Integrative system (Part 1) Flashcards
refers to processes—such a
summation and coordination— that produce coherency and result in harmonious function.
Integration
refers to the selective combination and processing
of sensory, endocrine, and central nervous system (CNS) information in ways that promote the harmonious functioning of the whole.
Whole-animal integration
The ___ sets the level of a variable (temperature, blood pressure, muscle force, and so on) that is being controlled.
control system
____is a cell that is specially adapted to generate an electrical signal—most often in the form of a brief, self-propagating impulse called an ____—that travels from place to place in the cell.
neuron; action potential
A neuron receives input—signals from other neurons or sensory cells—at specialized cell–cell contact points called ___
synapses.
____ – nucleus and metabolic center of the cell
Cell body
____ – fibers that extend from the cell body (dendrites and axons)
Processes
___ – relay sensory signals to integrative centers of the CNS
Afferent Neuron
____ – relay control signals (instructions) from the CNS to target cells that are under nervous control, such as muscle cells or secretory cells
Efferent Neuron
release hormones into the blood
Endocrine cells
Endocrine control has two essential features:
slow; broadcast.
______ such as neurons, muscle fibers, and a few others can generate electrical signals.
Excitable cells
are one of the most important kinds of electrical signals underlying the integrative activity of nervous systems.
Action potentials
_____result from voltage-dependent changes in membrane
permeabilities to ions
Action potentials
An ____ is initiated by a change in the resting membrane potential, specifically by a ____ sufficiently strong to open the voltage-gated channels.
action potential; depolarization
results from intense, localized increases in permeabilities to specific ions
action potential
Action potentials are propagated along the axons of neurones via ___
local currents
____ induce depolarisation of the adjacent axonal membrane.
Local currents
areas of the membrane that have recently depolarised will not depolarise again due to the ____
refractory period
The ability to store charge
Membrane Capacitance
The lower capacitance results in a ___ before the threshold is no longer reached.
greater distance
This depends on the number of ion channels open.
Membrane Resistance
The ___ the number of channels open, the ___ membrane resistance is
lower; greater
The ___ controls predominantly the fine, rapid movements of discrete muscles, the ____ typically controls more widespread, prolonged activities such as metabolic changes.
nervous system; endocrine system
is a specialized site of contact of a neuron with another neuron.
Synapse
Neurons are typically separated by a ___ (nm) space called the ___
20- to 30-nanometer; synaptic cleft.
a presynaptic signal—usually an action potential— affects a postsynaptic cell.
Synaptic transmission
Refers to the ability to change the functional properties of synapses.
Synapse Transmission
can change the synapse itself to make it stronger or weaker, and they can also produce long-lasting changes
in postsynaptic cell
Synaptic actions
A___can work chemically or electrically.
synapse
can act immediately and directly on the membrane potential of the postsynaptic cell, or they can have indirect and longer-lasting effects
Synapses
electric currents from one cell flow directly into the next cell, changing its membrane potential
Electrical Synapse
electrical synapses are found in ____ where speed is most important, and where synchronous activity of several cells is an advantage
nervous systems
The major structural specialization for electrical transmission is the
gap junction
is a specialized locus where protein channels bridge the gap between two cells, directly connecting their cytoplasm.
Gap Junction
provide a low-resistance path for current flow, electrically coupling the cells that they join.
Gap junctions
These receptors produce fast changes in membrane potential (depolarization or hyperpolarization) by directly increasing permeability to ions
Ionotropic receptors
These receptors have relatively slow, long-lasting modulatory effects on synaptic processes
Metabotropic receptors