NERVOUS SYSTEM Flashcards
Neurons
-functional units of nervous system
-functions to transmit information
Cell body
-houses the nucleus and cytoplasm
-neuron control center
-receives graded potentials
Axon
-propagation of the action potential
Dendrite
-receives information
-transmits graded potentials toward the cell body
Synaptic knob
-location where a neuron is connected to another neuron or effector
Axon hillock
-receives graded potentials
-initiates the action potential
Synapse
-specialized junction where neurons connect and transmit signals to each other
-a single neuron can contain thousands of synapses
Synaptic cleft
-small gap between neurons where communication takes place
-separates the presynaptic ending and the postsynaptic cell
Myelin
-insulating layer of fatty substances and protein that surrounds nerves
-enables electrical impulses t travel quickly
functions include:
-speeds up communication in the brain
-water balance
-cognitive function: helps neurons respond to signals involved in memory formation
and other cognitive functions
Neurofibril node
-gaps in myeline sheaths
Multipolar neurons
-multiple processes from cell body
-many dendrites and 1 axon
Bipolar neurons
-1 dendrite and I axon from cell body
Unipolar neurons
-single short process from cell body
Sensory (afferent) neurons
-convey action potentials (APs) into the CNS through cranial or spinal nerves
-most are unipolar
Motor (efferent) neurons
-convey APs away from the CNS to effectors in the periphery
-most are multipolar
Interneurons
-located within the CNS between sensory and motor neurons
Resting membrane potential
-difference in charge inside and outside of the cell
-voltage measured across the plasma membrane
-set up by leak channels
-Na/k pump
-voltage difference from inside and outside the cell at rest due to the RMP is -70mV
Electrochemical gradient
-when ion channels are open, they allow specific ions to move across the plasma membrane
-movement of ions depends on both the chemical gradient (concentration gradient) and the electrical gradient (electro chemical gradient)
-ions move form high concentration to low concentration=> chemical
-cations (+) move to negatively charged areas and anions (-) move to positively charged areas=> electrical
Ligand-gated ion channels
-open when a neurotransmitter latches onto its receptor