Muscle contraction ppt

Isometric & Isotonic Contraction

1. Types of muscle contraction and mechanism of contraction Dr. JASJYOT KAUR SABHARWAL (PT) J

2. Two types of Contractions Isotonic Contraction Isometric contraction

3. Isotonic Contraction Isotonic contractions maintain constant tension in the muscle as the muscle changes length.

4. Two type of Isotonic Contraction

5. Concentric contraction A concentric contraction is a type of muscle contraction in which the muscles shorten while generating force, overcoming resistance. For example , when lifting a heavy weight, a concentric contraction of the biceps would cause the arm to bend at the elbow.

6. Eccentric contraction An eccentric contraction results in the elongation of a muscle while the muscle is still generating force. Eccentric contractions can be both voluntary and involuntary.

7. Isometric contraction Isometric contractions generate force without changing the length of the muscle Isometric contractions are frequently used to maintain posture. Common in the muscles of the hand and forearm responsible for grip.

8. Sliding filament theory

9. When muscle contracts the actin filament slides into A band, overlapping with myosin. When muscle contracts: Z line moves close together. I band becomes shorter. A band stays at the same length.

10. The process of a muscle contraction can be divided: A nerve impulse arrives at the neuromuscular junction, which causes a release of a chemical called Acetylcholine (Ach) into the synaptic cleft. The presence of Acetylcholine causes Calcium (Ca+) to be released from the sarcoplasmic reticulum. In the presence of high concentrations of Ca+, the Ca+ binds to Troponin changing its shape. This moves Tropomyosin from the active site of the Actin to expose uncovered sites. Therefore, Myosin filaments can now attach to the Actin forming a cross-bridge.

11. 3. The cross bridge binds to the active sites. Energy from ATP is used to break the bond straighten the cross bridge and form new bond with another active site. 4. This process of muscular contraction can last for as long as there is enough ATP and Ca+ stores. Once the impulse stops the Ca+ is pumped back to the Sarcoplasmic Reticulum and the Actin returns to its resting position causing the muscle to lengthen and relax.

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