Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Pain is always a personal experience that is in any given moment influenced to varying degrees by biological, psychological, and social factors. Considering the complexity and subjectivity of the term, it is difficult to estimate the epidemiological situation in the world. Studies in individual countries indicate chronic pain prevalence close to 25%, whereas acute pain is the most common complaint which prompts patients to seek medical aid. In contrast to nociception which implies the neural process of encoding noxious stimuli, pain is a subjective experience and it doesn't necessarily stem from activity of sensory neurons nor does it correlate with severity of injury. Through the process of nociception, the nervous system detects and interprets a variety of thermal, mechanical, and chemical noxious stimuli. Nociception entails the processes of transduction, transmission, perception, and modulation of nociceptive signal. Nociceptors, sensory receptors of the peripheral nervous system, play a major role in nociception because of their capability of transducing noxious stimuli to action potential. Transmission refers to the passage of resulting nociceptive signal to the central nervous system where it is integrated and perceived as pain. Modulation pertains to processes of inhibition or facilitation of nociceptive transmission. Molecular basis of genesis, conduction and modulation of the nociceptive signal is the foundation of existing pain treatment. Furthermore, it opens doors to new treatments and pharmacological agents. Since it is essential to understand the mechanisms of pain generation in order to treat it successfully, the aim of this thesis is to describe the underlying biological components of both physiological pain processing and modulation of the pain response and involved neuroanatomical pathways.