NERVOUS SYSTEMS Flashcards
which senses does the nervous system control?
all five
taste, see, hear, feel and taste
two main types of nervous cells
neurons
neuroglia
general description of neurones?
transmit nerve impulses
general description of neuroglea?
support and nourish the neuron’s ( helper cells to the neurones)
how can neutrons be further divided into?
based on their proximity to central nervous system and the peripheral nervous system.
their function
organs in the central nervous system?
brain and spinal chord
what is considered the peripheral nervous system?
the other nervous tissue around the brain and spinal chord
what takes messages between the PNS and the CNS?
sensory neurons
How do sensory neurone operate? based on what senses?
using specialized structures that detect change in the environment ( pressure, light, heat, vibrations, etc)
where are the interneurons present ?
within the CNS
what’s the function of interneurones?
transport messages to the other neuron’s in the CNS
what is an effector?
port of the body that performs a function like muscles, glands or organs.
where are motor neurone situated ?
between the CNS and the effectors
what’s the function of Motor neurone?
takes msgs from the CNS to the effector
3 things that most neutrons have?
cell body
dendrites
axon
what does the cell body contain?
the cell nucleus and the organelles
do dendrites lead toward or away from the cell body?
toward
how would you describe a dendrite? consider the name.
tree like extension
what’s the function of the dendrites?
receive stimulus and rely the signal toward the cell body
do axons lead toward or away from the cell body?
away
what’s the function of the axon?
send signals away from the cell body toward other neurones or effectors
where can you find myelin sheaths ?
on portions of the axon
what is the myelin sheath made mostly of
lipids
what’s the use of the myelin sheath?
accelerate signal transmissions between cells
what kind of cells create myelin sheaths in the PNS?
neuroglia called Shawn cells
how doe swan cells create myelin sheaths in the PNS?
by wrapping around the Axon unto 100 times
what do you call the neuroglia that produces myelin in the CNS?
oligodendrocytes
how do myelin sheaths accelerate transmission speed?
by insulating portion of the axon so that the signal transmission can jump along the axon
what is saltatory conduction?
the conduction of the electrical transmission with the presence of myelin sheaths which speeds up the process
explain what nodes of ranvier are
the regular occurring gaps between the myelin sheaths where the electrical transmits essentially jump between.
two types of nervous tissue in the CNS?
white matter
gray matter
what types of neutrons dies the grey matter have?
neurone with short axons
why is grey matter grey?
the lack of myelin leaves the grey colour.
what types of neutrons dies the white matter have?
has longer mylienated axons
what are tracts?
the bundles of myelinated axons in white matter of the CNS
why is white matter white?
due to the presence of myelin
where does grey matter and white matter generally exist in the brain?
surface - grey matter
core - white matter
where does grey matter and white matter generally exist in the spinal chord?
surface - white matter
core - grey matter
what is voltage?
electric pressure
how is potential present in cells?
in the form of ions
what created the potential for movement of the charges?
separation of negative and positive charges
how doe nerves transmit signals?
through nerve impulses
what do we use to study nerve impulses?
through an oscilloscope
how does the oscilloscope work?
it measures the potential difference between two points along a neutron and graphs it.2
what’s resting potential?
the difference of charge between the inside of the cell and the outside of the cell
at what mV is the resting potential measured at? and what does that charge mean?
at -70 mV
meaning that initially, the inside of the cell is more negative than the exterior
is sodium ions more present inside of outside the neurone? ( at rest)
outside
what does the inside of the cell contain when the neurone is at rest?
smaller concentration of potassium ions
vary large concentration of very large anions (negative ions)
what maintains the separation of charge within and outside the neural membrane?
channel proteins and sodium potassium pumps
when does the sodium potassium pumps open?
when the nerve receives an impulse
what’s the role of sodium potassium pumps ?
pump sodium and potassium across the membrane against the concentration gradient to preserve the separation of charges
even though SP pumps open when received a nerve impulse, what reason might they have to be always be working?
as channel proteins cannot close and, ions will move according to the concentration gradient. to keep the balance the SP pumps will use active transportation to pump them back to where they came from
what brings the rapid change of polarity when a nerve impulse is fired?
the movement of ions across the membrane
what is action potential?
the rapid change of polarity when an impulse is fired due to the movement of ions across the membrane
4 steps of action potential in order
sodium gates open
potassium gates open
conduction of action potential
synaptic transmission
how does the action potential begin?
by the opening of the sodium gates and sodium ions moving into the neurone according to the concentration gradient
what change of charge does the opening of sodium gates induce within the cell?
the charge rises to mV 35 from - 70 mV
what’s the concentration os anions and cations within the neurone after the sodium gates open during depolarization?
there are more cations than anions as the Na+ rush in and the already presence of K+ ions
briefly explain what depolarization is
opening of the sodium gates and the change of polarity from negative to positive within the neurone as a result.
what happens after depolarization?
repolarization
first step of depolarization?
opening of potassium gates
what happens when the potassium gates open during repolarization?
K+ ions rush out of the neutron through the cell Wall using facilitated transport, following the concentration gradient
what does the potassium rushing out of the neurone do to the charges within and outside the neurone?
establishes the original charges, where the outside is positively charged and the inside is negatively charged .
what’s the minimum potential needed to trigger the depolarization process?
-55 mV to -50 mV from -70 mV
action potential is aka?
all or nothing process
how long does the whole process of action potential take?
2 milliseconds