Electrical Activity of Neurons Flashcards
What is the average charge inside a neuron?
Roughly -70 mV
What ion is primarily found inside the neuron?
K+
What leaky channels are “more leaky”?
The K+ outflow channels are more leaky than the Na+ inflow channels.
What are gated channels? What are the two types of them?
Gated channels are channels that require a signal to open or close. They can be electrically gated or chemically gated.
What are the two types of potential?
Action potential and graded potential.
What happens to overall charge of a neuron when it depolarizes?
The charge goes up.
What does decremental movement of an ion mean?
It means the charge lessens the farther it gets from the graded potential site.
In which direction does a graded potential travel?
In all directions away from the site of the graded potential.
What are the two types of graded potential? Describe both.
Generator-receptor potentials are a response to an external stimulus where a separate receptor cell will send a chemical messenger to open channels, and postsynaptic potentials happen in the secondary and tertiary neurons and are the result of a chemical transmission in the synapse.
What is the average amplitude of an action potential? What does this make the neuron’s most positive charge?
The average amplitude is plus 100mV so the neuron cytoplasm in the area goes from -70mV to 30mV.
Where do action potentials happen?
In the axons of cells.
What kind of channels are found in axons?
Voltage gated channels.
What are the three channel changes in an action potential?
Increase in Na+ permeability, restoration of Na+ impermeability, increase in K+ permeability
What is the threshold (of excitation)?
-50 to -55 mV
What is associated with the turning point of an action potential?
The activation of the inactivation gate of the Na+ channel.
Why would a cell hyperpolarize?
K+ pumps are slow to close.
What is the absolute refractory period?
It is a period where neurons are incapable of firing after a spike. The Na+ gates are already open.
What is the relative refractory period?
It is the period during/slightly before hyperpolarization. Na gates are closed but K gates are still open. A very strong stimulus could still fire an AP.
Why is an action potential said to propagate not conduct?
It is being recreated at different intervals. Not spread.
What are the gaps in the myelin sheathe called?
The Nodes of Ranvier
What keeps APs unidirectional?
The area behind the AP is hyperpolarized and therefore less likely to fire than the area in front of it.
What mathematically describes the threshold (of excitation?)
K+ outflow = Na+ inflow. The next ion decides whether the axon hillock will fire or not.
What two cell types are responsible for myelin sheathes?
Schwann’s cells in the PNS and oligodendrocytes in the CNS.
What is the composition of myelin sheathes?
They are fatty and lipid rich.
Define synapse
A junction between two neurons or a neuron and an effector.
What synapses are associated with smooth muscle and gap junctions? Why?
Electrical synapses, they can be synchronized
What is the other type of synapse?
Chemical synapse.
How many NT molecules will be released per axon terminal?
Approximately 300
What are the three ways a neurotransmitter will be terminated?
Degradation, reuptake, or diffusion
Why is there a synaptic delay?
Synaptic communication is the slowest step of the neurotransmission.
PSP stands for
Post synaptic potential
What are the two types of PSP summation?
Temporal/Spatial. Temporal happens close in time at the same place, and spatial happens at the exact same time in different places.
Where on the neuron are the most effective synapses?
Closest to the axon hillock.
What are the two types of NT classification?
Chemical and Functional
What are two types of neural circuit processing? Describe them.
Serial circuit processing and parallel processing. Serial is reflexes and immediate responses, and parallel processing involves thinking and interpretation.
What are the 4 types of circuits?
Diverging, converging, reverberating, parallel after discharge current
