How do the lungs excrete waste material from the body?
a. the lungs push carbon dioxide from red blood cells out of the body through exhalation.
b. the lungs convert poisonous gas into oxygen that the body can use.
c. the lungs push nitrogen into the digestive system so that it can be removed by the body.
d. the lungs protective cells in the body break down gaseous urea.

 A. The lungs push carbon dioxide from red blood cells out of the body through exhalation.

The lungs are the two vital organs of the body their function is to purify air containing carbon dioxide and lacking oxygen into oxygenated air. The movement of the lungs in the inhalation of oxygen and exhalation of carbon dioxide is controlled by the diaphragm. Carbon dioxide is a metabolic waste which needs to be expel out from all the cells of the body hence, the lungs helps in this process.

1. glaciers are melting

2. more water going into ocean (water's such as fresh waters, etc)

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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