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