Week 4 Muscle Excitation- Trachte Flashcards Preview

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Flashcards in Week 4 Muscle Excitation- Trachte Deck (21)
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1
Q

Lou Gehrig’s Disease/ Amyotropic lateral sclerosis

A

degeneration of motor neurons

2
Q

Lambert-Eaton

A

auto-antibodies against calcium channels in motor neurons resulting in an inability to relase acetylcholine

3
Q

Botulism

A

prevents acetylcholine relases by cleaving synaptic associated proteins (SNAPS)

4
Q

Myathenia Gravis

A

autoantibodies against nicotinic receptors in skeletal muscle

5
Q

Malignant Hyperthermia

A

mutation of the ryanodine receptor allowing excessive release of calcium, usually triggered by anesthetics

6
Q

Duchenne’s muscular dystrophy

A

a mutation in dystrophin, a skeletal muscle support protein

7
Q

What happens to the A band and I band during a muscle contraction?

A

The A band remains the same, the I band decreases in width

8
Q

What causes the power stroke in a muscle contraction?

A

Release of the phosphate causes the angle of the myosin head to revert to 45 degrees

9
Q

Describe the process of a muscle contraction

A
  • Ca+ is released and binds to troponin causing a conformational change in the tropomyosin, exposing the myosin binding site on the actin
  • ATP hydrolysis cocks the myosin head so it is ready to attach to actin
  • Myosin cross bridge binds Actin
  • Phosphate is released causing the power stroke (moves the head from 90 to 45 degrees toward M line)
  • ATP is required to myosin head to detach from actin
10
Q

What is required for muscle relaxation?

A
  • sequestration of calcium (this required ATP) by Ca ATPases

- this allows troponin-tropomyosin complex to inhibit bind of myosin

11
Q

***What is the amount of force generated by a muscle directly proportional to?

A

the number of actin-myosin crossbridges per cross-sectional area

12
Q

When do muscles work best?

A

Muscles work best when there is considerable overlap between actin and myosin

13
Q

What is an isometric contraction?

A

when the load is larger than the muscle’s ability to move it (the muscle contracts enough to pull the tendon taut but does not actually move the body attachment)

-trying to move something that won’t move

14
Q

What is an isotonic contraction

A

if the load on the muscle is constant

15
Q

Slow twitch fibers

A
Type 1 fibers
slower myosin ATPase enzyme
contain a lot of myoglobin
Red fibers
*Need myoglobin because they require lots of oxygen to maintain
16
Q

fast twitch fiber

A

Type II fibers
Faster myosin ATPase enyme
White fibers (less myoglobin)
Adapted for anaerobic metabolism

17
Q

Concentric contraction

A

muscle contracts resulting in shortening (typical biceps curl)

18
Q

Eccentric

A

muscle lengthens while attempting to shorten
(dropping a curl with resistance, running down a hill)
more damage to muscle with this type of contraction

19
Q

What are some big differences between cardiac and skeletal muscle?

A
  • Cardiac does not required innervation to contract, has autorhythmicity
  • more dependent on extra-cellular calcium
20
Q

Why is smooth muscle unique?

A
  • not striated
  • contraction not controlled by troponin or topomyosin
  • initiated by calcium interacting with a calcium-dependent myosin light chain kinase
  • oftenhas autorhythmicity (like intestinal muscle)
21
Q

What is the speed of a muscle contraction dependent on?

A

myosin ATPase activity