Muscle Metabolism Muscle metabolism ATP is energy source

Muscle Metabolism

Muscle metabolism • ATP is energy source for contraction • HOWEVER, muscle fibers only have enough ATP to contract for a short time • ATP must then be regenerated from ADP and P by the muscle cell: • creatine phosphate is the molecule that makes this possible • Creatine phosphate has high energy phosphate bonds

Muscle metabolism When ATP supply is sufficient enzyme creatine phosphokinase (in the mitochondria) catalyzes the synthesis of creatine phosphate. • Creatine phosphate stores energy in high energy phosphate bonds • Creatine phosphate is 4 -6 X more abundant in muscle cells than ATP • BUT it Cant be used directly as an energy source • So as energy from ATP is released and ADP is produced, creatine phosphate transfers energy to ADP to become ATP • Active muscles uses creatine phosphate quickly so cell respiration is required to generate more ATP

Creatine Supplements

O 2 and Cellular Respiration Aerobic respiration is a more complete breakdown of glucose When O 2 is present; mitochondria produce 36 ATP per 1 glucose (oxidative phosphorylation) Oxygen is delivered to the muscle by Red blood cells by 2 pigments: 1. Hemoglobin is pigment that carries O 2 2. Myoglobin another pigment- is a molecule with high affinity to oxygen and is produced in the muscle cells

Oxygen Debt • Strenuous use, • Need anaerobic respiration • glycolysis : 2 ATP formed per glucose and synthesis of lactic acid Consequence of anaerobic metabolism? FATIGUE Figure 12. 11

Liver and Lactate

Types of physical training • High intensity, short burst exercise: • Depend on more glycolysis • Synthesize more glycolysis enzymes • Aerobic Exercise • form more capillaries and mitochondria

Muscle fatigue: muscle loses ability to contract due to prolonged use Caused by: Decreased ATP Electrolyte imbalance Causes: - rapid build-up of lactic acid - decrease in oxygen supply - decrease in energy supply (glucose, glycogen, fatty-acids) - Decreased neurotransmitter at the synapse - psychological causes

Cramp • When muscle is fatigued • Sustained involuntary contractions • Changes in extracellular fluid surrounding muscle fibers trigger uncontrolled stimulation of muscle • Due to Low sodium, potassium, magnesium • Nocturnal cramps due to dehydration

Heat production • 40% of energy in glucose released as ATP • Rest released as heat • Blood transports heat to maintain homeostasis

Maxine