C2.2 Neural Signalling Flashcards
CNS
central nervous system in vertebrates
brain and spinal chord
PNS
Peripheral nervous system invertebrates
nerves that sensory information to the CNS and nerves that convey impulses to muscles and glands
nerve
nerve bundle of many nerve fibers connecting the CNS with parts of the body
neurone
a cell that carries electrical impulses
what are neurones specialised for
transmittion of information
dendrite
a fine fibrous structure on a neuron that receives impulses from other neurons
impulse
momentary reversal in electrical potential different across neurones membranes
motor neuron
Carries impulses away from CNS to effector many fine dendrites and a single long axon
long axon role in motor neuron
impulses away from body
dendrites role in motor neuron
impulses towards body
sensory neurone
carrying impulses from a sense organ or receptor to CNS
have a cytoplasmic fibre running to cell body
relay neurones other name
interneurones
relay neurones
connect sensory and motor neurone
like a thread like extention of a nerve cell
receptor
responds to stimulation by production of an action potential
axon
Fiber carrying impulses away from the cell body of a neuron
dendron
Fiber carrying impulses toward the cell body of neurons
Schwann cell
Cells of the PNS that wrap around axons of motor neurons and sensory neurons to form a myelin sheath
myelin sheath
insulating sheath around axons of nerve fibers formed by Schwann cells
node of ranvier
Gap in myelin sheath around a myelinated nerve fiber
resting potential
Potential difference across a nerve cell membrane when it is not being stimulated
resting potential mV
-70
how is an impulse transmitted
along nerve fibres, not an electrical current
is a change in positioning of charged ions between inside and outside of membrane of nerve fibres
how is resting potential difference re-established
after a nerve impulse has been transmitted
membrane poliration
a lipid membrane that has a positive electrical charge on one side and a negative charge on the other
resting potential is a product of
active transport of potassium ions in and sodium ions out
potassium ions symbol
K+
sodium ion symbol
Na+
how many potassiums in
2
how many sodiums out
3
what is a result of tissue fluid outside containing many more +ions
- negative charge developed inside
- polarised
membrane potential
Difference in charge between inside and out of a neuron which is created due to the unequal distribution of ions on both sides of the same membrane
action potential
potential difference produced across the plasma membrane of the nerve cell when stimulated reversing the resting potential from -70mV to 40mV
how long does the action potential last
2 miliseconds before reinstablishment of resting potential
role of myelinated fibres
faster conduction speed compared to unmyelinated
role of unmyelinated fibres
with a large diameter transmits action potential much faster than a narrow fibre
what does speed of transmission depend on
resistance offered by axoplasm
narrower the fibre, greater the resistance and lower the speed of conduction of action potential
R^2 method
shows how well the data fit the regression model (the goodness of fit).
variable predicted from independent variable
what happens if R^2 is close to 0
values y arent close to regression line
what happens if R^2 is close to 1
values of y are close to regression line
synapse
connection between the end of a nerve cell and another cell
functionally a tiny gap, the synaptic cleft, transferred by transmitted substances
presynaptic neurone
neurone upstream of a synapse
postsynaptic neurone
neurone downstream of a synapse
neurotransmitter
chemical released at presynaptic membrane of an axon on arrival of an action potential. which transmits the action potential across the synapse
what are neurotransmitter
- small molecules that diffuse quickly
- produced in golgi apparatus
- ensures signal can only pass in one direction
acetylcholine (Ach)
a neutransmitter that functions in both the central and peripheral nervous systems
neuromuscular junctions
specialised synapse between a motor neurone and muscular fibre
step 1 of synapse transmission
Action potential at synapse leads to change in polarity of number and open calcium ion channels
flows in
step 2 of synapse transmission
Calcium ions cause vesicles of transmitter substance to fuse with membrane
transmitter to synaptic cleft
calcium acts as a signal in chemical inside a neuron
step 3 of synapse transmission
Transmitter substance diffuses across cleft and binds with receptor sites accross channels to allow specific ions to pass
step 4 of synapse transmission
Transmitter substance inactivated by enzyme action
Causes channels to close and reestablishes resting potential
step 5 of synapse transmission
Inactivated products reenter presynaptic knob
- turned to neurotransmitter substance
- packed for reuse
