Unlike smooth and skeletal muscle, cardiac muscle tissue is capable of
The Correct Answer is {"dropdown-group-1":"D"}
A. Distension: Cardiac muscle tissue is capable of stretching to accommodate varying volumes of blood, a property shared with smooth muscle (in blood vessels and hollow organs) and skeletal muscle to some extent. Distension alone does not distinguish cardiac muscle from other muscle types.
B. Relaxation: Relaxation is a fundamental property of all muscle types, including skeletal, smooth, and cardiac muscle. After contraction, all these muscles return to their resting length to allow subsequent filling or preparation for the next contraction.
C. Contracting: Contraction is a universal property of all muscle types. Skeletal, smooth, and cardiac muscles all contract via actin–myosin cross-bridge cycling in response to appropriate stimuli.
D. Autorhythmicity: Cardiac muscle is unique in its ability to generate spontaneous action potentials without external nervous stimulation. Specialized pacemaker cells within the sinoatrial node initiate rhythmic depolarization, allowing the heart to maintain a coordinated and continuous heartbeat. This intrinsic automaticity is distinct from skeletal and smooth muscle, which require neural or hormonal stimuli to contract.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
N: Pulmonary valve- The pulmonary valve is a semilunar valve between the right ventricle and pulmonary artery. It prevents backflow into the ventricle during diastole, facilitating blood flow toward the lungs for oxygenation.
E: Fossa ovalis - The fossa ovalis is a shallow, thumb-sized depression located in the interatrial septum (the wall separating the right and left atria). In a developing fetus, the foramen ovale is an open "tunnel" that allows blood to bypass the lungs by flowing directly from the right atrium to the left atrium. Once a baby takes their first breath, the pressure changes in the heart cause a flap of tissue to close over this opening. Over time, it fuses shut, leaving behind the shallow indensee fossa ovalis.
O: chordae tendinae: Chordae tendineae are fibrous cords connecting the atrioventricular valve leaflets (mitral and tricuspid) to papillary muscles. They prevent valve prolapse during ventricular contraction, ensuring unidirectional blood flow.
J: Aortic arch- The aortic arch is the curved portion of the aorta that distributes oxygenated blood from the left ventricle to systemic arteries. It contains baroreceptors and helps regulate blood pressure.
Correct Answer is A
Explanation
A. Sympathetic stimulation releases norepinephrine (NE), which binds to beta-1 receptors, increasing heart rate: Sympathetic nerve fibers release norepinephrine, which binds to beta-1 adrenergic receptors on the sinoatrial node and ventricular myocardium. This increases the rate of depolarization in pacemaker cells, enhancing heart rate (positive chronotropy), and also increases contractility (positive inotropy), preparing the heart for increased cardiac output.
B. Parasympathetic stimulation releases norepinephrine (NE), which binds to beta-1 receptors, increasing heart rate: Parasympathetic fibers do not release norepinephrine; they release acetylcholine. Norepinephrine is specific to sympathetic innervation. Therefore, this description incorrectly attributes sympathetic neurotransmission to parasympathetic activity.
C. Sympathetic stimulation releases norepinephrine (NE), which binds to muscarinic receptors, slowing heart rate: Muscarinic receptors are activated by acetylcholine released from parasympathetic fibers, not by norepinephrine. Sympathetic stimulation increases heart rate, rather than slowing it, through beta-1 receptor activation.
D. Parasympathetic stimulation releases acetylcholine (ACh), which binds to the beta-1 receptors, increasing heart rate: Parasympathetic stimulation releases acetylcholine, but it binds to muscarinic receptors on pacemaker cells, not beta-1 adrenergic receptors. Activation of muscarinic receptors slows the heart rate (negative chronotropy) rather than increasing it.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.