Neurology Flashcards
Permanent Nerve Cell
Neuron
Non-permanent Nerve Cell
Neuroglia/Glial Cells/Supporting Cells
More numerous: Neurons or Glial Cells?
Glial Cells (10:1 ratio)
Produces CSF
Ependymal Cells
Macrophage of the Brain
Microglia
Regulate ECF ion levels; Provide mechanical support; Part of BBB
Astrocyte
Creates myelin in the CNS
Oligodendrocytes
Creates myelin in the PNS
Schwann Cells
Brain tumors from non-mature neurons
NeuroblastomaRetinoblastoma
Receiving portion of the Neuron
Dendrites, Cell Body
Where Action Potential is initiated
Axon Hillock
Function of Myelin Sheath
Insulator
Unmyelinated portions of the axon
Nodes of Ranvier
Branches of the Axons
Neural Fibrils
Terminal portion of a neural fibril that contains NT-containing vesicles
Axon Terminal (Boutons/End Feet)
Space between two Neurons
Synapse
Soma to Axon Terminal; Replenishes synaptic vesicles and enzymes for NT synthesis
Anterograde Axonal Transport
Axon Terminal to Soma; Recycles synaptic vesicle membrane for lysosomal degradation
Retrograde Axonal Transport
Protein responsible for Anterograde Axonal Transport
Kinesin
Protein responsible for Retrograde Axonal Transport
Dynein
Diseases utilizing Retrograde Axonal Transport
TetanusBotulism
Death of the Axon distal to the site of injury after an axon is transected
Anterograde/Orthograde Degeneration
Changes to the soma after an axon is transected
Axonal Reaction/Chromatolysis
Axonal regeneration occurs better in the CNS or PNS?
PNS
Secreted by: Nucleus Basalis of Meynert (Basal Ganglia); Synthesis: uses Acetyl CoA and Choline with enzyme: Choline Acetyltransferase; Degradation: produces Acetate and Choline with enzyme: Acetylcholinesterase (Choline is recycled)
Acetylcholine
Found mainly in the Substantia Nigra Pars Compacta & Ventral Tegmental Area; Removed via reuptake by MAO (in pre-synaptic nerve terminals), COMT (in tissues including liver)
Dopamine
Dopamine deficiency
Parkinson’s Disease
Dopamine excess
Schizophrenia
Secreted by Locus Ceruleus in the pons & post-ganglionic neurons of sympathetic nervous system; Control overall activity and mood of the mind, such as increasing the level of wakefulness; Maybe excitatory or inhibitory
NorepinephrineEpinephrine
Phenylalanine derivatives
PhenylalanineTyrosineL-DopaDopamineNorepinephrineEpinephrineThyroxineMelanin
Secreted mainly by the Median Raphe of the Brain Stem; Inhibitor of Pain Pathways in the Spinal Cord; “Happy Hormones”; From Tryptophan (W); Converted to Melatonin
Serotonin
Secreted in areas of brain responsible for Long-term behavior and Memory; From Arginine; Short-actin neurotransmitter; Not preformed and stored in vesicles
Nitric Oxide
From Histidine; Located mainly within the tuberomammillary nucleus of the Hypothalamus
Histamine
Inhibitory neurotransmitter usually found in spinal interneurons; Increases Chloride influx
Glycine
The number #1 Inhibitory Neurotransmitter in the Brain; Comes from Glutamate; Increases Chloride Influx (GABA-A) or Potassium Efflux (GABA-B)
GABA (Gamma Amino Butyric Acid)
The number #1 Excitatory Neurotransmitter in the Brain
Glutamate
Inhibit neurons in the brain involved in the perception of pain; Enkephalins, Endorphins, Dynorphins
Opioid Peptides
Involved in pain transmission; In specific areas of the brain, primary sensory neurons, GI plexus neurons
Substance P
Neurotransmitter deficient in Alzheimer’s Disease
Acetylcholine
-70mV; Potential difference that exist across the membrane; Exhibited by almost all cells; Refers to Intracellular Charge
Resting Membrane Potential (RMP)
Exhibited by Excitable Cells only (Neurons & Muscle Cells); Stereotypical size and shape; Propagating - non-decremental manner; “All-or-none”
Action Potential
Basis for Resting Membrane Potential (RMP) & Action Potential (AP)
Ion Channels
Making the membrane potential less negative
Depolarization
Making the membrane potential more negative
Hyperpolarization
Positive charges flowing into the cell
Inward current
Positive charges flowing out of the cell
Outward current
Membrane potential in which occurrence of Action Potential is inevitable
Threshold
Portion of the Action Potential where membrane potential is positive
Overshoot
Portion of the Action Potential where membrane potential is more negative than Resting Membrane Potential
Undershoot/Hyperpolarizing afterpotential
Period in which Action Potential cannot be elicited
Refractory Period
Nernst Potential for Na and K diffusion
+61mV and -94mV
Na-K Leak Channels
100x more permeable to K
Na-K-ATPase Pump
-4mV
Opening of Na-Activation gates
Sodium Influx (Depolarization)
Closure of Na-Inactivation gates and Opening of Potassium gates
stop Sodium Influx and Potassium Efflux (Repolarization)
Na-Activation Gates Closed; Na-Inactivation Gates Open; K Gates Closed
Resting state
Na-Activation Gates Open (Some); Na-Inactivation Gates Open; K Gates Closed
Depolarization
Na-Activation Gates Open (All); Na-Inactivation Gates Open; K Gates Closed
Rising phase of Action Potential
Na-Activation Gates Open; Na-Inactivation Gates Closed; K Gates Open
Falling phase of Action Potential
Na-Activation Gates Closed; Na-Inactivation Gates Closed; K Gates Open
Undershoot
Sodium Channel Blockers of Neurons
Tetradotoxin, Saxitoxin
Potassium Channel Blocker of Neurons
Tetraethylammonium
True or False: Na2+ and K+ gated channels are responsible for all types of Action Potential
False (eg: Ca2+ channels seen in muscles)
Stimulates nerve depolarization in the first place
Mechanical disturbance, Chemical, Electricity
Time periods after an Action Potential, during which a new stimulus cannot be readily elicited
Refractory Periods
Another Action Potential cannot be elicited, no matter how large the stimulus; Coincides with almost the entire duration of the action potential
Absolute Refractory Period
No Action Potential can occur until the Inactivation Gates open
Ionic Basis of Absolute Refractory Period
Action Potential can be elicited only if a larger than usual inward current is provided
Relative Refractory Period