Week 1

Reflection

Using the Gibb’s Reflective Model I will reflect on the first Lab session we had for this semester. It took place on the 2^nd of September.

Description: We performed the skills from the list of prerequisite skills and our teacher assessed our competency in each skill. I was competent in all the skills except providing effective manual chest compressions.

Feelings: Practicing the prerequisite skills made me feel more confident. I also felt excited to see that I still remembered exactly how to perform almost all the skills. However, I was a little surprised that my chest compressions had weakened.

Evaluation:  This lab session was a good experience since it refreshed my memory and I was able to perform almost every required skill very well. However, it was bad when I realized my chest compressions were not as effective as they used to be.

Analysis: In my opinion, I did a good job since I did well in all the skills except one, providing effective chest compressions. The reason was that I was not compressing to an adequate depth. I believe this happened because the last time I preformed chest compressions was 3 months before. However, the more I practiced, the better I was performing. Also, doing the video submission last semester allowed me to practice the airway management skills so many times that I remembered each one perfectly, even after a quarter of a year.

Conclusion: Providing adequate compressions is a skill that needs constant practice. If not practiced enough, my arms will get weaker and the compressions will not be effective.

Action Plan: I plan to practice my chest compressions regularly so as to get stronger and be able to provide effective chest compressions.

Picture 1: Manikin and AED that were used to practice CPR

Picture 2: Airway management manikin, suctioning machine, and airway adjuncts

Domain Knowledge: This week's lecture was condensed. It covered topics from the location of the heart,the internal and external anatomy of the heart, it's layers, fibrous skeleton, valves, circulation of the blood, the coronary circulation, including the coronary arteries and veins, the parts of the heart they supply, the conduction system, cardiac cycle, nervous control and chemical regulation of the heart, and the structure, function of arteries, veins and capillaries, as well as the pressure in them. I will insert some pictures of my notes  for this lecture below, to show what i learned.

Picture 3: Location and anatomy of the heart. I was really happy with this page!

 For the layers of the heart, there are 4 layers. From outermost to innermost: Fibrous pericardium, serous pericardium, myocardium and endocardium. Moreover, the serous pericardium is split into the parietal and visceral (epicardium) layers, with a pericardial cavity between them. The pericardial cavity contains pericardial fluid that lubricates and allows easier movement during contraction of the heart. There are some diseases that involve fluid accumulation which causes pressure on the heart.

Picture 4: Fibrous skeleton, AV and SL valves, and their characteristics

Picture 5: Blood circulation around the body

Picture 6: Coronary arteries, the process of supplying them, and veins

Picture 7: The heart's intrinsic conduction system and its effect on the myocardium

Picture 8: Stages of the cardiac cycle, the time each one takes, and some events during the cycle

Picture 9: Nervous and chemical regulation of the heart

Furthermore, for the structure and function of blood vessels. There are three layers in blood vessels, some vessels have all and some have one. Those layers are: the tunica intima, tunica media, and tunica externa (adventitia).

Tunica Intima	Tunica Media	Tunica externa
Endothelium and elastic tissue	Smooth muscle cells and sheets of elastin	Elastic and collagen fibers

                                        Table 1: Components of the three layers

There are 3 types of blood vessels in the body: Arteries, veins and capillaries. Arteries are further broken down into elastic(conducting), muscular(distributing), and arterioles. Elastic arteries have the biggest lumen of all the vessels and has all three layers, however, it's tunica externa is thicker than the tunica media. This is so that it can endure the high pressure of the blood pushed into it by the heart. For the distributing arteries they have the thickest tunica media, since it is active in vasoconstriction. Furthermore, arterioles are the smallest arteries and they are the connection between arteries and capillaries. Large arterioles have the 3 tunics but small arterioles have a single layer of smooth muscle around the endothelial lining. This makes only 2 layers. As for veins, there are venules, veins and the vena cavae. All three have the 3 layers tunica intima, media and externa.

Moreover, capillaries are the smallest of all vessels and they connect arterioles with venules, and form networks for the exchange of nutrients and wastes between blood and tissue cells, via the interstitial fluid. They only have one layer, the tunica intima. RBCs fit as single cells only.

Finally, the pressure in the aorta is 100mmHg. As the blood moves through the body's circulation, the pressure gradually decreases until it reaches the right atrium. At the rt atrium, the pressure reaches 0mmHg.

Enquiry and Research:

To help me fully understand everything I did some extra readings. First i read about the anatomy and physiology of the heart and about the structure of blood vessels.  Earlier i talk about how increases pericardial fluid exerts pressure on the heart. During my readings i read about pericarditis, which does the opposite. It results in a decrease of pericardial fluid which causes the pericardial layers to bind and stick to each other.This forms painful adhesions that interfere with heat movements (Marieb, 2015).

Also, i read about how the myocardial cells exhibit desmosomes, which strongly bind the cells together, and gap junctions, which allow ions to flow from cell to cell carrying a wave of excitement across the heart. Moreover, the endocardium is continuous with the linings of the blood vessels entering and leaving the heart (Marieb, 2015). 

Furthermore, i found out that atria are called "receiving chambers" and ventricles "discharging chambers". Also, the septum, which divides the heart longitudinally, is referred to as either interventricular or interatrial, depending on which chamber it separates. Moreover, the left ventricle's walls are much thicker than the right ventricle's because the lt. ventricle pumps blood over a much longer pathway, making it a stronger pump.

For the AV and SL heart valves there is a very good illustration of how they open and close and what causes that on page 386 of Marieb's Essentials of Human Anatomy and Physiology.

Also, angina pectoris is described. It is when there is tachycardia, the myocardium doesn't receive adequate blood supply due to shortened relaxation periods. This results in crushing chest pain, or angina. This pain should never be ignored since its a warning sign of possible occurrence of a myocardial infarction (MI) (Marieb, 2015). Angina is described in another book as not a disease itself but a symptom of MI (Aehlert, 2013).

Furthermore, blood circulation in capillary beds is called microcirculation and the arteriole before it is called the terminal arteriole and the venule after the capillary bed is the postcapillary venule(Marieb, 2015).

For the coronary circulation i was interested to know the locations each artery supplied. I found an excellent table showing the parts of the myocardium as well as the conduction system supplied by which arteries. 

Picture 10: Coronary arteries and the areas they supply. Adopted from (Aehlert, 2013)

Moreover, in the Huszar's textbook there is a paragraph about accessory conduction pathways. These pathways conduct impulses from the atria to the ventricles directly, bypassing the AV node and the bundle of His. These accessory conduction pathways depolarize ventricles earlier than they would if the impulse traveled down the electrical conduction system normally. 

This abnormality can cause premature ventricular complexes. Also, these pathways don't just conduct the impulse in the anterograde direction, but can also conduct them in a retrograde direction. This sets up the mechanism for reentry tachydysrythmias (Wesley, 2011).

References

Aehlert, B. (2013). ECGs made easy. St Louis, MO: Mosby.

Marieb, E.N. (2015). Essentials of human anatomy and physiology (11th ed.). In S. Beauparlant (Ed.),Chapter 11: The cardiovascular system (pp.380- 401). Essex, England: Pearson Education.

Wesley, K. (2011). Huszar's basic dysrythmias and acute coronary syndromes: Interpretation and management (4th ed.). St Louis, MO: Elsevier.