The Nervous System
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What is Action Potential?
Rapid change in voltage across cell membrane (neurons at axon of hilock)
What does polarize mean?
2 extreme differences +/- across a membrane
What is Resting Potential?
The neuron is polarized at -70mV, no electrochemical message being passed along neuron, although it is ready to fire
What is depolarization?
Lowering the difference in charge across the cell membrane
What does repolarize mean?
To re-establish electrochemical gradient across the membrane
What does hyper polarize mean?
An over-polarized cell
What is the refractory period?
The cell using active transport to get back to Resting Potential
What is a myelin sheath?
a lipid based layer around the axon of a nerve cell
What is the myelin sheath made up of?
Schwann Cells
What is the function of the myelin sheath?
To insulate and protect the axon, speeds up the rate of nerve impulse transmission
What is the Nodes of Ranvier?
Exposed areas of the axons of myelinated neurons, containing voltage gated sodium channels
What activity occurs at the Nodes of Ranvier?
Depolarization
What is saltatory conduction?
The nerve impulses “jumping” from each node, allowing for fast and energy efficient signal transmissions
What voltage does action potential take place at (triggered)
-50mV
What are the steps that happen during these impulses?
resting Potential (ready to respond -70mV), action potential (-50mV), massive depolarization (40mV-55mV), Closing of sodium gates, repolarizing, hyperpolarization, refractory period
What happens during massive depolarization?
Sodium gates open, sodium rapidly flows into neuron
What happens during repolarizing?
Potassium gates open, potassium flows into cell, causing hyperpolarization
What happens to the neuron during the refractory period?
Neuron cannot fire, no new impulse
True or False: action potential uses active transport
True
What are the two categories of the Nervous System?
Central Nervous system, peripheral nervous system
What makes up the central nervous system?
The brain and spinal cord
What makes up the peripheral nervous system?
The sensory pathway and motor pathway
What is the sensory pathway?
the five senses
What is the motor pathway?
movement