How a Sarcomere Works
By Isa Tomanelli
Basic Anatomy of a Sarcomere
Anatomy of an Actin Filament
On the actin filaments, there are rod-like structures called tropomyosin
Additionally, there are small molecules on the tropomyosin called troponin
Let's find out!
But what happens when muscles contract?
Hey, muscle, time to contract!
First, a neuron must signal for a muscle to contract
Acetylcholine molecules are released from the terminal of the neuron, thus signalling for the contraction process to begin. Once acetylcholine binds to the muscle fiber, the sarcoplasmic reticulum releases calcium ions, which bind to the actin filaments on the myosin binding sites.
Here's where the troponin and tropomyosin molecules come into play: when a muscle wants to contract, calcium ions bind with troponin molecules, which in turn shifts the position of the tropomyosin, allowing for binding between the actin and myosin filaments.