With the beginning of the middle proterozoic comes the first evidence of oxgen build up in the atmosphere. with is catastrophe came eukaryotic forms. these include multicellular algae, and toward the end of the proterozoic the first animals
7.5 too, its kinda of ratio, 1cm : 1Km to 7.5cm : x
x will be equal 7.5 km
It's the sodium ion.
When a neural impulse is fired in both neurons, it is always cause by an excited electron in one neuron moving to the other neuron to destabilize the balance of ions trying to keep them at equilibrium. This action either depolarizes or hyper-polarizes the membrane. If it does, then sodium ions--the key deficient ones--can flow into that region of low charge and maintain that state of low charge, keeping the cell membrane stable.
Neurological - by nerves
Endocrinological - by blood and secrets
