Skeletal Muscle Contraction Flashcards Preview

A&P Exam 2 > Skeletal Muscle Contraction > Flashcards

Flashcards in Skeletal Muscle Contraction Deck (18)
Loading flashcards...
1
Q

sliding filament theory

A

movement within the myofibrils in which the filaments of actin and myosin slide past one another, shortening the muscle fiber and pulling on its attachments

2
Q

Contractile proteins

A

actin and myosin

  • generate force
3
Q

Regulatory proteins

A

troponin and tropomyosin

  • function as the on/off switch
  • attached to actin
4
Q

Structural proteins

A

titin and actinin

  • large protein in body
  • keep thick and thin filaments of myofibrils in proper alignment, give myofibrils elasticity and extensibility, and link myofibrils to sarcolemma and extracellular matrix
5
Q

myosin molecule

A

composed of 2 twisted protein strands

6
Q

heads

A

globular projections along 2 strands of myosin

7
Q

actin molecule

A

globular structure with binding site to which the myosin heads can attach forming cross-bridges

8
Q

actin filament

A

actin molecule twist into a double strand (helix)

9
Q

troponin-tropomyosin complex

A

cover actin binding sites when at rest or unstimulated to contract

contraction cannot occur as long as these binding sites are covered

10
Q

sarcomere

A

as thick and thin filaments slide past each other, this shortens

11
Q

ATP in muscle contraction

A
  1. Calcium binds to the troponin, eventually changing its shape and altering the position of the tropomyosin
  2. Movement of the trop myosin molecules exposes the binding sites on actin filaments
  3. Linkage form between the actin and myosin filaments
  4. “power stroke” occurs receiving energy from ATP; it pulls the actin filaments towards the A bands
  5. The myosin head possesses stored energy, which will be released when myosin head binds to actin and pulls - recovery stroke
12
Q

ATPase

A

enzyme that releases energy stored in the terminal phosphate bonds of ATP molecules

  • breakdown ATP (adenosine triphosphate) to ADP (adenosine diphosphate) and phosphate
  • provides the force with which the cross-bridge pull
13
Q

ATPase binding with ATP

A

results in splitting into ADP and a phosphate

14
Q

ATP

A

contains adenine, which provides a carbon and nitrogen basem ribose, which is a 5 carbon sugar and 3 chemical groups called phosphates in a chain

15
Q

creatine phosphate

A

stores energy

16
Q

cellular respiration

A

releases energy from organic compounds

17
Q

ATP binding with cross-bridge

A

causes cross-bridge to release from actin even before ATP splits

  • requires fresh ATP attach to myosin ATPase
  • binds, but not yet broken down
18
Q

muscle cramp

A

result from lack of ATP to cause the release of the cross-bridges and/or required to shuttle calcium out