Structure Precautions Side effects Dose and uses Structure Morphine is obtained from opium, the juice secreted by the seeds of the poppy. It works on several types of receptors, widely found in nervous tissue. These other opioids may be natural occurring substances, such as morphine, or made in the laboratory such as pethidine.
Morphine works on receptors in the cell membranes.
These are protein-lipid molecules that alter their shape when stimulated to effect molecular changes within cells. There are thought to be three types of receptors that respond to opioids, mu, kappa and lambda. Morphine acts mainly on mu receptors to cause a wide variety of effects. The most important of these are relief of pain and respiratory depression. In anaesthesia morphine is used to relieve pain.