quiz 4 Flashcards
chapter 6&7
Muscle function
Skeletal muscles interact with skeleton, cause our bones to move and prevent them from moving, contract, relax and help us in all our task
Muscle
a group of individual muscle cells with the same origin and insertion and the same function
Synergistic muscle
Those working together to create the same movement (contracting and relaxing together
Agnostic muscles
Oppose each other
Fascicles
Muscle Bundles, Connective tissue (Fascia) covering each one. Whole muscles are covered in fascia layers
Muscle fibers
Muscle cells inside muscle bundles
Skeletal muscle contractile unit
Sarcomere (muscle osteoporosis)
Actin and Myosin
Z lines: attachment point for sarcomeres
4 conditions for a Skeletal muscle to contract and relax
Activation by nerve,
Nerve activation increases the concentration of calcium,
Calcium allows contraction and its absence prevents contraction,
Contraction ends when muscle is no longer stimulated by nerve
Nerve activation
Acetylcholine released, electrical impulse transmitted along t tubes triggers calcium released from Smooth ER, ca2+ diffused into cell cytoplasm and contact myofibrils
Nerve activation detailed
communication via releasing Acetylcholine, bind to receptors on cell membrane which opens ion channel. electrical impulses travel to smooth ER of muscle, Ca2+ travels to contracting protein, binds to troponin-tropomyosin complex. Myosinn binds to protein, pulls and shortens it
1, Acetylcholine
Exocytosis: releases at the neuromuscular junction causes electrical impulses to be generated in the muscle cell plasma membrane
2, Electrical impulse
Carried to the cells interior by the T tubules
3, Ca2+ release
The electrical impulses triggers the release of CA2+ from the sarcoplasmic reticulum,
Filaments
Thick filaments: Myosin
Thin filaments: Strands of actin molecules
Contraction: formation of cross-brides between thin and thick filaments that need to interact
After calcium binds troponin
Troponin+Tropomysin protein complex shifts position, myosin binding site exposed, myosin heads form crossbridges with actin, actin filaments pulled toward center of sarcomere (ATP required)
Energy required of contraction
Released Ca2+ transported back by active transport,
Muscle cells obtain ATP from: Stored ATP, Creatine phosphate, Glycogen, Glucose, and Fats
Myogram
graph representing muscle activity
Latent period, contraction & relaxation
Summation: high rate stimultion, high muscle force
Tetanus: state of max contraction
Muscle relaxation
Nerve activation ends, contraction ends: calcium removed from troponin, pumped back to sarcoplasmic reticulum, myosin binding site covered, no calcium = no cross bridges