31 Questions
What type of cells help with regulating synapses but do not send signals themselves?
Astrocytes
Which cells are responsible for the production and movement of cerebrospinal fluid (CSF)?
Ependymal cells
What is the main function of Oligodendrocytes in the nervous system?
Myelination of axons
Which type of cells act as 'brain macrophages' to protect the brain from pathogens?
Microglia
In neurons, which ions have a high concentration outside the membrane at rest?
Sodium and Potassium
What is the primary driving force for ions across the neuronal membrane?
Both concentration and electrical gradients
Which type of channels are always open and responsible for passive movement of ions in neurons?
'Leak channels'
Which type of ion channels in neurons are triggered by a change in membrane potential?
'Voltage-gated channels'
How many states do sodium voltage-gated ion channels have compared to potassium voltage-gated ion channels?
Sodium has 3 states, potassium has 2 states
What is the threshold value that has to be reached to trigger an action potential?
-50mV
Which type of ion enters the cell, making the membrane more positive during depolarization?
Na+
What happens to potassium (K+) channels during the repolarization stage?
They close rapidly
What causes 'overshoot' during an action potential?
Slow closure of Na+ channels
Which event triggers the opening of potassium (K+) channels during an action potential?
Voltage event
When are sodium channels completely inactivated during an action potential?
From threshold until resting potential
What contributes to making the membrane more negative than usual during hyperpolarization?
Slow closure of K+ channels
How is the resting membrane potential restored following an action potential?
By K+ leak and the sodium-potassium pump
What contributes to contiguous conduction during an action potential?
Presence of myelin sheath
Describe the difference in the number of gates between sodium voltage-gated ion channels and potassium voltage-gated ion channels.
Sodium channels have 2 gates (activation and inactivation gates), while potassium channels have 1 gate (activation gate).
What is the significance of reaching the threshold value of -50mV in triggering an action potential?
The threshold value of -50mV must be reached to initiate an action potential.
Explain the role of potassium channels during the repolarization stage of an action potential.
Potassium channels open during repolarization to allow K+ to leave the cell, restoring the net negative membrane potential.
What causes the 'overshoot' phenomenon during an action potential?
The delayed closing of K+ channels causes the membrane potential to go more negative than usual, leading to hyperpolarization.
Describe the process of resetting sodium channels after an action potential.
After an action potential, sodium channels quickly close and inactivate, resetting to prepare for the next action potential.
Sodium voltage-gated ion channels have both activation and inactivation gates.
True
Potassium voltage-gated ion channels have two gates - activation and inactivation gates.
False
During depolarization, potassium ions enter the cell, making the membrane more positive.
False
The threshold value required to trigger an action potential is +50mV.
False
During hyperpolarization, the membrane potential becomes less negative than usual.
False
2 forms of refractory periods?
Absolute and relative
what effects the speed of propagation?
axon diameter and myelination
in relative refractory period, AP is possible with larger stimuli
True
Learn about the various types of cells in the nervous system and their functions, including Glial cells such as Astrocytes, Ependymal cells, Oligodendrocytes, and Microglia. Understand how these cells contribute to the overall functioning of the nervous system.
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