What Blood Vessels Tell Us about Childhood Obesity

Little boy taking candy from jar

Credit: IStock

Did you know that blood vessels can “talk?” That’s right: Changes in the cells within blood vessels can communicate important information about the overall health of the cardiovascular system. The inside of blood vessels are lined endothelial cells—protective cells that form a tight barrier through which only certain substances such as water or glucose can enter. Endothelial cells also make many substances that keep the vessels healthy so that the heart can effectively pump blood to all of the tissues and organs. While strong, endothelial cells are also sensitive to changes or inflammation within the body. So, if the cells become damaged or stop functioning properly, it can indicate that there is a problem occurring elsewhere in the body.

Tuning in to the messages that blood vessels can reveal what’s going on inside our bodies, not just what’s happening within the vessels themselves.  For example, vessels can expose the effects of obesity and can help scientists discover links between body composition and the body’s response to food and sugar intake.

In a recent study published in the Journal of Pediatrics, researchers measured the endothelial function of teens ages 12–19 years for clues into the relationship between obesity and how the body handled sugar. By conducting the study in teenagers with a wide range of body compositions—from normal weight to obese—they were able to make conclusions about blood vessel health, how it relates to obesity, and how obesity contributes to the development of problems in the body’s ability to handle sugar properly. They found that obese young people had higher levels of endothelial cell damage that correlated with the body’s inability to handle sugar. Indeed, in this example, the endothelial cells in the vessels “spoke” to the researchers about the health of the study participants.

This study also underscores the importance of preventing childhood obesity, which has been linked to a reduction in the body’s ability to regulate the amount of sugar in the blood. Limiting the intake of processed, high-sugar food and drinks is a great start. The second step is to increase physical activity during childhood and adolescent years. These habits, when started early, may carry into adulthood and lead to a healthier life. September is Childhood Obesity Awareness Month. Find more tips for helping kids maintain a healthy weight on the CDC website.

Audrey Vasauskas

Shhh … I’m Hibernating!

Bear nest

Man crawling out of uninhabited bear hibernating den (not recommended). Credit: IStock

As the days grow shorter, many animals, such as bats, bears and bees, begin getting ready to hibernate. It’s a process that allows animals to spend the winter months conserving energy by reducing metabolism, oxygen consumption and body temperature. So why don’t humans do it, too? Well, a new study suggests that some humans—specifically those with chronic fatigue syndrome (CFS), which affects more than 2.5 million people in the U.S.—may be doing something similar to hibernating.

People with chronic fatigue syndrome experience extreme fatigue. But this is not your run-of-the-mill kind of post-holiday exhaustion. It is severe fatigue that does not get better, even with sleep. People with CFS may also experience issues related to memory and headaches. It’s not clear why people develop the disorder, but some theories point to infections, exposure to chemicals or stress as possible causes.

The new study, published in the Proceedings of the National Academies of Science, looked at specific molecules (metabolites) that are byproducts of energy production (metabolism) in the blood of people who have CFS and healthy people who do not have the disease. The researchers found that people with the condition had 80 percent fewer metabolites compared to the healthy control subjects. Those with chronic fatigue syndrome also had some impairment in the way their metabolism functioned. The findings suggest a less active metabolism in people with CFS similar to metabolic activity seen in animals that hibernate. Reduction in metabolic state is thought to be a defensive strategy all humans can use to cope with situations in which environmental or other stressors are present. The problem for people with CFS is that this defense mechanism stays turned on, slowing metabolism—and draining energy—on an ongoing basis.

What’s great about this study is that researchers and clinicians finally have a set of chemical markers in the blood that they can use to test people for CFS. The hope is that by understanding what’s going wrong, metabolically speaking, a treatment can be developed.

Karen SweazeaKaren Sweazea, PhD, is an associate professor in the School of Nutrition & Health Promotion and the School of Life Sciences at Arizona State University.

What Happens during Heat Stroke and How to Prevent It


Young kids are at increased risk of heat stroke. Credit: IStock

Temperatures in July and August 2016 were the hottest ever recorded on the planet and much of the U.S. is still struggling with a heat wave. Hundreds of heat-related deaths occur in the U.S. each year, and these rates are on the rise. Awareness of when the body is losing the ability to deal with heat and seeking treatment for heat illness and dehydration are key to reducing heat stroke-related deaths. So it’s extremely important to understand the causes and symptoms of heat illnesses, such as heat stroke, and who’s at risk.

Under normal physiologic conditions, the human body can counteract overheating by sweating and other means. Heat illness occurs when the body is overwhelmed by the heat and can no longer maintain its temperature. Heat stroke is the most dangerous type of heat illness, though heat fatigue, heat cramps and heat exhaustion can also occur. These conditions can have a variety of effects on the body, blood flow and a person’s mental capacity. For example, heat stress with mild to moderate dehydration can result in loss of blood flow to the brain and the inability to stay upright.

Who’s at Risk of Heat Stroke and How to Prevent It

Heat stroke can develop in people of any age or health status, but the sedentary elderly, very young people and individuals with chronic disease such as heart disease have a significantly higher risk of having one. People who take certain medications, drink alcohol, are very overweight or who have poor blood circulation (such as those with diabetes and heart disease) or reduced sweat production due to aging are also at an increased risk. Prolonged, intense exercise in a hot environment without proper hydration can cause a heat stroke during heat waves, even among young and healthy people.

The most effective ways to prevent heat stroke is to ensure that high-risk populations:

  • have access to air conditioning or a cool environment with air flow;
  • dress comfortably in layers that can be removed as the temperature rises;
  • stay hydrated by consuming water, fruits and vegetables (such as watermelon, tomatoes, lettuce, pineapple, cranberries and oranges), herbal tea, etc; and
  • understand the signs and symptoms of heat stroke.

