Lab3

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 contractions measured on the skin

Question 3

When does complete tetany develop?

Answer 3

When the muscle doesn’t relax, but shows continuous tonic spasm

Question 4

Maximal stimulus

Answer 4

The weakest stimulus strength that just causes complete contraction

Question 5

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

Answer 5

Relative length determined 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 fibers

Question 9

All or none law

Answer 9

Contracting maximally

Question 10

Physiological reason for muscle fatigue

Answer 10

Increasing concentration of metabolic by-products

Question 11

Steps of the “cross the bridge” cycle

Answer 11

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

Question 12

Latency period

Answer 12

Time period between the stimulus and the start of contraction

Question 13

What is meant by temporal summation?

Answer 13

Superposition

Question 14

What is the length tension curve?

Answer 14

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

Question 15

Which muscle exhaust latest?

Answer 15

Red muscle with slow-twitch fibers

Question 16

What is superposition?

Answer 16

Repeated stimulation before previous calcium transient has finished, give additional calcium release and increase concentration

Question 17

The three curves in measuring length-tension

Answer 17

Passive stretch curve, isotonic max curve and isometric max curve

Question 18

Briefly explain the passive stretch curve

Answer 18

Relative length of muscle for each weigh

Question 19

Red muscle

Answer 19

Oxidative with slow-twitch fibers

Question 20

White muscle

Answer 20

Glycolytic with fast-twitch fibers

Question 21

Which ion increases in the myoplasm as the action potential reaches the muscle?

Answer 21

Calcium

Question 22

How do we find the minimal stimulus of a muscle?

Answer 22

Increase stimulus strength gradually between 0 and 500 mV

Question 23

What is minimal stimulus?

Answer 23

The weakest stimulus strength that just elicits contraction