The Organization of a Skeletal Muscle Figure 7-1
Organization of a Skeletal Muscle Fiber Figure 7-2a
Organization of a Skeletal Muscle Fiber Figure 7-2 b-c
Sarcomere Shortening Figure 7-3
Sarcomere Shortening Figure 7-3
Structure and Function of the Neuromuscular Junction Figure 7-4 a
Structure and Function of the Neuromuscular Junction Figure 7-4 b
Structure and Function of the Neuromuscular Junction Figure 7-4
Structure and Function of the Neuromuscular Junction Figure 7-4
Structure and Function of the Neuromuscular Junction Figure 7-4
Structure and Function of the Neuromuscular Junction Figure 7-4
Structure and Function of the Neuromuscular Junction
The Contraction Cycle Five Steps of the Contraction Cycle – Exposure of active sites – Formation of cross-bridges – Pivoting of myosin heads – Detachment of cross-bridges – Reactivation of myosin
Molecular Events of the Contraction Process Figure 7-5 The active site is exposed following the binding of calcium ions to troponin.
Molecular Events of the Contraction Process Figure 7-5 The myosin cross bridge forms and attaches to the exposed active site on the thin filaments.
Molecular Events of the Contraction Process Figure 7-5 The attached myosin head pivots toward the center of the sarcomere and ADP and a phosphate group are released.
Molecular Events of the Contraction Process Figure 7-5 The cross- bridges detach when the myosin head binds another ATP molecule
Molecular Events of the Contraction Process Figure 7-5 The detached myosin head is reactivated as it splits the ATP and captures the released energy.
Frequency of Muscle Fiber Stimulation Three Phases of Twitch – Latent period before contraction: The action potential moves through sarcolemma Causing Ca 2+ release – Contraction phase: Calcium ions bind Tension builds to peak – Relaxation phase: Ca 2+ levels fall Active sites are covered Tension falls to resting levels
Twitch and Development of Tension Figure 7-6
Effects of Repeated Stimulations Figure 7-7
Types of Skeletal Muscle Fibers Fast fibers (White) – Light in color, large diameter – Few capillaries, few mitochondria – Uses glycolysis (2 ATP) – Little myoglobin – Power/speed – Fatigue rapidly
Types of Skeletal Muscle Fibers Slow fibers (Red) Red in color, small diameter Many capillaries, numerous mitochondria Uses Krebs cycle/Oxidative phosphorylation (34 ATP) Much myoglobin High endurance
Muscle Metabolism Figure 7-9
Muscle Metabolism Figure 7-9
Muscle Metabolism Figure 7-9