Biology 107

Study Guide: Movement and locomotion.

Chapter 49

1. What are the principle types of skeletons in larger animals? Which type do humans have? What are the purposes of a skeleton?

2. What is the structure of a skeletal muscle? You should know the relationship between a muscle fiber, a myofibril, and a sarcomere. The following parts of the sarcomere are also important: Z line, A band, I band, H zone. Know the relationship between each of these parts of the sarcomere and the locations of actin and myosin in the sarcomere.

3. What is the sliding filament model of muscle contraction? What is ATP used for? Which of the protein molecules (actin or myosin) actually bends to cause contraction? Do the myofilaments themselves contract? How is high-energy phosphate stored in the muscle? What happens if the muscle runs out of ATP?

4. Where is calcium stored in the muscle? What regulates its release? How is it removed from the muscle cell?

5. What are the roles of troponin and tropomyosin? How is their interaction with actin controlled?

6. Be able to trace the excitatory events starting from the release of acetylcholine at the motor neuron synapse and ending with muscle contraction. You should know the pathway of depolarization of the muscle cell, how this leads to calcium release, and how the calcium in the myofibril leads to muscle contraction.

7. How is a person able to partially contract a muscle (such as the bicep), when the fibers of a motor unit completely contract when stimulated by a motor neuron? How is this related to recruitment?

8. What causes cardiac muscle to contract for relatively long periods of time? How are actin and myosin arranged in smooth muscle?