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the nervous system ch 8 (8-1 the nervous system has anatomical and…
the nervous system ch 8
8-1 the nervous system has anatomical and functional divisions
nervous system-monitors the internal and external environments
integrates sensory information
coordinates voluntary and involuntary responses of many other organ systems
CNS-consisting the brain and spinal cord integrates and coordinates the processing of sensory data
PNS-neural tissue outside CNS
SNS-provides control over skeletal muscle contractions
ANS-provides automatic involuntary regulation of smooth muscle
8-2 neurons are specialized for intercellular communication
neurons-basic units of the nervous system
neuoglia-regulate the environment
dendrites-which reciece incoming signals
axon-carries outgoing signals
synaptic terminal-neuron communicates with another cell
nissal bodies- clusters of rough er and free ribosomes
synapse- site where a neuron where communicates with another cell
multipolar neuron- has 2 or more dendtites and a single axons
unipolar neuron-dendrites and axon are continuous and cell body lies off to one side
bipolar neurons-have two process one dendrite and one axon with the cell body between them
sensory neurons-in the human body form the afferent dividion of the pns
somatic sensory receptors-detect information about the outside world or our physical postion within it
motor receptors-of the efferent division carry instructions from the cns to to other tissues
8-3 in neurons,a change in the plasma membranes electrical potential
membrane potential- charges are seperated by a plasma membrane
resting potential-the membrane potential of an undisturbed cell
depolarization-as the number of positively charged ions on the inner surface of the plasma increases
hyperpolarization-stimulus that opens gated potassium ion channels will shift the membrane potential away
graded potentials- are changes in the membrane potential that cannot spread far from the site stimulation
action potential-is a prolonged change in the membrane potential of the entire plasma membrane
threshold-an action potential will not appear unless the membrane depolarizes sufficiently to a level
refractory period- the membrane cannot respond normally to further stimulation
saltatory propagation-action potential jumps from node to node
8-4 At synapses communcation occurs among neurons or between
snyaptic cleft-the opposing plasma membranes are separated by a narrow space
at the synapse between two neurons, the impuses pases the synaptic knob of the presynaptic neuron to the postsynaptic neuron
cholingeric synapses are widespread inside and outside of the cns
the neurotransmitters dopamine, gamma and serotonin function in the cns
there are 50 other neurotransmitters whose functions are well understand
8-5 the brain and spinal cord are surrounded by the three layers of membranes