How Neurons and Synapses Work

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

Local Potential When a stimulus causes a change in the body If its big enough it causes an action potential

Caused by different ions entering and exiting the cell Action Potential Series of permeability changes within the neuron that carry the electrical impulse down the axon Caused by different ions entering and exiting the cell Na+ moves in, while K+ moves out

Things that Speed up Impulse Conduction Myelin Sheath: Causes less ion channels to have to open and close in order to move the signal down the axon Wider Axon: Allows for ions to flow quicker through the axon https://www.youtube.com/watch?v=5V7RZwDpmXE

Refractory Period A period of time following stimulation in which a nerve cannot send another signal

Chemical Synapses Once the action potential reaches the axon terminal neurotransmitters are released from vesicles via exocytosis and are released into the synapse

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

Chemical Synapses Neurotransmitter is taken away from the synapse by an enzyme, to stop the neurotransmitter from continuously binding to the receiving cell

Important Neurotransmitters Acetylcholine: Controls skeletal muscles Norepinephrine: Control smooth 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

Synapse Video https://www.youtube.com/watch?v=WhowH0kb7n0