DENTAL CARIE, DRAWING Formation and development of a tooth decay. From left to right : - healthy tooth - tooth decay that attacks the enamel (stage 1). - tooth decay that affects the dentin (stage 2). - tooth decay that affects the dental pulp (stage 3). - tooth decay that affects the dental pulp with an abscess on the root.

Rheumatoid arthritis Joint destruction process, synovial hyperplasia, angiogenesis, edema, lymphocyte infiltration, treatments. In the upper left is a joint seen in section with articular destruction with abnormal secretion of synovial fluid, synovial hyperplasia with lymphocyte infiltration and angiogenesis. Below, zoom on the synovium and the process of synovial cell proliferation, the production of proteases and free radicals induced by cytokines TNFa and lymphokines IL1 causing joint destruction.

CIRCADIAN RHYTHM Illustration of the biological clock. Depending on sunlight perceived by the eye, signals are sent to the suprachiasmatic nucleus, home of the circadian clock, located in the hypothalamus, which controls various biological rhythms. The brain controls the secretion of melatonin (sleep hormone), which increases as light diminishes.

PACEMAKER Pacemaker implanted in the chest. Frontal chest x-ray.

HIV antiretrovirals HIV: site of action of antiretrovirals anti-HIV. On the left, the HIV virus binds to the CD4 T cell CD4 receptor, which will allow the co-receptor CCR5 to melt and release the viral RNA into the cytoplasm. After reverse transcription, the proviral DNA is integrated into the cellular genome and will synthesize viral precursor proteins and viral mRNA to then assemble and form new infectious viruses, released to the right of the image.

Meditation Pain Brain Meditation modifies the way the brain works, activating areas of the brain involved in pain control. Mindfulness meditation modifies the relationship to pain. The main difference has been found in the posterior cingulate, which is involved in concentration and self-awareness. The insular or insula cortex is associated with limbal functions, behaviours and emotions and the formation of memory, its anterior part is involved in anticipating pain and some regions of the prefrontal cortex. The placebo effect triggers the production of molecules with pain-relieving effects, comparable to those that a real drug would have produced. The psychological suggestion causes biochemical consequences, with activity in an area of the brain called the accumbens nucleus.