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Questions and Answers
Which mechanism involves the cell membrane engulfing substances to form a vesicle?
What is the primary role of exocytosis in cellular function?
Why is membrane potential significant for cell function?
What is the effect of increasing ion concentration outside a cell on its membrane potential?
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Cell polarization refers to which of the following states?
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What is the primary mechanism by which large molecules are transported into the cell?
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Which secretory pathway involves the direct release of substances from a cell?
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How is the membrane potential of a cell defined?
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What happens to the membrane potential when it becomes more positive than the resting potential?
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Which ion is primarily responsible for maintaining a negative resting membrane potential?
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If the membrane potential becomes more negative after resting potential, this change is called what?
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What is the typical range of membrane potential in human cells?
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What is the main characteristic of an action potential?
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During the upstroke phase of an action potential, which ion channels are primarily responsible for depolarization?
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What causes hyperpolarization during the repolarization phase of an action potential?
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What is the threshold voltage that must be reached to initiate an action potential?
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Which ion has a significantly higher concentration inside the cell compared to outside during resting membrane potential?
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What is the major intracellular anion mentioned in the physiology of action potentials?
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What occurs after the sodium channels become inactive during an action potential?
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Which of the following correctly describes the resting membrane potential (RMP)?
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What is the sequence of phases during an action potential?
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Which ion concentration outside the cell is higher than that inside the cell during resting membrane potential?
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Study Notes
Endocytosis
- The cell membrane engulfs substances to form a vesicle.
Exocytosis
- The primary role of exocytosis is to release substances from the cell.
Membrane Potential
- Membrane potential is the difference in electrical charge across the cell membrane.
- It is critical for nerve impulse transmission, muscle contraction, and other cellular functions.
Increasing Ion Concentration Outside a Cell
- Increasing ion concentration outside the cell makes the membrane potential more positive.
Cell Polarization
- Cell polarization refers to the difference in electrical charge between the inside and outside of the cell.
Transporting Large Molecules
- The primary mechanism for transporting large molecules into the cell is endocytosis.
Secretory Pathway: Direct Release
- This pathway involves the direct release of substances from the cell, bypassing the Golgi apparatus.
Defining Membrane Potential
- Membrane potential is defined as the difference in electrical charge between the inside and outside of the cell.
More Positive Membrane Potential
- When the membrane potential becomes more positive than the resting potential, it's called depolarization.
Negative Resting Membrane Potential
- The primary ion responsible for maintaining a negative resting membrane potential is potassium (K+).
Becoming More Negative
- When the membrane potential becomes more negative after resting potential, this change is called hyperpolarization.
Membrane Potential Range: Human Cells
- The typical range of membrane potential in human cells is -70 to -90 millivolts (mV).
Action Potential: Main Characteristic
- Action potentials are brief, rapid, and large changes in membrane potential.
Depolarization: Upstroke Phase
- Sodium (Na+) channels are primarily responsible for depolarization during the upstroke phase of an action potential.
Hyperpolarization: Repolarization Phase
- The inactivation of Na+ channels and the opening of potassium (K+) channels contribute to hyperpolarization during the repolarization phase.
Threshold Voltage
- The threshold voltage that must be reached to initiate an action potential is typically around -55 mV.
Higher Concentration Inside the Cell
- Potassium (K+) has a significantly higher concentration inside the cell compared to outside during resting membrane potential.
Major Intracellular Anion
- The major intracellular anion mentioned in the physiology of action potentials is chloride (Cl-).
Inactivation of Sodium Channels
- After sodium channels become inactive during an action potential, potassium channels open, allowing K+ to flow out of the cell and repolarize the membrane.
Resting Membrane Potential (RMP)
- The resting membrane potential is a stable, negative electrical charge across the cell membrane when the cell is at rest.
Phases of Action Potential
- The sequence of phases during an action potential is: resting potential, depolarization, repolarization, and hyperpolarization.
Higher Concentration Outside the Cell
- Sodium (Na+) concentration outside the cell is higher than that inside the cell during resting membrane potential.
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