Final answer:
Headaches can stem from different mechanisms, including migraines caused by vascular changes, tension headaches due to muscle tightening, and those resulting from systemic infections like meningitis and encephalitis.
Step-by-step explanation:
Headaches can have various causes, and some of the common mechanisms include migraine, tension headaches, and infections. Migraine headaches occur due to blood vessel swelling and increased blood flow, often accompanied by symptoms like severe pain, an upset stomach, and disturbed vision. Tension headaches, the most prevalent type, are caused by the tightening of facial and neck muscles and may be triggered by factors such as stress, poor posture, and sleep deprivation. On the other hand, systemic infections like meningitis and encephalitis can lead to headaches, fever, and additional serious symptoms. Meningitis, typically presenting with fever, headache, and a stiff neck, requires prompt medical treatment, especially when bacterial, to prevent severe outcomes. Encephalitis, another brain infection, can result in headaches, fever, drowsiness, and confusion, with the potential for brain swelling that can become life-threatening.