Power Point covering the Functions of the Muscular System from the Physiological Point of study from a Collegiate Anatomy and Physiology Class (super basic and easy to understand).

1. Functions of
the
Muscular
System

2. 1. Movement of the body.
Contraction of skeletal muscles is
responsible for the overall
movements of the body.

3. 2. Maintenance of posture.
Skeletal muscles constantly maintain
tone, which keeps us sitting or
standing erect.

4. 3. Respiration.
Muscles of the thorax carry out the
movements necessary for
respiration.

5. 4. Production of body heat.
When skeletal muscles contract, heat is given off as a
by-product.

6. 5. Communication.
Skeletal muscles are involved in all aspects of
communication, including speaking, writing, typing,
gesturing, and facial expressions.

7. 6. Constriction of organs and vessels.
The contraction of smooth muscle
within the walls of internal organs and
vessels causes those structures to
constrict. This constriction can help
propel and mix food and water in the
digestive tract, propel secretions from
organs, and regulate blood flow
through vessels.

8. 7. Contraction of the heart.
The contraction of cardiac
muscle causes the heart to beat,
propelling blood to all parts of
the body.

9. CHARACTERISTICS OF SKELETAL MUSCLE
1.Contractility is the ability of skeletal muscle to shorten with
force. When skeletal muscles contract, they cause the structures to
which they are attached to move.
2.Excitability is the capacity of skeletal muscle to respond to a
stimulus. Normally, the stimulus is from nerves that we consciously
control.

10. CHARACTERISTICS OF SKELETAL MUSCLE
3.Extensibility means that skeletal muscles stretch. After a
contraction, skeletal muscles can be stretched to their normal resting
length and beyond to a limited degree.
4.Elasticity is the ability of skeletal muscles to recoil to their
original resting length after they have been stretched.

11. Connective Tissue Coverings of Muscle
• Each skeletal muscle is surrounded by a connective tissue sheath called
Epimysium or muscular fascia
• Each whole muscle is subdivided by a loose connective tissue called
the perimysium into numerous visible bundles called muscle fasciculi
• Each fascicle is then subdivided by a loose connective tissue called
the endomysium into separate muscle cells, called muscle fibers

12. • Contraction of skeletal muscle tissue occurs as
actin and myosin myofilaments slide past one
another, causing the sarcomeres to shorten.
• Many sarcomeres are joined end-to-end to form
myofibrils.
• Shortening of the sarcomeres causes myofibrils to
shorten, thereby causing the entire muscle to
shorten.
Muscle Contraction

13. The sliding of actin myofilaments past
myosin myofilaments during contraction is
called the sliding filament model of muscle
contraction.

14. • A muscle twitch is the contraction of a muscle fiber
in response to a stimulus. Because most muscle
fibers are grouped into motor units, a muscle twitch
usually involves all the muscle fibers in a motor unit.
Muscle Twitch

15. A muscle twitch has three phases
1. The lag phase, or latent phase, is the time between
the application of a stimulus and the beginning of
contraction.
2. The contraction phase is the time during which the
muscle contracts
3. The relaxation phase is the time during which the
muscle relaxes.