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Ch. 12 Nervous System: Nervous Tissue (Functions (Collect information…
Ch. 12 Nervous System: Nervous Tissue
Functions
Collect information
Sensory, input
Receptors
Stimuli
Process and evaluate information
Initiate response to information
Motor, output
Effectors
Body's primary communication and control center
Integrating and regulating body functions through electrical activity transmitted along neurons
Neurotransmitters
Synthesized by neurons and stored within vesicles in synaptic knobs
Released from the vesicles when an action potential triggers calcium entry into the synaptic knob
Bind to a specific receptor in a target cell (neuron, muscle, or gland)
Trigger a physiologic response in the target cell
Function
Excitatory
Inhibitory
Neurons
Characteristics
Excitability
Conductivity
Secretion
Extreme longevity
Amiotic
Potentials
Graded potentials
Chemically gated channels open temporarily to allow passage of a relatively small amount of a specific type of ion across the plasma membrane
Membrane potential either becoming more positive (depolarization) or more negative (hyperpolarization) than the resting membrane potential (-70 mV)
Action potentials
Initiated when voltage-gated channels open in response to a minimum voltage change (threshold value)
Voltage gated Na+ channels open, allowing Na+ into a neuron to cause depolarization (reversal of membrane potential from negative to positive), these voltage-gated channels close
Voltage-gated K+ channels open, allowing K+ out to cause repolarization (return of membrane potential from positive to negative)
Saltatory propagation
Action potential along myelinated axon from one node of Ranvier to the next
Na+/K+ pump
Restoration of concentration of ions across a membrane
Synapses
Syn = together, hapto = to clasp
Functional contact of a nerve cell with another nerve cell, effector, or receptor
Chemical synapse
Presynaptic neuron (signal producer)
Postsynaptic neuron (signal receiver)
Electrical synapse
Presynaptic and postsynaptic neuron bound together