18. Excitation Contraction Coupling Flashcards Preview

04. MSK Exam 2 Final > 18. Excitation Contraction Coupling > Flashcards

Flashcards in 18. Excitation Contraction Coupling Deck (28)
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1

Where is the myosin when the ATP is hydrolyzed?

Cocked and ready to interact with actin and contract

2

What happens after the myosin head attaches to the actin?

Pi dissociates and the power stroke contracts the sarcomere.

3

What enzyme breaks down acetylcholine in the synaptic gap?

Acetylcholine Esterase

4

What small structures are made in the sarcolemma of the neuromuscular junction to increase the action potential going into the muscle?

Subneural Clefts

5

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

6

Where is the myosin head after ATP binds, but before ATP is hydrolyzed?

Released from the actin, but not yet cocked.

7

What are the three members of the troponin complex, and what do they bind to?

Troponin I: Actin

 

Troponin C: Calcium

 

Troponin T: Tropomyosin

8

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

9

Which type of muscle fibers are larger?

Type II

10

When we strength train, do we get more muscle fibers, or just bigger muscle fibers?

Just bigger muscle fibers

(more myofibrils per muscle fibers)

11

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

 

12

What receptors are responsible for initiating a local potential at the neuromuscular junction?

Ligand gated acetylcholine receptors

13

How do we make a muscle contract with more or less force?

Recruitment - activate more or fewer muscle units

14

How long can we use phosphocreatine for muscle contraction?

8-10 seconds

15

How long does Rigor Mortis last?

15-25 hours

16

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

17

What allows the sarcoplasmic reticulum to hold up to 40x more calcium than it otherwise would?

Calsequestrin

18

What enzyme is used to shuttle calcium from the sarcoplasm into the sarcoplasmic reticulum after a contraction occurs?

Calcium ATPase

19

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.

20

Which type of muscle fiber has more glycogen?

Type II

21

Which type of muscle fibers have more phosphocreatine?

Type II

22

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.

23

Which type of muscle fiber has more mitochondria and myoglobin?

Type I

24

How long can we use stored ATP for a muscle contraction?

Two seconds

25

How long can we use Glycolysis for a muscle contraction?

1.3 - 1.6 minutes

26

Where is the myosin head after a contraction, but before it binds a new ATP?

Still stuck to its binding site on the actin.

27

What is a motor unit?

All the muscle fibers innervated by a single nerve fiber.

28

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.