Which of the following is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber?

A. Tropomyosin shifts and unblocks the cross-bridge binding sites.

B. Calcium is released and binds to the troponin complex.

C. Transverse tubules depolarize the sarcoplasmic reticulum.

D. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP.

E. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane.

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#Question id: 12068

#Unit 7. System Physiology – Animal

Prolonged changes in neuronal activity are usually achieved through the activation of

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#Question id: 12069

#Unit 7. System Physiology – Animal

Post-tetanic facilitation is thought to be the result of

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#Question id: 12070

#Unit 7. System Physiology – Animal

A 26-year-old man develops glomerulonephritis, and his GFR decreases by 50% and remains at that level. For which of the following substances would you expect to find the greatest increase in plasma concentration?

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#Question id: 12071

#Unit 7. System Physiology – Animal

The most serious hypokalemia would occur in which of the following conditions?

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#Question id: 12072

#Unit 7. System Physiology – Animal

If the average hydrostatic pressure in the glomerular capillaries is 50 mm Hg, the hydrostatic pressure in the Bowman’s space is 12 mm Hg, the average colloid osmotic pressure in the glomerular capillaries is 30 mm Hg, and there is no protein in the glomerular ultrafiltrate, what is the net pressure driving glomerular filtration?

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#Question id: 12073

#Unit 7. System Physiology – Animal

The figure above shows the concentration of inulin at different points along the renal tubule, expressed as the tubular fluid/plasma ratio of inulin concentration. If inulin is not reabsorbed, what is the approximate percentage of the filtered water that has been reabsorbed prior to the distal convoluted tubule?