nervous system: functions&cellular composition Flashcards
(21 cards)
divisions of the nervous system
central nervous system (CNS)
peripheral nervous system (PNS)
3 functions of the nervous system
-sensory nerves gather info and carry it to the CNS
-inter nerves process or interpret the information brought to the CNS by the sensory nerves
-motor nerves convey info from the CNS to the muscles and glands to carry out the plans made by the CNS
neuroglia or glial
-most abundant type
-support, protect, insulate, nourish, and generally care for neurons
neurons
-do the communicating for the nervous system
-long shape makes them delicate
-cannot regenerate
types of neuroglia
-astrocyte: most abundant, feeds microglia
-microglia: fights off bacteria (phagocytosis)
-ependymal cells: produces cerebral spinal fluid
-schwann cells: produces myelin for PNS
-oligodendrocytes: produces myelin for CNS
structure of a neuron
-cell body
-dendrites
-axon
-axon terminals
axon
-myelin sheath
-nodes of ranvier (not covered by myelin)
-neurilemma
-axon terminal
what is afferent neurons?
they carry information from the periphery toward the CNS
what are efferent neurons?
carry information from CNS toward periphery
3 types of neurons
are they afferent or efferent?
sensory- afferent
motor- efferent
inter- connect sensory and motor nerves, only in CNS
white matter
made up of myelinated axons
gray matter
-unmyelinated axons
-cell bodies
-inter neurons
-synapses
nerve impulse
-aka action potential
-electrical signals convey information along a neuron
-move along sensory or motor neurons
polarization
resting state
-inside of the neuron is more negative than the outside when it’s polarized
depolarization
stimulated state
-change inside the cell from - to + when the neuron is stimulated
repolarization
return to resting
-inside of cell becomes negative again
what causes the nerve impulse?
polarization
-K+ leaks from neuron
depolarization
-Na+ rushes in
repolarization
-K+ rushes out
action potential
-forms at axons beginning
-regenerates along axon’s length
-enters axon terminal
-releases ACh from vesicles
what causes the nerve impulse to move quickly?
-myelin insulates axon
-myelin exposes some axonal membrane— nodes of ranvier
-action potentials jump quickly from node to node like a kangaroo
-this affect of jumping increases speed of the action potential
synaptic cleft
-receptors
-neurotransmitters
-inactivators
what happened in synapse
ACh is:
-secreted from neuron A
-diffused across synaptic cleft
-bound to receptors in neuron B
neuron B is activated
