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
Which NT is used in for pain relief/addiction?
Opiods
Which NT is related to vasodilation?
Nitric Oxide
Glutamate/Aspartate are which type of amino acids?
Excitatory
Which ion do NMDA receptors allow in?
Ca2+
Which receptor is going to have excess activation after a seizure/stroke/TBI?
NMDA receptors
Which NTs are going to be involved in consciousness, seizure disorders, excitatory effects of stroke/seizures/etc…?
Excitatory Amino Acids
Which NT is released at the synapse between the preganglionic and postganlgionic fibers?
Acetycholine
Which NT is released at the synapse between the postganlgionic fibers and the effector organ in sympathetic/parasympathetic?
Sympathetic: Norepinephrine
Parasympathetic: Acetylcholine
Which structure mainly controls the ANS?
Hypothalamus
What is produced by the Choroid Plexus?
Cerebrospinal Fluid
True or False. CSF has low Mg, protein, glucose and K when compared to blood.
FALSE
HIGH Mg2+ (but everything else is right)
Tight junctions between capillary endothelial cells and podocytes from glial cells make up __________ .
Blood Brain Barrier
___________ is responsible for moving many drugs/other substances from CSF to the Blood.
P-glycoprotein
What is it called when you get an accumulation of CSF in the CNS?
Hydrocephalus
Which Glucose transporter is involved in maintenance of the Blood Brain Barrier and is also insulin-independent?
GLUT-1
Which transporter’s activation is tied to K+ levels?
Na/K/2Cl Transporter
Related cerebral blood flow to the activity of neurons.
Direct Relationship
More active neurons = more metabolites = more blood flow due to vasodilation
If systemic blood pressure goes too high, activation of ____________ receptors on cerebral vasculature causes vasoconstriction which will prevent the high blood pressure from damaging the capillaries involved in the Blood-Brain Barrier.
alpha-adrenergic (probably alpha 1)