Podcast
Questions and Answers
What primarily influences the movement of K+ ions out of the cell?
What primarily influences the movement of K+ ions out of the cell?
- Solubility of K+ ions
- Electrical gradient
- Sodium-Potassium pump activity
- Concentration gradient (correct)
What is the effect of a negative intracellular charge on K+ ions?
What is the effect of a negative intracellular charge on K+ ions?
- It repels K+ ions from entering the cell.
- It prevents any ion movement across the membrane.
- It has no effect on K+ ion movement.
- It attracts K+ ions back towards the intracellular space. (correct)
What condition describes the resting membrane potential (RMP) of a cell?
What condition describes the resting membrane potential (RMP) of a cell?
- Intracellular space is positive.
- Extracellular fluid is anionic.
- Sodium concentration is higher inside the cell.
- Intracellular space is negative. (correct)
Which of the following correctly describes the role of the sodium-potassium pump?
Which of the following correctly describes the role of the sodium-potassium pump?
What causes the unequal distribution of ions across the membrane?
What causes the unequal distribution of ions across the membrane?
What occurs at the equilibrium potential for ions?
What occurs at the equilibrium potential for ions?
Which factor can affect the movements of ions across the cellular membrane?
Which factor can affect the movements of ions across the cellular membrane?
Why do K+ ions tend to exit the cell according to the concentration gradient?
Why do K+ ions tend to exit the cell according to the concentration gradient?
What occurs immediately after the removal of the stimulating electrode from a resting cell?
What occurs immediately after the removal of the stimulating electrode from a resting cell?
During the depolarization phase of an action potential, what happens to the sodium ions?
During the depolarization phase of an action potential, what happens to the sodium ions?
What defines the firing level (FL) in relation to membrane potential?
What defines the firing level (FL) in relation to membrane potential?
What is the term for the period after the peak potential during which the inside of the cell becomes more negative than the resting membrane potential?
What is the term for the period after the peak potential during which the inside of the cell becomes more negative than the resting membrane potential?
What is the primary ion responsible for the repolarization phase of an action potential?
What is the primary ion responsible for the repolarization phase of an action potential?
How does the ion distribution inside and outside the cell change after the action potential?
How does the ion distribution inside and outside the cell change after the action potential?
What characterizes the overshoot portion of the action potential?
What characterizes the overshoot portion of the action potential?
What occurs during the propagation of an action potential?
What occurs during the propagation of an action potential?
What does orthodromic impulse refer to in nerve conduction?
What does orthodromic impulse refer to in nerve conduction?
Which of the following best describes an antidromic impulse?
Which of the following best describes an antidromic impulse?
What is the mechanism of nerve impulse conduction in unmyelinated neurons?
What is the mechanism of nerve impulse conduction in unmyelinated neurons?
Which of the following is NOT a characteristic of orthodromic impulses?
Which of the following is NOT a characteristic of orthodromic impulses?
What role do Na+ ions play in the mechanism of nerve impulse conduction?
What role do Na+ ions play in the mechanism of nerve impulse conduction?
Which statement accurately reflects the nature of electrotonic conduction?
Which statement accurately reflects the nature of electrotonic conduction?
In what scenario would an antidromic impulse be most likely to occur?
In what scenario would an antidromic impulse be most likely to occur?
Which best describes the conduction speed in unmyelinated neurons compared to myelinated ones?
Which best describes the conduction speed in unmyelinated neurons compared to myelinated ones?
What is required for a subthreshold stimulus to elicit an action potential?
What is required for a subthreshold stimulus to elicit an action potential?
During which period is a stimulus that previously failed to elicit a response likely to succeed?
During which period is a stimulus that previously failed to elicit a response likely to succeed?
Which of the following factors contributes to supernormality?
Which of the following factors contributes to supernormality?
What occurs during the late subnormal period following the supernormal period?
What occurs during the late subnormal period following the supernormal period?
What type of stimulus is classified as suprathreshold?
What type of stimulus is classified as suprathreshold?
How does the proximity of the membrane potential (Em) to threshold affect excitability during the supernormal period?
How does the proximity of the membrane potential (Em) to threshold affect excitability during the supernormal period?
What characterizes the subnormal period of excitability?
What characterizes the subnormal period of excitability?
What leads to the formation of compound action potentials?
What leads to the formation of compound action potentials?
What determines when the resting membrane potential will equal the equilibrium potential for a particular ion?
What determines when the resting membrane potential will equal the equilibrium potential for a particular ion?
What is the primary function of the sodium-potassium pump?
What is the primary function of the sodium-potassium pump?
