Class Summary - Today we dug a little deeper in finding out how muscle contraction works. We talked a bit about what happens in the muscle fiber. A neuron connects to the muscle fiber through neuromuscular junctions. These junctions will release ACh into the synaptic cleft allowing an action potential to spread across the sarcolemma. The message then goes from the t-tubules into the sarcoplasmic reticulum relaying the message to release Ca ions. Those Ca ions then travel into the sacromere to bind to troponin making tropmyosin expose myosin binding sites on the actin. Myosin can now bind to acting. ATP cocks the myosin heads backward and then becomes ADP. ADP and phosphate are byproducts as the myosin heads create a powerstroke pulling actin filaments together shortening the sarcomere. Attached is the introductory fill in the blank review passage.
Homework - The test on muscle contraction is scheduled for Thursday. Fill in the blank review passage.
Objectives - Students will explain how skeletal muscle fibers are innervated and how they contract. Students will describe how ATP is made available for muscle contraction.