Problem: Modeling The Neuromuscular Junction
Directions: Understanding/learning the events or steps that cause contraction is confusing or a bit overwhelming. In this exercise you are going to outline the events that take place at the neuromuscular junctions. For reference see Figure 9.7 (pg 291), Focus Figure 9.1 (pg 292), Figure 9.8 (pg. 293), Focus Figure 9.2 (page 294-295) and Focus Figure 9.3 (page 297) of the 11th edition text.
Part A: Draw a picture of the neuromuscular junction and label the following parts
Motor Neuron Motor End Plate Synaptic Cleft Synaptic Vesicles
Voltage-gated Calcium Channel Acetylcholine Ligand Gated Channels
Acetylcholine Acetylcholinesterase Action potential Sarcolemma
Voltage-gated Sodium Channel Axon terminal
Part B: With your drawing outline the events of the neuromuscular junction beginning with action potential arriving at the axon terminal and ending with the triggering of an action potential in the muscle cell
Part C: Draw a second picture of the neuromuscular junction to illustrate where the drugs/toxins (see list below) are acting in the neuromuscular junction. Using the description of what the drugs/toxins do below; explain what you reasonably think will happen to muscle contraction.
Drugs/Toxins
Nicotine - Mimics the effects of acetylcholine on the acetylcholine ligand-gated channel
Ziconotide - Blocks/prevents opening of the neuronal voltage-gated calcium channel
Neostigmine - Inhibits acetylcholinesterase activity
Myasthenia Gravis - immune system generates antibodies that removes acetylcholine-ligand gated channels from the neuromuscular junction.