Divisions of the Nervous System
What are the two major divisions of the nervous system?
CNS & PNS
What part of the neuron carries signals away from the soma?
Axon
Which glial cell makes myelin in the CNS?
Oligodendrocytes
What is the resting membrane potential (RMP)?
~-70 mV
What rule do action potentials follow?
All-or-none
Which division carries signals from the CNS to muscles and glands?
Motor (efferent) division
What part receives information and sends it toward the soma?
Dendrites
Which glial cell makes myelin in the PNS?
Schwann cells
What ion enters the cell first during depolarization?
Sodium (Na⁺)
What phase happens when K⁺ leaves the neuron?
Repolarization
What division brings sensory information from organs like the stomach and heart?
Visceral sensory division
What type of neuron has one axon and multiple dendrites?
Multipolar neuron
Which glial cells help form the blood-brain barrier?
Astrocytes
What does the Na⁺/K⁺ pump do?
Pumps 3 Na⁺ out, 2 K⁺ in, helps maintain RMP
What type of conduction occurs along myelinated axons?
Saltatory conduction
Which branch of the autonomic nervous system prepares the body for action (fight-or-flight)?
Sympathetic division
What is the difference between multipolar and bipolar neurons?
Multipolar: many dendrites; Bipolar: one axon, one dendrite
Which glial cells help circulate CSF?
Ependymal cells
What voltage must be reached to trigger an action potential?
~-55 mV (threshold)
Why can't a neuron fire again during the absolute refractory period?
Na⁺ channels are still inactivated
What are the three basic steps the nervous system performs?
Sensory input → Integration → Motor output
Name the two motor proteins in axonal transport.
Kinesin (anterograde) & dynein (retrograde)
Which glial cells act as immune defense in the CNS?
Microglia
What does “decremental” mean in local potentials?
They get weaker as they spread
What ion movement causes hyperpolarization?
Excess K⁺ leaving the cell