What is the difference between systolic and diastolic heart failure?
The answer to this question lies in the function of systole and diastole. Systole is defined by the contraction of the ventricles to distribute blood throughout the body. Therefore, a person with systolic heart failure lacks the ability to efficiently contract the heart muscle and distribute blood. Thinking logically, these patients therefore often have weak ventricular muscles. On a echocardiogram, systolic heart failure would often be associated with "floppy" or thin ventricular walls and dilated ventricular chambers, as well as a low ejection fraction (<55%) Diastolic heart failure is a failure of diastole, which is the time of ventricular filling. Therefore, either due to ventricular hypertrophy or conditions that otherwise restrict the ventricles, the heart is unable to fill up with a physiological amount of blood. So while the ventricles are capable of a normal strength contraction, there is an insufficient amount of blood in the heart to begin with, leading to the classic symptoms of heart failure (lower extremity edema, fatigue, orthopnea, dyspnea). On an echocardiogram, the ventricles may be hypertrophied and often times the ejection fraction is within normal limits since the ventricles are still capable of ejecting a significant fraction of the blood volume.
What's the best way to deal with a term paper when you have writer's block?
A big term paper can be very overwhelming and it's sometimes difficult knowing where to begin. I've found that starting with a basic outline and fleshing it out step by step can be a relatively painless way to chip away at such a big task. For example, start out with a single sheet of paper and the overarching theme, such as the history of war time reporting. Then, below that brainstorm some general topics that could stand alone as thematic paragraphs: yellow journalism and the Spanish-American War; embedded reporters in the U.S. armed forces; female reporters of WWII. Create a long list of different directions in which you could take the paper, before narrowing it down to the subjects you feel are most relevant. Now it's time to break out the note cards (if we're going old school) or you could flesh this out in a Word document as well. But for each thematic paragraph, write a single sentence summarizing the key concept of this section of the paper. With editing, these will transfer to your final product as the first sentences of each section. If you feel comfortable, sketch out a general map of each section (e.g., which reporter will you focus on first). And then hit the books. Take each fact that you are going to cite, and rewrite the fact in your own words on a note card, while marking the source material on the card. This is the best way to avoid inadvertently plagiarizing. While this is the most time consuming part of the process,, essentially you are writing the paper with each new card you make. After you have all of the relevant facts that want to cite, then head back to your outline and sort the cards into thematic piles (i.e. all the cards relevant to WWII female reporters in one pile, the second being all the cards related to yellow journalism, etc.). And then within each pile, place the cards in the order that you want to cite them; here, your'e writing the paper by creating the flow of your citations. Once the order of all the cards is complete, your paper is practically done. Head back to your computer and just shape each fact into a sentence. The flow may not be perfect yet, but all of the essentials will be there. With a few edits and transitions, the paper will be complete!
How can I predict how a cell will react depending on whether it is immersed in a isotonic, hypertonic or hypotonic solution?
The most important concept to anchor to when predicting cell behavior in these different solutions is to remember that "water follows salt" and that the body wants to create an equilibrium, meaning that ideally, it wants the concentration of fluid in all of its compartments to be as similar as possible. So, in an isotonic solution, "iso" meaning equal, the concentration of the fluid within the cell and the concentration of the fluid surrounding the cell (in this example let's make the cell a red blood cell and the surrounding solution the plasma of the blood) are both the same. The concentration of solutes (e.g. sodium) within the red blood cell is equivalent to the concentration of solutes (e.g. sodium) in the plasma. Therefore, the two compartments are already in equilibrium and nothing happens. There is homeostasis. What happens in a hypotonic solution? First, let's define what the means. "Hypo" means below normal, meaning that the fluid surrounding our red blood cell has a lower than normal concentration of solutes in it. Therefore, the fluid within the red blood cell is more concentrated with solutes than the plasma fluid that is surrounding the cell. There is no homeostasis. In order to create equal concentrations between the two compartments, something needs to happen. And remember, water follows salt. Therefore, water will move into the red blood cells (which contain more solutes/sodium) in order to dilute the highly concentrated fluid within the cell. This lowers the concentration of the red blood cell interior. The red blood cell will continue to swell and fill with fluid until the two concentrations become isotonic, and equilibrium is achieved. And finally, in a hypertonic solution, there are more solutes in the plasma surrounding the red blood cell than in the cell itself. The plasma is more concentrated than the interior of the cell. What will happen? Again, water follows salt. In order to make the two concentrations similar, water will leave the less concentrated red blood cells and will move into the plasma, leaving the red blood cells shriveled up. However, this movement of water will result in a lowering of the plasma concentration and will create equilibrium between the two spaces.