Organization Of The NS Flashcards
Incoming signals
enter this neuron through synapses located mostly on the
neuronal dendrites, but also on the cell body.
output signal travels by way of
several axon leaving the neuron.
True or False
False. Single axon only
information enters the central nervous system through peripheral nerves and is con
ducted immediately to multiple sensory areas in
(1) the spinal cord at all levels;
(2) the reticular substance of the medulla, pons, and mesencephalon of the brain;
(3) the cerebellum;
(4) the thalamus; and
(5) areas of the cerebral cortex.
skeletal muscles can be controlled from many levels of the central nervous system, including
(1) the spinal cord;
(2) the reticular substance of the medulla, pons, and mesencephalon; (3) the basal ganglia;
(4) the cerebellum; and
(5) the motor cortex.
junction point from one neuron to the next.
determine the directions that the nervous signals will spread through the nervous system
synapse
function of the synapses
memory
Facilitation
Each time certain types of sensory signals pass through sequences of synapses, these synapses become more capable of transmitting the same type of signal the next time, a process called
facilitation
neuronal circuits in the cord can cause
(1) walking movements, (2) relexes that withdraw por tions of the body from painful objects,
(3) relexes that stifen the legs to support the body against gravity, and (4) relexes that control local blood vessels, gastrointesti nal movements, or urinary excretion.
True or False
upper levels of the nervous system often operate by sending signals directly to the periphery of the body
False. by sending signals to the control centers of the cord, simply “com manding” the cord centers to perform their functions.
subconscious control of arterial pressure and respiration is achieved mainly in
the medulla and pons.
combined function of the older portions of the cerebellum and the reticular substance of the medulla, pons, and mesencephalon.
Control of equilibrium
Feeding relexes, such as salivation and licking of the lips in response to the taste of food, are controlled by areas in the
medulla, pons, mesencephalon, amygdala, and
hypothalamus
emotional patterns such as anger, excitement, sexual response, reaction to pain, and reaction to pleasure can still occur after destruction of much of the cerebral cortex
True or False
True
an extremely large memory storehouse.
Fxns in association with lower centers of the nervous system.
cerebral corte
it is the cerebral cortex, that initiate wakefulness
True or False
False. it is the lower brain centers, not the cortex, that initiate wakefulness in the cerebral cortex
lower brain centers opens the cortex’s bank of memories to the thinking machinery of the brain
True or False
True
All these functions can
be classiied as synaptic functions of neurons.
each impulse (1) may be
blocked in its transmission from one neuron to the next,
(2) may be changed from a single impulse into repetitive
impulses, or
(3) may be integrated with impulses from
other neurons to cause highly intricate patterns of
impulses in successive neurons.
important neurotransmitters
acetylcholine, norepinephrine, epinephrine,
histamine,
gammaaminobutyric acid (GABA), glycine,
serotonin, and
glutamate.
useful in detecting the coincidence of simultaneous subthreshold depolarizations within a group of interconnected neu
rons; this enables increased neuronal sensitivity and pro
motes synchronous iring of a group of interconnected neurons
bidirectional transmis
sion of electrical synapses
it is this speciic transmission of signals to discrete and highly focused areas both within the nervous system and at the terminals of the peripheral nerves that allows the nervous system to perform its myriad functions of sensation, motor control, memory, and many other functions.
principle of one-way conduction
These diferences make neurons in diferent parts of the nervous system react diferently to incoming synaptic signals and, therefore, perform many diferent functions.
- the size of the cell body;
(2) the length, size, and number of dendrites
(3) the length and size of the axon; and
(4) the number of presynaptic terminals
structural changes of appropri
ately activated neurons do not occur, especially in long
term memory processes.
True or False
False. Do occur
he importance of having inhibitory, as well as excitatory, types of receptors is that
this feature gives an additional dimension to nervous function, allowing restraint of nervous action and excitation.
It is by far the most widely used means for causing excitation.
Opening of sodium channels to allow large numbers
of positive electrical charges to flow to the interior of the postsynaptic cell.
Depressed conduction through chloride or potas-
sium channels, or both make the internal membrane potential more posi
tive than normal, which is inhibitory.
True or False
False. Excitatory
two groups of synaptic transmitters.
small-molecule, rapidly acting transmitters. he other is made up of a large number of neuropeptides of much larger molecular size that usually act much more slowly.
neuropeptides prolonged actions
changes in numbers of neuronal receptors,
opening or closure of certain ion channels,
changes in numbers of synapses or sizes of synapses.
present in the proteoglycan reticulum that ills the space of the synaptic cleft.
cholinesterase
Acetylcholine is secreted by neurons in many areas of the nervous system but speciically by
1) the terminals of the large pyramidal cells from the motor cortex,
2) several diferent types of neurons in the basal ganglia
3) the motor neurons that innervate the skeletal muscles
4) the preganglionic neurons of the autonomic nervous system
5) the postganglionic neurons of the parasympathetic nervous system, and
6) some of the postganglionic neurons of the sympathetic nervous system
inhibitory efect of acetylcholine
inhibition of the heart by the vagus nerves.
Norepinephrine is secreted by
brain stem and hypothalamus
locus ceruleus
secreted by neurons that originate in the substantia nigra.
Dopamine
It is believed to always act as an inhibitory transmitter.
Glycine
GABA