Final answer:
Morphine and codeine are derived from the opium poppy plant, which contains these alkaloids along with other organic substances. These alkaloids act as powerful painkillers by changing the way a person experiences pain.
Step-by-step explanation:
Morphine and codeine are derived from the opium poppy, Papaver somniferum. Opium is obtained from the dried latex of the poppy plant, which contains morphine and codeine along with other organic substances. These alkaloids act as powerful painkillers by attaching to specific receptors in the brain, spinal cord, and gastrointestinal tract, which changes the way a person experiences pain.