Elephantiasis is an infectious disease in which blockage of the circulatory system by microscopic, parasitic roundworms results in a dramatic swelling of the tissues in the lower half of the body. What region is most likely blocked by these small, thread-like worms?

Question

A.  the superior vena cava
B.  lymphatic vessels and/or lymph nodes
C.  the left atrium of the heart
D.  a pulmonary artery
E.  a carotid artery

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?
 
Gather Content
What do you already know about the drainage of fluid from tissue? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  lymphatic vessels and/or lymph nodes

Clarify Question
What is the key concept addressed by the question?
        · This question is asking you to link a blockage of circulatory vessels to the swelling of tissue.
What type of thinking is required?
        · Apply level:
            o You are being asked to take what you already know and use, or apply, it to the impairment of drainage of fluid from tissue.
 
Gather Content
What do you already know about the drainage of fluid from tissue? What other information is related to the question?
        · Most excess fluid that occurs in tissues is absorbed at the venular end of capillaries.
        · The remaining fluid is picked up by lymphatic capillaries.
        · Lymphatic capillaries carry the fluid to lymphatic vessels, which carry it to the subclavian veins.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · Blockage of the left atrium, carotid artery, superior vena cava, or the pulmonary artery would result in a much more serious situation than just swelling. These structures are major components of the circulatory system.
        · All of the structures with the exception of the lymph vessels are in the upper part of the body, so blocking them would not result in swelling in the lower part of the body.
        · Blockage of the lymph vessels would result in retained fluid and swelling.

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Apply level:
            o Answering this question correctly depended on your ability to use the removal of excess fluid from the tissues in a new situation. If you got an incorrect answer, did you remember that most fluid is taken back into the circulatory system or that the lymphatic vessels take up the rest? Did you have trouble extending the removal of excess fluid to determine the correct answer?