The right atrium receives blood directly from:
The superior vena cava, inferior vena cava, and coronary sinus.
The superior vena cava and inferior vena cava only.
The superior vena cava, inferior vena cava, and pulmonary veins.
The pulmonary veins.
The Correct Answer is A
The right atrium receives blood directly from the superior vena cava, inferior vena cava, and coronary sinus.
The superior vena cava and inferior vena cava bring deoxygenated blood from the upper and lower body, respectively.
The coronary sinus brings blood from the heart muscle.
Choice B is wrong because it excludes the coronary sinus, which also empties into the right atrium.
Choice C is wrong because it includes the pulmonary veins, which carry oxygenated blood from the lungs to the left atrium, not the right atrium.
Choice D is wrong because it only includes the pulmonary veins, which are not connected to the right atrium at all.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Uterine contractions during childbirth illustrate a positive feedback mechanism.
A positive feedback mechanism is a process in which the end products of an action cause more of that action to occur in a feedback loop.
This amplifies the original action.
For example, when a woman goes into labor, the pressure of the baby’s head on the cervix stimulates nerve impulses that travel to the brain and trigger the release of oxytocin, a hormone that causes the uterus to contract.
The contractions increase the pressure on the cervix, which stimulates more nerve impulses, more oxytocin, and more contractions.
This cycle continues until the baby is delivered.
Choice A is wrong because body temperature control is an example of a negative feedback mechanism, which is when the end results of an action inhibit that action from continuing to occur.
For example, when the body temperature rises above normal, the skin sweats, and blood vessels dilate to release heat.
This lowers the body temperature back to normal and stops sweating and dilation.
Choice B is wrong because control of blood sugar is also an example of a negative feedback mechanism.
For example, when the blood sugar level rises after a meal, the pancreas secretes insulin, a hormone that helps cells take up glucose from the blood.
This lowers the blood sugar level back to normal and stops the insulin secretion.
Choice D is wrong because maintaining blood pressure is another example of a negative feedback mechanism.
For example, when the blood pressure drops due to blood loss or dehydration, the heart beats faster and stronger, and the blood vessels constrict to increase the blood pressure.
This restores the blood pressure back to normal and stops the heart rate and vessel constriction.
Correct Answer is A
Explanation
The correct answer is choice A. True.
Blood flow through a capillary is controlled by a precapillary sphincter, which opens or closes due to the requirements of the cells supplied by the capillary.
This allows blood to bypass the capillaries when they are not needed and to increase blood flow when they are needed.
Choice B. False is wrong because it contradicts the true statement in choice A. A precapillary sphincter is a ring of smooth muscle that surrounds the entrance of a capillary and regulates blood flow into it.
It is influenced by local factors such as oxygen, carbon dioxide, pH, and temperature.
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