Myasthenia gravis is a collection of muscle disorders that cause muscle fatigue and weakness. What is the major mechanism?
A. overproduction of acetylcholinesterase
B. autoimmune destruction of nicotinic acetylcholine receptors
C. demyelination of axons in motor pathways
D. autoimmune destruction of L-type Ca2+ channels.
E. a tumor that overproduces acetylcholine
B
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The submandibular ducts open into the floor of the oral cavity, lateral to the lingual frenulum.
Answer the following statement true (T) or false (F)
Positive feedback mechanisms
A) move conditions away from the normal state. B) bring conditions back to the normal state. C) usually produce stable conditions. D) cause long-term changes.
Just before it is ovulated, the egg completes meiosis II.
Answer the following statement true (T) or false (F)
Having extra digits is termed
A. polydactyly. B. polydipsia. C. polyploidy. D. polyuria.