Multiple Choice
The vessels that exhibit the lowest level of permeability are the __________.
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2. Cell Chemistry & Cell Components
Biological Membranes
3:19 minutesProblem 5
Textbook Question
At resting membrane potential, the cytoplasmic side of the membrane surface of the cell is___, and the cell extracellular membrane surface is___.
(a) slightly negative; slightly positive
(b) slightly positive; slightly negative
(c) slightly positive; neutral
(d) slightly negative; neutral
Verified step by step guidance1
Understand that the resting membrane potential refers to the voltage difference across the cell membrane when the cell is at rest, meaning it is not actively sending signals.
Recall that the resting membrane potential is typically negative inside the cell relative to the outside, due to the distribution of ions such as potassium (K+) and sodium (Na+).
Recognize that the cytoplasmic side (inside) of the membrane is more negatively charged because of the higher concentration of negatively charged proteins and ions inside the cell.
Understand that the extracellular side (outside) of the membrane is relatively more positive compared to the inside, due to the higher concentration of positively charged ions like sodium (Na+).
Based on this, conclude that at resting membrane potential, the cytoplasmic side is slightly negative, and the extracellular side is slightly positive, which corresponds to option (a).
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3mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Resting Membrane Potential
The resting membrane potential is the voltage difference across a cell's plasma membrane when the cell is at rest. It typically ranges from -60 to -70 mV in many cells, indicating the inside of the cell is negatively charged relative to the outside. This potential is essential for processes like nerve impulse transmission and muscle contraction.
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Resting Membrane Potential
Ion Distribution and Membrane Permeability
The resting membrane potential arises mainly due to the unequal distribution of ions, especially potassium (K+), sodium (Na+), and chloride (Cl-), across the membrane. The membrane is more permeable to K+, allowing it to leak out, making the inside more negative compared to the outside, which remains relatively positive.
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Charge Separation Across the Membrane
At rest, the cytoplasmic side of the membrane is slightly negative due to trapped anions and ion gradients, while the extracellular side is slightly positive. This charge separation creates an electrical potential difference, crucial for cellular excitability and signaling.
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