3. Skeletal Muscle Flashcards
Describe the structure of skeletal muscle
- bone connected to TENDON, tendon connected to EPIMYSIUM
- Epimysium is made of MUSCLE FIBERS and ENDOMYCIUM
- PARAMYCIUM raps fascicle and FASCICLE wraps the Epimysium
What is a sarcomere?
- it’s a functional unit of myofibril
- myofibril is the individual contractile component in a cell
What is a muscle fiber?
- muscles are bundles of muscle fibers
- muscle fibers are individual muscle cells
Muscle Fiber
- LUMEN in the middle, ENDOTHELIUM, INTERNAL elastic tissue, SMOOTH muscel, EXTERNAL elastic tissue, and FIBROUS connective tissue
What is the sarcoplasmic reticulum?
It is where calcium is stored
What is actin?
- thin filaments
- composed of 3 proteins
What is myosin?
- thick filaments
- ATP powered molecular motor
How do actin and myosin interact?
- myosin grabs on to actin (forming crossbridges)
- Myosin (thick filament) pulls the actin (thin filament)
- this makes the sarcomere (individual contractile component) smaller
How does the signal make it from the nerve to the muscle to cause contraction?
- action potential opens gate containing muscle’s calcium store
- calcium ions flow into cytoplasm with actin and myosin filaments
- calcium binds to actin filaments (myosin exposes binding sites; myosin then cycles cross-bridges contracting the actin)
Why is ATP needed for muscle contraction?
It allows the muscle to release to its normal state (resets myosin-actin cross-bridge)
Why is Calcium needed for muscle contraction?
It promotes cross-bridges between actin and myosin (allows the muscle to contract)
What happens when there is calcium, but no ATP?
Rigor Mortis (muscle can’t relax)
What is creatine?
increases the formation of ATP
What causes cramps?
Over shortening of a muscle
