Positive feedback mechanisms:
Usually produce stable conditions.
Cause long-term changes.
Move conditions away from the normal state.
Bring conditions back to the normal state.
The Correct Answer is C
Positive feedback mechanisms move conditions away from the normal state.
They amplify the original action and produce more of the same effect.
For example, blood clotting and childbirth are positive feedback mechanisms.
Choice A is wrong because positive feedback mechanisms usually produce unstable conditions.
They do not resist change but rather enhance it.
Choice B is wrong because positive feedback mechanisms do not cause long-term changes.
They are ultimately stopped by negative feedback loops once the process they were used for is complete.
Choice D is wrong because positive feedback mechanisms do not bring conditions back to the normal state.
That is the role of negative feedback mechanisms, which oppose the stimulus and restore homeostasis.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
The correct answer is choice B. False.
Arteries are strong, elastic vessels that carry blood away from the heart, except for the coronary arteries that supply blood to the heart muscle.
These are the first arteries to branch off the aorta, which is the main artery that takes blood to the body from the left ventricle.
Choice A is wrong because it contradicts the definition of arteries. Arteries carry blood away from the heart, not to the heart.
Correct Answer is B
Explanation
This is because erythroblastosis fetalis, also known as hemolytic disease of the newborn, is caused by Rh incompatibility between the mother and the fetus.
Rh incompatibility occurs when a Rh-negative mother is impregnated by a Rh-positive father, resulting in a Rh-positive fetus.
The mother’s immune system can detect the Rh factor on the fetus’s red blood cells as foreign and produce antibodies against them.
These antibodies can cross the placenta and destroy the fetus’s red blood cells, causing anemia, jaundice, edema, and other complications.
Choice A is wrong because a second Rh-negative fetus developing in an Rh-negative woman will not cause erythroblastosis fetalis.
The mother and the fetus have the same Rh factor, so there is no immune reaction.
Choice C is wrong because a first Rh-positive fetus developing in an Rh-negative woman will not cause erythroblastosis fetalis.
The mother’s immune system will not produce antibodies against the Rh factor until after the first exposure to it, which usually happens during delivery.
Therefore, the first pregnancy is usually unaffected.
Choice D is wrong because a first Rh-negative fetus developing in an Rh-negative woman will not cause erythroblastosis fetalis.
The mother and the fetus have the same Rh factor, so there is no immune reaction.
The normal range of red blood cell count for newborns is 4.1 to 6.1 million cells per microliter of blood.
The normal range of bilirubin level for newborns is 0.3 to 1.9 milligrams per deciliter of blood.
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