Active and Passive Immunity. Naturally acquired active immunity occurs when the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response. Artificially acquired active immunity can be induced by a vaccine, a substance that contains the antigen.
Lower back tightness can cause muscle twitching, pain and reduced range of motion. Lower back muscle tightness is the cause of a muscle spasm. This can be brought on by a strain, overuse or muscle weakness, according to BetterMedicine.com.
The sensation of tightness in the hamstrings is very common and can be caused by a variety of factors. Often, to reduce this sensation of tightness the first thing that most people will do is stretch the hamstrings.his is because the sensation of tightness in our muscles can be caused by two things: mechanical tightness or neurological tightness. 1  Mechanical tightness is when a muscle is in a constantly shortened/contracted state. 2  Over time the muscle(s) will adapt by becoming physically shorter and tighter.