Download Muscle contraction wkst

Neuron
Motor Unit
• Is one motor neuron and all muscle fibers
its branches innervate.
• Delicate control - a few muscle fibers per
motor unit. Stimulates 6 to ___ fibers.Eye
• Gross movement have over ______ muscle
fibers per unit.
• All fibers in a motor unit contract when
stimulated with a threshold stimulus.
NEUROMUSCULAR
JUNCTION
____ -the junction between a motor neuron
ending and a muscle fiber.
Composed of a motor neuron, and muscle
fiber.
Has a motor end plate.
Motor end plate is the junction between the
muscle fiber and the axon terminals.
Nerve Action
• 1. Action potential moves down the axon
• 2. Increase in _____causes acetylecholine to
be released.
• 3.Acetylecholine moves synaptic gap
• 4.Acetylecholine reaches motor end plate
• 5.Acetylecholine _______ with receptors
Nerve Action
• 6. Repolarized
• 7. Acetylecholine to _______
• 8. Acetylecholine is broken down to
A_____ and C______.
• 9. Ready again to receive an impulse.
Single Muscle Contraction
• 3 phases




Latent period
Contraction period
Relaxation period
Followed by recovery(refractory period)
ISOTONIC
• Equal + tension
• Force used to produce work
and work is ______.
• Object moves and muscle
shortens
Isometric
• Muscle produces heat but
_______work is done
• Muscle does not shortens
• Examples
 Standing
 Holding a door
Oxygen Debt
• A_____ of extra oxygen needed
to metabolize the accumulated
lactic acid and restore normal
______ levels.
Fatigue
• Lactic acid builds up and makes
the muscle to feel _________.
• Body needs oxygen to change
lactic acid into carbon dioxide and
water.
Aerobic
• With ________
• Pyruvic acid + oxygen
= CO2 + H2O +
_________.
Anaerobic
•Without oxygen
•Pyruvic Acid is
changed to lactic
acid.
Contraction speed
• Classified:
Fast-twitch (type II fiber)
Slow-twitch (type I fibers)
Fast-twitch
•
•
•
•
•
Relaxation cycle is about 30msc
More mitochondrea than slow-twitch
Pale in color - _______ muscle
Fast quick movement
Example
 Eye - Hand
 Sprinter
Slow-twitch
•
•
•
•
•
Relaxation cycle is about 3000msc
Fewer mitochondrea than fast-twitch
_______ Muscle
Prolonged, steady contractions
Example
 Back muscle
 Long distance runners
Smooth Muscle
• Appear smooth
• Involuntary muscles
• Contract and relation periods are slower
than skeletal muscle
• Action is ____________
• Contraction may last ____ sec or longer
• Examples - stomach, intestine, bladder,
uterus during child birth.
Smooth Muscle
• Poorly organized sarcoplasmic
reticulum
• NO Z line or T tubules
• Types
 Single unit - sphincters, pacemaker
cells
 Multiunit - iris of eye, goose bumps
Cardiac Muscle
• Found only in the __________!
• Huge #’s of mitochondrea
• Well developed sarcoplasmic reticulum and
T tubules
• Intercalated disk
• Refractory period is ______msc, almost as
long as the contraction
Cardiac Muscle
• Never stops beating in a life time
• ____________beats a day
• At 70 years old your heat would have
pumped 2.5 billion times.
• If oxygen is deprived _____ sec,
cardiac muscle cells may stop
contracting, resulting in heart failure.
When things Go WRONG!
Muscle injuries
• Skeletal muscle - satellite cells under the
endomysium cause cell division.
• Smooth muscle - causes the proliferation of
cells. Pregnancy enlarging of uterus.
• Cardiac muscle - childhood can regenerate
but in adults is replaced by connective
tissue.