Biology Chapter 11

• 1. acetylchole is released
• 2. electrical impulse transmitted along T tubules
• 3. Calcium is released
• 4. Calcium binds to troponin C
• 5. Troponin-tropomyosin complex shifts position
• 6. myosin binding site is exposed
• 7. myosin heads form cross-bridges with actin. cross bridge cycling occurs.
• 8. actin filaments are pulled toward center of sacromere
• 9. calcium is pumped back into sarcoplasmic reticulum
• 10. muscle relaxation

thick filaments

thin filaments

• z disk to z disk
• z disk = attachment point for sarcomeres

• Yes, energy is required.
• ATP production is important!

formation of cross-bridges between thick and thin filaments

• same length
• muscle not allowed to shorten
• TENSION and FORCE is measured

• same strength (weight)
• muscle allowed to shorten
• DISTANCE SHORTENED is measured

somatic motor neuron and all the muscles it stimulates

force exerted by a contracting muscle

mucle cells always contract completely each time they are stimulated by their motor neuron, and they do not contract at all if they are not stimulated by a motor neuron

intermediate level of force

accumulation of effects, especially those of muscular (or neural) activity

sustained maximal muscle contraction resulting from high frequency stimulation

• slow, steady contractions; muscles used for posture
• do not fatigue easily
• use aerobic pathway to generate ATP
• many mitochondria to produce ATP
• well supplied with blood bringing needed oxygen
• high oxygen store (myoglobin) within the muscle
• myoglobin and numerous blood vessels give muscle reddish color; "red" meat

• quick, powerful bursts of energy; muscles used by sprinters
• fatigue easily
• use anaerobic pathway (glycolysis) to generate ATP
• few mitochondria to produce ATP
• not supplied with much blood
• low myoglobin concentrated with muscle cells
• sometimes referred to as "white" meat

• resistance training
• short, intence
• builds more fast-twitch myofibrils

• builds endurance
• increases blood supply to muscle cells
• reach target heart rate at least 20 minutes, three times a week

voluntary (through somatic nervous system)

Involuntary

group of inherited muscle-destroying diseases. Duchenne's muscular dystrophy is due to lack of the protein dystrophin in the muscle cell.