Ch 45: Nervous System Flashcards
Neurons
Excitable cells
Cells that communicate with each other and other cells in the body through electrical and chemical signals
Functional cells of the nervous system
Initiate, receive, and process electrical activities
Electricity
Movement of electrons
In the body - the movement of ions across the plasma membrane
Soma
Area of the cell that directs all of the neuronal activities
Control part of the cell
Holds the nucleus
Dendrites
Extensions from the cell body
Receptive sites for electrical signals
Allow neurons to have multiple connections
Increase surface area for interaction
Axon hillock
Single major branch that connects the soma with the axon
Initiates the action potential
Axon
Part of the neuron that transmits the electrical signal away from the cell body
Conducts signal away from the soma
Nerve fibers
Axon terminals
Site where neurotransmitters are located
Vesicles of neurotransmitters bing to the membrane and are released
Schwann cells
Cells that produce myelin sheaths that insulate the axon
Nodes of Ranvier
Gaps in myelin sheaths along the axon
Hold a lot of sodium and potassium channels
No myelin
There is a jump from node to node
Myelin
Lipid insulator
Contains electrical activity
Afferent neurons
Neurons that send into of the CNS
Interneurons
Neurons that connect neurons within the CNS
Efferent neurons
Neurons that send information from the CNS
Motor neurons
Synapse
Where two neurons form a junction
Pre synaptic neuron meets a post synaptic neuron
Action potential
Ionic movement
Ability for ions to move across the membrane
Threshold
The all or nothing action potential point
When 600x more VGSC open
Depolarization
When membrane potential is less negative than resting potential
Hyperpolarization
When membrane potential is more negative than resting potential
Repolarization
When membrane potential returns to its resting potential - either from depolarization or hyperpolarization
Voltage gated sodium channels
Protein channel that is specific to sodium
Triggered to open at threshold
Has three states: closed, open, and inactivated
Voltage gated potassium channels
A protein channel that is specific to potassium
Triggered to open at the peak
Has two states: closed and open
Does not open when sodium channels are open
Refractory period
Amount of time that VGSC are inactivated
Everything after peak and before next action potential
Oligodendrocytes
Cells that make myelin in the CNS
Can mylenate multiple cells at once
Cell body
Perikaryon
Abundant protein synthesis organelle
