CSB #8: BMI and its Effect on Heart Rate, Blood Pressure, and Respiration Rate

Authors: Justin Lee, Andrew Jin, and Andrew Zhang


What is a “BMI”? Literally, it means a person’s Body Mass Index, but it is often considered as a comparing measure such as weight. If a person’s BMI is under 18.5, that person is considered underweight. Normal weight is between 18.5 and 24.9, and overweight is is a BMI of 25-29.9. Beyond that, obesity is a BMI of 30 or higher.The components used in order to calculate one’s BMI are the person’s weight and height. Our group’s experiment tests whether one’s BMI affects the increase or decrease in blood pressure, heart rate, and respiration rate after exercise. We predicted that a higher body mass index will result in a higher blood pressure, heart rate, and respiration rate after exercise because the heart will have to work harder to circulate the extra oxygen needed from the extra work load. Because of this heavy work load on the heart, we also wanted to see whether there was a possible correlation between higher BMI’s and probability of heart disease. In the heart attack video we saw in class, the victim was unfit from a poor diet, and experienced a heart attack after exercising beyond his heart’s capability. The independent variables are the BMI’s of the test subjects, and the dependent variables are the change in blood pressure, heart rate, and respiration rate after exercise. We measured these using the Vernier blood pressure and vernier respiration monitor.

In our experiment, we used the Vernier Lab Pro to connect a Vernier Blood Pressure Sensor and a Vernier Respiration Monitor into a laptop. We took four test subjects of different body mass indexes, and took a control for each, measuring their normal heart rate, blood pressure, and respiration rate. We had each subject sprint for 30 seconds, and measured their heart rate, blood pressure, and respiration rate immediately after. For example, subject #1 had a BMI of 21.5 had a 117/62 mmHg blood pressure, a 114 bpm heart rate, and breathed 10.54 breaths per minute. After exercise, the subject’s blood pressure increased to 134/70 mmHg, heart rate increased to 157 bpm, and respiration rate increased to 23.36 breaths per minute. After recording the data for all four subjects, we ran statistics on the increases or decreases from normal blood pressure, heart rate, and respiration rate to the numbers after exercise. We analyzed the data in three different ways for the best expression of the results. We first made a graph comparing BMI with a ratio of the results. The ratio was made by dividing the after exercise number with the before exercise number. For example, subject #1’s ratio in heart rate would be 157/114 which is 1.38, and we compared that with his BMI. The second way we analyzed the data was by comparing the BMI with the difference between the after exercise number and the before exercise number. The last way we analyzed the data was by comparing the BMI with the percent change in blood pressure, heart rate, and respiration rate. As seen in the graph below of BMI vs. ratio of change in blood pressure, there is a clear trend. The subjects with a higher BMI had an bigger increase in systolic, but a smaller increase in diastolic. The clear trend is shown when we calculated the correlation. The graph for systolic blood pressure had a correlation of 0.890, while the graph for diastolic blood pressure had a correlation of -0.726, all figures very close to an absolute value of 1.

Our project provides further insight into the circulatory system. Although the blood pressure, heart rate, and respiration rate increased after exercise as expected, we incorrectly predicted the effects of BMI on heart rate and blood pressure. If a person has high muscle mass compared to body size, BMI will increase. Therefore, the ratio of change for heart rate should be less because the heart and muscles are strong enough to pump the blood all across the body. Also, we were correct in believing both systolic and diastolic pressure would both increase after exercise. However, a larger BMI will cause systolic to increase at a higher rate and cause diastolic to increase at a lesser rate. This phenomenon can be explained by looking at the effects of exercise on the circulatory system. When a person undergoes exercise (in our case, sprinting) their body needs extra oxygen to be able to produce enough ATP to sustain the heightened level of energy usage. Therefore, blood is pumped faster through blood vessels, increasing systolic blood pressure. On the other hand. On the other hand, when systolic pressure increases, the blood vessels are temporarily stretched, allowing the blood to flow more freely through and decreasing diastolic pressure. The stronger the heart, the more drastic the change in systolic and diastolic pressure.

CSB #7: Tilapia, Feeding the Thousands (Literally)

Source: Tilapia Farm, The New York Times

(above) A tilapia farm at work in Lake Yojoa

Scholars surmise that the fish that Jesus used to feed the 5,000 would have been Tilapia. However, in modern times today, Tilapia fish are hauled out of cages teeming with the fish in Lake Yojoa. They are then converted into fillets in a cold slaughterhouse; Some arrive in the U.S. on dinner plates within 12 hours. 


