Muscle Tissue Skeletal Muscle Notes Interesting Muscle Facts

Muscle Tissue & Skeletal Muscle Notes

Interesting Muscle Facts What is the biggest muscle in your body?

How many muscles do you use to smile? 17

How many muscles do you use to frown? 43

Where is the strongest muscle in the body? In the jaw, it is called the masseter muscle.

NOTES – MUSCLE TISSUE AND THE SKELETAL MUSCLES • MUSCLE TISSUE ANATOMY • Epimysium • outer covering of muscles • Fascicle • a bundle of muscle fibers

• Perimysium • each fascicle is covered by the perimysium • Endomysium • thin covering around each muscle fiber • both perimysium & endomysium contain blood vessels and nerve endings

• MUSCLE TISSUE – MICROSCOPIC ANATOMY • Myofibrils • each muscle fiber (muscle cell) contains bundles of myofibrils

• made of 2 proteins: 1. ACTIN (Act-in) – the thin one 2. MYOSIN (Mi-o-sin) – the thick one • Sarcomere • formed by the arrangement of actin and myosin

Stand Up and Pair Up with a person with the same shoe color as you. Individually write down the breakdown of this picture on your notes sheet. Share, discuss, and be prepared to share.

SKELETAL MUSCLE – MICROSCOPIC VIEW

SKELETAL MUSCLE – MICROSCOPIC VIEW – CROSS SECTION

• Sarcomere (cont. ) • what gives skeletal muscle its STRIATIONS • A - BAND • area where actin & myosin overlap • I - BAND • area of actin only

• Z – LINES • where I – Bands attach (actin) • Z – Lines are also the boundaries of the sarcomere

• Sarcoplasmic Reticulum • surrounded by SARCOLEMMA (plasma membrane of the muscle cell ) • contains large stores of calcium

• T - Tubules • aka: Transverse Tubules T-TUBULE • function to help the electrical impulse for muscle contraction reach the cell’s interior • also allow calcium to reach myofibrils