SLIDING FILAMENT MECHANISM
Anis A. Makky, drg, MKes
Oral Biology Dept. - Dentistry Faculty
Airlangga University
Surabaya, May 07, 2009
MUSCLE
skeletal muscle
smooth muscle
cardiac muscle
SKELETAL MUSCLE
muscle fibers
contractile protein
no extracellular calcium
CONTRACTILE PROTEIN
actin : actin
troponin I, C, T
tropomyosin
myosin
titin
nebulin
SLIDING FILAMENT
MECHANISM
Figure 12-11a: Excitation-contraction coupling
Figure 12-11b: Excitation-contraction coupling
Cross-Bridge Formation in Muscle Contraction
Receptors in Muscle
• Muscle spindle– Detect dynamic and static changes in muscle length– Stretch reflex
• Stretch on muscle causes reflex contraction
• Golgi tendon organ (GTO)– Monitor tension developed in muscle– Prevents damage during excessive force generation
• Stimulation results in reflex relaxation of muscle
Muscle Spindle
Golgi Tendon Organ
• Central– "Feeling"– Lactic acid
• Peripheral– Glycogen depletion– Ca2+ interference
– High Pi levels
– ECF high K+
– ACh depletion
Muscle Fatigue: Causes not well known
Figure 12-14: Locations and possible causes of muscle fatigue