개념과 기본이 중요하다.
수동적 스트레치 동안 종축과 외측힘의 변환이 일어남. 초기에 결합조직 탄성구조가 연속적으로 길이 늘어남이 발생할때, 장력은 급격하게 증가함. 이 지점이후에 액틴-마이오신 교차연결다리의 기계적 파열이 발생하여 근절의 갑작스러운 늘어남이 야기됨. 때때로 근절 포기(Sarcomere give)라고 일컬어짐.
sarcomere give
Movements of the first order spectra relative to the zero order recorded during stretch reveal that S2 coincides with an abrupt elongation of the sarcomeres. This is termed sarcomere 'give' and it occurs when the filaments are displaced by 11-12 nm from their steady-state (isometric) position.
Sarcomere 'give' during stretch is considered to be due to forcible detachment of cross-bridges between the actin and myosin filaments. This results in recoil of the extended series elastic elements in the muscle at the expense of the sarcomers. The amount of filament displacement required to induce sarcomere 'give' (11-12 nm) is thought to represent the range of movement over which a cross-bridge can remain attached to actin during a stretch.
panic bird.
sarcomere give에 실험논문.pdfResponse to Stretch
When a muscle is stretched and elongates, the stretch force is transmitted to the muscle fibers via connective tissue (endomysium and perimysium) in and around the fibers. It is hypothesized that molecular interactions link these noncontractile elements to the contractile unit of muscle, the sarcomere.36
- 근육이 스트레치되고 늘어날때, 스트레치 힘은 결합조직(근내막과 근주막)을 통해 근섬유로 전달됨.
- 이러한 비수축구조에서 수축구조인 근육, 근절로 이어지는 분자생물학적 연관성이 가설로 제기됨.
During passive stretch both longitudinal and lateral force transduction occurs.36 When initial lengthening occurs in the series elastic (connective tissue) component, tension rises sharply. After a point, there is mechanical disruption (influenced by neural and biochemical changes) of the cross-bridges as the filaments slide apart, leading to abrupt lengthening of the sarcomeres, sometimes referred to as sarcomere give.52
- 수동적 스트레치 동안 종축과 외측힘의 변환이 일어남. 초기에 결합조직 탄성구조가 연속적으로 길이 늘어남이 발생할때, 장력은 급격하게 증가함. 이 지점이후에 액틴-마이오신 교차연결다리의 기계적 파열이 발생하여 근절의 갑작스러운 늘어남이 야기됨. 때때로 근절 포기(Sarcomere give)라고 일컬어짐.
Cross-bridge detachment and sarcomere 'give' during stretch of active frog's muscle.
Abstract
1. A study has been made of the tension responses and sarcomere length changes produced by servo-controlled stretches applied to isometrically contracting frog muscle. Sarcomere lengths were monitored by cine-photography of diffiraction spectra obtained by illuminating a small area of muscle with a laser.
2. The tension increment produced by a ramp-and-hold stretch of approximately 1 mm (ca. 4% of the muscle length) comprises three phases whose limits are defined by two points, S1 and S2, where the slope of the response decreases abruptly. S1 and S2 correspond to extensions of 0.13 and 1.2% of the muscle length.
3. Movements of the first order spectra relative to the zero order recorded during stretch reveal that S2 coincides with an abrupt elongation of the sarcomeres. This is termed sarcomere 'give' and it occurs when the filaments are displaced by 11-12 nm from their steady-state (isometric) position.
4. The stiffness of the sarcomeres, Es, up to S2 decreases with increasing sarcomere length. The maximum force sustained by the muscle at S2, PS2, also shows an inverse dependence on sarcomere length. Both Es and PS2 fall to zero at an extrapolated sarcomere spacing of 3.6-3.7 micrometer, coinciding with the length at which the actin and myosin filaments no longer overlap.
5. The ratio PS2/P0 (where P0 = maximum isometric tension) varies with temperature and speed of stretch. It increases with increasing speeds of stretch until a certain critical velocity, Vc, is reached, beyond which it is almost independent of any further increase. Vc has a positive temperature coefficient, increasing 5-6 in the range 0-30 degrees C (Q10 = 1.8). There is a positive correlation between the maximum speed of isotonic shortening (Vmax.) and Vc in different muscles.
6. Sarcomere 'give' during stretch is considered to be due to forcible detachment of cross-bridges between the actin and myosin filaments. This results in recoil of the extended series elastic elements in the muscle at the expense of the sarcomers. The amount of filament displacement required to induce sarcomere 'give' (11-12 nm) is thought to represent the range of movement over which a cross-bridge can remain attached to actin during a stretch.