An epoch is longer than an era.
The phosphorus cycle does not include an atmospheric component because phosphorus does not cycle through the atmosphere. In comparison, important processes of the carbon and nitrogen cycle occur in the atmosphere.
Answer:
The Greeks believed in the geocentric model of the universe.
According to this model, the Earth was present in the center whereas the Sun, moon, other planets etc revolved around it. According to Plato, the Earth was spherical in shape and it did not move. Greek philosophers, such as Aristotle and Plato, believed the Earth to be the center of the universe. All other heavenly bodies orbited around the Earth according to the Greek philosophers.
Answer:
The correct order of events is:
C) Nicotine binds to the transmembrane protein that normally binds the neurotransmitter acetylcholine.
A) The acetylcholine receptor is an ion channel, and when a ligand binds, the ion channel opens.
B) An influx of ions carries the signal to the reward areas of the brain.
D) The signal causes release of dopamine in the brain, which causes good feelings.
E) Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).
Explanation:
Nicotine acts on acetyl cholinergic receptors that are located in membranes of the midbrain neurons. Nicotine can activate those receptors or block them more efficiently than acetylcholine. Stimulation of nicotinic receptors leads to an increase in ions flow that reaches the brain and causes dopamine release in the nucleus accumbens through axonal prolongations of the dopaminergic pathway. This response is responsible for the smoker´s recompense sensation.
The dopaminergic pathway is the most important way in the process of nicotine dependence and addiction to the drug.
