Nervous System Flashcards
Why myelin sheath?
To prevent signal loss and to speed up signals
Name of cell body in nervous system
Soma
What produces myelin?
Oligodendrocytes in the central nervous system and Schwann cells in the periphery
Resting membrane potential
-70, the inside is more negative
Which ion is in a high concentration inside the neuron
[K+]
What restores the potential after action potential
Na+, K+ ATPase
What is the ratio of Na K movement when restoring gradient
Three Na+ out for every 2 K+ in
Inhibitory inputs cause
Hyper polarization because it makes the cell more negative
Threshold value
-55 to -40 will make an action potential go
What is the first step of depolarization
Na+ channels open and follow a strong electric and chemical gradient for sodium to move into the cell. This causes the cell potential to become positive.
At what point do the sodium channels close after depolarization
+35
What is the trigger for potassium gates channels to open
Positive potential caused by opened Ca channels
When do potassium channels close after depolarization
Once membrane potential is restored, although sometimes it is overshot resulting in hyper polarization
The movement down an axon terminal is called
Pulse propagation
The longer the axon, the ____ the resistance and the ___ the conduction
Higher, slower
Is the entire membrane permeable?
No only at nodes of ranvier, causing skipping
What is the skipping down the membrane called
Saltatory conduction
How are neurotransmitters broken down in the synaptic cleft?
Some are broken down by enzymatic reactions some use reputable carriers to be recycled back into the presynaptic neuron
Afferent neurons
Neurons that carry information from the periphery to the brain or spinal cord.
Efferent neuron
Carry info from the spinal cord or brain to the body
Interneurons
Only involved in local circuits
Neural cell bodies that cluster in the peripheral nervous system
Ganglia