A night-shift worker experiences extreme difficulty falling asleep due to being exposed to bright lights during both night and day.
The unusual pattern of light exposure is disturbing which controls the release of the hormone:
Metabolic rate; thyroxine.
Limbic system; thymosin.
Circulatory system; dopamine.
Circadian rhythm; melatonin.
The Correct Answer is D
Circadian rhythm is the term for the biological clock that regulates the sleep-wake cycle and other physiological processes in the body.
Melatonin is a hormone that is produced by the pineal gland in the brain in response to darkness.
It helps with the timing of the circadian rhythm and promotes sleep.
Choice A is wrong because metabolic rate is not affected by light exposure, and thyroxine is a hormone that regulates metabolism, not sleep.
Choice B is wrong because the limbic system is a part of the brain that is involved in emotions, memory, and motivation, not sleep.
Thymosin is a hormone that stimulates the development of T cells, which are part of the immune system.
Choice C is wrong because the circulatory system is the system of blood vessels and organs that transport blood throughout the body, not a part of the brain that controls sleep.
Dopamine is a neurotransmitter that is involved in reward, motivation, and movement, not sleep.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The mitral valve lies between the left atrium and left ventricle and prevents the regurgitation of blood from the ventricle back into the atrium.
It has two leaflets that open and close to allow blood to flow from the lungs into the left atrium and then to the left ventricle.
Choice B is wrong because the tricuspid valve lies between the right atrium and right ventricle and prevents the regurgitation of blood from the ventricle back into the atrium.
It has three leaflets that open and close to allow blood to flow from the body into the right atrium and then to the right ventricle.
Choice C is wrong because the pulmonary valve lies between the right ventricle and the pulmonary artery and prevents the regurgitation of blood from the artery back into the ventricle.
It has three leaflets that open and close to allow blood to flow from the right ventricle to the lungs, where it picks up oxygen.
Choice D is wrong because the aortic valve lies between the left ventricle and the aorta and prevents the regurgitation of blood from the aorta back into the ventricle.
It has three leaflets that open and close to allow blood to flow from the left ventricle to the rest of the body.
Correct Answer is C
Explanation
The sinoatrial (SA) node is the natural pacemaker of the heart.
It generates electrical impulses that cause the heart’s chambers to contract, setting the heart rate.
The SA node typically generates 60–100 heartbeats per minute when a person is at rest.
Choice A is wrong because Purkinje fibers are part of the electrical conduction system of the heart that carries impulses to the ventricles.
They are not the primary source of impulses.
Choice B is wrong because the AV bundle (also called bundle of His) is another part of the electrical conduction system of the heart that connects the atria and the ventricles.
It is not the natural pacemaker of the heart.
Choice D is wrong because an atrioventricular node is a relay station between the atria and the ventricles that delays the electrical impulses from the SA node.
It can act as a backup pacemaker if the SA node fails, but it is not the normal pacemaker of the heart.
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