February 2016 Answers

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(Feb. 28 – Mar. 5) Why does glucose appear in the urine of diabetics?

D) The nephron cannot reabsorb all the glucose from the filtrate. There is so much glucose in the blood of diabetics that when it gets filtered into the nephron at the renal corpuscle, it cannot all be reabsorbed back into the blood because the Transport Maximum (Tmax) of the glucose transporter is over-saturated. As a result, glucose remains in the filtrate and is detected in the urine. Secretion (C) happens from blood to filtrate and not from the filtrate. The type of sugar consumed by diabetics (A) and (B) does not relate to why glucose appears in the urine. (E) and (F) Growth Hormone has nothing to do with glucose detection in the urine. Additionally, GH is produced in the anterior pituitary gland.

(Feb. 21 – Feb. 27) The majority of reabsorption happens in what portion of the nephron?

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(C) PCT. Approximately 65% of salt water and 100% of glucose and amino acids are absorbed at the PCT. The loop of Henle is primary used to concentrate the filtrate before it becomes urine. The renal corpuscle is composed of the glomerulus (capillary network) and Bowman’s capsule and is where filtration happens.

(Feb. 14 – Feb. 20) What is another name for the right atrioventricular valve?

(B) Tricuspid valve. The left atrioventricular valve (AV) is known as the mitral and bicuspid. The left semilunar (SL) valve is known as the aortic and the right SL valve is known as the pulmonic/pulmonary.

(Feb. 7 – Feb. 13) Which one of the following values is closest to resting membrane potential of a neuron?

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H) -70 mV. Make sure the units are correct first and that would be millivolts (mV), not volts (V). 35 mV (A) is the peak of the action potential. Threshold is usually around -60/-55 mV and hyperpolarization is usually around -80 mV.

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(Jan. 31 – Feb. 6) If you inspire as much as possible and then expire as much as possible, what is that amount of air you breathe out called?

(F) The vital capacity. You have four volumes and four capacities. Two or more volumes added together make a capacity. The RV is the amount left in the lungs that prevents their collapse (atelectasis). The TV is the average amount of air you breathe in and out without exertion. The ERV and the IRV are the extra volumes you can breathe out and in, respectively. TLC is all four volumes. FRC is the volume of air present in the lungs at the end of a non-forceful (passive) expiration. IC is TV plus IRV, or the maximum amount of air you can breathe in after a passive expiration.