Nerve Impulse Transmission Flashcards
What is nerve impulse definition
A signal transmitted along a nerve fibre
What is resting membrane potential
A state where there is no net flow of ions across the membrane
What does the transmission of a nerve impulse require
Changes in the membrane potential of the neurons plasma membrane
What’s an action potential definition
A wave of electrical excitation along a neurons plasma membrane
What’s neurotransmitter’s definition
Chemicals that transmit a signal across a synapse
What do neurotransmitters do
Initiate a response by binding to their receptors(ligand gated ion channels) at a synapse
LEARN DIAGRAM SIMPLE BUT LEARN
Depolarisation definition
A sudden change in membrane potential usually from a negative to positive internal charge
What does depolarisation of the plasma membrane as a result of entry of positive ions do
Triggers the opening of voltage gated sodium channels and further depolarisation occurs
What restores the resting membrane potential
Inactivation of the sodium channels and the opening of potassium channels restores the resting membrane potential
What does binding of neurotransmitter do
Triggers the opening of ligand gated ion channels at a synapse
What happens when sufficient ion movement occurs and the membrane is depolarised at the plasma membrane
The opening of voltage gated sodium channels is triggered and the sodium ions enter the cell down their electrochemical gradient
What does sodium ions entering the cell down their electrochemical gradient do
Leads to a rapid and large change in the membrane potential
What happens a short time after opening the sodium channels
They become inactivated. Voltage gated potassium channels then open to allow potassium ions to move out of the cell to restore the resting membrane potential
What’s step 1 of sodium potassium ions moving in membrane
Stimulas starts the rapid change in voltage or action potential. This must reach above a threshold voltage to start membrane depolarisation
What’s step 2 of sodium potassium ions moving in membrane
Depolarisation is caused by a rapid rise in membrane potential opening of sodium channels non the cellular membrane, resulting in a large influx of sodium ions
What’s step 3 of sodium potassium ions moving in the membrane
Membrane repolarisation results from rapid sodium channel inactivation as well as a large effluent of potassium ions resulting from activated potassium channels
What’s step 4 of sodium potassium ions moving in the membrane
Hyperpolarisation is a lowered membrane potential caused by the efflux of potassium ions and closing of the potassium channels
What’s step 5 of sodium potassium ions moving in the membrane
Resting state is when membrane potential returns to the resting voltage that occurred before the stimulas occured
What does depolarisation of a patch membrane cause
Neighbouring regions of membrane to depolarise and go through the same cycle as adjacent voltage gated sodium channels are opened
Learn depolarisation, action potential and repolarisation diagrams
What happens when the action potential reaches the end of the neuron
It causes vesicles containing neurotransmitters to fuse with the membrane, this releases neurotransmitter which stimulates a response in a connection cell
What does restoration of the resting membrane potential allow
The inactive voltage gated sodium channels to return to a conformation that allows them to open again in response to depolarisation of the membrane
How are ion concentration gradients re established
By sodium potassium pump which actively transports ions in and out of the cell
What happens after repolarisation
The sodium and potassium ion concentration gradients are reduced
What does the sodium potassium pump do in nerve impulse stuff
Restores the sodium and potassium ions back to resting potential levels
