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?