There are many different parts of the body that marijuana has an effect on. The chemicals found in the drug have been known to alter sensory reactions in the brain. Also, long-term use of the drug may produce unfavorable changes in the brain. Over time, the lungs begin to show signs of respiratory damage from regular use of marijuana. As the lung tissue becomes damages, the worst cases evolve in a loss. Smoking marijuana also affects the heart rate and blood pressure of an individual. In regards to learning and functioning in society, the attention span, reaction time, and memory of a marijuana user also suffers damage, which can show at home, school, or work.