Blood Pressure and Electrocardiography - Assignment Example

Human Anatomy and Physiology Calculations Define diastolic blood pressure. "Diastolic" came from the Greek diastole meaning "a drawing apart."The term has been in use since the 16th century to denote the period of relaxation of the heart muscle. The diastolic pressure is specifically the minimum arterial pressure during relaxation and dilatation of the ventricles of the heart when the ventricles fill with blood. In a blood pressure reading, the diastolic pressure is typically the second number recorded. For example, with a blood pressure of 120/80 ("120 over 80"), the diastolic pressure is 80. By "80" is meant 80 mm Hg (millimeters of mercury). (Braunwald E, 2004; Moreno MN, 2006)) 2. Given a blood pressure of 125/80, what is the mean arterial pressure? Mean Arterial Pressure = DBP + 1/3(SBP-DBP) Given: SBP = 125 DBP = 80 80 + 1/3(125-80) = 95mmHg 3. Assuming a stroke volume output of 70 ml at rest that increases by 20% after exercise, and a heart rate of 60 at rest and 125 following exercise, calculate the cardiac output standing at rest and immediately after exercise. Cardiac Output = Stroke Volume x Heart Rate (at rest) SV = 70ml HR = 60bpm CO = 70 x 60 = 4200 ml/min / 4.2 L/min Immediately after exercise, increased by 20% CO (at rest) + 20% CO (at rest) = 4200 + 0.2(4200) = 5040ml/min or 5 L/min 4. The specific gravity of mercury 13.6 times that of water. If your blood pressure were 110/70 mm Hg, what would that be in cm H20? Conversion Unit :1cmH20= 0.736mmHg 110mmH x 1cm H20/0.736mmHg = 149.45cmH20 70mmHg x 1cm H20/0.736mmHg = 95.1cmH20 Final Answer: 149.45cmH2O/95.1cmH2O Electrocardiography 1. When the electrode pads are placed on the subject, where is the positive electrode placed? An electrocardiogram is obtained by measuring electrical potential between various points of the body using an amplifier. A lead records the electrical signals of the heart from a particular combination of recording electrodes which are placed at specific points on the patients body. When a depolarization wavefront (or mean electrical vector) moves toward a positive electrode, it creates a positive deflection on the ECG in the corresponding lead. When a depolarization wavefront (or mean electrical vector) moves away from a positive electrode, it creates a negative deflection on the ECG in the corresponding lead. When a depolarization wavefront (or mean electrical vector) moves perpendicular to a positive electrode, it creates an equiphasic (or isoelectric) complex on the ECG. Leads I, II and III are called limb leads. Lead I is a dipole with the negative (white) electrode on the right arm and the positive (black) electrode on the left arm. Lead II is a dipole with the negative (white) electrode on the right arm and the positive (red) electrode on the left leg. Lead III is a dipole with the negative (black) electrode on the left arm and the positive (red) electrode on the left leg (Moreno MN, 2006). 2. You can calculate your heart rate in two ways. First, you could simply count the number of pulses for a given time period and adjust that to the number of pulses per minute. Or, you could measure the cycle time of the cardiac cycle. If you measure the cycle time to be 0.575 sec, what is the heart rate? 60 sec / Cardiac Cycle time = 60/ 0.575 = 104.34 bpm 3. What does the P-wave of the ECG represent? The main electrical vector of the conduction system emanates from the SA node towards the AV node in normal depolarization. This spreads from the right atrium going to the left atrium. This turns into the P wave on the ECG, which is upright in II, III, and aVF (since the general electrical activity is going toward the positive electrode in those leads), and inverted in aVR (since it is going away from the positive electrode for that lead). A P wave must be upright in leads II and aVF and inverted in lead aVR to designate a cardiac rhythm as Sinus Rhythm. The relationship between P waves and QRT complexes helps distinguish various cardiac arrhythmias. The shape and duration of the P waves may indicate atrial enlargement. (Wyngaarde JB, 1992) Thoracic anatomy Identify the following structures in this dissection of the canine thorax: diaphragm, heart, lung, trachea Answers: A = Trachea B = Right Lung lobe C = Heart D = Diaphragm Endocrine System Histology Using these pictures as your guide, be able to identify the specified endocrine system organs. Your choices are thyroid gland, adrenal gland, pancreatic islets, pituitary gland. The Adrenal Gland cut at the junction of the Cortex and Medulla. The Macro- and Mircofollicles of the Thyroid Gland Sheep Heart Anatomy Identify the labelled structures: External view, front of heart L ventricle, pulmonary trunk, R ventricle Answers: A = Pulmonary trunk B = Right ventricle C = Left ventricle Dissection of R atrium and ventricle chordae tendineae, moderator band, papillary muscle, tricuspid valve Answers D = Tricuspid valve E = Moderator band F = Papillary muscle G = Chordae tendineae Dissection of L atrium and ventricle aortic semilunar valves, chordae tendineae, mitral valve, pectinate muscles, ventricular myocardium Answers H = Mitral valve J = Pectinate muscles K = Aortic semilunar valves L = Chordae tendineae M = Ventricular myocardium References Moreno MN, Human Structural Biology: Anatomy and Physiology for Allied Health Professionals, 2006, 3rd Ed., J.Enriquez Publishing. Braunwald E, Fauci A, Kasper D, Hauser S, Longo D, Jameson J., Harrisons Principles of Internal Medicine, 2004, 16th Ed, McGraw-Hill. Wyngaarde, JB, Smith LH, Bennett JC., Cecil Textbook of Medicine, Principle’s of Diagnosis and Management, 1992, 19th Ed., W.B. Saunders Company. Read More