Neurophysiology Review Flashcards
What is the general rule with size of neurons and their membrane potential?
The bigger they are, the more negative they are (i.e. Skeletal muscle and large neurons are -70 and -90 mV respectively)
What are the two ways that the membrane potential is maintained?
- Na/K ATPase
2. Selective permeability
Which two ions cannot pass the membrane at rest but do so through channels?
- Potassium (leak channels)
2. Chloride
Describe the phases of a fast action potential (include which gates are open/closed).
- Rapid depolarization (Voltage-gated Na Channels are open)
- Repolarization (Inactivation of Na Channels and opening of Voltage-Gated K Channels)
- @ Completion (Both Na and K Channels are closed)
- Activity of the Na/K ATPase returns concentration gradients
Describe the phases of a slow action potential (include which gates are open/closed).
- Depolarization (voltage-gated Ca Channels are open)
- Repolarization (K efflux and Ca channels are closing)
- @ Completion (both channels are closed)
- Na/K ATPase and Ca ATPase are required
Which refractory period cannot elicit an action potential?
Which gates are involved?
When does it occur?
Absolute Refractory Period
Voltage-Gated Na channels are open or inactive
Occurs during an on-going action potential
Which refractory period requires greater stimulation to produce an action potential?
Which gates are involved?
When does it occur?
Relative Refractory Period
At least some Voltage-gated Na channels are closed (others are in the inactive state-that’s why it is harder)
Occurs during repolarization and a bit after the on-going action potential has completed
What is the term when a neuron (or muscle cell) is forced to remain in a depolarized state for too long?
Describe how this works?
Voltage Inactivation (Depolarization Block)
In the inactive state, depolarization no longer opens the Na Channels
If the channel is open, the gradient for Na and/or K is abolished
What is the end result of Voltage Inactivation?
Depolarization block prevents the cell from releasing NT once the block has occured.
Essentially the cell is STUCK in the absolute refractory period!
What is the term used when an action potential jumps from node of Ranvier to node?
Saltatory Conduction
Which process is going to be decreased in patients with Multiple Sclerosis?
Saltatory Conduction
Explain how you increase your conduction velocity with Saltatory Conduction.
Myelin Sheath prevents the Na from leaving the cell!
Nodes have Voltage-Gated Channels and the rest of the axon does not have as many
What are Post-Synaptic densities?
Likely Neurotransmitter receptors on the post-synaptic terminal
Put these steps in order:
- Fusion of vesicle with cell membrane creates opening
- Depolarization of terminal by action potential causes the Voltage-Gated Ca channels to open.
- NT released in synaptic trough
- NT diffuses to post-synaptic cell and binds to its receptor.
- Ca binds to docking proteins
- Influx of Ca
- Docking proteins have vesicles associated with them and Ca will trigger a conformational change that will bring the vesicle to the plasma membrane
- NT must be removed from the synapse
2 - 6 - 5 - 7 - 1 - 3 - 4 - 8
Ca/Na can create a EPSP at the Post-Synaptic Membrane. Cl/K can create an IPSP at the post-synaptic membrane. What is the name of the receptor that they bind to?
Ionotropic
What are the names of the receptors that are located on the post-synaptic cell linked to GPCRs?
Metabotropic
Dopamine, Epinephrine and Norepinephrine all the same precursor named _________ .
Tyrosine
What is the precursor for histamine?
Histidine
What is the precursor for Serotonin?
Tryptamine
Which neurotransmitter is responsible for mood/affect?
Serotonin
Which neurotransmitter is responsible for Parkinson Disease/Mood/Affect/emotional experience?
Dopamine
Which neurotransmitter is responsible for awareness and memory/Alzheimer Disease?
Acetylcholine
Which neurotransmitter is inhibitory in nature and allows Cl into the cell? It is also used for general anesthesia and its activation is used to reduce spasticity.
GABA
Which neurotransmitter is inhibitory and stays in the spinal cord?
Glycine