10.3 & 4 Physiology of skeletal muscle contraction and metabolism Flashcards
Dihydropyridine receptors
Voltage gated Ca2+ receptors
Ryanodine receptors
Calcium release channels
Where are calmodulin and calsequestrin found and what do they do?
Found in the sarcoplasmic reticulum and they bind to calcium which is released when the Ca2+ gates in the SR are opened.
What does Myokinase do?
It converts two ADP molecules into one ATP molecule and one AMP molecule. 5-6 seconds of additional maximal muscle contraction energy provided.
Where is creatine phosphate located?
Tissue with both large and fluctuating needs for energy.
What does creatine kinase do?
Converts ADP and one creatine phosphate into ATP and creatine. This provides an additional 10-15 seconds of maximal energy for muscle contraction.
What nutrients can be broken down to produce ATP through aerobic cellular respiration?
Pyruvate, fatty acids, and amino acids
Describe the lactic acid cycle
Lactated is formed from pyruvate when there is not enough oxygen available for aerobic cellular respiration. The lactate then leaves the muscle, enters the blood, is converted from lactated into glucose via gluconeogenesis, and put back into the blood stream.
Define oxygen dept
The amount of additional oxygen that is consumed following exercise to restore pre-exercise conditions.
Where is oxygen being used that is required by the oxygen debt post exercise?
In skeletal muscle fibers to replace oxygen on myoglobin molecules, replenish ATP and creatine phosphate, and replace glycogen stores.
In the liver to convert lactate back to glucose through gluconeogensis.
What are the two types of muscle fibers?
Fast and slow twitch
What do oxidative fibers use as an energy source?
Cellular respiration. These are also called fatigue-resistant fibers. Red appearance because of large amounts of myoglobin and mitochondria.
What do glycolytic fibers use as an energy source?
They use glycolysis. White appearance. Fewer myoglobin and mitochondria. These tire easily.
Slow oxidative fibers
Type I fibers-slow myosin ATPase. Slower and less powerful contractions. Slow less powerful contractions. These are dark red because of large amounts of myoglobin and mitochondria. They use aerobic respiration.
Fast oxidative fibers
Type IIa/Intermediate fibers- least numerous. Fast myosin ATPase. Fast powerful contraction. ATP through aerobic cellular respiration. Lighter red than Type I fibers as they have somewhat fewer myoglobin and mitochondria.
