Muscle Contraction Essay

Exercise 8 Simple Muscle Contraction
• 3 Phases
AB
- lag phase or latent phase
- (shortest) 0.00sec, usually less than 0.01sec
- brief period that exists between the application of the stimulus and the start of contraction
BC
- contraction, 0.05sec
- peak
- shortening of the muscle occur
CD
- relaxation period, 0.05 sec
- Occurs when Ca+ is transported back in the sarcoplasmic reticulum
Single muscle contraction= 100vib/sec (tuning fork)= 0.10 sec
10vib (result)
Neuromuscular junction
- formed when several branches of axons form a single muscle fiber
- also called synapse
- connection between a muscle fiber and nerve
"All or none" law of muscle contraction
- refers to the action potential that influences a muscular fiber to stimulation
Exercise
walking, running, dancing: movements of the upper limb exhibit predominant isotonic contractions
1. Concentric isotonic contraction o contractions in which muscle tension increases as the muscle shortens o eg. bicep curling, straightening the arm, moving the hand from side to side
2. Eccentric isotonic contraction o contractions in which tension is maintained as the muscle lengthens o eg. person letting a heavy weight down slowly a person using his hamstring muscles when running downhill, overloading the bicep so that it straitens, contractions of quadriceps muscle when descending the stairs
Exercise 11 Pithing
Pithing
- destruction of CNS to render the frog free from pain
Signs of successful pithing
- needle has destroyed branches of the sciatic nerve
- frog's legs to extend forward and quiver a few moments
- with the withdrawal of needle, frog should remain limp throughout the experiment
Exercise 12 Muscle-Nerve Preparation
Purpose of teasing thigh muscles: to expose the sciatic nerve
Exercise 13 Applications of the Different Forms of Stimuli
Different forms of stimuli
A. Mechanical stimulus- single muscle contraction
B. Thermal stimulus
1. Hot water- single muscle contraction
2. Cold/iced water- single muscle