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 Creatine Supplements

O2 and Cellular Respiration Aerobic respiration is a more complete breakdown of glucose When O2 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 O2 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

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 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