There is external and internal so I'll list th external. The most important is skin then mucus, sweat or secretion, hair, nails and tears which are all part of the integumentary. Some internal defenses are white blood cells and T cells.
Answer:
D, they are all the same size.
Answer:
"Action potential is a rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane with a characteristic pattern."
It is the mode through which a neuron transports electrical signals.
Explanation:
- Option - (a) is the best choice to choose from,
- <u>The refractory period :</u>
A second action potential cannot occur until the membrane has recovered or reestablished, this is the refractory period. The absolute refractory period coincides with inactivation of voltage-gated sodium channels which makes it impossible to generate another nerve impulse.
I think it is D for mountains form from the movement of tectonic plates which create volcanoes that erupt and form mountains