H Anatomy Muscle contractions

Tendon

Connects muscle to bone

Fascicle

Groups of muscle fibers

Myofibril

Contractile organelles found in muscle fibers - these contain sarcomeres

Sarcomere

Make up myofibrils- where muscle contraction occurs

Actin and Myosin

Myofilaments found in sarcomeres

Sarcolemma

The cell membrane of muscle fibers - it has protein receptors for acetylcholine

Sarcoplasmic Reticulum

Wraps around each sarcomere - stores calcium

T- Tubules

Brings the action potential deeper into the muscle cell to trigger the sarcoplasmic reticulum to release calcium ions

Neuromuscular Junction

The place where a motor neuron connects with a muscle fiber - the axon terminal of the neuron releases acetylcholine to pass on the neuron’s action potential to the muscle fiber 

Direct phosphorylation of creatine phosphate

Very quick method of ATP generation that only yields 1 ATP - gives a very quick burst of energy that lasts 15 seconds for very intense exercise (ex. Sprinting or lifting a very heavy weight). Does not require oxygen.

Anaerobic cellular respiration

When your body is doing pretty intense exercise and it needs more oxygen to keep up with the amount of ATP needed, some ATP can be made without oxygen present - 2 ATPs. This provides about 40 seconds of energy

Aerobic cellular respiration

This takes a while to make ATP, but it yields the most ATP - around 32 ATPs per molecule of glucose broken down. This is done when oxygen is present and it can last for hours.

Step 1

Brain sends out a message to tell the muscles to move. This message travels via action potential - an increasing positive charge occurring on the inside of the neurons due to ion channels opening and Na+ ions flowing in

Step 2

At the neuromuscular junction, action potential arrives causing the axon terminal to release acetylcholine

Step 3

When acetylcholine attaches to the receptor proteins on the sarcolemma, that opens voltage gated sodium channels to allow Na+ ions briefly into the muscle fiber cell, the spreading action potential opens up more and more voltage gated sodium ion channels on the sarcolemma, until the action potential reaches a T Tubule

Step 4

Action potential travels down the T Tubule and then triggers the release of calcium ions from the sarcoplasmic reticulum

Step 5

Ca2+ ions bind to troponin, which causes it to change shape. As troponin changes shape, that also makes the position of tropomyosin shift around, thereby exposing the binding sites on actin filaments to myosin heads

Step 6

ATP is used to make the myosin heads pull the actin filaments towards the middle of the sarcomere, like oars rowing a boat

What is #1

Muscle (picture)

What is #2

Fascicle (picture)

What is #3

Muscle Fiber (picture)

What is #4

Myofibril (picture)

What is #5

Myofilaments (Picture)

What is #6 pointing to

Tendon (picture)

What is #7 pointing to

Epimysium (Picture)

What is #8 pointing to

Perimysium (picture)

What is #9 pointing to

Endomysium (Picture)

What is #10 pointing to

Sarcolemma (picture)

What is #11 pointing to

Sarcomere. (picture)