The term preload refers to:
the rate at which the heart beats per minute.
the resistance the left ventricle must overcome to eject blood.
the amount of blood returning to the heart that stretches the ventricles before contraction.
the pressure within the arteries during relaxation.
The Correct Answer is C
Choice A rationale
Heart rate is the frequency of cardiac cycles measured in beats per minute. This parameter represents the chronotropic state of the heart rather than a volume-related measurement. Normal resting adult heart rate typically ranges from 60 to 100 beats per minute. Preload specifically concerns the end-diastolic volume, whereas Choice A describes a temporal measure of cardiac activity that contributes to total cardiac output but does not define the mechanical stretching of the ventricular fibers before contraction.
Choice B rationale
This description refers to afterload, which is the systemic vascular resistance the left ventricle must push against during systole. Afterload is determined by factors like aortic pressure and systemic vascular tone. While preload is a volume measurement occurring before contraction, afterload is the tension or stress developed in the wall of the left ventricle during ejection. Increased afterload can lead to decreased stroke volume if the heart cannot compensate for the increased resistance within the arterial system.
Choice C rationale
Preload is defined as the initial stretching of the cardiac myocytes prior to contraction. It is directly related to ventricular filling and the end-diastolic volume. According to the Frank-Starling law, as preload increases, the force of contraction increases to a point. Normal central venous pressure, which reflects right-sided preload, is 2 to 6 mmHg. Increasing blood return to the heart stretches the myocardial fibers, optimizing the overlap of actin and myosin filaments for an effective contraction.
Choice D rationale
This statement describes diastolic blood pressure, which is the minimum pressure remaining in the arteries when the heart is in a state of relaxation. Normal diastolic blood pressure for an adult is typically less than 80 mmHg. While this occurs during the same phase of the cardiac cycle as preload, it measures the pressure exerted on vessel walls rather than the volume or stretch within the cardiac chambers themselves. It is a component of systemic vascular resistance.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale
The post-ictal phase is the recovery period that occurs immediately after a seizure ends. During this time, the brain is recovering from the intense electrical activity of the tonic-clonic event. Patients commonly experience deep sleep, confusion, fatigue, and difficulty with arousal as neurotransmitter levels and metabolic functions return to baseline. This phase can last from minutes to hours and is a normal, expected component of the seizure cycle following the convulsive stage.
Choice B rationale
An aura is a focal neurological phenomenon that occurs before the onset of a seizure, often serving as a warning sign. It may manifest as sensory distortions, such as smelling something unusual or seeing flashes of light. Since an aura happens prior to the ictal or convulsive phase, it cannot describe the sleeping and unresponsive state that occurs one hour after the seizure has finished. Auras represent the beginning of abnormal electrical activity in a specific area.
Choice C rationale
An absence seizure, formerly known as petit mal, is a brief lapse in consciousness often characterized by staring into space or subtle eyelid fluttering. These seizures usually last only seconds and do not involve the violent tonic-clonic movements or a prolonged, difficult-to-arouse recovery period. The patient in this scenario had a tonic-clonic seizure, which is a generalized convulsion, making the classification of an absence seizure incorrect based on the severity and the described post-event state.
Choice D rationale
A behavioral disorder refers to a persistent pattern of disruptive or antisocial behavior that deviates from cultural norms. Difficulty arousing a patient following a major medical event like a tonic-clonic seizure is a physiological consequence of brain exhaustion and not a psychological or behavioral condition. Labeling this transient medical state as a behavioral disorder would be a clinical error, as it ignores the underlying neurological recovery process known as the post-ictal period.
Correct Answer is C
Explanation
Choice A rationale
The frontal lobe is primarily responsible for motor function, problem-solving, spontaneity, memory, language, initiation, judgement, impulse control, and social and sexual behavior. A stroke in the frontal lobe would more likely cause hemiparesis, Broca's aphasia (difficulty speaking), or profound changes in personality. It does not contain the primary centers for auditory processing. Therefore, the patient's specific symptoms of hearing difficulty do not align with the functional specializations of the frontal cortex.
Choice B rationale
The occipital lobe is the visual processing center of the brain. It handles visual recognition, color perception, and depth perception. A stroke affecting the occipital lobe would result in visual field cuts or total blindness in specific areas of the visual field. It has no role in hearing or the regulation of emotional behaviors. Since the patient is presenting with auditory and emotional disturbances rather than sight issues, the occipital lobe is an unlikely site for the lesion.
Choice C rationale
The temporal lobe contains the primary auditory cortex and is heavily involved in processing sensory input into derived meanings for the retention of visual memory, language comprehension, and emotional association. The limbic system structures, such as the amygdala, are located within or near the temporal lobe and govern emotional behavior. Damage here frequently causes hearing deficits and emotional instability. This perfectly matches the patient's presentation of difficulty with hearing and altered emotional states following a stroke.
Choice D rationale
The parietal lobe is responsible for integrating sensory information from various parts of the body, specifically touch, pressure, and spatial awareness. It houses the somatosensory cortex. Damage to the parietal lobe typically results in hemispatial neglect, difficulty with mathematics (acalculia), or loss of sensation on one side of the body. It is not the primary site for auditory or emotional regulation. Thus, a parietal stroke would not explain the patient's hearing loss and behavioral changes.
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