When caffeine is consumed the heart beat becomes faster, along with the rate respiration, basal metabolic rate, and the production of stomach acid and urine; one other effect is that it relaxes smooth muscles, most likely the bronchial muscle. These symptoms can start anywhere from fifteen to forty five minutes after caffeine is consumed and the central nervous system which is affected between thirty and sixty minutes after ingestion. But these times depend on the person’s hormonal status, whether he/she smokes or takes medications, or has a disease that impairs liver functioning.