Skeletal Muscles- Contraction Prof. K. Sivapalan.
-
Upload
scott-nash -
Category
Documents
-
view
228 -
download
2
Transcript of Skeletal Muscles- Contraction Prof. K. Sivapalan.
![Page 1: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/1.jpg)
Skeletal Muscles- Contraction
Prof. K. Sivapalan
![Page 2: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/2.jpg)
Skeletal Muscle Contraction 2
Actin Filament
• It is made up of actin, tropomyosin and troponin.
• Troponin I is bound to actin and tropomyosin and covers the myosin binding site
• Ca++ binds to Troponin C
• This causes exposure of Myosin binding site.June 2013
![Page 3: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/3.jpg)
Skeletal Muscle Contraction 3June 2013
![Page 4: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/4.jpg)
Skeletal Muscle Contraction 4
Myosin Filament
• Myosin has a head and a tail
• Each filament may have 200 or more myosin molicules
• The tails are bundled as the body while the heads hang outwards on a small arm – cross bridge
• The head has ATPase activity
• The cross bridge is flexible at hingesJune 2013
![Page 5: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/5.jpg)
Skeletal Muscle Contraction 5
Contraction
June 2013
![Page 6: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/6.jpg)
Skeletal Muscle Contraction 6
Sliding of Actin on Myosin
• At rest ATP binds to the head of the myosin, converted to ADP, the energy stored in the head.
• At this state, the head is perpendicular to the filament.
• When binding site of the actin is exposed, actin – myosin binding occurs.
• This binding changes the conformation of the cross bridge and causes ‘power stroke’ with energy stored as a ‘cocked spring’
• the stroke results in detachment of the cross bridge, release of ADP and attachment of another ATP
June 2013
![Page 7: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/7.jpg)
Skeletal Muscle Contraction 7
Muscle Twitch- Experimental Design
June 2013
![Page 8: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/8.jpg)
Skeletal Muscle Contraction 8
Muscle Twitch
• When one single stimulus is given, the muscle contracts and relaxes after a latency
• The latency is the time taken for excitation- contraction coupling
June 2013
![Page 9: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/9.jpg)
Skeletal Muscle Contraction 9
Staircase Phenomenon
June 2013
![Page 10: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/10.jpg)
Skeletal Muscle Contraction 10
Summation
June 2013
![Page 11: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/11.jpg)
Skeletal Muscle Contraction 11
Tetanization
June 2013
![Page 12: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/12.jpg)
Skeletal Muscle Contraction 12
Length – Strength
• The force developed by the muscle depends on the length of the muscle.
• It increases to maximum and then decreases.
June 2013
![Page 13: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/13.jpg)
Skeletal Muscle Contraction 13
Actin-Myosin Overlap and Tension Developed
• When muscle shortened, action myosin linkages are less.
• When the length increases, more and more linkages become possible
• When over stretched, again linkages are less
June 2013
![Page 14: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/14.jpg)
Skeletal Muscle Contraction 14
Motor Units and Strength
• Muscle fibers innervated by one axon constitute one motor unit.
• The size of the motor unit is the number of muscle fibers in it.
• The tension developed will depend on the number of myofibriles in each fiber and the size of the motor unit.
June 2013
![Page 15: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/15.jpg)
Skeletal Muscle Contraction 15
Fast and Slow Fibers
• Muscle fibers vary in myosin ATPase activity, contractile speed and other properties
• The muscles can contain a mixture of three fiber types: – type I (or SO for slow-oxidative);
– type IIA (FOG for fast-oxidative-glycolytic)
– type IIB (FG for fast glycolytic).
June 2013
![Page 16: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/16.jpg)
Skeletal Muscle Contraction 16
Muscle Type and Response
June 2013
![Page 17: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/17.jpg)
Skeletal Muscle Contraction 17
Fiber Types
SO FOG FGColour [Myoglobin] Red Red White Myosin ATPase Slow Fast FastCa++ pumping out Moderate High High Diameter Small Large LargeGlycolytic capacity Moderate High High Oxidative capacity High Moderate Low
June 2013
![Page 18: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/18.jpg)
Skeletal Muscle Contraction 18
Metabolism in Muscle
• Glucose and free fatty acids
• Oxygen debt mechanism
• Importance of glycogen and myoglobin
• Depends on the muscle type
• Genetic suitability to type of sports
• Alcohol and muscle performance
June 2013
![Page 19: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/19.jpg)
Skeletal Muscle Contraction 19
Electromyography- EMG
June 2013
![Page 20: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/20.jpg)
Skeletal Muscle Contraction 20June 2013
![Page 21: Skeletal Muscles- Contraction Prof. K. Sivapalan.](https://reader038.fdocuments.net/reader038/viewer/2022102718/56649ce65503460f949b3b42/html5/thumbnails/21.jpg)
Skeletal Muscle Contraction 21
Effects of Denervation
• Atrophy – less myofibrils
• Fibrillations- receptor hypersensitivity
• Fasciculation – motor unit function
June 2013