YR12 - Chapter 2, The nervous system Flashcards
CNS
a major division of the NS comprising the brain and spinal cord, which receives neural messages from and transmits neural messages to the PNS
Brain
a complex organ contained within the skull that coordinates mental processes and behaviour, and regulates bodily activity
Spinal cord
a cable of nerve tissue that extends from the brain, connecting it to the PNS
PNS
a major division of the NS comprising every neuron in the body outside the CNS
Somatic nervous system
(SoNS)
a division of the PNS that transmits neural messages related to voluntary motor movement
Skeletal muscles
muscles connected to the skeleton that carry out voluntary motor movements
Autonomic nervous system
(ANS)
a division of the PNS that regulates visceral muscles, organs, and glands, and transmits neural messages to the CNS about their activity
Visceral muscles, organs, and glands
muscles, organs, and glands not connected to the skeleton that are predominantly self-regulating and do not require conscious control
examples - heart, liver, kidneys, adrenal, bladder, eye etc
Sympathetic nervous system
(SyNS)
a division of the ANS that activates visceral muscles, organs, and glands, preparing the body to respond to a threat or stressor
Parasympathetic nervous system
(ParaNS)
a division of the ANS that maintains the optimal and balanced functioning of visceral muscles, organs, and glands
Neuron
a nerve cell that receives and transmits neural information
Motor neurons / efferent neurons
neurons that transmit neural messages about motor movement from the CNS to the PNS
Sensory neurons / afferent neurons
neurons that transmit neural messages about bodily sensations from the PNS to the CNS
Interneurons
neurons that transfer neural messages between sensory neurons and motor neurons
Conscious response
a deliberate and voluntary action that is initiated by the brain and performed intentionally by the body
Sensory receptor
a nerve ending that detects internal sensations in the body and external sensations from the environment
Conscious response (method)
R.A.C.E.R.
Registered (by sensory receptors)
Afferent (tracts)
Coordinated (response by brain)
Efferent (tracts)
Response (by skeletal muscles)
Unconscious response
an automatic and involuntary action that is performed by the body independently of the brain
Spinal reflex/Reflex arc
an unconscious response to sensory stimuli that is initiated by interneurons in the spinal cord independently of the brain
Unconscious response (method)
- dangerous sensation occurs, sent through SoNS as sensory message
- interneurons in spinal cord (sensory –> motor)
- motor response (SoNS to skeletal muscles)
- message is send to the brain from spinal cord, it registers the sensation independently.
Neural synapse
the region that includes the axon terminals of the presynaptic neuron, the synaptic gap, and the dendrites of the postsynaptic neuron
Receptor site
a protein molecule on the dendrites of a neuron that receives neurochemicals
Neurochemical
a chemical substance that transmits neural information within the NS
Synaptic transmission
the chemical conveyance of neural information between two neurons across a neural synapse
Process of synaptic transmission
- Neurochemicals are produced in the axon terminals of the presynaptic neuron.
- Neurochemicals are released from the axon terminals of the presynaptic neuron into the synaptic gap.
- Neurochemicals bind to receptor sites on the dendrites of the postsynaptic neuron.
- Neurochemicals affect the postsynaptic neuron, either triggering or inhibiting a response.
Neurotransmitter
a chemical molecule that has an effect on one or two postsynaptic neurons
Action potential
an electrical impulse that travels down the axon of a neuron
Excitatory effect
when the neurotransmitter increases the likelihood of the postsynaptic neuron firing an action potential
Glutamate
the main excitatory neurotransmitter in the nervous system
- learning and memory
- strengthen synaptic connections
- thought and movement
Inhibitory effect
when the neurotransmitter decreases the likelihood of the postsynaptic neuron firing an action potential
GABA (gamma- aminobutyric acid)
the main inhibitory neurotransmitter in the NS
- preventing overexcitation of neurons, which reduces anxiety
- inhibits uncontrolled firing of action potentials, controlling risk of seizures
Neuromodulator
a chemical molecule that has an effect on multiple postsynaptic neurons
Dopamine
a neuromodulator primarily responsible for voluntary motor movement, the experience of pleasure, and reward- based learning
(both excitatory and inhibitory)
Serotonin
a neuromodulator primarily responsible for the regulation of mood and sleep
(inhibitory)
synaptic plasticity
the ability of synaptic connections to change over time in response to activity or experience
(adaptive and developmental)
3 main mechanisms
- sprouting
- rerouting
- pruning
sprouting
ability of dendrites or axons to develop new extensions/branches
rerouting
ability of a neuron that is connected to a damaged neuron to create an alternative synaptic connection with an undamaged neuron
pruning
the elimination of synaptic connections that are not adequately activated
Synaptic plasticity’s role in learning and memory
During learning & memory, neural synapses physically change in response to these experiences, forming, strengthening and/or weakening.
Long Term Potentiation (LTP)
the long-lasting and experience-dependent strengthening of synaptic connections that are regularly coactivated
(uses sprouting)
structural changes of LTP
- more receptor sites on dendrites
- bushier dendrites
- more synaptic connections
Long term depression (LTD)
the long-lasting and experience-dependent weakeningof synaptic connections between neurons that are not regularly coactivated
(uses pruning)
structural changes of LTD
- less receptor sites
- less dendrites
- less synaptic connections
