Describe the action potential of an autorhythmic cell in the heart. a) Indicate how the opening and closing of each ion channel affects the membrane potential of the cell. b) Provide one similarity between the action potential of an autorhythmic cell and the action potential of a neuron. c) Provide one difference between the action potential of an autorhythmic cell and the action potential of a neuron.

Which of the following occurs at this point of the membrane potential (marked by the black arrow) in autorhythmic cells?   (A) A (B) B (C) C (D) D

assume the frog heart tissue is placed in a temperature-controlled petri dish containing ringer's solution, will the heart continue to beat ? explain ?

Normal heart sounds are caused by which of the following events? A) friction of blood against the chamber walls B) closure of the heart valves D) blood entering and leaving the heart chambers E) excitation of the SA node

Describe the interactions of actin, myosin, and the troponin-tropomyosin complex in controlling heart function.

Which of the following would most likely cause a baroreflex-mediatedincrease in heart rate?A)Intravenous administration of an alpha- 1 adrenergic receptor agonist.B)Intravenous administration of vasopressin.C)Stimulation of the arterial baroreceptor afferents.D)Profuse sweating for an hour without any fluid replacement.

Frank-Starling law of the heart states: if you increase the stretch of the cardiac muscle fibers you will decrease the force of contraction a greater end diastolic volume will produce a weaker contraction of the ventricle by increasing the force of ventricular contraction you will increase the end systolic volume if you increase the stretch of the cardiac muscle fibers you will increase the force of contraction.

Ch. 5: A patient with a connective tissue disease experiences pulmonary vascular resistance. With time, you would expect the patient to show: a) no obvious changes in heart structure or function b) increased thickness of the right ventricular wall c) increased cardiac output from the right ventricle d) increased cardiac output from the left ventricle O e) increased thickness of the left ventricular wall

Which of the following statements best describes the differences in the regulation of cardiac and skeletal muscle contraction?     The amount of contractile force actively generated by muscle cells is increased by stretch in skeletal muscle and decreased by stretch in cardiac muscle.     Cardiac muscle is stimulated by motor neurons and skeletal muscle by neurones from the autonomic nervous system.     Skeletal muscle contractile force is augmented by increasing the firing frequency of action potentials whereas cardiac muscle contractile force is enhanced by noradrenaline increasing calcium influx through ion channels.     Ryanodine receptors in skeletal muscle are opened by a mechanism that requires calcium influx whereas in cardiac muscle membrane depolarisation alone without calcium influx is sufficient to open ryanodine receptors.

In a standard EPS, briefly explain what is the difference between “pacing after sensing” and “fixed pacing”; in the study of inducibility to ventricular tachycardia (VT)?