Last year, Americans ate 475 million pounds of tilapia, making it the most popular farmed fish the the U.S. It is referred to in the food industry as "aquatic chicken" for its bland taste and the fact that they are easy to breed. They are the perfect factory fish; they willingly eat pellets made of corn and soy, making them cheap to breed. Although the American Heart Association recommends eating fish twice a week, tilapia has its environmental and nutritional drawbacks. 


Tilapia fish have less beneficial omega-3 fatty acids, which are basically the reason that doctors recommend eating fish. The fatty acid combinations in farmed tilapia are less healthier than that of wild tilapia, because the farmed fish are fed corn and soy while the wild tilapia eat lake plants and algae. A vast majority of the tilapia fish consumed in the U.S. are harvested from "pens" and "cages" in Latin America and Asia. Today, environmentalists argue that unregulated fish farming methods is detrimental to ecosystems in poor countries. This is because the fish are mass farmed (overpopulated) in natural lakes, and as a result, the fish waste pollutes the water. 


However, defenders state that the Aquaculture Stewardship Council is toughening regulations to make sure tilapia farms are "responsibly farmed." They also argue that tilapia farming will only rise in importance as the population rises, and more people are fed and work jobs. “There are going to be more farmed fish each year,” said Kevin Fitzsimmons, a biologist at the University of Arizona. “Think about it: if we tried to get beef from hunting, there would be a lot of hungry people.”


However, it is this rise in importance that worries many biologists. They fear that the industry will become so important, that it will outweigh caution and destroy lake habitats and leave species extinct. Dr. McCrary has spent the past decade studying how a small, short-lived tilapia farm degraded Lake Apoyo in Nicaragua. “One small cage screwed up the entire lake — the entire lake!” he said of the farm, which existed from 1995 to 2000.

Waste from the cages polluted the ecosystem, and some tilapia escaped. An aquatic plant called charra, an important food for fish, disappeared, leaving the lake a wasteland.

I think that although it may be easy to farm, the tilapia farming industry is very risky as shown by Dr. McCrary in Lake Apoyo. Also, doctors state that salmon has ten times more omega-3 fatty acids than tilapia, giving it much less nutritional value. 

Source: 

Rosenthal, Elisabeth. "Another Side of Tilapia, the Perfect Factory Fish."
     The New York Times. New York Times, 2 May 2011. Web. 7 May 2011.
     <http://www.nytimes.com/2011/05/02/science/earth/
     02tilapia.html?pagewanted=1&_r=1&ref=earth>.

CSB #6: Trying to Bury Carbon Dioxide in the Ground

Source: Injecting Gas, New York Times

A pumping station at American Electric Power's Mountaineer plant in New Haven, West Virginia (above)

Global warming. It's a huge and significant environmental problem in the world today. However, the main cause of the actual warming of the planet is that of carbon dioxide (CO2). This gas is emitted by burning fossil fuels, such as oil and natural gas. Carbon dioxide is then put out into the atmosphere. From there, heat bouncing off of the Earth from the Sun is trapped by the carbon dioxide molecules' bonds, therefore heating the planet. 


There are many different ways in which scientists are trying to keep carbon dioxide out of the atmosphere, but the one that is focused in this post is that of burying this greenhouse gas into the ground. This method is called carbon capture and sequestration (C.C.S.) Sequestration is the act of taking possession of something, in this case, CO2. 


Near Meredosia, Illinois, there is a project to try and inject the gas into sandstone, a porous type of stone found under much of the Midwest and North America. The carbon dioxide that gets injected into the rock replaces the saline water inside the pores. In November 2010, Lisa P. Jackson, the administrator of the Environmental Protection Agency (EPA) approved a new rule that created a new class of wells to be used for injecting carbon dioxide. This rule focuses on the protection and safety of drinking water. Although carbon dioxide itself is not toxic, it can change the acidity of water. Because of this, the EPA does not allow for carbon dioxide to be injected in water that passes the drinking water standards; it will be injected in saline water that is deemed too salty to drink and for irrigation. 


“We’ve been very encouraged,” said Gary O. Spitznogle, the manager of carbon capture and sequestration engineering at American Electric Power, a company that produces electricity in 11 states, mostly by burning coal. In late 2009, it began capturing carbon dioxide from a portion of the flue gases at its Mountaineer coal plant in New Haven. 


In my opinion, the idea of tucking carbon dioxide into the ground is interesting. Of all of the ways I have heard about trying to prevent or slow down global warming, I have never heard about injecting CO2 into rocks. 


Source: 


Wald, Matthew L. "Tucking Carbon Into the Ground." The New York Times. The New
     York Times, 30 Mar. 2011. Web. 7 Apr. 2011. <http://www.nytimes.com/2011/
     03/31/business/energy-environment/31CARBON.html?pagewanted=1&_r=1&ref=earth>.

