My thinking on this question is that the shot, (I'm assuming you mean a vaccination) creates inflammation. What is being injected during a vaccination is usually whole bacterial cells or viral particles that have been attenuated (genetically altered) so that the genes that make them disease-causing are removed, but the antigens (glycoproteins) that mark them as non-self are intact. Your white blood cells, like your B-lymphocytes, use the antigens as molecular templates to make antibodies, which make you immune to future infections by the same germs, even though you never got sick. The immune system still responds to the presence of foreign, non-self cells in its generic way, though - by creating inflammation. Basophils release histamine, which dilate the blood vessels and make them "leaky". The fluid of the blood leaks out of the blood vessels and creates swelling, which puts pressure on free nerve endings, which is translated into pain by your brain. You can tell different people have more sensitive immune systems. My mom gets a huge, painful swelling in her arm after every Tetanus shot, but I never have.
Marlee,
ReplyDeleteMy thinking on this question is that the shot, (I'm assuming you mean a vaccination) creates inflammation. What is being injected during a vaccination is usually whole bacterial cells or viral particles that have been attenuated (genetically altered) so that the genes that make them disease-causing are removed, but the antigens (glycoproteins) that mark them as non-self are intact. Your white blood cells, like your B-lymphocytes, use the antigens as molecular templates to make antibodies, which make you immune to future infections by the same germs, even though you never got sick. The immune system still responds to the presence of foreign, non-self cells in its generic way, though - by creating inflammation. Basophils release histamine, which dilate the blood vessels and make them "leaky". The fluid of the blood leaks out of the blood vessels and creates swelling, which puts pressure on free nerve endings, which is translated into pain by your brain. You can tell different people have more sensitive immune systems. My mom gets a huge, painful swelling in her arm after every Tetanus shot, but I never have.