chapter 3: intro to the nervous system Flashcards
what are the functions of the nervous system?
movement, communication, secretion, state of consciousness
how is the nervous system organized?
- central nervous system (CNS): brain and spinal cord
-peripheral nervous system (PNS): autonomic and motor pathways
what is a neuron?
an excitable cell that transmits electrical impulses
what is the soma of a neuron?
the cell body, houses the nucleus
what do dendrites do?
receive sensory signals; triggers action potential
what do axons do?
end of the neuron; conduct nerve impulses away from one neuron and towards another
what happens at the synapse of neurons?
synapse: connection between 2 neurons; site where electric signal is transmitted
presynaptic membrane: neurotransmitter released
synaptic cleft: site where neurotransmitters travel through
postsynaptic membrane: neurotransmitters transfer signal to the receptor
how is action potential generated?
- at rest:
- Na^2+ higher outside neuron, K^+ higher inside cell
- resting potential= -70 mV - dendrite stimulated:
- depolarization: Na^2+ channels open and allow ions to rush into neuron
- neuron membrane potential: +30 mV - membrane potential reaches +40 mV:
- repolarization: K^+ channels open and allow ions to flow outside the cell
- neuron membrane potential: -90 mV - sodium-potassium pump moves sodium ions outside cell and potassium ions back inside cell to reestablish resting potential (-70 mV)
describe how neurotransmitters transmit a signal.
- depolarization at synapse= influx of Ca^2+
- exocytosis= synaptic vessels in presynaptic neuron release NT into synaptic cleft
- NT binds to receptors on postsynaptic membrane; triggers inhibitory or excitatory reaction
- after signal is released= NTs are inactivated and absorbed by presynaptic membrane
