Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
12 Cards in this Set
- Front
- Back
|
What changes occur to the sarcomere when a muscle contracts? |
- I band: shorter - A band: no change - Z line: move closer - Sarcomere: shorten - H zone: narrower |
|
|
What is the thick filament? |
- protein=myosin - made of 2 polypeptide chains twisted together - each ending in a large globular head - heads stick out=form cross bridge - myosin molecules stick together=thick filament |
|
|
What is the thin filament? |
- protein=action - contains tropomyosin=control muscle contraction - held in place by troponin |
|
|
What is the sliding filament theory for contraction? |
- muscle contracts=sarcomere smaller - filaments don't change length - slide past each other - actin filaments slide between myosin filaments and zones overlap - process repeats 100 times per second |
|
|
What is stage 1 in muscle contraction? |
- AP travels through T-tubules in sarcoplasm=sarcoplasmic reticulum - Ca2+ protein channels on sarcoplasmic reticulum open;diffuse into sarcoplasm - Ca2+ binds to tropin=change shape=tropomyosin moves=binding site on actin exposed |
|
|
What is stage 2 in muscle contraction? |
- ADP and Pi closely binded to myosin heads - myosin head binds to actin filament=actomyosin cross-bridge - Pi is released=initiates power stroke |
|
|
What is stage 3 in muscle contraction? |
- myosin head changes angle=pull actin filament along - end of power stroke, myosin head releases ADP - free ATP binds to myosin head=shape change=detach from actin filament |
|
|
What is stage 4 in muscle contraction? |
- ATPase in myosin head hydrolyses ATP=energy returns myosin to original position - Ca2+ remains in sarcoplasm/cycle repeats [continued stimulation] - stimulation stops=Ca2+ pumped into sarcoplasmic reticulum |
|
|
What is stage 5 in muscle contraction? |
- troponin/tropomyosin return to original position - contract complete, muscle fibre relaxed |
|
|
What is the energy released from hydrolysis of ATP used for? |
- movement of myosin heads - reabsorption of Ca2+ into sarcoplasmic reticulum by active transport |
|
|
What are the features of slow twitch muscle fibre? |
- red muscle fibres - contract slowly - stay in tetanus for long - rich blood supply - high levels of myoglobin - rely on glucose - aerobic respiration |
|
|
What are the features of fast twitch muscle fibre? |
- white muscle fibres - contract rapidly - fatigue quickly - few blood vessels - low levels of myoglobin - rich glycogen store to convert glucose - anaerobic/aerobic respiration |
