Download Muscle Contractions

Muscle Contractions
By Jarad Settles
5.19.04
Per. CD
Types of Muscles
 Skeletal
• The type we can see and feel.
• Attached to the skeleton and come in pairs,
one to move the bone one way and the other
the other way.
• These muscles are voluntary, which means you
control them.
• Can do a short twitch or a long one.
Types of Muscles Con’t.
 Smooth Muscles
• Found in your digestive system.
– Blood Vessels, Airways, Bladder, and in women, the
uterus.
• Has the ability to stretch and maintain tension
for long periods of time.
• Involuntary muscles, automatically contract
without you thinking about it.
Types of Muscles Con’t.
 Cardiac Muscles
• Only found in your heart.
• Endurance and Consistency.
• Can stretch a limited amount like the smooth
muscle.
• Can contract like the skeletal muscle.
• Twitch muscle.
• Contracts involuntarily.
Muscle Contractions
 Bundle of many cells called fibers.
• Long Cylinders
 Fibers are about 1 to 40 microns long and 10
to 100 microns wide. (100 microns =
diameter of a strand of hair. 10 microns = a
cell in your body.)
 A Fiber contains many myofibrils.
Muscle Contractions Con’t.
 Each muscle fiber contains myofibrils.
• Cylinders of enzymes.
 Enzymes are made up of proteins.
• Enzymes are the cause of all chemical
reactions. They allow the cell to carry out
chemical reactions quickly.
 Proteins are chains of amino acids.
Muscle Contractions Con’t.
 Myofibrils contain two types of filaments.
• Thick and Thin
 Arranged in hexagonal patterns, the
filaments run along the axis of the fiber.
 Filaments are attached to the Z-Line that
runs perpendicular to the long axis of the
fiber.
 Running down the Z-Line is the T-Tubule.
Muscle Contractions Con’t.
 Inside the fiber, between T-tubules is a
membrane system called the sarcoplasmic
reticulum, which releases the calcium ions
that make a muscle contract.
Triggering a Contraction
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Electrical signal travels down a nerve cell causing the release of a
chemical message into the synapse (gap between nerve cell and
muscle cell).
The neurotransmitter (chemical message) crosses the synapse,
binds to a receptor on the cell membrane and causes another
electrical signal in the muscle cell.
The signal travels along the muscle cell and enters the cell through
the T-tubule.
The signal triggers the release of calcium ions that bind to the
molecules located in the grooves of the filaments.
After the signal passes, the ions are stopped from being released and
calcium pumps remove calcium from the cytoplasm.
After this process, the muscle relaxes.
Contracting a Muscle
Thick and thin filaments do all the work of a
muscle.
 Thick filaments are made of proteins called
myosin and thin filaments are made of the protein
actin.
 During contraction the myosin grabs onto the
actin by forming crossbridges.
 The two fibers pull and make the muscle contract.
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Energy to Make a Muscle
Contract
 ATP is what muscles use to contract.
• ATP resets the myosin crossbridges and
releases the actin.
 The muscle creates ATP by:
• Breaking down creatine phosphate and adding
it to ADP.
• Then it carries out anaerobic respiration which
breaks down glucose, glycogen, and amino
acids to form lactic acid to form ATP.
Works Cited
 www.howstuffworks.com