3.2 Nerve Impulses

________ caused voltage gated calcium ion channels to open.

Local depolarisation

________ occurs= too many potassium ions cause the inside of the cell to be more negative than- 70 mV.

Hyperpolarisation

________- neurons need glucose → energy to function- always moving or faint.

Diabetes

________ move freely across the membrane.

Potassium ions

________ are absorbed by pre- synaptic neuron.

Breakdown products

A(n) ________= whole process, not just action potential- action potential is the letter being sent.

nerve impulse

Neurons are stimulated by ________ cells (respond to a stimulus e.g.

receptor

Voltage- gated ________ of myelinated neurons are confined to spots (nodes of Ranvier)

sodium channels

________ flow into the cell.

Calcium ions

________ is carried by chemicals called neurotransmitters.

Impulse

________ binds to neuroreceptors in the post- synaptic membrane.

Neurotransmitter

________= potassium leakage → makes it more negative inside cell.

Movement of positive ions

________ helps return to resting membrane potential.

Sodium potassium pump

________ causes voltage gated sodium channels to open and sodium ions rush in intracellular fluid.

Stimulus

Both ________ and K+ are able to leak through respective channels.

Na+

________ transfers a phosphate group= ADP + P- need mitochondria for energy= cellular respiration.

ATP

at rest

when a neuron is not sending signal

and Na+ have more difficult time crossing

Cl

will go from high concentration → low concentration till it reaches equilibrium

this is because diffusion will never stop

done by the pump

need a way of moving Na+ out of the cell and K+ into the cell

need mitochondria for energy = cellular respiration

ATP transfers a phosphate group = ADP + P

taste receptor cells open when a certain chemical in food binds to them

chemical-gated in tongue

action potential is the letter being sent

a nerve impulse = whole process, not just action potential

gate threshold

-55 mV causes more Na+ channels open for 0.5 ms

nothing can stop it

as soon as -55 mV is reached, rest of action potential is triggered

cant be deporalised again

Na+ channels cannot be opened

limits frequency of impulses

can last up to 10 milliseconds

triggers down the axon

different action potentials along neuron = propogate

due to organic anaions than K+ = negative on the inside

greater concentration of negatively charged ions

voltage gated calcium channels

at the end of the pre-synaptic neuron