. Cardiac output In the late 1860s, Adolf Fick, a professor of physiology in the Faculty of Medicine in Würzberg, Germany. developed one of the methods we use today for measuring how much blood your heart pumps in a minute. Your cardiac output as you read this sentence is probably about 7L/min. At rest it is likely to be a bit under 6 L/min. If you are a trained marathon runner running a marathon, your cardiac output can be as high as 30 L/min. Your cardiac output can be calculated with the formula where Qis the number of milliliters of CO, you exhale in a minute and D is the difference between the CO, concentration (ml/L) in the blood pumped to the lungs and the CO, concentration in the blood returning from the lungs. With Q - 233 ml/min and D - 97 - 56 - 41 ml/L, 233 ml/min 5.68 L/min, 41 ml/L fairly close to the 6 L/min that most people have at basal (resting) conditions. (Data courtesy of J. Kenneth Herd, M.D., Quillan Col- lege of Medicine, East Tennessee State University.) Suppose that when Q - 233 and D - 41, we also know that D is decreasing at the rate of 2 units a minute but that Q remains unchanged. What is happening to the cardiac output?

Sue goes to the gym and after an initial warm-up, she increases her exercise level pushing herself to maximum.  At this point her heart rate is 175 beats/min and her stroke volume is 135 ml/beat.  What is her cardiac output now?     At this point, by how many ml/min has her CO increased over her resting CO?        What % increase over resting is this?  (Use the following equation).                                          amount of increase in CO in ml/min % increase =  _____________ X  100%                       original CO (resting) ml/min         What term is used to describe this increase in CO?

When exercising, the American Heart Association recommends the intensity of your exercise regimen to be determined by your heart rate during exercise. This is known as a target heart rate zone and it is dependent on your current resting rate, age and fitness level. To calculate your target heart rate zone, complete the following: 1. Determine your maximum heart rate: • Subtract your age from 220. (Example, if you are 25 years old 220-25 = 195. 195 is your maximum heart rate). Record your maximum heart rate in box 1. 2. Determine your resting heart rate: • While sitting at your desk or sitting down, take 3 deep breaths. After taking the third breath, lightly rest your pointer and middle finger on your neck over your artery until you can feel your heartbeat. Count the number of times your heart beats in 15 seconds. Multiply that number by 4. This is your resting heart rate. Record your resting heart rate in text box 2. Activate Windows Go to Settings to activate

Caffeine lowers the heart rate by increasing rates of depolarization at the SA node   True False   Nicotine raises the heart rate because it stimulates the activity of the sympathetic neurons in medulla oblongata   True False   The Frank-Starling Law of the Heart states that the force of heart contraction is directly proportional to the initial length of the muscle fiber, within optimal limits of length   True False If the sarcomeres stretched beyond the optimal length, the force of contraction would go down, but that can potentially happen only during open heart surgery when the heart is not constrained by the pericardium, lungs, ribs and diaphragm.   True False It is the Na+ channel-driven spontaneous depolarization that is affected by sympathetic and parasympathetic inputs to speed up or slow down the firing rate of the SA node and other conductive cells.   True False