cslavin's blog

The spread of disease can be classified in two different catagories: communicable and non-communicable. Communicable dieases are diseases that are spread by direct or indirect contact. Direct contact is when an infected host comes in physical contact with an unifected host and the pathogen is spread. Examples of these include handshakes, kissing, or sex. When the direct contact is from a liquid from a cough or a sneeze it is called droplet infection. On the other hand, indirect contact involves an intermediate step. It is passed from the host to another host via a fomite or vector. A fomite is an object that harbors a a disease. Examples of fomites include door knobs, towels, and drinking glasses. A vector is a living organism that carries the disesase from one individual to the next. An example is a misquito transmitting malaria. Humans can also be vectors. Healthcare workers that do not properly wash their hands in between patients and pass the disease onto the next patient is an example of how that is possible. Other diseases are spread through the fecal-oral route, where improper sanitation causes infection. Noncommunicable diseases are diseases that not spread through direct or indirect contact. These infection can be endogenous or environmental. Endogenous diseases occur when normal bacteria in the body spread to places it does not belong. An example of this is a urinary tract infection. An environmental infection occurs typically from an introduction of the bacterial by a traumatic injury or ingestion of the bacteria. These infections are always bacterial.

The methods project requires students to construct a multi-panel scientific figure of an interspecific interaction on the UMass Amherst campus and write a detailed methods section describing how it will be made. Another student will then follow those methods and try to recreate the original figure. Because a primary goal of science is replication, the goal of this project is to write a method section with enough detail to allow another student to reproduce the same results as the orignial. This project also promotes critical thinking skills as it requires students to distinguish differences in observations and inferences by comparing and contrasting the original figure to the replicate and by helping students to think about what potential factors need to be controlled in the expirement. 

The interspecific interaction in this project is a tree and moss. Because another student has to recreate it, the two organisms should be immobile in order to allow relocation of the same organisms. The location of the organisms are limited to the UMass Amherst campus, however it is also important to make the location of the interaction of the organisms accessible. Therefore, the interaction between the tree and the moss will be near the ground making it accessible to all heights. Specific distances, camera angles, and body positions will also be factors that need to remain constant to recreate the image. Controlling these variables will help allow for similar amounts and areas of background. It will also keep the proportions of the images similar. 

A simple endocrine loop is one that involved one hormone and maintains homeostasis. Most loops are stimulated by a humoral stimuli, or a change in interstitual fluid. An example of a simple endocrine loop is the parathyriod hormone. When there is a decrease in blood calcuim, the parathyroid glad acts as a sensor and control center, recognizing the change and signalling to an effort tissue. The signal is the release of the parathyroid hormone, which effects the bones, kidneys, and digestive tract. In the bones, osteoclasts break down bone and release calcium. The kidneys and digestive tract increase calcium reabsorption. Calcium levels increase in the blood until the normal level of blood calcium is achieved. A complex endocrine loop uses multiple hormones and has varied responses. For example, thyroid hormone is released when the body needs to increase metabolism. The signal goes to the hypothalamus which produces thyroid releasing hormone, which stimulates the anterior pituitary gland. The anterior pituitary glad then relases thyroid stimulating hormone which stimulates the thyriod gland to release thyroid hormone. Thyroid hormone stimulates every cell in the body with a receptor for thyroid hormone to increase metabolism, heat generation, and growth and devlopment. 

A ECG is way to measue electrical signal in the heart. This measurement produces a PQRST graph. The P wave represents atrial depolarization by the SA node. The signal is then delayed, and atrial depolarization is complete before the QRS complex. At the QRS complex ventricle depolarization begins at the apex and atrial repolarization occurs. Following this, the ventricle depolarization completes. At the T wave, ventrical repolarization occurs. Then at the plataeu ventrical repolarization is completed. The electrical signal is important because it leads to contraction which in turn create pressure that moves blood. Therefore, depolarization of the SA node is important to keep a normal heart rate. If there was a problem with spontaneous depolarization of the SA node, the AV node would control the heart rate. This would cause a lower heart rate. 

