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.
True
False
The Correct Answer is A
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
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.
Correct Answer is B
Explanation
Innate defenses counter specific disease-causing agents, whereas adaptive defenses include mechanical and chemical barriers.
Choice A is wrong because it confuses the two types of defenses.
Innate defenses are nonspecific and include physical barriers such as the skin, molecules that are toxic to invaders, and phagocytic cells that ingest invaders.
Adaptive defenses are specific and are activated by the innate immune system.
They involve the production of antibodies and specialized cells that recognize and eliminate specific pathogens.
Normal ranges are not applicable in this question as it is about the definitions of innate and adaptive defenses.
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