Transcript muscular system - OCPS TeacherPress

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SKELETAL – attached to bone/voluntary
CARDIAC – heart/ involuntary
SMOOTH – other organs/involuntary
1.
2.
3.
Producing body movements
Stabilizing body positions
Generating heat
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Organs
Wrapped in connective tissue
◦ Extends to form tendons – attaches muscle to
bone
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Fascicles:
bundles of
muscle fibers
(cells).
Connective tissue
around each
fascicle.
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Long, skinny cylinders – a cell
Cytoplasm = glycogen
Contains myofibrils
◦ Thin (actin) and thick (myosin) filaments inside
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Muscle surrounded by connective tissue.
Inside are many bundles (surrounded by
connective tissue).
Many muscle fibers inside bundle (fascicles)
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Inside muscle fiber are myofibrils
Filaments inside myofibrils
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What triggers it?
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A neuron connects to a muscle fiber [called
the neuromuscular junction (NMJ)]
Arrival of nerve impulse causes release of
acetylcholine (ACh: a neurotransmitter – a
chemical).
ACh diffuses to receptors on muscular
membrane, opening a Na+ ion channel,
causing Na+ to enter the muscle fiber.
Changes electrical conditions and produces
an action potential (electrical current)
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Action potential triggers :
◦ Unblocks actin (thin) so myosin (thick) heads can
bind to them
◦ Filaments slide past one another, shortening the
muscle (Sliding filament mechanism)
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What triggers a muscle contraction?
What is the location called where a neuron
connects with a muscle?
Does a muscle contraction mean it gets
longer or shorter?
Do muscle fibers fold or slide to get shorter?
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Botulinum toxin from bacterium Clostridium
botulinum blocks exocytosis of ACh
◦ BOTOX
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Muscle fibers: all-or-none
Strength of muscle contraction: depends on
# of contracting fibers
Affects energy usage
◦ Energy = capacity to do work
◦ Types: chemical, mechanical, heat, electrical
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ATP broken down during contraction
Store little ATP, must produce it
3 ways:
◦ Aerobic respiration: slow, requires O2, lots ATP
made
◦ Anaerobic glycolysis and lactic acid formation:
faster, no O2 needed, less ATP made
◦ Creatine phosphate and ADP: CP not found in
other cells, very fast, doesn’t last
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No contraction
even with
stimulation occurs from
oxygen debt
(lactic acid builds
up and ATP runs
low)
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The more oxygen your body can take in and
use determines your endurance
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The reaction of creatine phosphate and ADP
generates ATP quickly or slowly?
The ability of your body to use oxygen to
produce ATP is _____ respiration.
True or False: The strength of a muscle
contraction is determined by the amount of
muscle fibers that are contracting.
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Why are some
people better at
endurance
activities?
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Why are some
people FAST?
Is it genetic? Is it
training?
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1. Slow oxidative fibers
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2. Fast oxidative-glycolytic fibers
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3. Fast glycolytic fibers
◦ Little power (small in diameter); fatigue resistant;
many mitochondria. Adapted for maintaining
posture & endurance activities
◦ Intermediate in diameter, faster than #1 but
briefer in duration. Adapted for:
walking/sprinting
◦ Large diameter (contract strongly/quickly); tire
quickly; large amount lactic acid build up
◦ Short, rapid, intense movement
◦ Adapted for intense anaerobic movements of
short duration: weight lifting/throwing a ball
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Muscles are a combo of different fibers
Proportion of fibers is individual
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Muscles tug on tendons which pull on bones
One bone is pulled towards another
Insertion towards origin
Origin stays still
Most cross a joint
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Flexion –
decreases angle
of joint
Extension –
increases joint
angle. Past 180 is
hyperextension
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Rotation – around
the longitudinal
axis
Abduction –
moving limb away
from body
midline
Adduction –
moving limb
towards midline
Circumduction –
whole limb
outlines a cone
(circular)