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Muscle Works
Chapter 6 (still)
Contraction of a Muscle as a Whole
The law of “all-or-none” applies to the
muscle cell not the entire muscle
Graded Responses of Muscle Contraction
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Each muscle cell that is stimulates, reacts
Fine adjustment is made by:
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Changing the speed of a contraction
Changing the number of muscle cells being stimulated
Muscles response to strong stimuli
The stronger the stimulus, the more
individual cells contract; causing a forceful
contraction.
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The same hand that sooths can deliver a
stinging slap
Providing Energy for Contractions
Each Muscle cell only saves 4-6 seconds of
energy

Aerobic Respiration – Makes more energy for
cells. It is a slow process and is apparent during
rest or light activities
Must have a constant flow of Oxygen. 36 ATP is
produced per 1 Glucose
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Anaerobic Respiration – Glucose is broken down
without Oxygen.
2 ATP is produced per 1 Glucose
2 ½ times faster
Produces Lactic Acid
Muscle Fatigue
Unable to contract…Any!
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Believed to be caused by oxygen debt
Very high amounts of lactic acid is found in
muscle
Rarely occures
Types of Contrations
Isotonic (same tension) – most common.
Examples include moving any body part
freely.
Isometric (same length) – you try to
contract a muscle, but can’t. Examples
include lifting an elephant
Muscle Tone
Aerobic Exercise – increases endurance
and flexibility.
Resistance Training – increases muscle
size and strength
Muscle will go through small contractions to
keep toned. But if you do not use the
muscle regularly, it will become soft and
eventually atrophy.
Muscle Movements
Terms
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Origin – point where muscle attaches to an
immovable bone
Insertion – point where muscle attaches to a
movable bone.
Belly – the body of the muscle
Tendon – dense connective, avascular tissue
that attaches muscle to bone.
Types
Flexion – typical of hinge joints. Brings
bones together.
Extension – opposite of flexion. Takes
bones in opposite direction.
Hyperextension – extension
is greater than 180 degrees
Abduction – limb moves away from midline
Adduction – limb moves toward midline
Circumduction - combo
of flexion, extension,
abduction, and adduction.
Proximal end is stationary
and distal end rotates
Rotation – limb moves around its
longitudinal axis
Pronation – palm moves from upwardfacing to downward-facing.
Supination – palm moves from downwardfacing to upward-facing.
Inversion – sole of foot faces medially
Eversion – sole of foot faces laterally
Dorsiflexion – toes move toward tibia
(standing on your heel)
Plantar flexion – toes point toward floor (tip
toes)