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The Muscular System
- Types of muscles
- Smooth: Involuntary (no
control), found in hollow
organs (digestive tract),
fatigue slowly
- Cardiac: Heart,
intertwined, cells act as
1 unit, fatigues slowly,
more mitochondria
- Skeletal: Voluntary,
connected to skeleton,
allows for movement
(contract, relax)
- Smooth: Involuntary (no
control), found in hollow
organs (digestive tract),
fatigue slowly
- Functions
- Body movement: Muscles
consciously controlled attached to
bones, CNS instructs them to
contract=movement
- Adequate posture:
Muscles always work
to ensure maintain
good posture
- Essential bodily functions:
Involuntary muscles (no conscious
control), always function, e.g. heart,
blood vessels, digestive organs
- Body movement: Muscles
consciously controlled attached to
bones, CNS instructs them to
contract=movement
- Muscle fibre arrangement
- Muscles made up of many
muscular cells (fibres) joined
and they way they're joined is
determined by the function of
the muscle
- Muscles made up of many
muscular cells (fibres) joined
and they way they're joined is
determined by the function of
the muscle
- Muscle fibre types
- Intro: Muscles are
made of a number of
fibres joined. The way
they're joined is
determined by the
function of the muscle
- Pennate: Run at angles to tendons, little
mobility, designed for strength, more
pennation = slower muscle but more
force, allows more fibres packed in, force
increases by proportional amount, 3 categories
- Unipennate: Calf
muscles, quads
- Bipennate: Rectus femoris,
dorsiflexors, gastrocnemius
- Multipennate muscles:
Deltoid, plantar flexors
- Unipennate: Calf
muscles, quads
- Fusiform: Fibres run the length of muscle
belly, force over large range, mobility over
strength, fibres run same direction as
tendon, few fusiform, biceps brachii
- Radiate: Mobile, produce large
force and power, radiate from one
main tendon, pectoralis major
- Pennate: Run at angles to tendons, little
mobility, designed for strength, more
pennation = slower muscle but more
force, allows more fibres packed in, force
increases by proportional amount, 3 categories
- Intro: Muscles are
made of a number of
fibres joined. The way
they're joined is
determined by the
function of the muscle
- Control of muscles
- Types of contractions
- Isotonic: Most common, length changes as
force is developed, muscle length shortens =
concentric contraction, muscle lengthens =
eccentric contraction, squats
- Isometric: Generates force without changing length, causes stress of CV
system (blood vessels constricted by contraction of muscles (causing
abrupt fatigue), plank hold
- Isokinetic:Contract at constant speed, only occurs if
weight or force being moved alters while the muscle is
contracting (usually through weight training/rehab)
- Isotonic: Most common, length changes as
force is developed, muscle length shortens =
concentric contraction, muscle lengthens =
eccentric contraction, squats
- Motor units:"The nerve and muscle
fibre it controls"m muscles contain
100's, each fibre has a nerve, this
muscle allows the muscle to alter
the amount of force applied overall
by changing the number of muscle
fibres being activated
- All or nothing
- Muscle fibres contract completely or not at all, all fibres in a motor unit contact at
the same time, amount of force generated depends on number of motor units
activated, NS controls pull/force exerted by a muscle, electrical impulse must reach
a certain threshold before all fibres of the motor unit contract at the same time and
as forcefully as possible (none will contract until), once impulse surapsses the
threshold, ATP stored in the muscle is split and the energy realeased allows a
muscular contraction
- Muscle fibres contract completely or not at all, all fibres in a motor unit contact at
the same time, amount of force generated depends on number of motor units
activated, NS controls pull/force exerted by a muscle, electrical impulse must reach
a certain threshold before all fibres of the motor unit contract at the same time and
as forcefully as possible (none will contract until), once impulse surapsses the
threshold, ATP stored in the muscle is split and the energy realeased allows a
muscular contraction
- Reciprocal inhibition
- The process of the agonist contracting and
its opposite muscle (the antagonist) relaxing
- The process of the agonist contracting and
its opposite muscle (the antagonist) relaxing
- Types of contractions
- Sarcomeres
- Function: The repeating subunits of a myofibril
and the smallest unit of muscle contraction.
Muscles contract = thick filaments (myosin) pull
the thin filaments (actin) towards the M-line. This
results in the muscle fibres shortening causing
the muscle to contract and exert its
force/strength
- Function: The repeating subunits of a myofibril
and the smallest unit of muscle contraction.
Muscles contract = thick filaments (myosin) pull
the thin filaments (actin) towards the M-line. This
results in the muscle fibres shortening causing
the muscle to contract and exert its
force/strength
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