Human Anatomy at Colby

Lauren Shirley: My Experience in BI265j

February 24th, 2015 · Comments Off on Lauren Shirley: My Experience in BI265j

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Anatomy and physiology form the cornerstone of medicine. Without A&P, medicine as a field would fail to exist. Thus, as a premed student, I saw it as my duty to take A&P to give myself a solid background for my other medical interests and the internships I hope to pursue. After working in a cadaver lab for several summers where I completed dissections of many different joints, I imagined that I had a fairly solid background in anatomy. Additionally, my experience as an EMT and the basic anatomy and bodily processes I had learned as part of my training should make this easy. Right?? Boy was I wrong.

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The musculoskeletal anatomy that I had mastered in my lab before was approximately two hours of lecture in a month-long class. My imagination had certainly underestimated the breadth of the class and the many different topics that would be covered. While my previous experiences definitely helped me a little, they gave me nowhere near the advantage I imagined.

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I was most challenged by the pace of the class. As we conquered a new body system each day, in both its anatomy and its physiology, there was little time to absorb the details of each system. Rather, the class served as an overview of many main components and processes within the body. We covered everything from the skeletal framework of the body to the minute electrical conduction pathways in the heart, and none of it really got half the time it deserved. However, this class did give me a new appreciation of the miracle of the human body and its myriad evolutionary advantages. I cannot even comprehend the different evolutionary events that would have had to occur for it to reach its current state.

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Organs we take for granted, such as the eye or ear, give us a plethora of information about the world around us. While I knew the basic function and makeup of these organs before the class, I had no idea about their underlying intricacies. I was fascinated by the different components that makeup our vision. While the rods in our eyes give us “night vision,” it lacks the color and “high definition” quality that cones provide. While these components appear in different densities in different places on the retina, the brain is able to take in all of the information, which synapses through the optical nerve to create a coherent image of our surroundings. It was information such as this that I learned in the class which gave me a new appreciation for the human body and its physiology.

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While this class definitely pushed me to learn a maximum of information in a minimum of time, I really ended up enjoying the Anatomy and Physiology class and would highly recommend it to any other students who are considering taking it for Jan Plan in the future. However, my advice to these students would be this: you get out of the class what you put in to it. Your interest and effort is key to your success in and enjoyment of the class.

 

 

Tags: Bi265j

Lauren Shirley: BI265J and Personal Health

February 24th, 2015 · Comments Off on Lauren Shirley: BI265J and Personal Health

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One interesting aspect of BI265j was the emphasis that Dr. Klepach placed on personal health. On the first day of class, we were given sheets to track our sleep, exercise, stress, and eating habits. Initially, I was overwhelmed with the amount of information to absorb and the sheer scope of the class. Suddenly, I was trying to fit 4 hours of class, three hours of lecture online, sufficient exercise, three square meals and at least eight hours of sleep into a day, not to mention the actual studying part of learning for the class!

The first week was a bit rocky for me: trying to learn to use my time efficiently enough to get everything done while not succumbing to mental exhaustion at the amount of information I was trying to absorb was a challenge to say the least. However, switching back to a traditional classroom environment from the flipped environment was a lifesaver! By eliminating two hours of lecture from my homework load, I had sufficient time to study and exercise. I was able to go to the gym almost every day of the week (when I wasn’t fighting a flu).

I really enjoyed having part of the class be about maintaining our own personal health as a means to more effective learning. By placing an emphasis on exercise, I didn’t feel guilty leaving the library to go the gym for a study break. Instead, I embraced this new lifestyle opportunity and learned to play squash, something I had always wanted to do since coming to college, but had never been able to justify the time to do! Interestingly, I noticed that as I exercised more and put more of an emphasis on my own health rather than on numerical success in class, my stress decreased. I can’t say my quiz grades necessarily improved, but I felt like I was better able to absorb the material that was presented to me and was much happier while I was learning.

Also, by tracking my eating, I noticed that when my stress increased, my cravings for unhealthy foods increased as well. While I am not normally a person that eats a lot of baked goods or sugary foods, I definitely wanted them more when I didn’t exercise as much or get as much fresh air. This made me realize the importance of diet as a result of exercise.

Finally, I really enjoyed making sleep a priority during Jan Plan and received around eight hours of sleep every night on average with the exception of nights I was on duty as an EMT.

Thus, this class really taught me that my exercise habits impact both my stress and my diet, and that when I exercised less, other areas of my life would suffer. I was it metaphorically as similar to instructions for putting on an oxygen mask in a plane: Put on your own mask first before you help those around you. By focusing on my own health, effective learning and success will follow. Also, success is not defined just by numbers academically, but by your quality of life in general and how you feel.

