Human body to comparative physiology and ecophysiology. Most recently, evolutionary physiology has become a distinct subdiscipline. Human body The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a head, neck, trunk (which includes the thorax and abdomen), arms and hands, legs and feet. The study of the human body involves anatomy, physiology, histology and embryology. The body varies anatomically in known ways. Physiology focuses on the systems and organs of the human
Effect of spaceflight on the human body deleterious effects on human health. Humans are well-adapted to the physical conditions at the surface of the earth, and so in response to weightlessness, various physiological systems begin to change, and in some cases, atrophy. Though these changes are usually temporary, some do have a long-term impact on human health. Short-term exposure to microgravity causes space adaptation syndrome, a self-limiting nausea caused by derangement of the vestibular system. Long-term exposure causes multiple health problems, one of the most significant being loss of bone and muscle mass. Over time these deconditioning effects can impair astronauts' performance, increase their risk of injury,