Na+ ions out of the cell for every two K+ ions moving in, using ATP. This process converts ATP to ADP.
Osmotic Balance and Cell Integrity
- Water follows the movement of electrolytes across cell membranes.
- Continuous removal of Na+ from the cell prevents osmotic rupture of the cell by drawing water out.
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Description
This quiz covers the roles of sodium and potassium ions in extracellular and intracellular fluids, their influence on plasma osmolality, and the mechanisms of active transport through ion pumps such as the Na+/K+ ATPase. Understanding these concepts is crucial for comprehending osmotic balance and cell integrity.
