Anatomy lab - Action Potential Flashcards
What allows for the action potential to occur?
Voltage-gated Na+ channels
What are the two voltaged-gated channels?
Na+ and K+
At resting potential, voltage-gated Na+ channels are what?
Closed
Conformational changes open voltage-gated channels when the membrane is what?
Depolarized
What happens during resting potential?
Both voltage gated Na+ and K+ channels are
closed
What is initial depolarization?
Some Na+ channels open and if so then the threshold is surpassed and an action potential is initiated.
What happens during the rising phase of action potential?
Na+ channels open quickly. K+ channels are still closed.
What happens during the falling phase of action potential?
Na+ channels self-inactivate, K+ channels are open.
Why does the membrane potential increase during depolarization of the action potential?
The voltage gated Na+ channels are open, but the voltage gated K+ channels have not opened yet.
Why does the membrane potential decrease during hyperpolarization of the action potential?
The voltage gated K+ channels open, the voltage gated Na+ channels close.
What does action potential jump from on the axon?
Node to node
What wraps around the axon?
Schwann cells
What does Schwann cells form?
myelin sheath
What is the term for the axon terminal?
Pre-synapse
What is the term for the middle terminal?
Synapse
What is the term for dendrite?
Post-synapse
What synapse would likely INCREASE firing the action potential?
Excitatory synapses
What synapse would likely DECREASE firing the action potential?
Inhibitory synapses
Excitatory postsynaptic
potential (EPSP)
Depolarization, Na+ influx
Inhibitory postsynaptic
potential (IPSP)
Hyperpolarization, K+
efflux, Cl– influx
EPSP + IPSP
Depolarization and
hyperpolarization
stimuli applied
Avg. mV for resting potential
-70
What are the 3 types of gates?
Closed, active, inactive
Avg. mV for threshold potential
-55
Avg. mV for action potential
+30
When neurons transmit electrical signals what can vary?
Frequency
In a neuron, what is the structure that separates ions?
Membrane
The intercellular environment of a neuron is more what?
Negative relative to the outside of the cell.
The extracellular environment is more what?
Positive relative to the inside of the cell.
Which ions are in the intracellular space of a neuron?
Potassium
Which ions are in the extracellular space outside a neuron?
Sodium
What are the 3 types of ion channels?
Voltage-gated channel, mechanically-gated channel, ligand-gated channel
How do you generate an action potential in a neuron?
To depolarize its resting neurons.
What is the ion responsible for depolarization of the neuron?
Sodium ions
What is the ion responsible for repolarization of the cell membrane?
Potassium
Nodes of Ranvier
The gaps in the myelin sheath of a neurons
Myelin sheath
The structure that affects the transmission speed of an action potential
What is the cell body?
The cells life support center
What is a dendrite?
Receive messages from other cells
What is the axon?
Passes messages away from the cell body to other neurons
What is a neural impulse?
Action potential; electrical signal traveling down the axon
What is the terminal branches of axon?
Form junctions with other cells
