A&P - Chapter 17 (Part 3) Flashcards
What are 5 types of muscle contractions?
- Twitch
- Tetanic
- Tonic
- Isotonic
- Isometric
Myography
Method of graphing the changing tension of a muscle as it contracts
What kind of movement are twitch contractions? (3)
- Quick
- Jerky
- Not related to normal muscle activity
Where are twitch movements seen?
In isolated muscle fibres
What are twitch contractions caused by?
Single contraction of muscle fibres caused by a single threshold stimulus
What kind of movements are tetanic contraction? (2)
- Sustained
2. Steady muscular contractions
What are tetanic contractions caused by?
A series of stimuli bombarding a muscle in rapid succession this series of stimuli join forces to produce a long contraction
What is tetanic contractions dependant on?
Ca
Why do people have arched backs in tetanic contractions?
Back muscles are stronger than the front
What kind of movement is tonic contraction? (2)
- Continual
2. Partial contraction of a muscle
What happens during tonic contraction at any one time?
A few muscle fibres within a muscle are contracting to produce a certain amount of tension or tone
Flaccid
Muscles have less tone than normal
Spastic
Muscles have more tone than normal
What is muscle toned maintained by?
A negative feedback mechanism
What do the skeletal muscles contraction strength depend on? (4)
- Metabolic condition of individual fibres
- Number of fibres contracting at the same time
- the more you have the stronger the contraction - The number of motor units involved
- The intensity and frequency of the stimulation
What is a muscle’s max strength directly dependant on?
The initial length of its fibres
Which muscle length gives you a stronger contraction? Why?
- Longer muscle’s
2. Have more to contract/shorten
What happens if sarcomeres are compressed?
It reduces the muscle’s contractile potential
What happens if the sarcomeres are overstretched?
Actin and myosin are too far apart to bind
When is the muscle contraction the strongest?
When the muscle is at its optimal length
What can influence the strength of the contraction?
The load a muscle is exposed to
What does the body try and do in response to an increase load?
Constant muscle length
Threshold stimulus
Minimal level of stimulation required to cause a muscle fibre to contract
- muscles wont contract without it
All-or-nothing response
Once stimulated by a threshold stimulus, a muscle fibre will completely contract
What allows muscles to preform contractions that are specific to different weight loads?
Different muscle fibres in a muscles are controlled by different motor units with different thresholds
- all or nothing still applies but just different parts of the muscle
