1. November 7, 2016
Journal: What is the difference between dendrites and the axon terminal?

2. How Neurons and Synapses Work

3. Excitable Cells Neurons, glands, and muscle cells
Can carry an electrical charge when stimulated

4. Local Potential
A stimulus causes a response in a cell called a local potential aka graded potential
If its big enough it causes action potential

5. Occurs in response to an internal or external change
Action Potential
Occurs in response to an internal or external change
Series of permeability changes within the neuron that carry the electrical impulse down the axon
Impulse conduction

6. How Action Potential Works
When a cell is not excited it is said to be at rest
A resting cell is considered to be polarized
Meaning that there is a difference in charge across the cell membrane with more negative charges inside the cell

7. How Action Potential Works
When a neuron becomes stimulated, sodium ion channels open and let Na+ ions to travel into the neuron, making the cell more positive
This is called depolarization

8. How Action Potential Works
Then K+ leaves the cell through potassium ion channels
These positive charges leaving the cell begin to return the cell back to a resting state.
This is called repolarization.

9. How Action Potential Works
Hyperpolarization - cell becomes more negative then when at rest
Sodium-potassium pump works to restore equilibrium
Refractory Period – Cell is unable to accept another stimulus until it returns to rest

10. How Action Potential Moves Down the Axon
As the Na+ comes into one section of the axon, it triggers the sodium ion channels in the neighboring section to open
Continues in a domino effect

11. Myelin Sheath Speeds up Impulse Conduction
If a myelin sheath is present around the axon the impulse conduction will move faster

12. Axon Diameter Speeds up Impulse Conduction
The wider the axon diameter the faster the ions will flow because there is more room for the ions to flow
Action Potential Video:

13. November 7, 2016
Journal: Explain how an impulse is conducted down the axon of one neuron.

14. Chemical Synapses

15. Chemical Synapses
Step 1: Sodium arrives at the axon terminal

16. Chemical Synapses
Step 2: The terminal depolarizes and calcium enters through calcium ion channels

17. Chemical Synapses
Step 3: Neurotransmitters are released from vesicles via exocytosis and are released into the synapse

18. Chemical Synapses
Step 4: Neurotransmitters bind to the cell receiving signal and causes gates to open or close, either exciting or calming down the receiving cell

19. Chemical Synapses
Step 5: Neurotransmitter is taken away from the synapse by an inactivator, usually an enzyme, to stop the neurotransmitter from continuously binding to the receiving cell

20. Important Neurotransmitters
Acetylcholine: Controls skeletal muscles
Norepinephrine: Control visceral and cardiac muscle
Dopamine: Controls motivation and mood
Epinephrine: Adrenaline; Increased fight or flight response
Serotonin: Regulates mood and anxiety
Endorphins: Increase pleasure and decrease pain

21. Synapse Video