Ch 1: Bio Basis Flashcards
(52 cards)
houses the neuron’s nucleus and other large organelles
soma
projections off the cell body which can connect to input from other nerves or other specialized sense organs
dendrites
single, long projection from the soma
structure through which neuron outputs its action potentials
axon
where a neuron integrates various input signals and decides whether to send a signal down the axon
axon hillock
insulating material around some axons to allow more rapid action potential conduction
myelin or myelin sheath
breaks in the myelin sheath dotted along a myelinated axon
nodes of Ranvier
where cell can synapse with another nerve cell, muscle, or gland
nerve terminal
highly specialized cell designed to integrate inputs and outputs in form of an action potential
neuron
phase in which a neuron remains, since no longer undergoing normal cell cycle
G0 resting phase (no longer dividing)
normal voltage potential inside a cell membrane relative to the area outside the plasma membrane?
negative voltage potential (relative to the outside)
Voltage for a nerve cell resting potential?
-70mV
how is resting potential maintained?
action of the Na+/K+ pump that pushes 3 Na+ out for every 2 K+ in to maintain electrochemical gradient
how is resting potential maintained?
action of the Na+/K+ pump that pushes 3 Na+ out for every 2 K+ in to maintain electrochemical gradient
threshold potential (voltage) to trigger an action potential?
-55mV
failed initiation
when signal fails to bring neuron up to threshold potential to trigger an action potential
Depolarization phase
Na+ voltage-gated channels open and Na+ rush into the cell. This continues until full depolarization happens at 40mV. Then the Na+ channels close and the K+ channels open to allow K+ out of the cell.
Repolarization
K+ ions rush out of the cell through the pumps that are now open, due to electrical potential and its own concentration gradient. Continues until the cell overshoots the -70mV level, becoming temporarily hyperpolarized.
Refractory period
When cell is hyperpolarized due to K+ ion movements. Cell cannot be depolarized again until Na+/K+ pumps re-establish resting state of the cell.
Where do action potentials begin and end?
axon hillock to the axon terminal in the synapse area
How does signal conduction work in unmyelinated axon?
Slow and smooth along cell membrane
Signal conduction in myelinated axon?
Rapid as potential jumps from one Node of Ranvier to the next down the axon. Only need to contribute 15mV to next Node to trigger in action potential there (-70 to -55mV).
How are neurotransmitters released from the axon terminal?
Ca2+ voltage-gated channels are triggered, allowing Ca2+ to rush into the axon terminal, triggering the cell to use exocytosis to push the NT’s out into the synaptic cleft.
How are NT’s cleared from the synaptic cleft?
1) Broken down by enzymes (eg, AChase for ACh)
2) Taken back up by axon for use later (can be blocked by stuff like SSRIs)
CNS and PNS are what?
CNS= Central Nervous System PNS= Peripheral Nervous System
