Part 2: Biophysics of Muscle Contraction Flashcards
1
Q
What increases muscle strength?
A
- 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
Q
Afterload:
A
the thing you want to move.
3
Q
Preload:
A
- the ability of the muscles to displace a load (contractile force/strength). if the preload if larger than the afterload, displacement will occur.
4
Q
When will displacement occur?
A
preload > afterload
5
Q
Isometric contraction:
A
- no displacement, no work, no velocity.
- when afterload > preload.
6
Q
Isotonic contraction:
A
- displacement occurs.
- preload > afterload.
7
Q
What is the preload and afterload in the heart?
A
- Preload: Myocardial contractile force (left ventricle)
- Afterload: Blood pressure (“the weight”)
Preload > afterload in order for
displacement to occur.
8
Q
Systole:
A
anytime a chamber in the heart contracts
9
Q
Muscle twitches summate to form:
A
- a fused tetanus which causes muscle contraction to occur.
10
Q
The three types of muscle tension:
A
- passive tension
- active tension
- total tension (active + passive)
11
Q
Passive muscle tension is due to:
A
- elastic properties of muscle: muscle acting like a rubber-band like structure.
12
Q
Passive tension increases as:
A
muscle is stretched.
13
Q
Passive tension decreases as:
A
muscle is relaxed.
14
Q
Active muscle tension is:
A
- 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
Q
Active muscle tension decreases as:
A
muscle contracts
