To describe: The effect of calcium channels blockers and beta receptor blockers on the heart, and the mechanism by which these drugs reduce the cardiac output.
Introduction: Ca2+ enters the contractile cell through voltage-gated L-type Ca2+ channels present in the cell membrane. When Ca2+ enters into the contractile cell, it opens ryanodine receptors located on the sarcoplasmic reticulum. This leads to the release of Ca2+ into the cytosol. The Ca2+ released during this process is required for heart contraction. Beta receptors can bind to epinephrine and norepinephrine that flow into the blood. These receptors play a role in increasing heart rate and contraction, and therefore, help in the cardiac output.
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Human Physiology: An Integrated Approach (7th Edition)
- a) A consequence of the Frank-Starling law of the heart is that the outputs of the right and left ventricles match. Explain why this is important and how this match is made.b) The excitation-contraction matching mechanism within the heart muscle is different from that of the skeletal muscle. How might these differences be related to the difference between action potentials in cardiac muscle and skeletal muscle?arrow_forwardRoberto is a 78-year-old male who has recently been diagnosed with Class III Congestive Heart Failure (CHF). His physician told him that his left ventricle has become stiff and cannot relax. Although there is no current treatment that can “fix” Roberto’s condition, he is prescribed two medications: an ACE inhibitor and beta blockers.Briefly describe how ACE-inhibitors will influence Roberto’s heart function.arrow_forwardWe analyzed the difference between the action potential of a cardiac contractile cell and an action potential in a neuron. Describe the physiological mechanisms behind the primary difference in the shape of these two action potentials. Why is this feature important to the normal workings of the heart?arrow_forward
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- If all plasma membrane Ca21 channels in contractile cardiac muscle cells were blocked with a drug, what would happen to the muscle’s action potentials and contraction?arrow_forwardRoberto is a 78-year-old male who has recently been diagnosed with Class III Congestive Heart Failure (CHF). His physician told him that his left ventricle has become stiff and cannot relax. Although there is no current treatment that can “fix” Roberto’s condition, he is prescribed two medications: an ACE inhibitor and beta blockers. Which of these statements is most likely true of Roberto’s current symptoms? He doesn’t experience any symptoms at all at rest or during exercise. He has no symptoms at all during rest, but experiences palpitations, fatigues, and shortness of breath during mild exercise. He experiences fatigue, shortness of breath, and palpitations at rest and is not able to participate in any physical activity.arrow_forward1) A drug was applied to a person that blocked the pore/channel in the L-type calcium channel in cardiac muscle cells. The drug had no other effects. True/false: Cross-bridge cycling and tension production would occur normally in drug-treated fibers. 2) The plateau phase of a cardiac action potential is an absolute refractory period.True/false 3) If a heart lacked gap junctions, an organ-level contraction would occur.True/false 4) During a pacemaker potential, what is caused in neighboring muscle fibers when threshold potential is reached. Group of answer choices a)cross-bridge cycling b)Receptor potential c)An action potential d)A graded potentialarrow_forward
- What is the consequence of the prolonged plateau of depolarization in ventricular myocytes? a-it causes ventricular myocytes to contract for a longer time, allowing the ventricles time to empty b-it gives additional time for the atria to contract, filling the ventricles more completely c-it causes repolarization to be delayed which slows heart rate d-it allows the ventricles a moment to rest before completing contractionarrow_forwardBriefly define 1) Starling’s Law of the heart, 2) the basic cellular mechanism thought to mediate this response, and 3) the physiological significance of this effect.arrow_forwardHow does the fact that cardiac muscle does not undergo tetanus (as skeletal muscle does) affect the functioning of the heart?arrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning