Chapter 9: Muscle and Muscle Tissue ● Epimysium: it has fascicles and wraps the entire muscle. Irregular Connective Tissue. ● Fascicles: muscle ﬁbers ● Perimysium: wraps each fascicle to separate. Irregular Connective Tissue ● Endomysium: Wraps muscle ﬁber. Areolar Connective Tissue ● Muscle Fibers: myoﬁbrils ● Myoﬁbrils: contains sarcomere ● Sarcolemma: myoﬁlament ● Epimysium, Perimysium, and Endomysium ALL are sheats that contribute to blood vessels/nerve ﬁbers ● Direct Attachment: Epimysium fuses to the bone outing (Periosteum) ● Indirect Attachment: rope tendons, most common due to durability, and small size (space) ● Tendons: connects Muscle to Bone ● Ligaments: Connects Bone Joints Chapter 9: Muscle and Muscle Tissue Strucure of Muscle Fiber ● Z-Disc to Z-Disc = 1 sarcomere ● Thin Filaments contain actin ● Thick Filaments: contain Myosin ● Elastic ﬁlaments help this to uncoil when sti ● The role for both the Sarcoplasmic Reticulum and T tubule is to provide signals for contractions ● Sarcoplasmic Reticulum: stores calcium ● T-Tubule: increases surface area, sends message to the deepest part Skeletal Muscle Events 1. Events neuromuscular junction , releases ACH which leads to depolarization 2. Muscle Fiber Excitation. EPP leads to Action potential 3. Excitation Coupling: Sarcolemma → T-Tubule → Calcium (ﬁnal contraction) . **The calcium exposes binding sites. Troponin changes** 4. Cross-Bridge Cycling: Myoﬁlaments Slide Chapter 9: Muscle and Muscle Tissue Muscle Twitches ❖ Large Motor Units: less precise ❖ Small Motor Units: Fine control ❖ Latent period: cross bridge begin ❖ Period of Contract: cross bridges are active ❖ Period relaxation: Calcium is back into the Sarcoplasmic Reticulum ❖ Isometric: tension increases but no movement ❖ Isotonic: muscle shortening/lengthening overcomes load ➢ Concentric: “CONCENT-rate on picking up baby” ➢ Eccentric: “EASILY put it down”