What is the unit of structure for microscopic bone and is described as a set of concentric circles?

Which type of muscle decreases the size of an opening?

What happens to the calcium once the nerve impulse has passed and the muscle needs to relax?

Where in the neuron is the acetylcholine stored?

Which of the following contributes to fatigue in low intensity, long term exercise?

During muscle contraction, myofilaments slide over each other.

Label the structure below.  sarcomere.png

Label the Skeletal Muscle Structure. skeletalmuscle.png

Match the type of smooth muscle to the information. 

What type of muscle is shown below? smoothone.png