Human body of different cavities, separated areas which house different organ systems. The brain and central nervous system reside in an area protected from the rest of the body by the blood brain barrier. The lungs sit in the pleural cavity. The intestines, liver, and spleen sit in the abdominal cavity Height, weight, shape and other body proportions vary individually and with age and sex. Body shape is influenced by the distribution of muscle and fat tissue. Human physiology is the study of how the human body functions. This includes the mechanical, physical, bioelectrical, and biochemical functions of humans in good health,
Passions of the Soul in reality the actions of the body on the soul (art. 25). The soul suffers the influence of the body and is entirely subject to the influence of the passions. In the manner by which Descartes explains the human body, the animal spirits stimulate the pineal gland and cause many troubles (or strong emotions) in the soul. The passions attack the soul and force the body to commit inappropriate actions. It was therefore necessary for Descartes to study in the second part of his treatise the particular effects of each separate passion and its manners of manifestation. The study of