Is this internal or external respiration?

The layers make up the ________.

Is this muscle contracting or relaxing during inspiration?

What gas would be diffusing is this direction (blue arrow)?

_______________are the rod-like structures that make up 80% of muscle cells.

In muscle cells sarcoplasmic reticulum is ___________surrounding each myofibril like the sleeve of a sweater.

When comparing the three pathways that ATP is regenerated, which one of these pathways provides 95% of the ATP used for muscle activity and provides for hours of energy?

    When fascicles are arranged in concentric rings called sphincter muscles as illustrated above with the orbicularis oculi, this would be an example of a

This type of muscle tissue found in the walls of hollow organs is nonstriated and involuntary with contractions that are slow and sustained.

The banding pattern of a myofibril results from the