January 2016 Answers

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(Jan. 24 – Jan. 30) The doctor explains to Maria that the valve proximal to allowing blood to flow towards the carotid arteries is stenotic. Which valve is damaged?

(F) The left semilunar valve is also known as the aortic valve. Blood flows from the left ventricle to aorta by flowing through the aortic valve. After blood enters the aorta it travels to the head through the carotid arteries. The bicuspid valve (A) is also known as the left AV valve (C) and the mitral valve (E). The tricuspid valve (B) is also known as the right AV valve (D). The right SL valve (G) is also known as the pulmonic valve and it allows blood to flow towards the lungs.

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(Jan. 17 – Jan. 23) Amy was told that her gastrointestinal problems were due to a slow peristalsis. What type of muscle would this involve?

(A) The gastrointestinal system is lined with smooth muscle. Smooth muscle also lines many other organ systems, like the respiratory and vascular systems. Cardiac muscle is located in the heart. Skeletal muscle is attached to bones. Both cardiac and smooth muscle are involuntarily controlled. Both cardiac and skeletal muscle are striated.

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(Jan. 10 – Jan. 16) Which one of the following choices correctly describes the process that happens at the neuromuscular junction (NMJ)?

(E) Then neurotransmitter at the NMJ is acetylcholine and it binds to a ligand-gated receptor. A ligand-gated receptor is a protein channel that opens/closes when a substance binds to it. A voltage-gated channel is a channel that opens/closes when there is a change in the voltage across the membrane. The ion that flows across the channel to depolarize the myocyte (muscle cell) is sodium and it flows into the cell making the interior side more positive.

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(Jan. 3 – Jan. 9) What will happen to a red blood cell (RBC) if placed in a hypotonic solution?

(B) Hypotonic means less vs. hypertonic which means more. Therefore, if the surrounding solution is less, then the solute concentration inside the cell is more. Water will move to an area of greater solute concentration and hence cause the cell to swell. An easy way to remember that a cell will swell in a hypotonic solution is to spell the word with a capital ‘O’ as in hyp’O’tonic, which represents a cell swelling up. (A) is true of an isotonic solution. (E) is true of a hypertonic solution.

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