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Nervous System - Coggle Diagram
Nervous System
Neurons communicate at synapses
The transmission of signals between neurons: Or between neurons and effector cells occurs at junctions called synapses
electrical signals: Pass between cells at electrical synapses
at chemical synapses: neurotransmitter
the neurotransmitter: Crosses the synaptic cleft and binds to a receptor on the surface of the receiving cell
Chemical synapses makes complex information processing possible
a neuron may receive information from hundreds of other neurons via thousands of synaptic terminals
some neurotransmitters excite the receiving cell, other types of neurotransmitter inhibit the receiving cell's activity by decreasing its ability to develop action potentials
the summation of excitation and inhibition determines whether or not a neuron will transmit a nerve signal
a variety of small molecules function as neurotransmitter: many small, nitrogen-containing molecules
Neurons are the functional units nervous systems
neurons: cells specialized for carrying signals
neuron consists of : a cell body, two types of extensions (fibers) that conduct signals, dendrites and axons
Many axons are enclosed by cellular insulation called the myelin sheath : speeds up signal transmission
Nerve signals and their transmission
A neuron maintains a membrane potential across its membrane
At rest, a neuron’s plasma membrane has an electrical voltage called the resting potential
The resting potential: Is caused by the membrane’s ability to maintain a positive charge on its outer surface opposing a negative charge on its inner surface
The action potential propagates itself along the neuron
action potentials
Are self-propagated in a one-way chain reaction along a neuron
are all-or-none events
Propagation of the action potential along an axon
The frequency of action potentials, but not their strength: Changes with the strength of the stimulus
A nerve signal begins as a change in the membrane potential
A stimulus alters the permeability of a portion of the membrane
Allowing ions to pass through and changing the membrane’s voltage
a nerve signal, called an action potential: Is a change in the membrane voltage from the resting potential to a maximum level and back to the resting potential
Nervous System Structure and Function
Nervous systems receive sensory input, interpret it, and send out appropriate commands
The nervous system obtains and processes sensory information: sends commands to effector cells, such as muscles, that carry out appropriate responses
sensory neurons: Conduct signals from sensory receptors to the central nervous system (CNS)
The CNS: Consists of the brain and spinal cord
Interneurons in the CNS: Integrate information and send it to motor neurons
Motor neurons: Convey signals to effector cells
automatic responses called reflexes: Provide an example of nervous system function
peripheral nervous system: Consists of nerves (bundles of fibers of sensory and motor neurons) and ganglia (clusters of cell bodies of the neurons)