People may be developing heat illness if they appear confused or faint, are not sweating or have flushed skin after being exposed to the heat. Any individual experiencing these symptoms should be removed from the heat, offered fluids and examined for the possibility of heat illness or heat stroke.


Robert Carter, III, PhD, MPH, FACSM, is an adjunct professor of emergency medicine at the University of Texas Health Science Center at San Antonio and the product manager for medical simulation at the Program Executive Office for Simulation, Training and Instrumentation in Orlando.

What Is Physiology?…and Why You Should Care


Credit: IStock

Physiology provides an explanation of life, and everyone—not just doctors and scientists—would benefit from understanding some essential physiological concepts. But to learn how physiology applies to everyday life, you must first understand what it is.

Physiology is the study of how living organisms function in sickness and in health. Physiologists study functions that may take place on a small scale, such as in molecules or individual cells, or in whole animals such as humans. Physiological research has led to breakthroughs in our understanding of how we move, reproduce, gain and lose weight, live, thrive, die and much more. Because of this, a strong grasp of physiology is imperative for doctors and other health care providers who see patients and treat disease.

But it’s also important for the average person to have an understanding of physiology. It can help patients understand why their doctor recommends that they work out, eat less salt or take a certain medicine. Physiology can also inform our everyday decisions related to diet, exercise and sleep.

Integrative physiologists, like me, study how the body responds to stimuli such as exercise. Some examples of the type of functions we study include:

  • How oxygen supports metabolism, how its use determines how many calories we “burn” at rest and during exercise and how it can help determine a person’s cardiorespiratory fitness level.
  • How the body controls blood pressure, what happens to blood pressure when we exercise, and what can be done to lower blood pressure and prevent it from getting too high.
  • The critical role of sodium (salt) in regulating fluid levels in the body and how it can raise blood pressure and damage tissues when too much is consumed.
  • The importance of blood flow regulation in delivering nutrients and oxygen to the working muscles at rest and during exercise, which is critical for athletes and for slowing down age-related declines in physical function.

Key physiology concepts provide the framework for addressing these issues, and there is still so much to learn and explore!

To quote one of physiology’s forefathers, Arthur C. Guyton, “Physiology is indeed an explanation of life. What other subject matter is more fascinating, more exciting, more beautiful than the subject of life?” I agree (though I may be biased). But whether you’re intrigued by physiology or not, the insights into health and disease that it uncovers hold a benefit for us all.

william-farquharWilliam B. Farquhar, PhD, is a professor and chair in the department of kinesiology and applied physiology at the University of Delaware. He is a Fellow of the American College of Sports Medicine and member of the American Physiological Society.

A 10,000-Foot View from the ALMA Observatory in Atacama

Atacama Telescope

Rare clouds drift behind a telescope at the ALMA Observatory in Chile.

After fulfilling the main purpose of our trip—to build relationships with universities in Santiago, the capital city of Chile—we headed north to the Atacama Desert, the driest non-polar desert in the world.  The small town of San Pedro de Atacama serves as a starting point for adventure travelers looking to experience all this beautiful landscape has to offer. It is also the closest town to the Atacama Large Millimeter/submillimeter Array (ALMA)—a multi-national space observatory that seeks to understand our cosmic origins.

My colleagues and I boarded a public tour bus to the ALMA operations center. The on-board safety video once again put physiology front and center as it discussed a reality that locals here deal with every day: the effects of altitude on the human body.

San Pedro, and most of the Atacama Desert, is located at around 8,000 feet above sea level. The ALMA control center sits above the town at around 10,000 feet. Most impressively, the radio telescopes that make the observations are located on a plateau at 16,000 feet high. For comparison, Mount Whitney, the highest mountain in the continental U.S., is 14,505 feet above sea level.

UV Warning Atacama

A warning to ALMA visitors about prolonged UV exposure.

Spending time at high altitudes can have an impact on the cardiovascular and respiratory systems. The increased ultraviolet exposure is significant, and ALMA visitors (even just to the control center) are cautioned against spending prolonged periods in the sun and are advised to wear sunscreen and protective clothing. The extremely arid Atacama Desert also challenges the body’s ability to maintain proper hydration, so water is frequently provided to visitors.

The safety video explained that at 10,000 feet, the control center is considered “moderate” altitude that most people can tolerate well. However, we learned that any visitors to the actual telescopes—which the general public is not allowed to visit—must go through a medical screening that includes taking vital signs (heart rate, blood pressure, blood oxygenation) and assessing signs and symptoms of altitude sickness (dizziness, headaches, nausea). Telescope visitors must also spend a minimum of one night getting used to the high elevation (acclimatizing) in Calama (the town where the nearest airport is) or San Pedro to prepare the body for this challenging environment. They are also given supplemental oxygen to help prevent any altitude-related issues and to allow them to perform physical tasks that might otherwise be too difficult.

All of these physiological challenges of visiting and working at ALMA ultimately are what makes it perfectly suited for its main purpose, observing our skies. Dryness, high altitude, no clouds and minimal light or radio pollution from nearby sparsely populated towns (it’s not easy to live in the Atacama!) are perfect conditions for the ALMA scientists to try to solve important astronomical mysteries.

Anne Crecelius - Chile

Crecelius puts safety first during her visit to the ALMA Observatory.

This post is part two of a three-part series by physiologist Anne Crecelius, PhD, chronicling her summer of research and travels through South America. (Read part one here.) Crecelius is assistant professor at the University of Dayton.