Part 2: Biophysics of Muscle Contraction Flashcards Preview

SF1.12 Muscle Physiology (ZACHOW) > Part 2: Biophysics of Muscle Contraction > Flashcards

Flashcards in Part 2: Biophysics of Muscle Contraction Deck (19)
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1

What increases muscle strength?
 

  • Work = the displacement of load.
  • Strength is a function of size; larger muscle = more strength.
  • Muscle contraction without sufficient work does not increase strength.

2

Afterload:

the thing you want to move. 

3

Preload:

  • the ability of the muscles to displace a load (contractile force/strength). if the preload if larger than the afterload, displacement will occur.

4

When will displacement occur?

preload > afterload

5

Isometric contraction:

  • no displacement, no work, no velocity.
  • when afterload > preload. 

6

Isotonic contraction:

  • displacement occurs.
  • preload > afterload.
     

7

What is the preload and afterload in the heart?

  • Preload: Myocardial contractile force (left ventricle)
  • Afterload: Blood pressure (“the weight”)

Preload > afterload in order for

displacement to occur.

8

Systole:

anytime a chamber in the heart contracts

9

Muscle twitches summate to form:

 

  • a fused tetanus which causes muscle contraction to occur.

10

The three types of muscle tension:
 

  1. passive tension
  2. active tension
  3. total tension (active + passive)

11

Passive muscle tension is due to:

  • elastic properties of muscle: muscle acting like a rubber-band like structure.

12

Passive tension increases as:

muscle is stretched.

13

Passive tension decreases as:

muscle is relaxed.

14

Active muscle tension is:

  • everything that happens as you contract a muscle.
  • decreases as muscle contracts, and eventually hits zero because actin and myosin run out of room.

15

Active muscle tension decreases as:

muscle contracts
 

16

Maximum tension is the maximum force of a muscle. It occurs at:

the start of contraction.

17

Power = 

  • P = Fv
  • P = F (ΔX/ΔT)

18

Relationship between load and velocity of muscle fiber contraction:

  • as load increases, velocity of muscle fiber contraction decreases
     

19

Relationship between the resting length of a muscle and power:

  • as resting length increases, power increases