Case Study: Under Pressure
Looking at the photo of a football game above, you can see why it is so important that the players wear helmets. Football often involves forceful impact to the head as players tackle each other. This can cause damage to the brain — either temporarily as in the case of a concussion, or long-term and more severe types of damage. Helmets are critical to reducing the incidence of traumatic brain injuries (TBIs), but they do not fully prevent them.
Take the example of 43-year-old Jason. As a former professional football player who also played in college and high school, Jason sustained many high-impact head injuries over the course of his football playing years. A few years ago, Jason began experiencing a variety of troubling symptoms, including the loss of bladder control (i.e. the involuntary leakage of urine), memory loss, and difficulty in walking. Symptoms such as these are often signs of damage to the nervous system, which includes the brain, spinal cord, and nerves, but they can result from many different types of injuries or diseases that affect the nervous system. In order to treat him properly, Jason’s doctors needed to do several tests to determine the exact cause of his symptoms. These included a spinal tap to see if he had an infection, and an MRI (magnetic resonance imaging) to see if there were any problems they could observe in and around his brain.
The MRI revealed the cause of Jason’s symptoms. There are fluid-filled spaces within the brain called ventricles, and Jason’s ventricles were enlarged compared to normal ventricles. Based on this observation combined with the results of other tests, Jason’s doctor diagnosed him with hydrocephalus, a term that literally means “water head.” Hydrocephalus occurs when the fluid that fills the ventricles, called cerebrospinal fluid, builds up excessively. This causes the ventricles to become enlarged and puts pressure on the brain, which can cause a variety of neurological symptoms including the ones Jason was experiencing. You can see the difference between normal ventricles and ventricles that are enlarged due to hydrocephalus in the illustration below. Notice how the brain becomes “squeezed” due to hydrocephalus in the image on the right.
Hydrocephalus often occurs at birth, due to genetic factors or events that occurred during fetal development. Because babies are born with skull bones that are not fully fused, the skull of a baby born with hydrocephalus can expand and relieve some of the pressure on the brain, as reflected in the enlarged head size shown above. But adults have fully fused, inflexible skulls, so when hydrocephalus occurs in an adult, the brain experiences all of the increased pressure.
Why did Jason develop hydrocephalus? There are many possible causes of hydrocephalus in adults, including tumors, infections, hemorrhages, and TBIs. Given his repeated and long history of TBIs due to football, and the absence of any evidence of infection, tumor, or other cause, Jason’s doctor thinks his head injuries were most likely responsible for his hydrocephalus.
Although hydrocephalus is serious, there are treatments. Read the rest of this chapter to learn about the cells, tissues, organs, cavities, and systems of the body, how they are interconnected, and the importance of keeping the body in a state of homeostasis, or balance. The amount of cerebrospinal fluid in the ventricles is normally kept at a relatively steady level, and the potentially devastating symptoms of hydrocephalus are an example of what can happen when a system in the body becomes unbalanced. At the end of the chapter, you will learn about Jason’s treatment and prognosis.
Chapter Overview: Introduction to the Human Body
In this chapter, you will learn about the general organization and functions of the human body. Specifically, you will learn about:
- The organization of the body from atoms and molecules up through cells, tissues, organs, and organ systems.
- How organ systems work together to carry out the functions of life.
- The variety of different specialized cell types in humans, the four major types of human tissues, and some of their functions.
- What organs are and the 11 major organ systems of the human body.
- Spaces in the body called body cavities, and the organs they hold and protect.
- The tissues and fluid that protect the brain and spinal cord.
- How organ systems communicate and interact in body processes such as cellular respiration, digestion, the fight-or-flight response to stressors, and physical activities such as sports.
- How homeostasis is maintained to keep the body in a relatively steady state, and the problems that can be caused by loss of homeostasis, such as diabetes.
As you read the chapter, think about the following questions:
1. What is the normal function of cerebrospinal fluid?
2. What is a spinal tap and how does it test for infection?
3. In Jason’s case, what organs and organ systems are probably affected by his hydrocephalus? What are some ways in which these organ systems interact?
4. The level of cerebrospinal fluid is normally kept in a state of homeostasis. What are other examples of types of homeostasis that keep your body functioning properly?