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 C
Explanation
The thymus gland is an essential part of the immune system that produces and matures T cells, a type of white blood cell that defends the body from infections.
Thymosins also regulate immune cell production and inhibit aging.
Choice A is wrong because thyroxines are hormones produced by the thyroid gland, not the thymus gland.
Thyroxines control metabolism and affect growth and development.
Choice B is wrong because melatonins are hormones produced by the pineal gland, not the thymus gland.
Melatonins control circadian rhythms and sleep cycles.
Choice D is wrong because prostaglandins are not hormones, but lipid compounds that have hormone-like effects.
Prostaglandins control inflammation, blood pressure, muscle contraction, and other functions.
Correct Answer is C
Explanation
This is because the external jugular vein drains blood from the face and scalp into the subclavian vein.
Some possible explanations for the other choices are:
Choice A. Superior vena cava.
This is wrong because the superior vena cava is a large vein that collects blood from the head, neck, chest, and upper limbs and returns it to the right atrium of the heart.
It does not drain blood from the face and scalp directly.
Choice B. Subclavian vein.
This is wrong because the subclavian vein is a vein that receives blood from the external jugular vein, the internal jugular vein, and the vertebral vein and joins with the internal thoracic vein to form the brachiocephalic vein.
It does not drain blood from the face and scalp directly.
Choice D. Cephalic vein.
This is wrong because the cephalic vein is a vein that runs along the lateral side of the arm from the hand to the shoulder and empties into the axillary vein.
It does not drain blood from the face and scalp at all.
Normal ranges for blood pressure vary depending on age, gender, health status, and other factors, but a general guideline is that systolic blood pressure (the pressure when the heart contracts) should be less than 120 mmHg and diastolic blood pressure (the pressure when the heart relaxes) should be less than 80 mmHg.
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