A red blood cell contains a large nucleus; it is thicker near the center and thin around the rim of the cell:
False
True.
The Correct Answer is A
Red blood cells do not contain a large nucleus; in fact, they do not contain a nucleus at all when they are mature.
This is an adaptation that allows them to carry more hemoglobin, the protein that binds oxygen, and to squeeze through narrow capillaries.
Choice B is wrong because it contradicts the fact that red blood cells are enucleated (lacking a nucleus) in humans and most mammals.
Some vertebrates, such as birds and fish, have nucleated red blood cells, but they are not thick near the center and thin around the rim of the cell.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A person who is stressed usually will have increased blood pressure because stress causes the body to release a surge of hormones that make the heart beat faster and the blood vessels narrow.
This can cause a temporary spike in blood pressure, which usually returns to normal once the stressor is gone.
Choice A is wrong because resistance to infections is not increased by stress.
In fact, chronic stress can weaken the immune system and make a person more prone to infections.
Choice B is wrong because the activity of the spleen and other lymphatic organs is not increased by stress.
The spleen and other lymphatic organs are part of the immune system, which can be affected by chronic stress in a negative way.
Choice C is wrong because the number of lymphocytes in the blood is not increased by stress. Lymphocytes are a type of white blood cell that help fight infections.
Chronic stress can reduce the number and function of lymphocytes and impair the immune response.
Correct Answer is A
Explanation
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.
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