Lab III. - Questions

Question 1

Give the steps in making isometric maximum curve

Answer 1

Supramaximal single stimuli and provide isotonic conditions in each step

Question 2

What is the electromyogram (EMG)?

Answer 2

Potential differences from muscle contraction measured on the skin

Question 3

When does complete tetany develop?

Answer 3

When muscle does not relax but show continous tonic spam

Question 4

Maximal stimulus?

Answer 4

The weakest stimulus that just causes complete contraction

Question 5

Give the steps and principle in passive stretch curve to measure muscle function?

Answer 5

relative lenght determind by different weights

Question 6

What happens when Ca binds to TnC?

Answer 6

Shift tropomyosin-troponin complex to the groove of the actin filament

Question 7

Which muscle, and which nerve is used in the classical frog-nerve experiment?

Answer 7

m. gastrocnemius and sciatic nerve

Question 8

Explain the importance of the muscle reacting to different threshold potentials?

Answer 8

the “all-or-none” law of the muscle fibres

Question 9

All or none law?

Answer 9

An adequate stimulus causes maximal contraction (if threshold is reached)

Question 10

Physiological reason for muscle fatigue?

Answer 10

Increasing concentration of metabolic by-products

Question 11

Steps of “cross the bridge” cycle?

Answer 11

Formation of actomyosin complex, sliding of filament and dissociation of ATP-dependent terminal phase

Question 12

Latency period?

Answer 12

The time period between the stimulation and the start of contraction

Question 13

What is meant by temporal summation?

Answer 13

Superposition

Question 14

What is length tension curve?

Answer 14

Diagram with passive stretch curve, isotonic max curve and isometric max curve

Question 15

Which muscle exhaustes latest?

Answer 15

red muscles with slow-twitch fibres

Question 16

What is superposition?

Answer 16

Repeated stimulation before previous calcium transient has finished, give additional calcium release and increased contraction

Question 17

The three curves in measuring lenght-tension?

Answer 17

passive stretch curve, isotonic max curve and isometric max curve

Question 18

Brief explain the passive strech curve?

Answer 18

Relative length of muscle for each weight

Question 19

Red muscle?

Answer 19

oxidative with slow-twitch fibres

Question 20

White muscle?

Answer 20

glycolytic with fast-twitch fibres

Question 21

Which ion increases in the myoplasm as the action pot. reaches the muscle?

Answer 21

Calcium

Question 22

How do we find the minimal stimulus of a muscle?

Answer 22

Increase stimulus strenght gradually between 0 and 500 mV

Question 23

What is minimal stimulus?

Answer 23

the weakest stimulus that just causes complete contraction