18. Excitation Contraction Coupling Flashcards
How long does Rigor Mortis last?
15-25 hours
Which type of muscle fiber has more mitochondria and myoglobin?
Type I
What receptors are responsible for initiating a local potential at the neuromuscular junction?
Ligand gated acetylcholine receptors
What are the three members of the troponin complex, and what do they bind to?
Troponin I: Actin
Troponin C: Calcium
Troponin T: Tropomyosin
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 enzyme breaks down acetylcholine in the synaptic gap?
Acetylcholine Esterase
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.
How do we make a muscle contract with more or less force?
Recruitment - activate more or fewer muscle units
Where is the myosin head after ATP binds, but before ATP is hydrolyzed?
Released from the actin, but not yet cocked.
What happens after the myosin head attaches to the actin?
Pi dissociates and the power stroke contracts the sarcomere.
How long can we use phosphocreatine for muscle contraction?
8-10 seconds
Besides the muscle cell hypertrophy, what changes in the muscles of a trained athelete vs someone like me (a nerd)?
More mitochondrial enzymes
More glycogen
More phosphocreatine
More stored fat
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
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.
Where is the myosin when the ATP is hydrolyzed?
Cocked and ready to interact with actin and contract
What enzyme is used to shuttle calcium from the sarcoplasm into the sarcoplasmic reticulum after a contraction occurs?
Calcium ATPase
Which type of muscle fibers have more phosphocreatine?
Type II
Which type of muscle fiber has more glycogen?
Type II
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
DHP
Which type of muscle fibers are larger?
Type II
How long can we use Glycolysis for a muscle contraction?
1.3 - 1.6 minutes
What allows the sarcoplasmic reticulum to hold up to 40x more calcium than it otherwise would?
Calsequestrin
What small structures are made in the sarcolemma of the neuromuscular junction to increase the action potential going into the muscle?
Subneural Clefts
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.
Where is the myosin head after a contraction, but before it binds a new ATP?
Still stuck to its binding site on the actin.
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 long can we use stored ATP for a muscle contraction?
Two seconds
