Nitrous oxide enters the blood by diffusion from the alveoli whilst it is being inhaled, but does not bind with hemoglobin. n2o inhibits nmda receptors in the brain whilst simultaneously encouraging the stimulation of the parasympathetic gaba receptors. this eventually produces an effect.

The correct answer would be - anesthetic effect.

Explanation:

The mechanism of entering and affecting the CNS or central nervous system by inhibiting NMDA receptors and simultaneously stimulating the parasympathetic GABA receptors to cause an anesthetic effect in the body is explained in question too.

This mechanism is responsible for the anesthetic effect and vigorous oxide increase the release of endorphins of opioid neurotransmitters which is act as pain killers. This anesthetic effect causes less or no pain instead of a limbic depressor.

Thus, the correct answer is - anesthetic effect.

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."    

he movement of air through earth's or any planet's atmosphere is called wind, and the main cause of earth's winds is uneven heating by the sun. this uneven heating causes changes of atmospheric pressure, and winds blow from regions with high pressure to those with low pressure.

i hope this : )