The central sleep apnea is a condition, in which the person rapidly stops and starts breathing during the sleep.
The condition of the central sleep apnea is due to the change in the signaling pattern during the time of sleep. During this process, the respiratory centers present in the brain do not respond well and sometimes do not send signals to the muscle responsible for respiration.
Hence, the given blank can be filled with central sleep apnea.
The organ is the LUNGS.
The lungs excrete carbon dioxide and water vapour through metabolism.
The lungs are used for breathing in humans, through the lungs we take in oxygen which is carried by the blood to all the part of the body and we exhale carbon dioxide which is a waste product generated as a result of the reactions that occur in the body.
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.
Liquid water, which is necessary for life as we know it, continues to exist on the surface of Earth because the planet is at a distance, known as the habitable zone, far enough from the Sun that it does not lose its water to the runaway greenhouse effect.