Structure and Function of Muscle Tissues

What are muscle tissue composed of?

many fibers and their surrounding endomysium

What are skeletal muscle fibers and how are they formed?

• thin cylinders but can be quite long and thick

• skeletal muscle fibers are formed by the fusion of many embryonic myoblasts giving each fiber multiple nuclei

What are myofibrils?

the most abundant organelle made mostly of contractile proteins

Why are skeleton muscles multinucleate?

muscle fiber arise from the fusion of multiple embryonic cells called myoblasts

What is the sarcolemma?

the plasma membrane of a muscle fiber but differs from a PM because of its structure

What is the sarcoplasm?

muscle fiber’s plasma membrane

What is the sarcoplasmic reticulum?

modified smooth ER that surrounds the myofibrils and stores and releases calcium ions, allowing muscle contraction and relaxation

What are transverse tubules?

• deep inward extensions of sarcolemma that are filled w/ ECF

• they surround each myofibrils, forming a tunnel-like network to allow for simultaneous contraction

What are Terminal Cisternae?

enlarged sections of sarcoplasmic reticulum found flanking each T-tubule