Thursday, July 15, 2010

Chapter 1

2. The author points out many ways in which iron impacts life. Identify/describe atleast five.
  • Iron serves as a carrier of oxygen from the lungs to the bloodstream via red blood cells (RBC).
  • The enzymes that are responsible for the chemical heavy lifting performed within our bodies contain iron.
  • The most common kind of anemia are caused by iron deficiencies. The lack of RBCs in the body can result in fatigue, shortness of breath, and heart failure.
  • Iron exceeding the standard three or four grams in a human’s system is considered unhealthy. Cells containing too much iron is home to the growth and rapid multiplication of bacteria and other pathogens such as cancer cells.
  • Individuals with the genetic condition of Hemochromatosis are actually less likely to contract an infection of some sort that inflicts sickness despite greater levels of iron in the body. This is because the iron within a particular white blood cell known as a macrophage, are at substantially lower levels, allowing for the maximization of depleting any harmful invaders in the body.

3. In the context of this chapter, explain the author’s reference to Bruce Lee and to the barber pole.

The author’s reference to the iconic figure Bruce Lee was to emphasize the effective and powerful role of the iron-deprived macrophages in the immune system. Hemochromatic macrophages are much better at combating bacteria due to the substantially lowl evels of iron. The lack of iron in the macrophages is the reason why hemochromatosis continues to be passed down the family tree- it prevents the spreading of disease into the body, despite the perverse effects that it can have in the long-term. The barber pole had the initial purpose of symbolizing the once-popular practice of bloodletting, or bleeding. The brass bowl at the top modeled where the leeches were kept. Second, the brass bowl at the bottom represented a space for blood collection. Furthermore, the red and white stripes symbolized medieval bandages that swirled as they dried.

4. Distinguish between the three types of diabetes.

Diabetes can be classified into three types: Type I, Type II, and gestational diabetes. Type
I is most commonly referred to as juvenile diabetes. Dubbed as an autoimmune disease, Type I incorrectly causes the body to mislabels cell that make insulin as intruders. Due to the lack of normal insulin production at such an early age, the only treatment options include self-administered insulin injections or a surgically implanted insulin pump. Furthermore, Type II Diabetes, most commonly known as adult-onset, are caused by a mix of factors that include genetics and lifestyle choices. Approximately 85 percent of those with Type II diabetes are obese. As obesity becomes an epidemic at the current time, even young obese children are suffering from a diagnosis that is expected at mid-life. Adult-onset diabetes are popular along demographic groups, due to changes in lifestyles that can be traced back to centuries ago, as it is with the case of the southwestern Pima Indians. Finally, gestational diabetes only occur in pregnant females. As a matter of fact, about four percent of pregnant women in the U.S., or about 100,000 women. It is a temporary condition that has the ability to resolve itself, for once the child is born, there is no longer a need for the fetus to intake the extra glucose flowing in the bloodstream via the placenta. Babies who are born to mothers who have gestational diabetes often have macrosomia, or excessive chubbiness due to the extra sugars.

5. What did the ice cores of 1989 reveal about the Younger Dryas?

The ice cores revealed that the Younger Dryas only spanned three years. The estimates regarding the length of this period had originally been overestimated by scientists, and continually dwindled down as data began to surface. Research showed that the onset of the Younger Dryas only took a mere ten years, proving that climate change could take place rapidly.

6. Describe the body’s “arsenal of natural defenses” against cold.

The body defends itself in chilly environments in very natural processes. The body’s first move is shivering, rigid muscle movements that burn stored sugar into heat. Next, the body inhibits emaciated capillaries in the extremities. The numb and tingly sensation first reaches the fingers and toes before creeping up the arms and legs. Blood from the closed walls of the capillaries head to the torso, where it can circulate and bestow heat to the vital organs. For those whose ancestry can be traced back to the extreme cold, frostbite to the extremities can be avoided by the Lewis wave or “hunter’s response”. Blood from the constricted capillaries briefly expand to distribute warm blood to shunned areas. For example, Inuit hunters can increase hand temperature from freezing to fifty degrees in few minutes. Brown fat is another natural defense of the body when it comes to combating the cold. With its instantaneous ability to create heat due to its heat-generating tissue, brown fat can last for as long as it is fed. Unlike other tissues, it doesn’t need insulin to carry sugar into the cell and can burn up to a staggering 70 percent more fat than an average fat cell. But with great defenses comes a downfall- brown fat can only be acquired through prolonged exposure in extremely cold climates. Last, urination is a natural response to cold weather. As more blood floods into the core of the body, the kidneys are directed to relieve of the body of unnecessary fluids.

7. Describe the connection between Rana sylvatica and diabetes.

During the months of winter, the Rana sylvatica, or commonly known as the wood frog, has the ability to completely freeze solid as a form of hibernation during the cold months of winter. It can easily be mistaken for dead, for there is no heartbeat, no breathing, and no recordable brain activity. But the freezing up is only a natural defense against the cold, for once the wood frog thaws out of its icy state, it is already hopping away. As temperatures decrease, the fluids within the frog all pool into the abdomen. As this is happening, glucose is gathering in the bloodstream along with the release of more sugar alcohols. A spike in sugar levels results in a lower freezing point, and acts as an anti-freeze. The whole process of increasing blood sugar levels to deal with the cold is a proposed explanation to the adaption of diabetes in humans during the turbulent period known as the Younger Dryas.

8. In chapters I and II several inherited disorders were discussed. Create and complete a chart with the following information: Disease/disorder, Symptoms, Evolutionary Advantage.

Symptoms: Fatigue, tiredness, skipping heart beat, joint pain
Evolutionary advantage: During the times of the Bubonic plague, the infectious disease was spreading like wildfire in Europe, particularly the western half. Since iron is a breeding house for bacteria, those with lower iron levels within their white blood cells were less likely to contract the devastating disease. So, with the main goal of survival to reproduce, Hemochromatosis, a genetic condition that decreases iron in a macrophage, came to be an evolutionary advantage.

Diabetes- Type I, II, and Gestational
Symtpoms: Dehydration, fatigue, irritability, frequent urination, excessive thirst
Evolutionary advantage: The Younger Dryas was a rapid period of extreme cold that swept Earth about 13,000 years ago. In terms of dealing with the rapid shift in climate, individuals who were accustomed to a temperate climate had to adapt themselves in order to follow the motto of evolution- survive and reproduce. In response to the extreme cold, it is estimated that the process of accumulating blood sugars in the body as insulin levels dropped occurred in order to survive the brief period known as the Younger Dryas.

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