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Tags: Bi265j · Human Health

Lauren Shirley: Cardiology: Getting to the heart of the matter

February 22nd, 2015 · Comments Off on Lauren Shirley: Cardiology: Getting to the heart of the matter

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One of the highlights of my experience in BI265j was the cardiac section and in particular, the heart dissections we got to do. I had a fairly solid understanding of the heart coming into the class from my EMT training. I knew that the blood came into the heart through the vena cava entered the right atrium passed through the tricuspid valve to the right ventricle, was pumped to the lungs through the pulmonary arteries to receive oxygen and then returned to the heart through the pulmonary veins into the left atrium then through the mitral valve to the left ventricle and out to the ret of the body through the aorta. What my EMT training had failed to teach me, however, was the beauty of this process, which is almost artful in its simplicity and elegance. This class gave me a greater appreciation of the elegance of the heart and the mechanisms behind its continuous beating. I was fascinated by the spread of electrical signal and its motion through the myocardium. The depolarization starting at the sinoatrial node, which spreads to the atrioventricular node then through the bundle of His and out to the Purkinje fibers is a highly linear path, simple yet powerful. While the lecture on the heart and studying plastic models in lab fascinated me, it was the opportunity to dissect the heart that truly solidified by understanding of it.

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We dissected preserved cow hearts. Initially, I was impressed by the thickness of the muscle in the heart walls. It took quite a bit of work with a scalpel and scissors in order to get down into the different chambers of the heart. The sheer thickness of the walls and the work it took to get through them spoke to the sheer power of the heart as a muscle and the strength needed to supply a large body, such as a cow, with blood. Once inside the heart, I was fascinated by the sheer strength of the chordae tendinae, the fibers that keep backflow from occurring in the tricuspid and mitral valves. Despite pulling on these relatively thin cords, they didn’t tear! This further illustrated the necessary strength of the heart to me and the great pressure and quantity of blood that it pumps.

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While it was really exciting to get to see a real life illustration of the models we had studies (that wasn’t color coded), it was even better to have a chance to share our newfound knowledge of the heart with the high school students who visited. I felt that teaching them what I knew solidified it in my mind. However, it was also exciting to see the “next generation” of young science students and how fascinated they were with the human body and its functions. I felt that my enthusiasm for cardiac function was almost contagious as I eagerly showed them how to dissect ad encouraged them to explore and understand the heart in front of them.

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Long story short, this class got me pumped for cardiac anatomy and physiology and a possible career in cardiology. Ironically, I love the heart!

Tags: Bi265j · Lab · Special Activities

Grand Rounds: Postpartum Coronary Artery Dissection

January 28th, 2015 · Comments Off on Grand Rounds: Postpartum Coronary Artery Dissection

Lauren Shirley, Allison O’Connor, Cal Robbins

Grand Rounds Synopsis

Case 28-2010 A 32-Year-Old, 3 Weeks Postpartum with Substernal Chest Pain

Grand Rounds Case Presentation powerpoint pdf

Onset

A 32-year old woman had an uncomplicated, spontaneous vaginal delivery after 39 weeks of gestation. This was the patient’s second pregnancy. During her first pregnancy, she was diagnosed with preeclamptic toxemia which was treated with magnesium sulfate. Mild hypertension (systolic 120-140 mm Hg) was reported during the first and third trimesters of her second pregnancy followed by a return to normal blood pressure. Upon delivery, it was noted that her placenta weighed 340 g (below the fifth percentile for gestational age, mean 540 g) with increased amounts of perivillous fibrin (suggesting placental ischemia- lack of blood and thus oxygen and glucose to tissue).

The patient was admitted three weeks post partum when she developed pain in the left jaw and substernal area. The patient called EMS and was given oxygen which resolved her symptoms after 20 minutes and EMS personnel left. The pain returned shortly and EMS returned whereupon the pt scored her pain as a 7 out of 10. Blood pressure was noted as 148/74 and an electrocardiogram (ECG) revealed normal sinus rhythm of 90-100 bpm and ST-segment elevation of 4 mm in leads V2 and V3 (Abnormalities in ECG). Oxygen, acetyl-salicylic acid, nitroglycerin and morphine were administered. When examined at the hospital, the pt’s blood pressure was 143/92 mm Hg in her left arm and 137/81 mm Hg in her right arm with a pulse of 83-92 bpm.

Diagnosis

With a chief complaint of chest pain the patient could have been experiencing cardiovascular, pulmonary, gastrointestinal or musculoskeletal complications. Since the patient was 32 years old, cardiovascular complications would seem unlikely, however, since the patient was three weeks postpartum cardiovascular complications need to be considered more carefully since the risk of acute myocardial infarction is increased during pregnancy and the postpartum period and since pregnancy is a risk factor for aortic dissection. The risk of pulmonary embolism (a blockage of an artery in the lungs) is also increased during the postpartum period.

