the nervous system Flashcards
what are the three functions of the nervous system
sensory input, integration and motor output
neurons
nerve cells that transfer information within the body
ganglia
simple clusters of neurons instead of a brain in simple organisms
what is the function of a neuron ?
transmission of signals
what are dendrites
branched extensions that receive signals from other neurons
What is the axon?
longer extension than the dendrites transmitting signals
where are most of a neurons organelles?
in the cell body
what are glia cells
support the neuron and are for structural integrity and function
what is membrane potential?
a voltage(difference in electrical charge) accross its plasma membrane
how are messages transmitted?
as changes in membrane potential
what is the resting potential?
the membrane potential of a neuron not sending signals. ion pumps and ion channels maintain the resting potential of a neuron. K+ higher inside, Na+ higher outside.
what is the refractory period a result of?
a temporary inactivation of the Na+ channels.
refractory period
is a period of normal repolarization when the Na+K+ pump restores the membrane to its original polarized condition. It prevents the backward signal transmission
how does the action potential travel
regenerating itself along the axon
what direction to action potentials travel?
travel in only one direction toward the synaptic terminals
what causes action potentials speed to increase?
the axons diameter
and the myelin sheath
where are action potentials formed?
only at nodes of Ranvier, gaps between shwann cells in the myelin sheath
saltatory conduction
jumping between the nodes of Ranvier
synapse
is a junction between cells controlling communication
electric synapses
direct current flow between neurons
chemical synapses
neurotransmitter carries information across the synapse
presynaptic cell
releases neurotransmitters in synaptic vesicles
what causes the release of the neurotransmitter
the action potential
postsynaptic cell
receives signals
what happens neurotransmitters after release?
can diffuse, be reabsorbed or degraded
Cephalization
is the clustering of sensory organs at the front end of the body
central nervous system
Brain and spinal cord
grey matter
contains cell bodies and dendrites
white matter
contains myelinated axons
peripheral nervous system
transmits information the the CNS. includes cranial and spinal nerves
two components: motor system& autonomic nervous system
reflex
the bodys automatic response to a stimulus
afferent neurons
transmit information to the CNS
efferent neurons
transmit information away from the CNS
what does the brainstem do?
coordinates and conducts information between brain centers
what are the three parts of the brainstem ?
the midbrain, the pons, and the medulla oblongata
the midbrain
sensory integration
the pons
breathing regulation
medulla oblongata
controls vital functions
cerebellum
coordinates motor functions
involved in learning motor skills
what is the diencephalon ?
the epithalamus, the thalamus, and the hypothalamus
epithalamus
produces cerebrospinal fluid
thalamus
processes sensory and motor information
hypothalamus
regulates homeostasis and survival behaviours
cerebrum
two hemispheres connected by corpus callosum.
four lobes: frontal, temporal, occipital & parietal.
controls voluntary movement and cognitive functions
what system processes emotions
the limbic system
what is the limbic system?
Is a ring of structures around the brainstem that includes the amygdala, hippocampus and parts of the thalamus.
where is emotional memory stored?
the amygdala
what part of brain is short term memory?
the hippocampus
where is long term memory stored?
the cerebral cortex
what is the main input centre for sensory information to the cerebrum?
Thalamus
what is the simplest type of nervous system arrangement found in cnidarians?
nerve net
