This member of the AKAP family, designated mAKAP, anchors both PDE and the regulatory subunit  of PKA to the nuclear membrane, maintaining them in a negative feedback loop that provides close local control of the ATP level and PKA activity.

B- The basal level of PDE activity in the presence of hormone (resting state) keeps cAMP levels below those necessary for PKA activation. 

C- Activation of β-adrenergic receptors causes an increase in cAMP to a level in excess of that which can be degraded by PDE. 

D- The resulting binding of cAMP to the R subunits of PKA releases the active catalytic (C) subunits into the cytosol. Some C subunits enter the nucleus, where they phosphorylate and thus activate certain transcription factors . Other C subunits phosphorylate PDE, stimulating its catalytic activity.

E-  Active PDE hydrolyzes cAMP, thereby driving cAMP levels back to basal levels and causing re-formation of the inactive PKA C-R complex. Subsequent de-phosphorylation of PDE returns the complex to the resting state.

TLS Online TPP Program

#Question id: 12658

#Unit 7. System Physiology – Animal

In a person on a high (200 mmol/day) potassium diet, which part of the nephron would be expected to secrete the most potassium?

TLS Online TPP Program

#Question id: 12561

#Unit 7. System Physiology – Animal

Given the following measurements, calculate the filtration fraction: glomerular capillary hydrostatic pressure = 50 mm Hg; Bowman’s space hydrostatic pressure = 15 mm Hg; colloid osmotic

pressure in the glomerular capillaries = 30 mm Hg; glomerular capillary filtration coefficient (Kf) = 12 ml/min/mm Hg; and renal plasma flow = 400 ml/min.

TLS Online TPP Program

#Question id: 12560

#Unit 7. System Physiology – Animal

If GFR suddenly decreases from 150 ml/min to 75 ml/min and tubular fluid reabsorption simultaneously decreases from 149 ml/min to 75 ml/min, which of the following changes will occur (assuming that the changes in GFR and tubular fluid reabsorption are maintained)?

TLS Online TPP Program

#Question id: 12559

#Unit 7. System Physiology – Animal

Which part of the renal tubule would have the lowest tubular fluid osmolarity in a patient who has complete lack of antidiuretic hormone due to “central” diabetes insipidus?

TLS Online TPP Program

#Question id: 12514

#Unit 7. System Physiology – Animal

Acute metabolic acidosis tends to _____ in intracellular K+ concentration and _____ in K+ secretion by the cortical collecting tubules.

TLS Online TPP Program

#Question id: 12513

#Unit 7. System Physiology – Animal

A 26-year-old construction worker is brought to the emergency room with a change in mental status after working a 10-hour shift on a hot summer day (average outside temperature was 97°F). The man had been sweating profusely during the day but did not drink fluids. He has a fever of 102°F, heart rate of 140 beats/min, and blood pressure of 100/55 mm Hg in the supine position. On examination, he has no perspiration, appears to have dry mucous membranes, and is poorly oriented to person, place, and time. Assuming that his kidneys were normal yesterday, which of the following sets of hormone levels describes his condition, compared with normal?