Question

At rest, about \(12 \%\) of the total calories consumed are used for a. protein synthesis. b. cell transport. C. the \(\mathrm{Na}^{+} / \mathrm{K}^{+}\)pumps. d. DNA replication.

Short answer

The correct answer is option (c), Na+/K+ pumps. At rest, about 12% of total calories consumed are used to maintain the function of the Na+/K+ pumps, which are essential for proper functioning of cells, particularly neurons and muscle cells, by maintaining the electrochemical gradients of sodium and potassium ions across the cell membrane.

Step-by-step solution

Identifying the primary processes at rest

When your body is at rest, it still consumes calories to maintain vital functions, such as maintaining body temperature, regular heartbeat, and hormone synthesis. The given options are: a. protein synthesis; b. cell transport; c. Na+/K+ pumps; d. DNA replication.

Eliminating the incorrect options

Option (d), DNA replication, is not the correct answer since the process accounts for a smaller percentage of calories burned at rest, and it's highly dependent on cell cycle and repair activities. Option (a), protein synthesis and option (b), cell transport are significant energy-consuming processes, but they represent a smaller percentage of total calories consumed than the given value of 12%.

Choosing the correct answer

The correct answer is option (c), Na+/K+ pumps, which are responsible for maintaining the electrochemical gradients of sodium and potassium ions across the cell membrane. These pumps are essential for proper functioning of cells, particularly neurons and muscle cells. The function of Na+/K+ pumps is to pump 3 Na+ ions out of the cell and 2 K+ ions into the cell. The process is powered by ATP (adenosine triphosphate), which is a source of energy for cells. At rest, about 12% of total calories consumed are used to maintain the function of the Na+/K+ pumps.

Key concepts

Na+/K+ Pump

The sodium-potassium pump, often abbreviated as the Na+/K+ pump, is an essential part of cell physiology. It is a type of active transport mechanism found in the plasma membrane of cells. The pump maintains the gradient of sodium (Na+) and potassium (K+) ions, which is crucial for various cellular functions.

The Na+/K+ pump operates by moving 3 sodium ions out of the cell and 2 potassium ions into the cell using energy derived from ATP (adenosine triphosphate). This mechanism is vital to maintain the electrochemical gradient across the cell membrane, which is necessary for nerve impulse conduction and muscle contractions.

• The pump is an enzyme known as Na+/K+-ATPase.
• Plays a pivotal role in sustaining the resting potential of cells.
• Each cycle of the pump consumes one molecule of ATP, which ultimately contributes to the cell's overall energy consumption.

At rest, the Na+/K+ pump accounts for a significant portion of a cell's energy usage. This continuous operation is a key reason for the 12% of total caloric expenditure attributed to it when the body is not engaged in heavy activity.

Caloric Consumption at Rest

Even when we are at rest, our bodies are still hard at work. This restful state, often referred to as the Basal Metabolic Rate (BMR), involves energy use for vital bodily functions necessary for survival. Without doing anything more than keeping you alive, your body uses calories to maintain organ function, circulation, respiration, and temperature balance.

The Na+/K+ pumps, protein synthesis, and various cellular transport mechanisms are some of the key processes that consume energy even when we're sitting still.

• The Na+/K+ pumps alone account for about 12% of this resting energy expenditure.
• Energy is vital for processes like rebuilding and repairing cells, maintaining ion gradients, and providing fuel for vital organs like the heart and brain.
• These processes ensure that your body's homeostasis is maintained even when you are not performing any physical activity.

Understanding these energy demands helps appreciate why a restful state isn't devoid of bodily activity, and highlights the critical roles fulfilled by seemingly invisible cellular processes.

Electrochemical Gradients

Electrochemical gradients are the combined result of concentration differences and electrical charge across a membrane. They are fundamental in numerous biological processes and are primarily established by pumps like the Na+/K+ pump in cell physiology.

The gradient is essential for maintaining cellular potential, enabling action potentials in neurons, and driving the transport of substances such as glucose and amino acids into cells.

• The Na+/K+ pump creates a higher concentration of Na+ outside the cell and a higher concentration of K+ inside the cell.
• This difference in ions results in a voltage across the cell membrane known as the membrane potential.
• Electrochemical gradients are pivotal for nutrient uptake, waste removal, and signal transduction processes.

Without these crucial gradients, nerve impulses could not be transmitted, muscles could not contract properly, and cells would not communicate efficiently. Consequently, maintaining these gradients is a fundamental task the body performs even when at rest. These gradients showcase the intricate balance and coordination at the cellular and systemic level required for maintaining life.