1. What is the part of the neuron that receives signals? Sends them?
Daily Warm-up March 6th
What is the part of the neuron that receives signals? Sends them?
HW:
-Read 37.3
Turn in:
-Nothing

2. Ions & Resting Potential
Cell is negatively charged compared to surroundings
Difference is potential energy in form of voltage
Membrane potential= resting potential when neuron is at rest
Stimuli can change membrane potential

3. Formation of Resting Potential
Potassium ions (higher in the cell)
Sodium ions (higher outside)
1. Sodium-potassium pump
Active transport
Transport Na+ out of cell and K+ into cell
Three Na+ for two K+
But only a few millivolts!!! So where is the charge coming from?
2. Ion channels

4. What about the Ion Channels?
Gradient favors outflow of K+
Very few open sodium channels when at rest
K+ outflow causes negative charge

5. When there is a stimulus…membrane potential changes
Action potential
Changes occur because of gated ion channels
Open or close in response to stimuli
Hyperpolarization
Cell becomes more negative
Depolarization
Cell becomes less negative

6. Two Types of Potential Change
Graded Potential- strength depends on stimulus
Action Potential- all or nothing
-Constant magnitude
-Regenerate along neuron membrane
-Spread along axons
-Signaling

7. Action Potential Voltage-gated ion channels
Open or close when membrane potential reaches threshold
Depolarization of voltage-gated sodium channel?
Positive feedback
Potassium channel will open at end to return neuron to resting state

9. Movement of the Signal
Once area rises above threshold have signal moving

10. Saltatory Conduction

11. Neuron-Neuron Communication
Some can be electrical signals, but most are chemical
Neurotransmitters
Communication occurs at a synapse