Lecture 8 Flashcards
What is muscle covered by?
- sheath of connective tissue that penetrates from surface into the muscle and envelops each fiber and divides muscle into columns or bundles
- etension of this tissue= tendons
What do antagonistic muscles do?
-move a body part in two opposing directions
What do flexors do?
-bend a limb
What do extensors do?
-straighten a limb
Why are muscle fibres grouped into whole muscles?
- twitch is too weak to be useful
- muscles can act cooperatively, stronger than a twitch
What is twitch summation?
-when APs close together then the muscle twitches combine= increase in strength
What happens in tetanus?
- lot of APs close together, doesn’t have time to relax (the muscle fibre)
- normal process
- there is a disease as well but that’s uncontrolled tetanus
More muscle fibres contracted results in=
= greater tension
What’s a motor unit?
-motor neurons and all the muscle fibres it supplies
What’s motor unit recruitment?
- muscle divided into more muscle units, more units activated= more strength, more tension
- size of the motor units also affects the tension
What is asynchronous recruitment of motor units?
-during prolonged contraction brain switches which units it’s using and moves it around so they don’t get as tired, only possible when the strain isn’t too big, then all are used!
Do larger motor units have more relative strength?
-yes
What does whole muscle tension depend on?
- number of muscle fibres contracting
- the tension on each fibre
What does a single AP do in a muscle fibre?
- all or none twitch
What does repetitive stimulation of a muscle fibre achieve?
-contractions with longer duration and greater tension