Which of the following correctly describes how the resting membrane potential (RMP) is altered?
Which of the following correctly describes how the resting membrane potential (RMP) is altered?
What is the Nernst Equation used for?
What is the Nernst Equation used for?
What occurs when the threshold stimulus is applied?
What occurs when the threshold stimulus is applied?
How many sodium ions are exported for every ATP molecule used by the sodium-potassium pump?
How many sodium ions are exported for every ATP molecule used by the sodium-potassium pump?
Which method is used to measure resting membrane potential?
Which method is used to measure resting membrane potential?
What happens to potassium ions during the operation of the sodium-potassium pump?
What happens to potassium ions during the operation of the sodium-potassium pump?
What initiates the action potential in excitable membranes?
What initiates the action potential in excitable membranes?
During the depolarization phase, what happens to the inside of the cell membrane?
During the depolarization phase, what happens to the inside of the cell membrane?
What is the result when the sodium ion channels open during depolarization?
What is the result when the sodium ion channels open during depolarization?
What is hyperpolarization during the repolarization phase?
What is hyperpolarization during the repolarization phase?
What is the all-or-nothing principle in relation to action potentials?
What is the all-or-nothing principle in relation to action potentials?
What causes repolarization to occur following the peak of action potential?
What causes repolarization to occur following the peak of action potential?
What is the initial stage of depolarization?
What is the initial stage of depolarization?
What describes the phase of repolarization following the action potential?
What describes the phase of repolarization following the action potential?
Flashcards
High Selectivity
High Selectivity
The ability of a membrane to preferentially allow certain molecules to pass through, depending on their solubility (water or lipid soluble).
Concentration Gradient
Concentration Gradient
The difference in the concentration of a substance between two sides of a membrane. Higher concentration to lower concentration.
Electrical Gradient
Electrical Gradient
The difference in electrical charge between two sides of a membrane. Opposite charges attract.
Membrane Potential
Membrane Potential
Signup and view all the flashcards
Resting Membrane Potential
Resting Membrane Potential
Signup and view all the flashcards
Equilibrium Potential
Equilibrium Potential
Signup and view all the flashcards
Active Transport
Active Transport
Signup and view all the flashcards
Sodium-Potassium Pump
Sodium-Potassium Pump
Signup and view all the flashcards
Resting Membrane Potential (RMP)
Resting Membrane Potential (RMP)
Signup and view all the flashcards
Equilibrium Potential
Equilibrium Potential
Signup and view all the flashcards
Nernst Equation
Nernst Equation
Signup and view all the flashcards
Sodium-Potassium Pump (Na+/K+ ATPase)
Sodium-Potassium Pump (Na+/K+ ATPase)
Signup and view all the flashcards
Action Potential
Action Potential
Signup and view all the flashcards
Threshold Stimulus
Threshold Stimulus
Signup and view all the flashcards
Intracellular Recording
Intracellular Recording
Signup and view all the flashcards
Membrane Permeability
Membrane Permeability
Signup and view all the flashcards
Action Potential
Action Potential
Signup and view all the flashcards
Depolarization
Depolarization
Signup and view all the flashcards
Repolarization
Repolarization
Signup and view all the flashcards
Threshold
Threshold
Signup and view all the flashcards
All-or-None Principle
All-or-None Principle
Signup and view all the flashcards
Electrical recording
Electrical recording
Signup and view all the flashcards
Extracellular recording
Extracellular recording
Signup and view all the flashcards
Intracellular recording
Intracellular recording
Signup and view all the flashcards
Resting Membrane Potential (RMP)
Resting Membrane Potential (RMP)
Signup and view all the flashcards
Action Potential (AP)
Action Potential (AP)
Signup and view all the flashcards
Depolarization Phase
Depolarization Phase
Signup and view all the flashcards
Repolarization
Repolarization
Signup and view all the flashcards
Hyperpolarization
Hyperpolarization
Signup and view all the flashcards
After Potential (AP)
After Potential (AP)
Signup and view all the flashcards
Ion Channels
Ion Channels
Signup and view all the flashcards
Propagation of AP
Propagation of AP
Signup and view all the flashcards
Orthodromic Impulse
Orthodromic Impulse
Signup and view all the flashcards
Antidromic Impulse
Antidromic Impulse
Signup and view all the flashcards
Electrotonic conduction
Electrotonic conduction
Signup and view all the flashcards
Impulses in unmyelinated neurons
Impulses in unmyelinated neurons
Signup and view all the flashcards
Mechanism of nerve impulse conduction
Mechanism of nerve impulse conduction
Signup and view all the flashcards
Wave of action potentials
Wave of action potentials
Signup and view all the flashcards
Anterograde
Anterograde
Signup and view all the flashcards
Retrograde
Retrograde
Signup and view all the flashcards
Subthreshold Stimuli
Subthreshold Stimuli
Signup and view all the flashcards
Threshold Stimuli
Threshold Stimuli
Signup and view all the flashcards
Suprathreshold Stimuli
Suprathreshold Stimuli
Signup and view all the flashcards
Supernormal Period
Supernormal Period
Signup and view all the flashcards
Subnormal Period
Subnormal Period
Signup and view all the flashcards
Compound Action Potential
Compound Action Potential
Signup and view all the flashcards
Supernormal Period Factors
Supernormal Period Factors
Signup and view all the flashcards
Late Subnormal Period
Late Subnormal Period
Signup and view all the flashcards
Study Notes
Exitable Tissues
- Complex animals have four primary tissue types: epithelial, connective, muscle, and nervous.
