Which of the following heart valves lies between the left atrium and left ventricle and prevents the regurgitation of blood from the ventricle back into the atrium?
Mitral valve.
Tricuspid valve.
Pulmonary valve.
Aortic valve.
The Correct Answer is A
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Pathogens are disease-causing agents. They can be bacteria, viruses, fungi, protists, or parasitic worms.
They can infect other organisms and cause various diseases.
Choice A is wrong because phagocytic leukocytes are a type of white blood cell that can engulf and destroy pathogens.
They are part of the immune system and help fight infections.
Choice B is wrong because antibodies are proteins that can bind to specific antigens on the surface of pathogens and mark them for destruction by other immune cells.
They are also part of the immune system and help fight infections.
Choice D is wrong because agents that alter DNA base sequences are not necessarily pathogens.
They can be mutagens, such as chemicals or radiation, that can cause changes in the DNA of cells.
Some mutagens can also be carcinogens, which can cause cancer.
Correct Answer is C
Explanation
A newborn is protected against certain digestive and respiratory infections by IgA received via the mother’s milk.
IgA is the main antibody found in breast milk, and it coats and seals the baby’s respiratory and intestinal tract to prevent germs from entering the body and bloodstream.
Choice A is wrong because the blood does not contain IgA, which is the main antibody that protects mucosal membranes.
Choice B is wrong because the placenta does not transfer IgA to the fetus, but only some other antibodies such as IgG.
Choice D is wrong because the intestine does not produce IgA in newborns, as they are born with low levels of IgA.
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