Is this muscle contracting or relaxing during inspiration?

Is this vessel transporting oxygen or carbon dioxide?

Inspiration or Expiration?

Identify layer of alimentary canal.

Is this internal or external respiration?

What is the connective tissue sheath that surrounds an individual muscle fiber?

An ______is a muscle that opposes a particular movement.

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

In the steps of muscle contraction, the function of the heads of the myosin myofilament is to

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