- Nerve and muscle tissues respond to stimuli (chemical, electrical, mechanical) and generate transmittable signals (action potential), classifying them as excitable tissues.
- Cells have intracellular and extracellular compartments separated by the cell plasma membrane.
- The cell membrane is semi-permeable, regulating the passage of molecules.
- Factors affecting movement across membranes include electrical charge, molar mass, and polarity.
- Ions (e.g., K+, Na+, Cl-) require specific channels for movement due to membrane structure.
Factors Mediating Ion Movement
- Concentration gradient: drives ions from high to low concentration.
- Electrical gradient: attracts opposite charges and repels like charges.
- Active transport: requires energy to move ions against their gradient (e.g., sodium-potassium pump).
- K+ ions, due to their concentration gradient, tend to exit the cell, but the electrical gradient also attracts them back. The equilibrium between these opposing forces determines the equilibrium potential (EK) for K+.
Membrane Potential
- Membrane potential (Vm): difference in electrical potential across the cell membrane.
- Resting membrane potential (RMP): the electrical potential difference across the membrane when the cell is at rest (typically around -70mV).
- Equilibrium potential: the membrane potential at which the net movement of an ion is zero. This occurs when the concentration gradient's drive to move ions is balanced by the electrical gradient's opposing force.
Action Potential
- Action potential: a rapid, transient change in membrane potential.
- Depolarization: membrane becomes more positive (inside becomes more positive).
- Repolarization: the membrane restores its negative potential.
- Voltage-gated channels play a critical role in generating and transmitting action potentials. These channels open and close in response to changes in membrane potential.
- Threshold stimulus: the minimum stimulus needed to trigger an action potential.
- All-or-none response: an action potential either occurs completely or not at all; the size and shape are consistent.
- Refractory period: after the action potential occurs, the cell is temporarily unable to respond to another stimulus.
Propagation of Action Potentials
- Propagation of action potentials: action potentials spread along the nerve or muscle fiber.
- Orthodromic: the action potential travels in the normal direction of the impulse.
- Antidromic: the action potential travels in the opposite direction of the impulse.
- Electrotonic conduction: local current flow in unmyelinated axons.
- Saltatory conduction: action potentials "jump" between nodes of Ranvier in myelinated axons, resulting in faster conduction.
- Myelin: fatty substance surrounding the axon in myelinated fibers, increasing the speed of impulse transmission.
- Nodes of Ranvier: gaps in the myelin sheath where action potential generation occurs.
Refractory Period
- Absolute refractory period: cell cannot respond to any stimulus, because Na+ channels are inactivated.
- Relative refractory period: cell can respond to a very strong stimulus, because K+ channels are open.
- Supernormal period: a period after absolute refractory period where the threshold for a stimulus is reduced (i.e. excitability is increased).
- Subnormal period: a period after supernormal period where the threshold for a stimulus is increased (excitability is decreased).
Compound Action Potential
- Compound action potential (CAP): the combined action potentials of multiple nerve fibers.
- CAP is affected by factors including stimulation intensity, temperature, blood supply, oxygen supply, and presence of pressure.
Nerve Cells (Neuron)
- Neurons: primary structural and functional units of nerve tissue.
- Parts of a neuron include dendrites, cell body, axon, axon terminals and the synapse.
- Dendrites: receive signals from other neurons.
- Cell body: contains the nucleus and other organelles.
- Axon: transmits signals away from the cell body.
- Axon terminals: transmit signals to other neurons or target cells.
- Myelinated versus unmyelinated: based on presence of myelin sheath.
- Types of nerves (A, B, C): differentiated by size and speed of transmission.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.