Tamara's muscle weakness and fatigue becomes progressively worse over the course of the day. this is a hallmark sign of myasthenia gravis, an autoimmune disorder that affects the ability of a motor neuron to communicate with a muscle fiber. what synaptic events must happen first for excitation to occur?

a. the action potential travels down the t tubules in the sarcolemma and triggers the release of calcium ions from the sarcoplasmic reticulum.
b. calcium binds to tropomyosin, shifting it from the active site on actin, allowing cross bridge formation to occur as myosin binds to the active site.
c. acetylcholine is released from the axon terminal and diffuses across the synapse to bind to a receptor in the surface of the motor end plate.
d. sodium ions from the extracellular fluid diffuse into the cytosol of the muscle fiber, triggering the generation of an action potential in the sarcolemma.

Give the names of the following body motions produced by muscle actions: increases the angel of a joint. turns the palm downward. decreases the angle of a joint. points the toes.

Describe the effects and potential risks associated with pica. include lead poisoning in the discussion.

Harold, a fifty-eight year old grocery store manager, had recently been waking up in the middle of the night with abdominal pain. this was happening several nights a week. he was also experiencing occasional discomfort in the middle of the afternoon. harold decided to schedule an appointment with his physician. the doctor listened as harold described his symptoms and then asked harold some questions. he noted that harold's appetite had suffered as a result of the pain he was experiencing and as a result of the fear that what he was eating may be responsible for the pain. otherwise, harold seemed fine. the doctor referred harold to a physician that specialized in internal medicine and had harold make an appointment for a procedure called an endoscopy. the endoscopy was performed at a hospital later that week. during the procedure, a long, thin tube was inserted into harold's mouth and directed into his digestive tract. the end of the tube was equipped with a light source and a small camera which allowed the doctor to observe the interior of harold's stomach. the endoscope was also equipped with a small claw-like structure that the doctor could use in order to obtain a small tissue sample from the lining of harold's stomach, if required. the endoscopy revealed that harold had a peptic ulcer. analysis of a tissue sample taken from the site showed that harold also had an infection that was caused by helicobacterpylori bacteria. the doctor who performed the endoscopy gave harold prescriptions for two different antibiotics and a medication that would decrease the secretion of stomach acid. the doctor also instructed harold to schedule an appointment for another endoscopy procedure in 6 months. 1. list the subjective findings in this case study. 2. what is an endoscopy? (2 points) what is a biopsy? 3. how was a biopsy performed on harold? 4. differentiate between gastric and duodenal ulcers by location. 5. what role does h. pylori play in the formation of peptic ulcers? 6. define occult and frank blood. (4 points) what is a guaiac test? 7. how can peptic ulcers cause bleeding? 8. why were antibiotics prescribed? 9. why would a medication that would decrease the secretion of stomach acid be beneficial?