8. Muscle Mechanics

Question 1

What does the tension developed depend on in isometric muscle contraction?

Answer 1

Initial length of muscle before contraction

Question 2

What is the initial length of a muscle determined by?

Answer 2

Preload with stop removed

Question 3

What is afterload?

Answer 3

Extra weight on the lever after the stop has been replaced

Question 4

What does the Huxley model show?

Answer 4

Maximum length of sarcomere for maximum force

Question 5

What is summation?

Answer 5

Muscle is stimulated several times before it relaxes at high frequencies of activation

Question 6

What is tetanus?

Answer 6

Maximum level of tension produced by summation

Question 7

What is the Treppe phenomenon?

Answer 7

‘Staircase’ effect
Muscle is stimulated repeatedly at a frequency below that which causes summation
Increase in tension each time until maximum twitch is reached

Question 8

Name types of multiunit smooth muscle

Answer 8

Ciliary muscle
Iris
Piloerector muscles
Large arteries and veins
Arteriovenous shunt vessels
Bronchial smooth muscle

Question 9

Name types of visceral smooth muscle

Answer 9

Intestine
Uterus
Bladder
Ureters
Ducts of exocrine glands
Precapillary sphincters
Small blood vessels