Taking It on the Chin by DeMarco, Woods and Stephens

Part III—Day 3

After another restless night, Mr. Gower wakes up sweating. The window is open, he is completely uncovered, yet he feels hot. His jaw is still shut, his neck seems rigid, his mouth is very dry, and he feels like his lips are stuck to his teeth in a foolish grin.

“Are you all right, John?”

“I feel awful, Nance.”

“I’ll take your blood pressure.”

“Not now. I think it’s time to go to the Emergency Room.”

Nancy walks into the bedroom and turns on the light. Her husband’s face is drawn back, in a contorted grimace. She draws back at first, then walks over and puts her hand on his forehead.

“Oh John, you look terrible and you’re burning up.”

Questions

1. What new symptoms does Mr. Gower exhibit?
2. Is there a common factor between his jaw being locked shut, his rigid neck, and his lips being drawn across his mouth in a constant grin?
3. Look at the diagram of three nerve cells on the right. At the bottom, there is a postsynaptic cell, which receives chemical synapses from two presynaptic cells, which are shown at the top of the diagram. One of the presynaptic cells is labeled excitatory and the other is labeled inhibitory. Assume that a single action potential in a presynaptic cell does not produce an action potential in the postsynaptic cell. Show (by drawing a graph of membrane potential against time) how the membrane potential of the postsynaptic cell changes if there is one action potential in:
   
   1. only the excitatory presynaptic cell.
   2. only the inhibitory presynaptic cell.
   3. both the inhibitory and the excitatory presynaptic cells.
4. Now think about how the two presynaptic cells could produce an action potential in the postsynaptic cell.
   
   1. Which presynaptic cell must have action potentials to produce one or more action potentials in the postsynaptic cell?
   2. What phenomena must take place for the small postsynaptic potentials to reach threshold and produce action potentials?
   3. If the frequency of action potentials in this presynaptic cell (#4a) increases, what happens to the number of action potentials in the postsynaptic cell?
   4. What happens to the number of action potentials in the postsynaptic cell if the other presynaptic cell (#4a) also produces action potentials?
5. Assume that the postsynaptic cell in the diagram is a motor neuron. If Mr. Gower’s problems are associated with maintained muscle contraction, what must take place in the motor neuron to produce a maintained muscle contraction?
6. Assume that both presynaptic neurons have action potentials. What two conditions in these presynaptic cells would produce an increase in the number of action potentials in the postsynaptic (motor) neuron?
7. Do you wish to change or modify your diagnosis of Mr. Gower’s problem?

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