CARDIOLOGY´╗┐This unit discusses the structure, functions and disorders of the heart. STRUTURE OF THE HEART

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The heart is made up of powerful cardiac muscles and is a little bigger than your fist. The heart has two different pumps that send blood throughout the body carrying nutrients, oxygen, and helping remove harmful wastes. The right side of the heart receives blood low in oxygen. The left side of the heart receives blood that has been oxygenated by the lungs. The blood is then pumped out into the Aorta and to all parts of the body. Right Atrium: The right atrium has two major veins that return blood to the heart from various parts of the body. The two major veins returning the blood to the heart are the superior vena cava and the inferior vena cava. The superior vena cava returns the deoxygenated blood from the upper part of the body while the inferior vena cava returns the deoxygenated blood from the lower part. The right atrium also receives blood back from the heart muscle itself. From there, the blood is pumped through the right ventricle and then through the tricuspid valve.Left Atrium: The left atrium receives blood from the pulmonary veins. The blood received from the lungs has been oxygenated. This oxygenated blood that has been collected in the left atrium is then pumped into the left ventricle through the Bicuspid Valve.´╗┐Right Ventricle: The right ventricle receives blood from the right atrium. Upon heart contractions, the blood is pushed through the pulmonary Semilunar valve and pulmonary artery. Left Ventricle: The oxygenated blood that the left ventricle receives from the left atrium has to be pumped throughout the body. The bicuspid valve closes and the blood is collected in the left ventricle. The closing of the bicuspid valve stops the backflow of blood. From there, heart muscle contractions force the blood through the aortic valve and then finally passes through the aorta to be distributed throughout the body. This video is a great source to understand how the heart looks and functions.





ATHEROSCLEROSIS/CARDIAC ARRYTHMIAS
Atherosclerosis is a disease process of the hardening of arteries that eventually can lead to the obstruction of normal blood flow. Through it's contribution to stroke and heart disease, it accounts for 50% of deaths in the US, Europe and Japan. In atheroslerosis, localized plaques protrude into the middle of the artery reducing blood flow and serving as sites for blood clots. In the beginning, clots will heal up and shrink but it will harden and narrow the artery. Sometimes it can even lead to complete closure of the artery which will leave organs with insufficient blood and oxygen flow. The progression of atherosclerosis can be gradual, but sometimes the soft plaque will rupture and cause a thrombus completely cutting off blood flow. The plaque build up and eventual atheroslerosis is contributed from smoking, high blood pressure, high cholesterol and diabetes.

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BLOOD PRESSURE & HYPERTENSION
Blood pressure is the pressure of circulating blood against the walls of the blood vessels. Obtaining blood pressure is one of the primary vital signs and can be a quick indicator of health with the normal adult value being around 120/80. A pressure cuff and sphygomanometer are used to measure blood pressure as well as a stethoscope to ausculate the blood pressure related with arterial sounds. Hypertension is a condition characterized by high blood pressure. Nearly 20% of American adults have the condition. It is generally caused by increased cardiac output and/or total peripheral resistance.

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APPLICATION

Understanding the normal functions of the heart is vital to be able to understand and treat a heart condition. The heart is very complex, and in my opinion, fragile. As a nurse, I treat many conditions of the heart to prevent alterations in circulation. I understand and use many different medications to treat heart conditions and to prevent further issues including beta blockers, antihypertensives, anticoagulants, ACE inhibitors, nitrates, etc. I am also knowledged in knowing what to expect with a heart condition (edema, headaches, localized left side pain, blurred vision). Being able to read EKG/EKC strips and differentiate between different serum markers (Elevated tropinin is a sure way to detect a myocardial infarction).

ESSENTIAL QUESTION: "What are the three most important variables that effect blood pressure? Explain each variable and how it affects blood pressure. Describe two reflexes that help maintain blood pressure within normal limits.

Cardiac Output: Cardiac output is the total amount of blood being pumped per minute and is a function of stroke volume and heart rate. When cardiac output increases, blood pressure goes up as well.
Total Peripheral Resistance: The total peripheral resistance refers to the sum of vascular resistance to the flow of blood for circulation. Because of their small radii, arterioles provide the greatest resistance to blood flow in the arterial system. Resistance and pressure are directly related to each other. If resistance increases, then pressure increases too.
Blood Volume: Blood volume is the amount of blood circulating in the body and is again correlates with blood pressure. If there is an increase in blood volume, there will be an increase in venuous return. This will trigger the stroke volume to increase, making the heart work harder and the cardiac output to increase. Thus, causing blood pressure to rise.

Two reflexes include:
Baroreceptors: The baroreceptor reflex is a homeostatic mechanism for maintaining blood pressure. It provides a negative feedback loop where an elevated blood pressure reflexively causes heart rate and in turn, blood pressure to decrease. These receptors detect changes in blood pressure and send signals to the brain.
The nervous system: Blood pressure is monitored minute by minute by nerves. If an increase in blood pressure is needed, the sympathetic nervous system will vasoconstrict vessels. If a decrease in blood pressure is needed, the parasympathetic nervous system will cause the blood vessels to vasodialate.
http://www.biosbcc.net/doohan/sample/htm/COandMAPhtm.htm)
http://www.healthylivingsense.com/understanding-how-the-nervous-system-regulates-blood-pressure/
http://en.wikipedia.org/wiki/Baroreflex


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