end show slide 1 of 37 copyright pearson prentice hall 36–2 the muscular system

End Show

Slide 1 of 37

Copyright Pearson Prentice Hall

36–2 The Muscular System

End Show


Slide 2 of 37


Muscles

The function of the muscular system is movement.

More than 40% of the mass of the average human body is muscle.

End Show


Slide 3 of 37


Types of Muscle Tissue


What are the three types of muscle tissue?

End Show


Slide 4 of 37



There are three different types of muscle tissue:

• Skeletal (is striated muscle)

• Cardiac (is striated muscle)

• Visceral (is smooth muscle)

End Show


Slide 5 of 37



Skeletal Muscles

Skeletal muscles:

• are usually attached to bones.

• are responsible for voluntary movements.

• have many nuclei.

• are made of striated muscles.

End Show


Slide 6 of 37



Cardiac Muscle

Cardiac muscle:

• is ONLY found in the heart.

• is striated muscle.

• may have one or two nuclei.

They are connected by gap junctions that allow electrical impulses to travel among muscle cells.

End Show


Slide 7 of 37



Visceral Muscles

Smooth muscles:

• are usually involuntary control (most body organs).

• are spindle-shaped.

• have one nucleus.

• are made of smooth muscle.

• are found in many internal organs and blood vessels.

End Show


Slide 8 of 37



Most smooth muscle cells can function without nervous stimulation.

They are connected by gap junctions that allow electrical impulses to travel among muscle cells.

End Show


Slide 9 of 37



Smooth muscle vs. Striated muscle

End Show


Slide 10 of 37


Muscle Contraction

Muscle Contraction

The fibers in skeletal muscles are composed of smaller structures called myofibrils.

Each myofibril has smaller structures called filaments.

The thick filaments contain a protein called myosin.

The thin filaments contain a protein called actin.

End Show


Slide 11 of 37


Muscle Contraction

Filaments are arranged along the muscle fiber in units called sarcomeres.

Sarcomeres are separated by regions called Z lines.

When a muscle is relaxed, there are no thin filaments in the center of a sarcomere.

End Show


Slide 12 of 37


Muscle Contraction

Skeletal muscle

Bundle of muscle fibers

Muscle fiber (cell)

Myofibril

Z line

Sarcomere

Myosin

Actin

End Show


Slide 13 of 37


Muscle Contraction

How do muscles contract?

End Show


Slide 14 of 37


Muscle Contraction

A muscle contracts when the thin filaments in the muscle fiber slide over the thick filaments.

This process is called the sliding filament model of muscle contraction.

End Show

Slide 15 of 37



Muscle Contraction

During muscle contraction, the actin filaments slide over the myosin filaments, decreasing the distance between the Z lines.

These lines are the same length. Notice that the contracted muscle is much shorter than the relaxed muscle.

End Show


Slide 16 of 37


Muscle Contraction

Binding sitesMyosin

Cross-bridge

Actin

Movement of Actin Filament

End Show


Slide 17 of 37


Muscle Contraction

During muscle contraction, the head of a myosin filament attaches to a binding site on actin, forming a cross-bridge.

End Show


Slide 18 of 37


Muscle Contraction

Powered by ATP, the myosin cross-bridge changes shape and pulls the actin filament toward the center of the sarcomere.

End Show


Slide 19 of 37


Muscle Contraction

The cross-bridge is broken, the myosin binds to another site on the actin filament, and the cycle begins again.

End Show


Slide 20 of 37


Muscle Contraction

When many myosin cross-bridges change shape in a fraction of a second, the muscle fiber shortens with considerable force.

The energy for muscle contraction is supplied by ATP.

End Show


Slide 21 of 37


How Muscles and Bones Interact


Skeletal muscles are joined to bones by tendons.

Tendons pull on the bones so they work like levers.

The joint functions as a fulcrum.

The muscles provide the force to move the lever.

End Show


Slide 22 of 37



Opposing Muscles Contract and Relax

End Show


Slide 23 of 37



Opposing Muscles Contract and Relax

End Show


Slide 24 of 37



A controlled movement requires contraction by both muscles.

END OF SECTION

End Show

- or -Continue to: Click to Launch:

Slide 26 of 37


36–2

End Show

Slide 27 of 37


36–2

Skeletal muscles are joined to bones by tough connective tissue called

a. ligaments.

b. tendons.

c. filaments.

d. bursae.

End Show

Slide 28 of 37


36–2

Muscle cells that are large, have many nuclei, and striations are

a. skeletal muscle cells.

b. smooth muscle cells.

c. cardiac muscle cells.

d. involuntary muscle cells.

End Show

Slide 29 of 37


36–2

Muscle that is found in the walls of blood vessels and intestines is

a. skeletal muscle.

b. smooth muscle.

c. cardiac muscle.

d. striated muscle.

End Show

Slide 30 of 37


36–2

The filaments found in skeletal muscle cells are

a. actin and myosin

b. myosin and myofibrils

c. actin and Z lines

d. actin and sarcomeres

End Show

Slide 31 of 37


36–2

The type of muscle found only in the heart is

a. skeletal muscle.

b. striated muscle.

c. cardiac muscle.

d. smooth muscle.

end show slide 1 of 37 copyright pearson prentice hall 36–2 the muscular system

Documents