3. MUSCLE ENERGETICS

4. Frank starling Law Greater the initial length of the Sarcomere,
Greater will be the Force of Contraction

5. LENGTH-TENSION Diagram (Frank-Starling Law)
Greater the initial length of the Sarcomere,
Greater will be the Force of Contraction Z Z M A X I U

6. Energy Sources & metabolism in skeletal Muscles
ATP- (Immediate source)
Phosphocreatinine
Anaerobic glycolysis
Aerobic Glycolysis

7. Muscle Contraction
In muscular system contraction means muscle fibers generating tension with the help motor neurons and while under tension the muscle may shorten ,lengthen or remain the same.

8. Muscle tension:
The force exerted on an object by a muscle is known as muscle tension
Muscle Load:
The force exerted on the muscle by an object is the muscle load.

9. Characteristics of Whole Muscle Contraction.
Isotonic.
Length changes but Tension remains constant.
Two Forms of Isotonic Cont.
1. Concentric (Muscle shortens while lifting the weight)
2. Eccentric ( while putting the weight back, the muscle lengthens)
Or walking down hill
Types of Contraction

10. Types of Contraction Isometric.
Tension is increased but Length remains constant.
.e.g Isometric Contraction in the heart

11. Isometric versus Isotonic contraction
Latent period is longer in isotonic contraction as compared to isometric contraction

12. Characteristics of Whole Muscle Contraction
Simple Muscle Twitch;
Comprised of 3 phases:
Latent Period.
Contraction Phase
Relaxation phase

13. Isometric Contractions for different Types of muscles

14. Treppe (Stair-Case Phenomenon)
When a series of maximal stimuli are delivered to Skeletal muscle just below the tetanizing frequency, the tension developed by each Twitch increases
(Second stimulus elicits a stronger response)
Perhaps due to increase in intracellular Ca2+.

15. TETANIZING FREQUENCY
How many times you are stimulating the nerve fiber per second to obtain full tetanization.
10-15 stimuli/sec

16. SUMMATION
The adding together of individual twitch contractions to increase the intensity of overall muscle contraction is called summation.
Multiple fiber summation
Frequency summation----Tetanization

17. Motor Unit
Single Motor Neuron & all Muscle Fibers it innervates constitute a single Motor Unit.
α- motor N

18. Some Diseases related to Muscles

19. MUSCLE FATIGUE
Prolonged and strong contraction of a muscle leads to muscle fatigue.
Characteristics of Fatigued muscle
1.Decreased shortening velocity
2. Slower rate of relaxation

20. Onset and rate of development of Fatigue include
1. Type of skeletal muscle fiber that is active.
2. Intensity and duration of contraction.
3. Degree of individual fitness.

21. TYPES OF FATIGUE High frequency fatigue
Includes high frequency short duration exercise e.g weight lifting.
Low frequency fatigue
Includes low intensity long duration exercise e.g long distance running.
Central command fatigue

22. Causes of high frequency fatigue
Conductive fatigue
Lactic acid build up
Inhibition of cross bridge cycling.
Causes of low frequency fatigue
Decreased muscle glycogen
low blood glucose
Dehydration
Junctional fatigue

23. Central command fatigue
Appropriate regions of cerebral cortex fail to send excitatory signals to the motor neurons.

24. Fatigue results mainly from inability of the contractile and metabolic processes of the muscle fiber to continue supplying the same work output.