Transcript Muscular System

Muscular System
Three Types
• Skeletal or striated – attached to bones,
allows motion, voluntary control
• Smooth - work internal systems,
involuntary i. e. digestive and circulatory
• Cardiac – heart muscle, involuntary
Skeletal Muscle
• Works in pairs, one bends joint the other
extends or straightens joint
• For full motion opposite muscle must relax
while one flexes or contracts
• Muscle cells contract in response to
nerves signals
• Contracting unit of a muscle – myofibril
• Under voluntary control
Myofibril
• Two types of proteins in contracting unit:
myosin and actin
• Proteins slide over each other and overlap
when contracted
Skeletal Muscle cont.
• Two proteins (myosin and actin) give
muscles a striped effect under a
microscope – striated means banded or
striped
• Two types of cells:
– Red muscle cells – work longer
– White muscle cells – work stronger
Skeletal Muscle cont.
• Humans have muscles with both types of
cells
• Exercise increases the size of your cells
• Skeletal muscles have multiple nuclei
Cardiac Muscle
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Found in the heart
Average adult heart rate – 60 – 100 bpm
Less striped than skeletal muscle
Have only one nucleus per cell
involuntary
Smooth Muscle
• Short non-striped muscle cells
• One nucleus per cell
• Found in cell walls of veins, arteries,
digestive system, respiratory system etc.
• involuntary
Healthy Muscles
• Diet needs to include enough protein
• Enough energy to fuel muscles
• Strongest at about 25 years old
Identifying Injuries
• X-Rays – form of energy that travels in
waves
• Shows bones, good for detecting fractures
• Goes through soft tissue but not bones
• Bones show up as white areas
• Need to be careful of exposure to X-Rays
MRI
• Magnetic Resonance Imaging
• Clear images of both bones and soft tissue
• Magnetic energy causes atoms in your
body to vibrate (resonate). Computer
analyzes vibration pattern to form image
• No evidence it cause any harm
• Fairly expensive
Muscles to Know