7.Macroscopic events of muscle contraction

Question 1

Elements

Answer 1

CC,SEC,PEC

Question 2

Elements what happens during stimulation

Answer 2

first SEC element will reach equilibrium with load because of the CC contraction, this is followed by constant tension

Question 3

twitch: what is it

Answer 3

a single contraction- relaxation cyle

Question 4

twitch: what is virtual latency

Answer 4

the sum of the tow latencies

Question 5

Twitch: isometric contraction

Answer 5

Only tension is changed but not the length of
the muscle
- Occurs when muscle tries to lift such heavy
load which it is not able to move

Question 6

Twitch: isotonic contraction

Answer 6

Muscle shortens with constant tension
- Regular physiological behaviour

Question 7

Twitch: auxotonic contraction:

Answer 7

In natural conditions, muscle shortens and in
the same time, tension is also increasing in it. -

Question 8

Twitch: auxotonic contraction example

Answer 8

Example: when a muscle works against a
spring.

Question 9

Twitch: preload

Answer 9

After stimulation contractile machinery will
first stretch SEC elements, and when tension reaches equilibrium with the load, contraction becomes isotonic, twitch is continued with shortening of the muscle.

Question 10

Twitch: afterload

Answer 10

If we block the free movement of the muscle
with a frame, then no more shortening is possible from a certain level, but muscle is still able to increase tension.
- At the beginning it is isotonic, then an isometric period follows.

Question 11

what it Summation

Answer 11

addition of skeletal muscle contraction forms caused by different reasons

Question 12

Summation: all- or- none:

Answer 12

A single fiber under constant metabolic conditions contracts according to the “all-or-none” law = to an adequate stimulus, response is maximal, to smaller stimulus there is no response.

Question 13

Summation: Quantal summation:

Answer 13

If the increase of tension is caused by the participation of more and more fibers. If the demand is higher, a more frequent AP recruits more and more fibers.

Question 14

Summation: Contraction summation:

Answer 14

Repetitive stimuli may cause increasing contraction, when a new stimulus elicits additional calcium release. Thus, the amplitude of contraction is increased.

Question 15

Summation: Staircase effect (treppe):

Answer 15

New stimuli applied shortly after the end of a twitch may elicit new contractions with gradually increasing amplitudes: it is caused by IC calcium, which has no time to be removed in between stimuli

Question 16

Summation: Tetanus

Answer 16

: If we apply stimuli with increasing frequency we enhance possible summation modes: finally muscle reaches maximal contraction state