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 only.
The superior vena cava, inferior vena cava, and pulmonary veins.
The pulmonary veins.
The Correct Answer is A
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Veins are the type of blood vessel that holds the greatest volume of blood and serve as reservoirs for blood.

According to 1, veins contain about 70-80% of the blood volume in circulation.
Veins are also called capacitance vessels because they can expand and store more blood when needed.
Choice A. Capillary is wrong because capillaries are very thin and narrow vessels that allow the exchange of gases and nutrients between the blood and the tissues.
Capillaries have a very small volume compared to veins.
Choice C. Arteriole is wrong because arterioles are small branches of arteries that regulate blood pressure and blood flow to the capillaries.
Arterioles have a higher resistance and lower volume than veins.
Choice D. Artery is wrong because arteries are thick and muscular vessels that carry oxygen-rich blood away from the heart to the rest of the body.
Arteries have a higher pressure and lower volume than veins.
Normal ranges for blood volume vary depending on age, sex, weight, and health status, but generally range from 4 to 6 liters for adults.
Correct Answer is B
Explanation
As a result of the allergen-antibody reaction, mast cells release histamine.
This is because when mast cells are exposed to an allergen that binds to IgE antibodies attached to their FcɛRI receptors, they release histamine and other inflammatory mediators.
Histamine causes vasodilation, increased capillary permeability, mucus secretion, and smooth muscle contraction, which result in allergic symptoms such as itching, swelling, sneezing, and wheezing.
Mast cells do release histamine in response to allergen-antibody reactions. Some additional sentences are:
Normal ranges of histamine levels vary depending on the tissue and the method of measurement, but they are usually low in healthy individuals and elevated in allergic conditions.
Histamine can be degraded by enzymes such as diamine oxidase and histamine N- methyltransferase, or inhibited by drugs such as antihistamines.
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