What are possible effects of hypokalemia? Check all that apply. Check All That Apply Neurons become hyperpolarized and are less excitable. Electrical activity of the heart becomes irregular.

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?

Norepinephrine acts on heart muscle cells by: Group of answer choices blocking the action of calcium. increasing heart contractility. causing a decrease in stroke volume. causing threshold to be reached more quickly. more than one of the above.

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