Where is the myosin when the ATP is hydrolyzed?
Cocked and ready to interact with actin and contract
What happens after the myosin head attaches to the actin?
Pi dissociates and the power stroke contracts the sarcomere.
What enzyme breaks down acetylcholine in the synaptic gap?
What small structures are made in the sarcolemma of the neuromuscular junction to increase the action potential going into the muscle?
What receptors have to change confirmation to allow calcium to release into the sarcoplasm?
Which one is located in the membrane of the T Tubule?
DHP and RYR
Where is the myosin head after ATP binds, but before ATP is hydrolyzed?
Released from the actin, but not yet cocked.
What are the three members of the troponin complex, and what do they bind to?
Troponin I: Actin
Troponin C: Calcium
Troponin T: Tropomyosin
Besides the muscle cell hypertrophy, what changes in the muscles of a trained athelete vs someone like me (a nerd)?
More mitochondrial enzymes
More stored fat
Which type of muscle fibers are larger?
When we strength train, do we get more muscle fibers, or just bigger muscle fibers?
Just bigger muscle fibers
(more myofibrils per muscle fibers)
How do we induce a smooth, continuous muscle movement within a single motor unit when our neurons can only produce all or nothing responses?
Summation and tetanization
Increasing frequencies of stimulation increases the rate of contraction
What receptors are responsible for initiating a local potential at the neuromuscular junction?
Ligand gated acetylcholine receptors
How do we make a muscle contract with more or less force?
Recruitment - activate more or fewer muscle units
How long can we use phosphocreatine for muscle contraction?
How long does Rigor Mortis last?
Where are the two hinges in a myosin molecule?
Hinge 1: Separating the two heads
Hinge 2: One on each of the myosin heads, allowing independent movement
What allows the sarcoplasmic reticulum to hold up to 40x more calcium than it otherwise would?
What enzyme is used to shuttle calcium from the sarcoplasm into the sarcoplasmic reticulum after a contraction occurs?
When is a sarcomere able to produce the maximum amount of force?
When there is no overlap in actin, and every myosin head is able to access a binding site.
Which type of muscle fiber has more glycogen?
Which type of muscle fibers have more phosphocreatine?
Would smaller, more precise muscles have more or less muscle fibers?
More muscle fibers
This allows them to regulate the force of their contraction more precisely.
Which type of muscle fiber has more mitochondria and myoglobin?
How long can we use stored ATP for a muscle contraction?
How long can we use Glycolysis for a muscle contraction?
1.3 - 1.6 minutes
Where is the myosin head after a contraction, but before it binds a new ATP?
Still stuck to its binding site on the actin.
What is a motor unit?
All the muscle fibers innervated by a single nerve fiber.
How long can we use oxidative phosphorylation to sustain a muscle contraction?
Until the muscle runs out of things to throw into the TCA cycle.