Figure Q3-4 Documents the Quantal Release of Neurotransmitter

question 23

Essay

Figure Q3-4 documents the quantal release of neurotransmitter. Figure Q3-4
A. The investigators stimulated the nerve in low-Ca²⁺ and high-Mg²⁺ saline so that they had many failures with nerve stimulation. Why was the presence of failures so important?
B. In the top trace, there were three motor nerve stimulations that occurred at the arrow. Why is the flat trace flat and, based on what we know now, what is the reason that the other two traces are multiples of each other?
C. The investigators compared the evoked EPPs in low Ca²⁺/high Mg²⁺ saline to spontaneous EPPs (mEPP). What did they find (see figures on the right) and what did they conclude?
D. Based on the findings in this figure, what did they conclude about transmitter release in an evoked EPP in normal saline?

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Definitions:

Deprotonated

Refers to the removal of a proton (H+) from a molecule, resulting in the formation of a negatively charged ion.

Resonance

A phenomenon in chemistry where a molecule or ion can be represented by two or more equivalent structures, indicating the delocalization of electrons.

Anion

A negatively charged ion, which has more electrons than protons.

CCC Bond Angle

The internal angle formed between three consecutively bonded carbon atoms in a molecule, often approximated to 109.5° in a tetrahedral arrangement.