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
what happens after a portion of the neutron undergo action potential? and what do you call this process?
the neighbouring region will undergo it as well due to the change in charge
chain reaction that pushes the impulse along the axon
what is the refractory period?
small window where another action poetical cannot occur immediately after the firing of one.
what happens during the refractory period?
SP pumps works to re establish the ion concentration inside and outside the cell membrane
where does action potential occur in myelinated axons?
in the nodes of ranvier
what’s at the end of each axon?
a small bulb like terminal called axon terminal
to what structure is the axon terminal close to but doesn’t touch?
the dendrite of the neighbouring neurone
synapse vs synaptic cleft
synapse - area where the axon terminal is close to the dendrite
synaptic cleft - the actual space between the dendrite and the axon terminal
presynaptic neuron?
the neurone before the gap ( the neurone with the axon terminal )
post synaptic neuron?
the neurone after the synaptic cleft ( the neurone with the dendrites )
what’s a neurotransmitter?
the signal that an action potential represent
what happens once the action potential reach the synapse?
gated calcium channels open and Ca+ enter the axon terminal.
what does calcium ions do in the axon terminal?
triggers the contraction of the contractile proteins which pull the vesicles containing neurotransmitters to the synapse.
what happens once the vesicles containing neurotransmitters reach the synapse?
they fuse with the pre synaptic membrane and let out the neurotransmitters they carried via exocytosis
what happens to the neurotransmitters in the synaptic cleft?
diffuse across to the post synaptic membrane and pin to specific receptor proteins present there
what are the two reactions the binding of neurotransmitters do to the post synaptic neurone?
begin action potential across itself or act as an inhibitor
can dendrite and body of one neutron be connected to many axons?
yes
dendrite/cell body can receive ___ as well as ____ ,at signals at _____ time.
excitatory as well and inhibitory
at the same time
sum of total of the signals that the neurone receives?
integration
once a signal has been sent, the receptors must be___, or the the neurotransmitters must be removed to prevent _____ ______
receptors must be reset
to prevent continuous firing
how do neutrons ensure that the won’t be any continuous firing? (2 methods)
the neurotransmitters can be broken or altered so that they are unable to bind to the receptor
or
they can be reabsorbed by the the presynaptic membrane to be used later ( recycle )
5 famous neurotransmitters?
adrenaline
norepinephrine
serotonin
acetylcholine
dopamine
what’s the main function of the central nervous system?
receive sensory information and initiate motor response
what 2 components protect the 2 CNS organs?
bone and meninges
what’s in-between the meninges and nervous structures?
cerebrospinal fluid
describe ventricles in the brain
hollow interconnecting cavities that produce and store cerebrospinal fluid
where is excess fluid drained in the nervous system?
into the cardiovascular system
is the spinal chord the same thing as the spine?
no
what’s the spine?
a collection of vertebrae that makes up the backbone
wants the spinal chord?
collection of nervous tissue that runs between the vertebra
what’s between each vertebra
fluid filled disks that act as cushioning
what’s most abundant in the spinal cord?
white matter
what’s the H shaped component in the spinal chord made of??
grey matter
what’s at he centre of the spinal chord?
central canal
what holds the cerebrospinal fluid in the spinal chord?
meninges surrounding the chord and central canal
what kind of nerved are connected ted along the spinal chord?
peripheral nerves called spinal nerves
what’s the spinal chords main purpose?
provide means of communication between the brain and th peripheral nerves
four main portions the human brain can be divided into?
cerebrum
brainstem
diencephalon
Cerebellum
what’s the largest portion of the brain?
cerebrum
what’s the most important function the cerebrum serve?
ability to perform conscious thought
what functions does the cerebrum serve?
responsible for controlling voluntary actions and conscious thought
two sections the cerebrum of divided into?
the cerebral hemispheres
what divides the two cerebral hemispheres?
a deep longitude fissure
what bridges the two cerebral hemispheres?
corpus callosum
function of corpus callosum
allow communication between the hemispheres
what do we call the wrinkled surface of the brain?
cerebral cortex
what are the creases in the Brian termed?
