Otto Loewi Won a Noble Prize in 1936 for Showing

question 30

Short Answer

Otto Loewi won a Noble Prize in 1936 for showing that nerves release chemical transmitters. For one of his experiments he showed that stimulating the vagus nerve caused the heartbeat to slow down. He then collected the 'releasate' from nerve stimulation and put it on another heart, in which the heartbeat slowed as well. The substance that was release was later identified as ACh. What do we know now about the mechanism by which ACh decreases heart rate? Fill in the blanks in the following sentence.
ACh binds to the _____ cholinergic receptor, which activates a specific G protein, ____. This causes the dissociation of the trimeric G protein complex and the _____subunits bind to and activate a class of channels called _______, which OPEN/CLOSE (choose one) and result in ______ions moving INTO/OUT (choose one) of the cell. This DEPOLARIZES/HYPERPOLARIZES (choose one) the muscle cells, slowing the heartbeat.

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Definitions:

Latissimus Dorsi

The large muscle of the back.

Pectoralis Major

A large muscle in the front of the chest that attaches to the shoulder and sternum, involved in movements of the shoulder and arm.

Deltoid

Refers to the triangular muscle on the shoulder, involved in arm movements and known for its shape.

Circular Sphincter

A circular muscle that constricts or dilates to regulate the passage of substances through an opening in the body, such as the pyloric sphincter in the digestive system.