1 Quiz 06 Results The statistics are calculated based only on the attempts being used in the grading option (Last attempt, First attempt, Lowest Score, Highest Score, or Average of Scores). If Average of Scores is the grading option, then all attempts are included in the statistics. Content Name Quiz 06a Attempt Score 1.13758 Attempts 149 (Total of 151 attempts for this assessment) Question 1: Multiple Choice Average Score 0.4698 points Caldesmon is a regulatory protein in smooth muscle that binds to tropomyosin and actin in thin filaments. When caldesmon binds to thin filaments, it inhibits the myosin ATPase. This action of caldesmon is inhibited when caldesmon is phosphorylated by protein kinase C or when caldesmon binds Ca2+-calmodulin. Imagine that a hormone binding to its receptor on a smooth muscle cell activates the mechanisms shown in the slide entitled “DAG/IP3 System” in the Cell Communication lecture. What would be the likely effect of this hormone on contraction of the smooth muscle cell? Correct Percent Answered The hormone would inhibit contraction. 3.356% The hormone would stimulate contraction. 93.96% The effect of the hormone cannot be predicted because of its opposite effects on caldesmon and myosin light chain kinase. 2.685% Don't choose this one. 0% Unanswered 0% Question 2: Multiple Choice Average Score 0.36242 points Rho kinase is a regulatory enzyme in smooth muscle cells. Rho kinase phosphorylates myosin light chain phosphatase, inhibiting its activity. Which one of the following would most likely result from administration of a drug that inhibits Rho kinase? Correct Percent Answered increased cytoplasmic Ca2+ concentration 4.027% relaxation of vascular smooth muscle 72.483% increased cross-bridge cycling 20.805% elevation of blood pressure 2.685% Unanswered 0% Question 3: Multiple Choice Average Score 0.30537 points While volunteering with a medical relief mission in Africa, a college student sampled some local food of dubious origin, and came down with a bad case of diarrhea. Unable to eat for 3 days, his metabolism2 switched to using energy sources other than carbohydrates. Which of the following would you not expect to happen? Correct Percent Answered ketosis 0.671% lipolysis 1.342% alkalosis 61.074% glycogenolysis 14.094% gluconeogenesis 7.383% increased levels of urea in the blood 15.436% Unanswered 0% Question 4: Essay Average Score 0 points Give an example of a disease or abnormal condition that can be effectively treated with a smooth muscle relaxant, and briefly describe the mechanism by which this drug works. Given Answers Kidney stones can be effectively treated with a smooth muscle relaxant, which will expand the lumen of the ureter and therefore allow the stone to pass. Ca channel blockers inhibit contraction because they block voltage gated Ca channels and decrease the amount of intracellular Ca. The decrease in Ca inhibits the muscle's ability to contract therefore widening the lumen and allowing the stone to pass. Frequent urination can be teated with a smooth muscle relaxant. By administrating the drug that promotes smooth muscle relaxant or inhibits the brossbridge cycling, the smooth muscle will less contract, or relax, and hence, prevent the patient from urinating frequently. Irritable bowel syndrome is the most common disease diagnosed by gastroenterologists, and has been found to be effectively treated with smooth muscle relaxants. One example of a smooth muscle relaxant is Otilonium bromide, which is a quaternary ammonium salt with GI spasmolytic properties. OB inhibits the baseline and chemically or physiclly stimulated GI motility by interfering with calcium ion movement from intracellular and extracellular sites, blocking calcium channels, and binding to muscarinic and tachykinin neurokinin-2 receptors, all which reduces hypermotility and modulates visceral sensation and reduce pain. Irritable bowel syndrome (IBS) may be treated with a smooth muscle relaxant. Drugs that are classified as smooth muscle relaxants are anticholinergenic, meaning that they inhibit the effects of acetylcholine. For a patient with IBS, symptoms such as abdominal pain and cramping may be partially relieved through anticholinergic mechanisms which inactivate receptors for the neurotransmitter and thus inhibit postsynaptic depolarization. Asthma or chronic inflammation of the airways, which I have suffered from my entire life, occurs due to bronchia constriction where the smooth muscle constricts and makes it very difficult to breath. This could be treated with a smooth muscle relaxant to calm the airway constrictions and therefore make breathing easier. I have been on albueterol for much of my life, and this question allowed to me to research how it works as a smooth muscle relaxant! Albueterol is an adregenic receptor antagonist where it binds to the ligand on a g-protein coupled receptor, that then activates adenyl cyclase leading to the production of cAMP. cAMP activates protein kinases that inhibit myosin p'lation, that slows down cross bridge cycling and causes constricted smooth muscles to relax.3 One disease that can be treated with a smooth muscle relaxant (such as calcium channel blockers) is hypertension. Hypertension occurs when the smooth muscle cells contract, causing vasodilation and pressurizing the blood within as it is now trapped within a smaller space. This contraction is mediated by Ca2+, as Ca2+ binds to calmodulin and activates Calcium-calmodulin myosin LC kinase, which phosphorylates the myosin head and leads to rapid crossbridge cycling. Calcium channel blockers bind to voltage-gated calcium channels, in particular those found on smooth muscle cells, and prevent the influx of Ca2+ during depolarization. Because there is less Ca2+ available to activate Ca2+-Cal myosin LC kinase, less rapid cycling is able to occur, leading to an overall relaxation of the muscle. When the muscle relaxes, vasodilation occurs, allowing for blood pressure to decrease and counteracting the hypertension problem. Erectile dysfunction is a condition in which it is difficult for a male to get or maintain an erection for an extended period of time. A smooth muscle relaxant, also known as an antipasmodic, can help treat this condition. Papaverine is an opium alkaloid which inhibits phospdiesterase preventing the inhibition of the cAMP signalling pathway. 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