Muscles Flashcards
What are tendons?
Consist of collagen fibres & very strong
Attach skeletal muscle to periosteum covering bone
What are connective tissue?
-Surrounds muscle, muscle bundle & fibres
-These layers give muscle shape & smooth surface to allow other muscles, muscle bundles & fibres to glide during contractions
-All 3 layers of connective tissue connected to each other & tendon allowing moment to place muscle contracts
What are myofibrils?
Consist of long lines of sacromeres - basic operational building blocks for muscle contractions
What part of the body are responsible for movements?
Motor units consisting of motor neuron & groups of muscle fibres
Describe the makeup of a motor neuron
- Cell body containing cell nucleus, cytoplasm & mitochondria
- Dendrites which receive electrical impulses from spinal chord & transmit them to cell body
- Axon links cell body to muscle fibres, as it reaches muscle, axon splits into branches to myelin allow single cell to control many muscle fibres
- Motor end plates connect axon to muscle cell allowing motor nerve to stimulate muscle fibres & cause muscle contractions
Outline the cause of muscle contractions
Occur when neural messages transmitted by electrochemical process from CNS to muscle fibres via motor unit
Describe slow twitch fibres
Smaller & contract at about 1/5 of rate of fast twitch fibres
High oxidative structures makes them very resistant to fatigue
Describe fast twitch fibres
Larger, produce greater force faster but tire rapidly
Outline the effects of training on muscle fibres
-Fast twitch fibres can be made faster & stronger with correct training methods (speed, power, plyomertric training)
-Fast twitch can become ‘slower’ through prolonged low intensity training
-Type 2B muscle fibre can be converted to type 2A muscle fibres
Outline controlling the force of a contraction
-Strength of movement controlled by number of motor units recruited by CNS to complete required movement & by freq of contraction
-Not all motor units within muscle needed for fine skill or gentle movement, whilst all motor units may be needed for gross skill or dynamic movement
-Slow freq of contractions produce light or weak contractile forces, whilst rapid freq will produce stronger contractions
-Slow twitch fibres normally recruited first in any movement, fast twitch muscles only recruited when intensity of movement reaches certain level
Outline wave summation
Contractile strength increased if motor unit continuously activated by stimulus before it’s completely relaxed from previous contractions
Known as wave summation - force produced grows in series of waves until point stimuli so fast there’s no relaxation possible
This is termed a Tetanic & Absolute Contraction
What is the difference between wave summation and spatial summation graphs?
Wave = typically fast twitch 2B
Spatial = Long distance/continuous activity
Outline spatial summation
-Motor units within muscle activated slightly different times & not all together
-By spreading out contraction & relaxation, muscle able to sustain continuous contraction over period of time; not just split-second
-Staggering contractions within muscle called spatial summation
Outline flexors & extensors
Flexors = bend a joint
Extensors = straighten joint
Outline agonists
Muscle that shortens/contracts to move joint
E.g. bicep muscles in lifting phase of curl