suci ( sin.sulcus)
what are the bumps in the brain termed?
gyril( sin. gyrus)p
why are there folded in the brain?
to increase the surface area
how can the cerebrum be divided into 4?
temporal
occipital
frontal
partial
tasks of the primary motor and sensory areas?
receive sensory information and control the fine movements
tasks of the association areas?
where memories are stored and used in recognition
tasks of the processing centres ?
higher level analytical functions like reasoning and planning
what tissue makes up the majority of the area under the cerebral cortex?
white matter
what’s the largest area where white matter is in the brain?
corpus callosum
what is basal nuclei and what’s a another name or it?
the grey matter under the cerebral cortex that’s responsible for regulating motor commands
aka basal ganglia
what region of the Brian content he hypothalamus and thalamus ?
the diencephalon
function of the hypothalamus?
maintain homeostasis and control the pituitary gland
function of the pituitary gland?
secrets hormones that control functions of other endocrine glands
what’s the link between the endocrine system and the nervous system?
hypothalamus as it controls the pituitary gland
what senses does the thalamus gas receive?
every sense except smell
how do information arrive to the thalamus?
cranial nerves and tracts from the spinal chord
what’s the function of the thalamus?
relay necessary information to the relevant part of the brain
(filter out unnecessary information)
what section of the brain does the pineal gland belong to?
diencephalon
whats the function of the pineal gland?
release melatonin and control the sleep wake cycle
where is the cerebellum?
beneath the occipital lobe at the posterior end of the skull
what’s the cerebellum mostly composed of?
white matter
what’s the main function of the cerebellum? (3)
coordinate the body
receive sensory input from joints and muscles
receive motor output from the cortex about where portions of the body should be located
what is proprioception?
personal understanding of where one’s body is in space ( like in a maze)
3 parts of the midbrain?
midbrain
pons
medulla oblongata
function of midbrain?
works as a relay station between cerebrum and spinal cord or cerebellum
function of pons?
contains axons that travel between cerebellum and the CNS. works with the medulla oblongata to control breathing rare
function of medulla oblongata?
resposible for regulating autonomous vital functions like breathing and blood pressure
which part contains the RAS (majority) ?
brainstem
what does RAS stand for?
reticular activating system
what is the function of RAS system
respond to external stimuli
what makes up the reticular activating system?
collection of nuclei and fibres
what does the RAS send a signal to?
the thalamus
what’s the next level of division of the peripheral nervous system?
sensory and motor pathways
what are sensory pathways?
chains of neutrons that travel from the receptor to the cerebral cortex
what are motor pathways?
chains of neutrons that travel from the brain to motor neurones
two components of the PNS?
neurons
ganglia
what are nerves in the PNS made of?
assembles of axons that are referred to as nerve fibres
what are ganglia in the PNS referred to?
the swollen regions in the nerve that contain collections of cell bodies
how many cranial nerves are there?
12
where are the cranial nerves connected to?
links the brain to the regions of the face neck and torso
how many spinal nerves are there?
32
where does the spinal nerves emerge from?
between the openings in the vertibral column.
how are the spinal nerves arranged?
in a manner where 2 short branches ( dorsal root and ventral root) attach to the spinal chord and join together moving away from it.
what does the dorsal root of the spinal nerves contain?
cell body termed dorsal root ganglion
what composes the dorsal root?
sensory fibres conducting impulses towards the spinal cord.
what does the ventral root contain?
contains motor fibres that conduct impulses away from the apical cord to effectors
how can you divide the motor pathways?
somatic and autonomic nervous system
what composes the somatic nervous system?
nerves that serve the skin, skeletal muscles and tendons
tasks of the somatic nervous system? (2)
take sensory information from receptors to CNS
take motor commands from the CNS to the skeletal muscle
what nervous system contains the reflex arcs?
the somatic nervous system
describe reflexes
automatic involuntary response to stimulus
what are reflex arcs?
nerve pathways that go around the spine and cause a reflex, then send the signal to the brain
how is the reflex arc different to the normal reaction?
usually a stimulus received by the sensor cells go tot he brain and the brain sends a command back but in this case, the body reacts faster
