exam 7 Flashcards
chapter 17 (43 cards)
what is an isotonic contraction?
is where the tension remains the same and the muscle changes length
what arw the 2 types of isotonic contraction?
- concentric
- eccentric
what is a concentric contraction?
the muscle shortens as it contracts
what is an eccentric contraction?
the muscle lengthens while under tension
what’s a isometric contraction?
where the muscle remains the same and the tension increases
what is a sarcomere?
its the segment of a myofibril that’s responsible for muscle contraction
what are the characteristics of a sarcomere? 5
- somposed of thick and thin filaments
- each sarcomere is separated by z discs
- they facilitate muscle contraction through a sliding filament mechanism
- they have A, I, and H zone
- they contain elastic proteins
what’s the A band
segment that runs the entire length of thick filaments
what’s the I band?
segement that includes the z disk and ends of thin filaments where they don’t overlap thick filaments
what’s the H band?
middle region of thick filaments where they don’t overlap thin filaments
what’s the z disc?
marks the boundary of each sarcomere
what’s the process of contraction? 10
- nerve signal
- electrical impulse that travels down t-tubules
- calcium releases
- calcium binds to troponin
- cross-bridges are formed
- where energy is released
- detachment from actin filament
8.. re-cocking making it ready to form another cross-bridge - this cycle repeats leading to muscle contraction
- relaxation of muscle
how do filaments contract?
through the sliding filament theory
what’s the sliding filament theory? 6.
- myosin and actin are 2 main filaments
- myosin bind to actin filaments making cross-bridhes
- after they bind they pull actin toward center of sarcomere called a power stroke
- filaments slide past each other
- detachment from actin and re-cock to their original position
- the cycle repeats
what ions and chemicals are involved in muscle contraction? 5
- calcium ions
- ATP
- sodium ions
- potassium ions
- acetylcholine
what do calcium ions do?
calcium binds to troponin that exposes the binding sites for myosin
what does ATP do?
required for the myosin heads to detach and re-cock
- without ATP muscles would remain in a contracted state
what do sodium ions do?
sodium channels open which initiates the contraction process
what do potassium ions do?
prepares for next muscle contraction and restores
what’s atrophy?
the reduction in size or wasting away of a muscle or tissue
why does atrophy occur?
decrease in munber of muscle fibers of loss of muscles structural proteins
what is hypotonic?
solution that has lower concentration of solutes compared to another solution
whats hypertonic?
solution that has a higher concentration of solutes compared to another solution
what is hypertrophy?
increase in size of muscle fibers which increases overall muscle mass