Since the patient’s ECG showed ST-segment elevation in conjunction with chest pain, an acute myocardial infarction would be suspected. Approximately 35% of postpartum women who present with myocardial infarction have a coronary artery dissection. There are two main types of coronary artery dissections, those that are caused by mechanical precipitation and those that are spontaneous. A spontaneous dissection is a tear in the artery where the tunica media and tunica externa separate, allowing blood to pool in between these layers. SCAD are rare, however 75% of patients who present with spontaneous aortic dissections are women and 30%  of those women are peripartum, suggesting that this patient’s coronary artery dissection was spontaneous. There are four subgroups of spontaneous coronary artery dissections, however peripartum status and idiopathic spontaneous coronary-artery dissections or those caused by coronary shear stress are the two subgroups relevant to this case. Since the chest pain began after the patient picked up her toddler, there is a high index of suspicion that this dissection may have been caused by the patient’s peripartum status and coronary shear stress caused by lifting her toddler. Angiographic projections showed 35mm long segment of narrowing in the left anterior descending coronary artery.  The lack of vascular disease in other coronary arteries along with the patient’s postpartum status as well as her test results are consistent with the diagnosis of a postpartum coronary-artery dissection.

Treatment Options

Unlike aortic dissections, the usual chest pain drugs (asprin, nitroglycerin, etc) which thin the blood can actually help, keeping the true lamen patent. Beta-blockers and nitrates are often used to prevent superimposed vapospasm.  In cases of myocardial ischemia or compromised coronary flow, reperfusion therapy is used.  In patients with severe ischemia, coronary-artery bypass  grafting is done. In this case, the patient was given an intra aortic balloon pump which helps to increase myocardial oxygen supply by being placed in the aorta where it inflates and decreases based on the heart beat.  Since the patient had no pain and the Percutaneous Coronary Intervention could have entered the false lumen, and since coronary dissections can heal by themselves, the balloon pump makes the most sense.  This increased blood flow to the coronary artery.  Aspirin as an antiplatelet, ß-blockers, and statins were used in case of intramural hematoma in the coronary vessel.  Because of the potential for emergency cardiac surgery, the patient was not given glycoprotein IIb/IIIa inhibitors.

 

After 2 days a significant improvement was noted, the pump was terminated, and since surgery was now unlikely, glycoprotein inhibitors were initiated  for a minor myocardial infarction discovered during treatment of the aortic dissection. This would be discontinued in a year, while aspirin was recommended indefinitely. The patient was able to return to her normal life with no further complications.

 

Little evidence exist in terms of the cause of spontaneous coronary artery dissections, but the current theory is that  inflammation is caused by hormones, which explains the prevalence in post partum women.  Several studies also included women taking oral contraceptives as being at risk for coronary artery dissections.  The eosinophils release the histolytic agents between the tunica media and the tunica adventitia, which cause dissections in coronary arteries.

 

References

  1. Sabatine, Marc S., Farouc A. Jaffer, Paul N. Statts, and James R. Stone. “Case 28-2010: A 32-Year-Old Woman, 3 Weeks Post Partum, with Substernal Chest Pain.”The New England Journal of Medicine (2010): n. pag. Web.
  2. James, A. H. “Acute Myocardial Infarction in Pregnancy: A United States Population-Based Study.” Circulation 113.12 (2006): 1564-571. Web.
  3. Koul, Ashok K., Gerald Hollander, Norbert Moskovits, Robert Frankel, Leo Herrera, and Jacob Shani. “Coronary Artery Dissection during Pregnancy and the Postpartum Period: Two Case Reports and Review of Literature.” Catheterization and Cardiovascular Interventions 52.1 (2001): 88-94. Web.
  4. Mcintyre-Spatar, Leslie, and Kevin H. Silver. “Spontaneous Coronary Artery Dissection in a Postpartum Woman: Literature Review.” The Journal for Nurse Practitioners 7.9 (2011): 770-73.
  5. Oliveira Marta Silvia, Goncalves Alexandra, Dias Paula, Maciel Júlia Maria. “Spontaneous Coronary Artery Dissection: a Diagnosis to consider in Acute Coronary Artery Syndromes” Artigos de Revisão. (2009): 28 (6): 707-713
  6. Heart Assist Devices. Texas Heart Institute, 2015. (Accessed January 20, 2015 at http://www.texasheart.org/Research/Devices/iabp.cfm)
  7. CBC. MedlinePlus, 2015. (Accessed Janury 25, 2015 at http://www.nlm.nih.gov/medlineplus/ency/article/003642.htm)
  8. Placental Pathology. University of Chicago. (Accessed January 20, 2015 at https://pathology.uchicago.edu/sites/pathology.uchicago.edu/files/uploads/PDFs/Placental%20Pathology%20Notes%20Aspen%202014%20-Fritsch%20final.pdf)
  9. Electrolytes. AACC, 2013. (Accessed January 25, 2015 at http://labtestsonline.org/understanding/analytes/electrolytes/tab/test/)
  10. CK-MB. AACC, 2013. (Accessed January 25, 2015 at http://labtestsonline.org/understanding/analytes/ckmb/tab/sample/)

 

Tags: Grand Rounds