Physiology of Nerve & Muscle 2 Flashcards
(21 cards)
What drives the membrane potential?
The membrane potential is driven by both electrical and chemical gradients
Electrical potential is charge-dependent, while chemical potential is concentration-dependent.
What is the Nernst equation used for?
The Nernst equation calculates the equilibrium potential for a given ion
It indicates the potential difference where there is no net movement of that ion across the membrane.
What does a larger concentration difference lead to in terms of voltage?
A larger concentration difference leads to a larger voltage (Eion)
This is because the concentration difference provides the driving force for ion movement.
What is the Goldman-Hodgkin-Katz equation used for?
It calculates the resting membrane potential (RMP)
It accounts for the concentration gradients and permeability of main ions.
What are passive (local, graded) potentials?
Local changes in membrane potential caused by opening/closing of ion channels in response to external events
They occur at sensory receptors and synapses.
What is the primary function of graded potentials in the nervous system?
All information processing in the nervous system is based on graded potentials.
What happens to graded potentials with distance from the stimulus site?
They decay with distance due to outward leak of positive charges.
What triggers the generation of an action potential?
The action potential is generated at the axon hillock when the membrane depolarizes to threshold.
What is the all-or-nothing response in action potentials?
Once the threshold is reached, the action potential will occur fully or not at all.
What role do voltage-gated Na+ channels play in action potentials?
They open rapidly during depolarization, allowing Na+ to flow into the cell.
What occurs during the repolarization phase of an action potential?
Voltage-gated K+ channels open, causing K+ to flow out and the membrane potential to return to resting levels.
What is the absolute refractory period?
A period during which no new action potential can be generated, regardless of stimulus strength.
What is the relative refractory period?
A period during which a stronger-than-normal stimulus is needed to generate an action potential.
Fill in the blank: The equilibrium potential for Na+ (ENa) is _____ mV.
+ 61 mV
Fill in the blank: The equilibrium potential for K+ (EK) is _____ mV.
- 97 mV
What can changes in extracellular K+ concentrations lead to?
Changes in RMP, affecting excitability and potentially causing paralysis or cardiac arrhythmia.
What is tetrodotoxin (TTX) and its effect on action potentials?
TTX blocks voltage-gated Na+ channels, preventing action potentials from occurring.
What is the significance of local anesthetics like lidocaine?
They block voltage-gated Na+ channels, inhibiting action potentials, particularly in pain fibers.
What happens during afterhyperpolarization (AHP)?
K+ channels remain open longer, making it harder to evoke another action potential.
What is the role of ion pumps in membrane potentials?
Ion pumps maintain electrochemical gradients, while ion channels determine resting potential.
What is the importance of graded potentials in terms of spatial and temporal summation?
They allow integration of inputs over time and space, crucial for processing information.
