The Nervous System
Nervous System Network of connected cells, tissue, and organs Controls thoughts, movement, life processes Quick responses Ex: Sunny day pupils shrinking
CNS and PNS
Neurons AKA: Nerve Cells Transfer electrical impulses to/from the brain 3 Main Parts Cell body: contains nucleus and organelles Dendrites: branches that receive messages from neighboring cells Axon: extension that carries messages away from the cell body
Resting Potential Defined: Neuron at rest Neuron Exterior: Positive charge Mainly Na+ outside the cell Neuron Interior: Negative charge (from various proteins) K+ inside the cell
Action Potential Defined: Electrical impulse is triggered Front end of impulse Channels open and allow Na+ to enter the cell Negative impulse attracted towards positive Na+ Back end of impulse Channels open to allow K+ to exit the cell Interior returns to normal Impulse pulled along by the changing of electrical charges
impulse
Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ negative impulse K+ K+ K+ K+ K+ K+ K+ Na+ K+ Na+ K+ K+ K+ K+ K+ K+ Na+ K+ K+ K+ Na+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+
Synapse Defined: Gap between neurons Problem: Impulse cannot cross the gap Solution: Impulse converted into chemical molecules (neurotransmitters) Steps: Impulse reaches neuron’s end Vesicle releases neurotransmitters Neurotransmitters attach to neighboring neuron New impulse created
Impulse stimulates a vesicle, which contains neurotransmitters Vesicle exits the cell and dissolves impulse Start of another cell End of one cell
Neurotransmitters stimulate a new impulse cross the synapse and attach to receptors of a neighboring neuron impulse impulse Start of another cell End of one cell
Brain …. …. …. …. Feet
Motor neurons reach the muscles… and causes MOVEMENT!
Kobe Kuiz What is the function of the nervous system? List the 3 main parts and describe the purpose of the 3 main parts of a neuron. Describe the internal and external environment of a neuron in resting potential. What is a synapse and why is it a problem for neurons? What are the roles of the following during an action potential? NA+ K+ Neurotransmitters