Sodium and Potassium Ion Transport Quiz

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Questions and Answers

What is the primary role of Na+ in the extracellular fluid (ECF)?

Transporting glucose into cells
Regulating intracellular pH levels
Facilitating nerve impulse transmission
Determining plasma osmolality (correct)

Which of the following correctly describes the function of the Na+,K+ ATPase ion pump?

Exchanges three Na+ ions for two K+ ions while consuming ATP (correct)
Establishes equilibrium of Na+ and K+ across the cell membrane
Predominantly functions without altering ATP levels
Moves two Na+ ions into the cell for every three K+ ions out

How does the movement of Na+ affect water in relation to cell volume?

Na+ influx leads to increased cell volume
Na+ removal draws water out of the cell, preventing rupture (correct)
Water follows Na+ into the cell, causing swelling
Na+ movement has no effect on water balance in the cell

What would happen if Na+ diffuses into the cell without being actively transported out?

Equilibrium would be established between the inside and outside of the cell (C) Signup and view all the answers

What physiological consequence is most likely if the Na+,K+ ATPase pump fails?

Cellular osmotic rupture due to excess Na+ (C) Signup and view all the answers

Which statement about the concentration of Na+ in the ECF compared to inside the cells is true?

Na+ concentration is much larger in the ECF than inside the cells (B) Signup and view all the answers

Flashcards

ECF's Major Cation

Sodium (Na+) is the most abundant positively charged ion (cation) in the fluid surrounding cells (extracellular fluid, ECF). It makes up 90% of all cations in this fluid.

Sodium's Role in Osmolality

The amount of dissolved particles (osmoles) in a solution is called osmolality. Sodium (Na+) and its associated negatively charged ions (anions) contribute significantly to the osmolality of blood plasma.

Sodium Concentration Gradient

The concentration of sodium (Na+) is much higher outside cells than inside. This difference is maintained by active transport systems like the sodium-potassium pump.

Sodium's Passive Movement

Without active transport, sodium (Na+) would passively move from an area of high concentration (outside cells) to an area of low concentration (inside cells) until both sides were equal.

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Sodium-Potassium Pump

The sodium-potassium pump actively moves sodium out of the cell and potassium into the cell using energy from ATP. This process maintains the concentration gradient and keeps the cell from swelling due to water.

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ICF's Major Cation

Potassium (K+) is the most abundant positively charged ion (cation) inside cells (intracellular fluid, ICF).

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Study Notes

Sodium (Na+) in Extracellular Fluid (ECF)

Sodium (Na+) is the most abundant cation in the ECF, comprising 90% of extracellular cations.
It significantly influences plasma osmolality.
Normal plasma osmolality is approximately 295 mmol/L, with 270 mmol/L attributed to Na+ and associated anions.
Na+ concentration is substantially higher outside cells compared to inside.

Maintaining Sodium Gradient

Passive diffusion of Na+ across cell membranes would lead to equilibrium.
Active transport mechanisms (ATPase ion pumps) in all cells prevent this.
The pumps maintain the concentration gradient.

Potassium (K+) and Intracellular Fluid

Potassium (K+) is the primary intracellular cation.
Like Na+, K+ would naturally diffuse to equilibrium without active transport.

Na+/K+ ATPase Pump

The Na+/K+ ATPase pump actively transports ions.
It moves three Na+ ions out of the cell for every two K+ ions pumped in, using energy from ATP conversion to ADP.
This process maintains the concentration differences.