BIO 394 Problem Set 2

In Conn's syndrome, overproduction of aldosterone leads to hypokalemia. This symptom arises because aldosterone increases the activity of which of the following in the kidney?

ENaC and Na+/K+ pump

Aldosterone binds to the mineralocorticoid receptor (MR) and activates genes like ENaC. If a competitive inhibitor blocks MR binding, what symptom arise?

Hypotension from reduced Na+ reabsorption

Cortisol's anti-inflammatory effects involve upregulation of lipocortin-1, which suppresses integrins. Based on this information, which of the following would be the most logical effect of the cortisol-lipocortin-1 pathway?

Leukocyte extravasation by blocking ICAM binding

Epinephrine binding to α1 receptors in GI blood vessels activates PLC and IP3, releasing Ca2+. This causes which of the following in the GI blood vessels?

Vasoconstriction

In the smooth muscles of the GI tract, β2 receptors activated by epinephrine inhibit MLCK, which phosphorylates myosin to facilitate actin binding. Which of the following is the most likely result of this signaling?

Relaxation of muscles, slowing digestion

In pheochromocytoma, a chronic over-production of epinephrine, symptoms like pallor and sweating are due to:

Epinephrine's effects on α and β receptors altering blood flow and metabolism

Hyperparathyroidism leads to osteoporosis because excess PTH:

Activates osteoclasts to resorb bone

Diabetic ketoacidosis (DKA) acidifies blood because:

Ketone bodies from fat metabolism lower pH

LH stimulates Leydig cells to produce testosterone. If LH is low, this could lead to:

Reduced spermatogenesis and secondary sex characteristics

Epinephrine's opposite effects in GI tract (α1 vasoconstriction, β2 relaxation) serve to:

Redirect blood and slow digestion during stress

T3/T4 increase lipolysis. In hypothyroidism, this could lead to:

Weight gain from reduced fat breakdown

In iodine deficiency, the feedback loop involves:

Low T3 stimulating TSH, leading to goiter

Women with PCOS will fail to have the surge of progesterone that comes from the development of the corpus luteum. This lack of progesterone contributes to which of the following?

Unstable endometrium and amenorrhea

In adherens junctions, classical cadherins connect to actin filaments via adaptor proteins. If a mutation disrupts α-catenin binding (one of the adaptor proteins), what cellular consequence is most likely?

Weakened cell-cell adhesion leading to tissue fragility

Epidermolysis Bullosa is a genetic condition that is characterized by sensitive skin and other epithelial tissues that are prone to severe blistering. Which of the following is the most likely cause of EB?

Mutation in integrin that disrupts the hemidesmosome

Co-receptors like TβRIII can promote or inhibit TGFβ signaling via ectodomain shedding. If excessive shedding were to take place, what would be the most likely result?

impairing ECM remodeling and angiogenesis

In Marfan syndrome, mutant fibrillin disrupts elastic fibers and frees TGFβ, leading to:

Aortic weakening and disregulated bone growth

A naughty, naughty, Bio 394 student didn't listen to Dr. Greulich and decided to lick a Colorado River Toad because Dr. Greulich is "unc and doesn't like fun". Which of the following might happen post-toad lick?

All of the above

Poison dart frogs can cause numbness, difficulty breathing, and cardiac arrythmias as a result of its binding to voltage-gated sodium channels. How would binding and opening a sodium channel cause these problems?

Neurons are locked into a depolarized state, inhibiting their ability to fire action potentials

Congratulations! You have discovered the first alien species known to humankind and have named them the klyntar. Unfortunately, the klyntar you have encountered is less than friendly, and you are starting to feel the effects of what must surely be a neurotoxic venom...but your name will live on forever as the great scientist who discovered alien life, and that makes it worth it, right? As the paralysis starts to set in, you find yourself thankful that your sensory neurons have already failed, meaning you don't have to feel the excruciating pain of the klyntar eating you alive. In your final moments, your insatiably curious mind wonders which pathway this new neurotoxin is acting through. Which of the following is most likely NOT an accurate explanation of the venom's mechanism of action?

Presence of RGD-domain containing disintegrins that competitively inhibit integrin binding

Which of the following components of a venom are likely to cause hemotoxic effects?

metalloproteinases

Toxins can sometimes be re-purposed for a desired, therapeutic effect. What benefit might come from a drug derived from a pit viper's venom?

Reduced likelihood of heart attack

Which symptom would you predict to arise from chronic levels of high cortisol?

Slower wound healing

Parathyroid hormone is produced by the parathyroid gland to regulate blood calcium levels. A patient comes to see you with a parathyroid adenoma, that has caused excessive production of PTH. Which symptom are they most likely exhibiting?

Kidney stones

Type 1 diabetes mellitus is characterized by an inability to produce insulin. Which of the following would likely NOT be experienced by an untreated patient?

low urine output