Seminar 6 The Muscular System
Introduction Muscular tissue enables the body and its parts
to move Movement caused by ability of muscle cells
(called fibers) to shorten or contract Muscle cells shorten by converting chemical
energy (obtained from food) into mechanical energy, which causes movement
Three types of muscle tissue exist in body
3 Types of muscle Skeletal Cardiac Smooth
Structure and Function Cardiac:
involuntary; heart Smooth:
involuntary; linings Skeletal: voluntary;
attaches to bone
Functions of muscle? Movement Posture Heat production
Let’s discuss how…
Movement
How does this help us?
Movement Biceps brachii –
synergist Triceps brachii -
antagonist
Posture Posture or
muscle tone
Heat Production
Heat Production Requires ATP Contraction of muscle fibers produces heat
How relevant is this function???
Muscle Tissue Function—all muscle cells specialize in
contraction (shortening) Contraction requires:
Stimulus (nerve) Muscle fiber Calcium ATP Chemical rxn No stimulus
Must occur in EACH muscle fiber All-or-none
Figure 7-3, page 158
The Step Test
Step Test Which type of muscle tissue is being used in
this test?
Answer the poll question ---
Step Test, con’t Why do breathing and heart rate remain
elevated after exercise stops?
Step Test, con’t Why would a “physically fit” person return to
normal breathing and heart rate levels more quickly than an unfit person?
Step Test, con’t increased efficiency of the respiratory and
circulatory systems an increase in the number of blood vessels in
muscles more efficient delivery of oxygen and glucose
to muscle fibers more oxygen is available = the less “oxygen
debt” there will be in the muscles.
Step Test, con’t Aerobic training also increases the number of
mitochondria in muscle fibers.
Why would this benefit the muscle contraction process?
Step Test, con’t Mitochondria are cellular organelles that convert
glucose to ATP Contraction of muscle cells requires ATP Increase in the number of mitochondria in a muscle
cell increases the speed with which ATP is produced in the cell.
Mitochondria = ATP rate
Step Test, con’t http://www.health.harvard.edu/newsweek/
Aerobic_Fitness_Test_The_Step_Method.htm
Time for Q and A! Do you have any questions?