CSB #5: The Promise of Silk in the World

Source: "The Reinvention of Silk," New York Times

(Above) Silk creations by Tufts University researchers include a coil made of silk substrate and gold that can help tell when food goes bad.

Silk is one of the most versatile materials in the world. Spiders are usually associated with this useful substance, for they have evolved over millions and millions of years to develop silks that can be used by people. Even in nature, silk is important, for it acts as a natural glue. There has been talk for years that spider silk could be used to make cables stronger and more flexible than steel, or that it could be used to make bulletproof vests that are more effective than the current ones of Kevlar. However, the biggest problem that is faced by scientists is the fact that spiders do not generate enough silk. Also, spiders live alone, and they require a diet of other insects; sometimes they can be cannibals, meaning that they eat other spiders. As a result of this, scientists can not gather a group of spiders and mass produce their silk. 

A way that researchers are working to solve this problem is that they are trying to unlock the secrets of spider silk, so that scientists could reinvent it in a laboratory. However, the artificial silk that they have created is not as strong, elastic, and other qualities of the real thing. 

David Kaplan and other researchers at Tufts University work with silkworms to try and reinvent silkworm silk, because of the fact that they are vegetarians, unlike spiders. However, silkworms also have their drawbacks: they only have one kind of spinneret, whereas spiders have a whole set of spinnerets, allowing it to produce many different silk fibers. The main aspect of natural silk that scientists can't seem to produce, is that the silk is in a liquid form while it is inside a spider or something of the sort, and then comes out as a solid silk. 

The process of making silk into useful things in life, such as transparent films, is "green," meaning that it is water based and that it only requires low temperatures to regulate. “Silk is a wonderful material because it’s biocompatible,” said Dr. Kharlampieva, who is continuing her research at the University of Alabama, Birmingham. “The main drawback is it’s soft. If you want to use it for optical applications, you need to reinforce it.” 

Source: 

Fountain, Henry. "The Reinvention of Silk." The New York Times. The New York 

     Times, 7 Mar. 2011. Web. 7 Mar. 2011. <http://www.nytimes.com/2011/03/08/
     science/
     08silk.html?pagewanted=1&_r=1&adxnnl=1&ref=science&adxnnlx=1299558239-0DSwQnNbU6c
     94Ywx87NmEg>.

CSB #4: Where Did All the Methane from the BP Oil Spill Go?

Definitions: 
1.) hydrocarbon - an organic compound consisting of only carbon and hydrogen.
2.) methane - an odorless, colorless, flammable hydrocarbon, CH_4. It is used as a fuel and contributes greatly to global warming. 


Summary: 
A question that scientists were asking before last Thursday, was: Where did all the methane from the BP Oil Spill go? The question has been very important, because methane is more than 20 times more effective at trapping heat in the atmosphere than carbon dioxide. However, scientists finally reported on Thursday that bacteria had eaten nearly all of the methane from the spill. Fortunately, the bacteria managed to consume all of the methane before it could rise from the sea bottom and rise up into the atmosphere. Two months after the BP spill, methane was not being consumed in and around the wellhead, and many scientists got the idea in their heads that the methane would rise to the atmosphere. The oil spill was an "accidental experiment" and showed that particular bacteria with an all-methane diet, would multiply rapidly. Many other organisms dealt with the other hydrocarbons involved in the spill, such as ethane and propane. 


Discussion: 
The fact that the bacteria consumed all of the methane in the ocean before it could reach the atmosphere is very fortunate, especially considering the fact that nearly 200,000 tons of methane -- more than any other single hydrocarbon emitted in the accident -- were released from the wellhead, and nearly all of it went into the Gulf. Also, the methane-consuming bacteria were the last to arrive to the oil spill. I decided to write about this article because of the fact that methane is so effective in trapping heat in the atmosphere and so much of it was emitted in the oil spill. I wanted to know where all of it went, and by reading the article, I discovered the answer. If the bacteria hadn't multiplied so quickly by consuming the methane, then a significant amount of the hydrocarbon would have risen to the atmosphere and caused climate change, something that should be avoided. 


Questions: 
1.) Was there anything different about the bacteria that consumed the methane?
2.) When was all of the methane completely consumed?


Sources: 
Article: 
Zabarenko, Deborah. "Bacteria Gobbled Methane from BP Spill: Scientists." 
     Scientific American. Scientific American, 6 Jan. 2011. Web. 9 Jan. 2011.
     <http://www.scientificamerican.com/
     article.cfm?id=bacteria-gobbled-methane-bp>.

Image: 

http://www.scientificamerican.com/article.cfm?id=bacteria-gobbled-methane-bp