The METHODS project was had each student create multi-panel scientific figures and document the methods used while creating the figure. The set of methods was then followed by a different student, and the two figures were compared. The purpose of the METHODS project was to highlight the importance of specificity in method sections of scientific papers. While choosing an interaction to document, it was necessary to keep in mind that the interaction would have to be captured again by another student. Therefore, mobility was a key factor in the selection process. Any interaction with an organism that moves a lot would not be ideal. The location of the interaction was also limited by accessability and identification of the organisms. This interaction had to be somewhere that all students could get to on campus and there had to be a clear understanding of the exact organism used. Factors that had to be considerd while capturing an interaction were camera angle, distance from the object, and body position. 

It is a common misconseption that arteries carry oxygenated blood and veins carry deoxygenated blood. This is true in the systemic pathway, where blood is delivered to the body, but it is not true in the pulmonary pathway. The pulmonary system is when the blood is delievered to the lungs. Here deoxygenated blood is carried by arteries and oxygenated blood is carried by the viens. Ultimately, viens carry blood towards the heart and arteries carry blood away from the body. The arteries have a greater amount of pressure than viens due to the fact that blood is pumped out of the heart. Because of that, there is also significantly less blood volume in the arteries than the viens. 

Nonpolar molecules tend to clump together when in aqueous environments. A nonpolar molecule tends to have a majority of nonpolar covalent bonds that occur between molecules of similiar electronegativity causing it to be hydrophobic. For example, carbon-carbon and carbon-hydrogen bonds are examples of bonds between two molecules that have a similar electronegativity. These molecules can generate some temporary, partical charges that allow the molecule to make very weak nonpolar interactions, which are called Van de Waal interactions. However, when in aqueous environments these molecules tend to clump together in order to increase the entropy of the water molecules. Greater entropy is favored in natural environments due to the fact that it requires less energy. When the nonpolar molecules clump together, this decreases the surface area of nonploar molecules that are surrounded by water. A cage of water molecule forms around the hydrophobic molecules preventing the nonpolar and polar molecules from interacting. If the nonpolar molecules were not clumped, there would be more organized water molecules involved in these individual cages. Molecules that are amphipatic contain both hydrophobic and hydrophilic molecules. In aqueous environments, the hydrophobic molecules will clump and the hydrophilic molecules will arrange themselves on the outside. 

The results did not support the hypothesis that there would be greater tree growth in areas of higher sunlight. The south slope receives the greatest amount of sunlight, and the north slope and notch had a greater basal area than the south slope. Light availability is not the only factor that effects tree growth. Competition between trees for resources is limiting on growth. Competition between two organisms has a negative effect on both competitors. Trees compete for not only light availability but also soil water and nutrients. There is limiting amount of nitrogen and phosphorus present in the soil. When two or more trees are competing for these nutrients, the trees will spend additional energy to outcompete other trees for the resources. In species that compete for water and nutrients, the tree may put energy into growing their roots instead of their diameter. Greater competition for resources could also be due to different soil compositions at different slopes. Some soil types make water and nutrients more accessible to trees, and thus promote higher growth rates.  In areas with poorer soil, there is an increase in competition for the scarce resources. 

Blood flow can be affected by restriction forces, specifically blood vessels. A smaller blood vessel diameter creates more friction between the blood and the blood vessel and restricts blood flow. When a blood vessel is dialated, the blood vessel diameter is larger and blood can flow more easily. The human body uses this technique to control blood pressure. When someone works out, blood flow is increased to the contracting muscles. In this time blood is also restricted to areas of the body that are not involved in the work out. When a person in cold, blood vessels that are not supplying blood to digestive organs are restricted. Blood vessels supplying blood to digestive organs are dialated to increase the break down of glucose. 

Blood flows through the heart from the atriums to the ventricles. Blood first comes into the heart through the superior and inferior vena cava into the right atrium. The right atrium then pumps the blood through the right AV valve into the right ventricle. From the right ventricle, the blood is pumped into the pulmonary artery to the lungs and back through the pulmonary vein. It enters the left atrium and then is pumped through the left AV valve into the left ventricle. This is the largest chamber of the heart. It pumps the blood to the entire body.