Flashcards in Lecture 41 Deck (23):
True or False:
Myosin is an enzyme?
Thick filaments are primarily made up of ____ and thin filaments are primarily made up of ___, ___. and _____.
What part of the thin filament will bind calcium?
Where is the enzymatic activity of myosin contained? What does this activity entail?
-Binds actin and splits ATP
What happens to intracellular Ca2+ concentration upon muscle contraction?
Released from SR and rises
How does a rise in Ca2+ concentration aid in muscle contraction?
-Ca2+ binds to troponin allowing myosin/actin interaction (myosin binds troponin) creating a crossbridge
-Release of ADP + P from myosin (power stroke) pulls z-line toward center of sarcomere
How is muscle contraction stopped?
-Binding of new ATP to myosin allows release of actin from myosin
-Finally ATP is hydrolyzed to ADP + P by myosin in preparation for another contraction signal
1 myosin head splits ____ ATP molecule at a time using the enzyme ____
____ is a major high energy phosphate reservoir in muscle
How does creatine phosphate enable muscle contraction?
-Creatine phosphokinase transfers phosphate from creatine phosphate to ADP to make more ATP to fuel muscle contraction
How is creatine phosphate regenerated in a resting muscle cell?
-Resting cell builds ATP back up and re-phosphorylates creatine
How can creatine be used clinically?
Elevated plasma levels of creatine phosphate indicate muscle cell damage (leaking out from broken muscle cell)
How does myokinase work?
Uses 2 ADP to make 1 ATP + 1 AMP
-AMP signals pathways to produce energy (AMPK; phosphofructokiase) --> need to regenerate ATP
How is vasodilation signaled in muscle contraction?
-Myokinase is generating AMP. Nucleotidase can remove a phosphate from AMP and generate adenosine which is a signal for increased vasodilation.
During prolonged muscle contraction some ATP is lost to generation of what waste product?
Explain the use and re-synthesis of ATP for muscle contraction over the course of exercise.
-Initially muscle reserve ATP is used quickly
-Creatine phosphate is used to rephosphorylate ADP
-After this begins to be depleated anaerobic glycolysis from phosphorylase kinase and PFK stim generates more ATP
-Eventually a shift to aerobic glycolysis happens which allows glycogen supply of muscle as well as FFA to provide energy
How does exercise enhance glucose uptake?
-stimulates GLUT4 translocation to cell surface and thus increased glucose uptake
How does exercise affect insulin sensitivity?
-Lower amounts of insulin will accomplish same metabolic activity
During initial exercise periods most of fuel is being provided by ____. Over time ____ is depleted from the muscle and ____ will provide most of the energy.
Over prolonged exercise indicate what will happen to each:
1. Blood glucose
2. Lactate concentration
3. Fatty acid production and use
4. Insulin production
5. Glucagon production
6. Hormone (cortisol, epinephrine, norepinephrine)
1. Remains same
In general why is anaerobic glycolysis occurring in a resting muscle?
-Regenerate ATP to rephosphorylate creatine to make creatine phosphate
Spontaneous breakdown of creatine generates ____.