Ch 2- Nervous System Flashcards
CNS
comprised of the brain and the spinal cord, its primary roles are to process info received from the bodys internal and external environ
neural pathway
comprises one
or more circuits of interconnected
neurons that form a communication network.
spinal cord
the long, thin bundle of nerve
fibres that extends from the base of the brain to the
lower back. It is encased in a series of bones called
the vertebrae that extend further than the actual cord
Two major functions of the spinal cord are
- receive sensory information from the body
(via the peripheral nervous system) and send
these messages to the brain for processing.
receive motor information from the brain and
send it to relevant parts of the body (via the
peripheral nervous system) to control muscles,
glands and internal organs so that appropriate
actions can be taken.
peripheral nervous system (PNS)
Its primary, overarching role is to carry information
to and from the CNS.
* carries information to the CNS from the body’s
muscles, organs and glands (about the internal
environment) and from the sensory organs
(about the external environment)
* carries information from the CNS to the body’s
muscles, organs and glands.
somatic nervous system (SNS)
Sensory information is received at sensory receptor
sites in the body (skin, muscles, joints and tendons)
and carried along sensory neural pathways by sensory
neurons. Motor information is carried along motor
neural pathways by motor neurons to skeletal muscles
to control their activity by causing them to contract
or relax. Skeletal muscles are attached to our bones
and respond to messages from the CNS to initiate,
change or stop movement.
autonomic nervous system (ANS)
connects the CNS to the body’s internal organs (such
as the heart, stomach and liver) and glands (such
as sweat, salivary and adrenal glands), providing
feedback to the brain about their activities.
The ANS consists of three sub-divisions
- the sympathetic nervous system, which is
responsible for increasing the activity of most
visceral muscles, organs and glands in times of
vigorous activity, stress or threat - the parasympathetic nervous system, which
is responsible for decreasing the activity of
most visceral muscles, organs and glands, and
restoring body functioning to its normal state - the enteric nervous system, which is dedicated
to the gastrointestinal tract and therefore helps
regulate digestion.
sympathetic nervous system
activates internal
muscles, organs and glands to prepare the body
for vigorous activity or to deal with a stressful or
threatening situation.
parasympathetic nervous system
helps
to maintain the internal body environment in a
steady, balanced state of normal functioning.
enteric nervous system (ENS)
embedded
within the walls of the gastrointestinal tract and
is dedicated to its functioning.
Oesophagus
Stomach
Duodenum
Large intestine
Small intestine
Rectum
conscious response
reaction that involves awareness.
unconscious response
reaction that does not involve awareness
spinal reflex
an unconscious, automatic
response controlled solely by neural circuits in the
spinal cord. It is often referred to as a reflex arc
because the response to an incoming stimulus is
automatically ‘reflected back’ from the spinal cord
without any initial input from the brain and before
the brain processes a conscious perception of the
stimulus.
synaptic gap
the tiny
space between the terminal buttons of one neuron,
which release the neurotransmitter, and the dendrites
of another, which receive the neurotransmitter.
neural synapse
the site
where communication typically occurs between
adjacent neurons. The other two components are
the terminal buttons of the presynaptic (‘sending’)
neuron and the dendrites of the postsynaptic
(‘receiving’) neuron
Neurotransmitter
s a chemical substance produced
by a neuron that carries a message to other neurons
or cells in muscles, organs or other tissue.
excitatory effect
stimulate
or activate postsynaptic neurons to perform their
functions.
inhibitory
effect
block or prevent postsynaptic neurons
from firing
Glutamate (Glu)
the main excitatory
neurotransmitter in the CNS. This means that
glutamate enhances information transmission by
making postsynaptic neurons more likely to fire.
Gamma-amino butyric acid (GABA)
the primary
inhibitory neurotransmitter in the CNS. It works
throughout the brain to make postsynaptic neurons
less likely to fire (i.e. it ‘inhibits’ firing).
neuromodulators.
s may ‘modulate’, or
influence, the effects of other neurotransmitter
Dopamine
a modulatory neurotransmitter known
to have multiple functions depending on where
in the brain it acts.
serotonin
a modulating
neurotransmitter that has a wide range of functions,
depending on where in the brain it acts.
Synaptic plasticity
refers to the ability of the synapse to change in response to experience.
Sprouting
the creation of new extensions on a
neuron to allow it to make new connections with
other neurons.
Rerouting
occurs when new connections are made
between neurons to create alternate neural pathways.
Pruning
the elimination of weak, ineffective or
unused synapses (and therefore connections to other
neurons).
Long-term potentiation (LTP)
refers to the long-
lasting enhancement of synaptic transmission due
to repeated strong stimulation.
Long-term depression (LTD)
the long-lasting
decrease in the strength of synaptic transmission
and neuronal response (which is the opposite
of LTP).
