Ever felt carsick, airsick or seasick? Motion sickness is the most common medical problem associated with travel. As a child I was always told that "it was in my head," that if I wanted to, I could make it go away. I was made to believe that motion sickness was a psychological problem. To certain extend it is true that it is in my head, but it is not a psychological defect, but rather, a disorder that occurs when conflicting sensory information is sent to the brain. This mild and self-treatable disorder can affect anyone, but recent studies seem to imply that motion sickness may affect certain groups of people more than others. This paper will discuss the causes of motion sickness and will question the genetic and racial implications as contributing factors.
The anatomy of balance
Balance is maintained by a complex interaction of sensory parts of our body. The first are the inner ears, which monitor the directions of motion (such as side to side, back to front, up and down, and turning). Some people may feel dizzy without having to be spinning or turning. This dizziness is sometimes caused by an inner ear problem. Changes of fluids in the semicircular canals of the inner ear are one of the attributing factors of motion sickness. (1). Second, the eyes monitor where the body is in space and also the direction in which the motion is taking place. Third, the skin pressure receptors (joints and spine) send messages to the brain to inform what part of the body is down and touching the ground. Lastly, the muscle and joint sensory receptors are in charge of informing the brain which parts of the body are in motion. Through the interaction of all these parts, the central nervous system (the brain and the spinal cord) receives and processes all the information sent by the above mentioned four systems to make some sense of coordination. (2) If any of the four sensory systems are not in accordance with the rest of the systems, this resulting conflict thus leads to symptoms of nausea, dizziness, and sometimes vomiting. These symptoms are all pertinent to motion sickness. For example, suppose you are riding on Greyhound for thanksgiving, and decide to read a cookbook. While you are reading recipes, your eyes sense that your body is stationary. Your eyes cannot detect you are moving because you are inside the bus reading a book. However, your skin receptors and your inner ear fluids sense that your body is in motion since you are riding a moving bus. Consequently, your brain receives mixed messages, thus being...