The interaction between Ca2+ and calmodulin in smooth muscle cells has been described as a second messenger system. Develop an argument to support this position, using another second messenger system you have studied for comparison.
What will be an ideal response?
Ca2+ forms a complex with calmodulin. This complex activates myosin light chain kinase, which in turn phosphorylates the myosin light chain allowing the myosin to form a crossbridge with actin, triggering the contraction cycle. The second messengers cGMP and cAMP also lead to the phosphorylation of proteins to affect cell activity.
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Structurally, enzymes are generally
A. globular proteins. B. fibrous proteins. C. spherical carbohydrates. D. elongated carbohydrates. E. four-ring steroids.
The medial pterygoid muscle inserts into the
A. zygomatic arch. B. lateral surface of the lateral pterygoid plate. C. medial aspect of the mandibular ramus. D. infratemporal crest of the sphenoid bone. E. coronoid process of the mandible.
Trace the path of a drop of blood, starting at the right atrium and returning to the right atrium, through the pulmonary and systemic circuits of the cardiovascular system. Identify the chambers, valves, and vessels (except specific systemic blood vessels that are not directly associated with the heart), and indicate whether the blood is oxygenated or deoxygenated in each area
What will be an ideal response?
Which of the following is clinically significant as an ectopic pacemaker of the heart?
a. drinking several cups of caffeinated coffee b. extrasystole contractions associated with angina pectoris c. excessive smoking d. anxiety