Flashcards in Chapter 48-49: Neurons, Synapses, and Nervous Systems Deck (38)
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?
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?
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.
At the resting potential, there is a _____ [Na+] outside of the cell, and a _____ [K+] inside of the cell.
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
1) Resting State:
- membrane potential is neg
- gates closed
- 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
4) Na+ channels close
- threshold is met
- K+ channels open
- more negative
- 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)
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?
Are neurotransmitters hydrophobic or 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.
What does the Inhibitory postsynaptic potential (IPSP) do?
Hyperpolarize the membrane
(bringing it further from the threshold)
- decrease the voltage
Why does IPSP happen?
K+ ions went out of the cell.
What happens when the gate of an ion channel opens?
The ions move in and the cell becomes more positive.
What are some properties of neurotransmitter?
- diffuse fast
Explain the two ways that neurotransmitter signaling can be terminated.
1) Enzymatic breakdown
- inactivating enzymes cut up the neurotransmitter and destroy them
- there is a neurotransmitter transport channel at the bottom of the Axon that transports neurotransmitters back into a vesicle within the Axon in order to be reused