C2.2 Neural Signalling Flashcards by Anvika Khaitan

CNS

central nervous system in vertebrates
brain and spinal chord

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PNS

Peripheral nervous system invertebrates
nerves that sensory information to the CNS and nerves that convey impulses to muscles and glands

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nerve

nerve bundle of many nerve fibers connecting the CNS with parts of the body

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neurone

a cell that carries electrical impulses

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what are neurones specialised for

transmittion of information

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dendrite

a fine fibrous structure on a neuron that receives impulses from other neurons

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impulse

momentary reversal in electrical potential different across neurones membranes

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motor neuron

Carries impulses away from CNS to effector many fine dendrites and a single long axon

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long axon role in motor neuron

impulses away from body

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dendrites role in motor neuron

impulses towards body

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sensory neurone

carrying impulses from a sense organ or receptor to CNS

have a cytoplasmic fibre running to cell body

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relay neurones other name

interneurones

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relay neurones

connect sensory and motor neurone

like a thread like extention of a nerve cell

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receptor

responds to stimulation by production of an action potential

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axon

Fiber carrying impulses away from the cell body of a neuron

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dendron

Fiber carrying impulses toward the cell body of neurons

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Schwann cell

Cells of the PNS that wrap around axons of motor neurons and sensory neurons to form a myelin sheath

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myelin sheath

insulating sheath around axons of nerve fibers formed by Schwann cells

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node of ranvier

Gap in myelin sheath around a myelinated nerve fiber

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resting potential

Potential difference across a nerve cell membrane when it is not being stimulated

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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

how many sodiums out

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