Learn how muscles contract and relax
Discover the relationship between ligaments, tendons and muscles
* muscles tendons ligaments
* actin, myosin protein filaments, crossbridge
What stimulates muscles to contract?
Muscles are a soft tissue that contract when they receive signals from a nerve. Muscles produce force and motion. But what makes them contract? They receive signals from a nerve.
Work together with tendons and muscles
A tendon is a fibrous connective tissue which attaches muscle to bone.
This allows the muscle to actually move the bone.
A ligament is a fibrous connective tissue which attaches bone to bone.
They slightly stretch. Their job is to limit how far a joint can move. This helps protect against injury. They hold structures together.
Muscles work in pairs
They can only contract; they can’t relax
So how we can pull back an arm, once it is extended?
Contract the muscle on the opposite side of the bone!
Here we see the biceps contract, pulling the forearm up.
Then we see the triceps contract, pulling the forearm back down.
How do joints work?
When muscles pull bones, they rotate. A group of bones that rotate around each other are basically a simple machine. The joints in our body are similar to joints we use when building things.
Here we see the ankle joint in motion.
Inside your muscle, how are muscle fibers organized?
muscle fibers bundes
Single, long muscle fiber (one long cell)
These long cells contain proteins, repeated in units called sarcomeres.
As seen below, sarcomere are the basic functional unit.
Sarcomeres are the machine that make muscle cells contract
Let’s look at muscle under a microscope. We see the sarcomere – the basic unit of muscle tissue
It is made of alternating thin lines that can contract and expand.
We discovered that these thin lines were long, thin strands of protein, working together like a machine.
Sarcomere is the basic unit of muscle tissue
Here we see the thin and thick lines contracting, and being pulled apart.