Posted by Inside Brochure Outside Brochure
^^Images for my project can be found here.
There are many intricacies we do not think about when contracting a muscle. Firing a muscle is not just a thought, it takes place through many steps. In relation to how complex activating a muscle is, is similar to how an airport works, both inside and out. My project further explains how a neuromuscular junction excitation is similar to how an airport works and overall just hopefully give everyone another way to envision what is happening.
To begin, when you want to fire a muscle you first have to have the idea. The junction consists of the points of contact between axon terminals of a motor neuron and the motor endplate of a skeletal muscle fiber. Nerve Impulses (action potentials) travel from the brain/spinal cord to trigger muscles. Then there are seven consecutive steps that occur in order to fire the muscle altogether.
Step one: an action potential travels down a motor neuron and excites a skeletal muscle fiber.
Step two: voltage-gated calcium channels open and calcium ions diffuse into the terminal.
Step three: calcium ion entry causes synaptic vesicles to release acetylcholine via exocytosis.
Step four: acetylcholine diffuses across the synaptic cleft and binds to acetylcholine receptors which contain ligand-gated cation channels. The ligand-gated channels open.
Step five: sodium ions enter the muscle fiber and potassium ions exit the muscle fiber.
Step six: once the membrane potential reaches the threshold value an action potential travels along the sarcolemma.
Step seven: neural transmission to a muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Acetylcholine diffuses from the synapse. Acetylcholine is broken down by the enzyme acetylcholinesterase to acidic acid and choline is transported to the axon terminal for the resynthesis of acetylcholine.
After all of these steps are complete, a muscle can contract. A correlation can be made between this process and how an airport works. This brochure includes the differences between the body and how it is connected, on the inside right-hand page. To better understand each step, you must read one step on the inside and compare it to the step on the back. Each sentence is paralleled to the next to better understand both standpoints. Similar to step one above, we can see that an action potential travels down a motor neuron and excites a skeletal muscle fiber. In this case, an action potential is an airplane, a motor neuron is a flight route, and a skeletal muscle fiber is an airport.
Step two explains how voltage-gated calcium channels open and calcium ions diffuse into the terminal. In this instance, the voltage-gated calcium channels are the jet bridge walkways, and the calcium ions themselves are the gate agents flowing into the terminal. The following steps are the same.
An airport and neuromuscular junction both have many steps, either to firing a muscle or getting a plane off the ground. Similarly, they both occur in many places: all over the body or all over the world. They are constantly being used simultaneously in many locations.
Emily Moretz did her STEAM project on neuromuscular junction excitations in relation to airport functions. I find her project particularly interesting since she was able to take a process in the human body we learned about this semester and related it to an action most people are more familiar with, airline travel. Her brochure was professionally done and well thought out. It was a nice touch to add the key-word differences between the two step by step actions. There are seven total steps in the muscle a person is trying to use. The first step in firing a muscle is to start with the idea of movement which causes an action potential to travel to skeletal muscle fiber and excite it. This was compared to the airplane lands at the airport. The second step is the opening of the calcium channels that allows the calcium ions to diffuse into the terminal which was compared to the exiting of gate agents into the terminal. The third step is where the acetylcholine is released upon the entry of the calcium ion entry. This is compared to flight attendants leaving and the TSA opening the gates once they are ready. The fourth step is acetylcholine binding to its respective receptors and the ligand-gated channels open. This was compared to arrival passengers entering the sitting area while the departure passengers exit. In the fifth step, sodium ions enter and potassium ions exit the muscle fibers. Which is compared to the mishandled baggage report percentage reaching the threshold value. The sixth step is the membrane potential reaching the threshold value an action potential is able to travel along the sarcolemma. This was compared to the cleaning of the aircraft and the rampers leaving the bagwell. The final step is the removal of acetylcholine from the synaptic cleft to stop neural transmission to the muscle fibers. Acetylcholine is broken down to acidic acid and choline and transported to the axon terminals for resynthesis. Overall I thought it was a great idea to break down the steps into a more commonly understood concept. It helped me to gain a better understanding of neuromuscular junction excitations.