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posted: 1/20/2014 11:53 AM

It's important to understand how your body works

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  • In a 2011 game, left-hander Doug Davis pitches for the Chicago Cubs against the Boston Red Sox while right-handers shortstop Starlin Castro and left fielder Alfonso Soriano watch. Handedness is determined during early childhood, but no one really knows how.

      In a 2011 game, left-hander Doug Davis pitches for the Chicago Cubs against the Boston Red Sox while right-handers shortstop Starlin Castro and left fielder Alfonso Soriano watch. Handedness is determined during early childhood, but no one really knows how.
    ASSOCIATED PRESS

 

You wanted to know

Students in Elise Diaz's fifth-grade class at Prairie Trail School in Wadsworth asked these questions about how the body works: "What determines traits like eye color? Why am I right-handed? How does your body grow taller?"

Knowing how the body functions is important. If you understand how a body operates, then you'll know if everything is working the way it's supposed to. And knowing why it operates the way it does helps you to know how to develop a lifelong plan for good health.

Experts at the Ann & Robert H. Lurie Children's Hospital of Chicago had these answers to students' questions about the body:

• "What determines traits like eye color?" Chances are, most people reading this have brown eyes. That's because brown is a dominant eye color, determined by genes and by pigment in the eye. Blue is recessive, meaning the gene for blue eyes will only be dominant if both parents carry genes for blue eyes.

"Eye color is definitely genetic," said Dr. Barbara Burton, professor of pediatrics, Northwestern University Feinberg School of Medicine, attending physician, division of Genetics, Birth Defects and Metabolism at Lurie Children's Hospital.

"People used to think it was just one gene. There's one major gene and there are other genes as well."

Burton explained that brown coloration means there's more pigment in the eye and blue means there's an absence of melanin, the pigment that makes skin, hair and eye color.

"A modifier in additional genes can create effects on the major gene to create hazel- or gray-colored eyes," Burton added.

Genetics, the process by which parents pass traits to their children, is a science that has been well researched for nearly two centuries. Within the past 50 years, scientists have developed gene therapies and medications to help people born with genetically-caused disorders, such as phenylketonuria, commonly called PKU.

Burton's research includes helping people with PKU and Hunter's syndrome, a progressive brain disease affecting the brain and other organs.

"In genetics, you can understand the disease from the gene to the molecule to the biochemistry to the organ and the patient. It's a fascinating field and intellectually challenging," Burton said.

• "Why am I right-handed?" Handedness -- right- or left-handedness or even the ability to use either hand, called ambidexterity -- has no known source or cause.

"Handedness develops around the age of 2 or 3," said Dr. Charu Venkatesan, pediatric neurologist at Lurie Children's Hospital. "Babies' and kids' brains have plasticity," she explained.

Under normal circumstances the left side of the brain directs the right side of the body and the right side of the brain drives the left. In babies, the brain will compensate if one side is impaired and push the other side of the brain to take on new functions.

One piece of the puzzle about left- and right-handedness is that, in most people, language stems from the left side of the brain.

"In 90 percent of people, left is dominant," Venkatesan said. That's why most people are right-handed. "Language is not the reason," she said.

Both functions occur on the same side of the brain -- either the right or the left.

"In people who are bi- or trilingual, it's represented differently in their brains."

The brain plasticity seen in babies makes it much easier for young people, younger than age 9, to learn to speak a different language with no foreign accent.

"It's fascinating how capable a young brain is," Venkatesan said.

Venkatesan's research includes understanding how the young brain responds to injury and how repairing processes can be improved.

• "How does your body grow taller?" A whole symphony of body functions are involved in growth. Genetics, diet and brain-triggered hormones contribute to each individual cell's function and your body's growth plan. Growth begins before you're born, with the biggest growth spurt happening in the womb.

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