[The physiological and cultural roots of pain]

Pain serves as a critical warning signal that alerts the body to potential or actual harm. When mechanical pressure on the skin is intense, such as from a sharp pinch, the sensation transitions from touch to pain. Similarly, extreme temperatures, like a hot pot handle, convert the sensation of heat into pain. Pain can also result from overstimulation of other senses, such as blinding light, loud noise, or the intense heat from habañero peppers. This ability to sense pain is essential for...

Nociception—the ability to feel pain—is essential for an organism’s survival and overall well-being. Noxious stimuli such as piercing pain from a sharp object, heat from an open flame, or contact with corrosive chemicals are first detected by sensory receptors, called nociceptors, located on nerve endings. Nociceptors express ion channels that convert noxious stimuli into electrical signals. When these signals reach the brain via sensory neurons, they are perceived as pain. Thus, pain helps the...

Pain is critical to various clinical pathologies, provoking an urgent need for effective management. Pain, whether acute or chronic, is a complex neurochemical process. Its alleviation depends on the type, with nonopioid analgesics effective for mild to moderate pain, such as musculoskeletal or inflammatory pain, while neuropathic pain responds best to anticonvulsants, tricyclic antidepressants, or serotonin/norepinephrine reuptake inhibitors. For severe acute or chronic pain, opioids may be...

Bones are dynamic organs that require a rich supply of oxygen and nutrients. Around 5% to 10% of the cardiac output supplies blood to the bones. A typical long bone has three main sources: the nutrient artery, the metaphyseal and epiphyseal arteries, and the periosteal arteries.
Nutrient Artery
The nutrient artery is the main blood vessel that enters the diaphysis via the nutrient foramen. While most long bones have only one nutrient foramen, large bones, such as the femur, may have two. This...

Primary motives such as sleep, sex, and pain avoidance are crucial drivers of behavior in humans and animals. These motives ensure survival, reproductive success, and overall well-being by prompting actions that meet essential bodily needs.
Sleep is a fundamental physiological drive that fosters a state of restfulness crucial for several bodily functions. It facilitates body restoration, the process by which the body repairs, rejuvenates, and maintains itself during sleep, including memory...

The James-Lange theory of emotion, proposed by William James and Carl Lange in the late 19th century, asserts that emotions are the result of physiological reactions to external stimuli. Contrary to the traditional view, which suggests that emotions directly arise from the perception of stimuli, this theory proposes that emotions occur as a consequence of the body's responses to such stimuli. According to this framework, an emotional experience is a cognitive interpretation of physiological...