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There are major differences in the metabolism of morphine and the illegal drug heroin. Morphine mostly produces its CNS effects through m-receptors, and at k- and d-receptors. Heroin has a slight affinity for opiate receptors. Most of its actions are due to metabolism to active metabolites (6-acetylmorphine, morphine, and morphine-6-glucuronide).
Of the estimated 2 million heroin users in the United States, 600,000–800,000 are considered hardcore addicts. Heroin addiction is considered to be one of the hardest addictions to recover from.
Each year in the United States, there are approximately six million pregnancies. This means that at any one time, about 4% of women in the United States are pregnant.
Thyroid conditions cause a higher risk of fibromyalgia and chronic fatigue syndrome.
A strange skin disease referred to as Morgellons has occurred in the southern United States and in California. Symptoms include slowly healing sores, joint pain, persistent fatigue, and a sensation of things crawling through the skin. Another symptom is strange-looking, threadlike extrusions coming out of the skin.
![The absorption of cerebrospinal fluid from the subarachnoid space (blue) into a major sinus. Note ...](https://biology-forums.com/gallery/30/medium_548020_02_06_17_12_10_51_30203561.png)
![The anterior arm (shoulder, axilla, anticubital, and inner wrist areas). Approach deep pressure in ...](https://biology-forums.com/gallery/32/medium_380798_22_08_17_12_15_35_32802119.jpeg)