SKELETAL MUSCLE ENERGETICS Flashcards
What is a isometric contraction
(Same length )
Wen the activated muscles generate force without shortening
Responsible for maintaining body posture
What is a isotonic contraction
(Same force)
When the activated muscles shorten as they develop force
Generate limb movements
What is a titanic contraction
Is caused by a series of action potentials at short intervals
Explain the relationship between contractile force and sarcomere length
As contractile force increases sarcomere length increased till then point where it starts to decrease (due to being stretched beyond normal limits- myosin and actin overlap decreases)
At what sarcomere length is the contractile force the greatest
2-2.2 micrometers
This length permits the max number of cross bridges between actin and myosin
What is the muscular power output
Is the product of the velocity of muscle shortening and the force developed by the muscle
The force developed by the muscle is linearly dependent on the external load and the velocity of shortening
What are the 3 major muscle fibre types in mammals
Slow (type 1) Fast oxidative glycolytic (type 2a) Fast glycolytic (type 2b)
What are the major metabolic properties of slow (type 1 )muscle fibres
Small Motor Unit (MU) Many mitrochondria High fatigue resistance Low speed of contraction Aerobic respiration - oxidative phosphorylation Typical function = posture
What are the major metabolic properties of type 2a muscle fibres
Fast oxidative glycolytic Intermediate size of MU Many mitrochondria Slightly fatigue resistant Fast twitch Aerobic respiration- oxidative phosphorylation Typical functions = walk, run
What are the major metabolic properties of type 2b muscle fibres
Fast glycolytic fibres Very Large MU Not fatigue resistant Anaerobic glycolysis High speed of contraction Few mitochondria Typical function= jump, throw
Outline the process leading to muscle fatigue
Can be a result of vigorous exercise, 2 main causes:
- neural fatigue
- metabolic fatigue
During exercise don’t take in enough O2 for aerobic respiration, so switch to anaerobic - produces lactic acid- acid conditions - activity of myosin heads is reduced at low pH
What is neural fatigue
Limitations of the nerves ability to generate a sustained signal (action potential)
What is metabolic fatigue
Reduced ability of the muscle fibre to contact
Describe the interaction of antagonistic muscles, their tendons and the bones that they are attached to in the movement of a joint
When one muscle contracts (agonist ) the other is relaxed (antagonist )
On the contracting muscle the tendons are under tension
