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Questions and Answers
Which mechanism involves the cell membrane engulfing substances to form a vesicle?
Which mechanism involves the cell membrane engulfing substances to form a vesicle?
What is the primary role of exocytosis in cellular function?
What is the primary role of exocytosis in cellular function?
Why is membrane potential significant for cell function?
Why is membrane potential significant for cell function?
What is the effect of increasing ion concentration outside a cell on its membrane potential?
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?
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?
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?
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?
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?
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?
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?
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?
What is the typical range of membrane potential in human cells?
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What is the main characteristic of an action potential?
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?
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?
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?
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?
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?
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?
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)?
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?
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?
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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