Chapter 48-49: Neurons, Synapses, and Nervous Systems Flashcards
What are the two important parts of the neuron structure? What are their functions?
Dendrites - receiving antennas (receives messages)
Axon - transmitting antenna (transmits messages to next cell)
What is the synaptic terminal?
Where neurotransmitters go to the other cell
What is the resting potential?
The negative and positive difference between the inside and the outside of the cell
What is the membrane potential?
Has values
The membrane potential is negative under resting conditions and becomes positive during an action potential.
What is the action potential?
When the potential switches from increasing to decreasing
What pumps are responsible for the resting potential?
Na+ and K+ pumps and ion channels
What do the Na+ and K+ pumps do for the resting potential?
Create electrochemical gradients
They have gates
Is the inside of the cell positive or negative at rest?
Negative
What is the threshold?
When there is a change
When the membrane depolarizers and creates an action potential
When will an action potential be fired?
- direct stimulation
- receives neurotransmitters from another neuron
Action potentials _______ ATP.
Require
At the resting potential, there is a _____ [Na+] outside of the cell, and a _____ [K+] inside of the cell.
High, high
What are gated ion channels?
An ion channel protein with a gate. If there’s a voltage change the gate will open.
What is hyperpolarization?
When the membrane potential inside the cell becomes negative
What is depolarization?
When the cell becomes more positive
Explain the 5 stages of the action potential
Depolarization
1) Resting State:
- membrane potential is neg
- gates closed
2) Depolarization:
- a stimulus opens the Na+ channel
- mem. pot. becomes positive
3) Wave of Opening:
- open Na+ channel causes other Na+ channels to open
- more positive
Hyperpolarization
4) Na+ channels close
- threshold is met
- K+ channels open
- more negative
5) Undershoot
- K+ is still open
- refractory period (getting back to step 1)
- can be too hyperpolarized, too neg
______ insulates Axons.
Prevents charges from flowing in and out
Myelin
What is triggered when a signal comes down the Axon?
The Ca2+ channel opens and ca goes into the cell
How does the Ca2+ help the communication at the synapse?
It allows neurotransmitters to diffuse and attach to the ligand-gated channels
What happens when the neurotransmitter touches the channel protein across the synapse?
Gate opens
Are neurotransmitters hydrophobic or hydrophilic?
Hydrophilic
What are the two ways that a ligand-gates ion channel receives neurotransmitter signals?
1) Excitatory postsynaptic potentials (EPSP)
2) Inhibitory postsynaptic potentials (IPSP)
What does the Excitatory postsynaptic potential (EPSP) do?
Depolarize the membrane
(bringing it closer to the threshold)
- increase the voltage
Why does EPSP happen?
There was an influx of positively charged ions (Na+) into the cell.
