The Muscular System

Skeletal & Muscular Systems - video

Your Muscular Body• Your muscles are responsible

for every move you make:– Blinking, breathing, running and

lifting.

• Muscle make up about 40% of your body mass.

Muscle Types

• Two Kinds:1. Involuntary muscles

• Not under our conscious control (breathing, heart beating, digestion)

2. Voluntary muscles• Under our conscious control (smiling, bending or standing)

• Muscle is make up of muscle tissue. – Three kinds: Skeletal, Smooth, and Cardiac

• Each type is specialized to perform a different function in the body.

Muscle Types

1. Skeletal Muscle (Striated)A. Attached to the bones of your skeleton by

tendons used for movement.i. Pulls on bones to make the body move.ii. Voluntary – you control them.

B. Made up of long, thin cells that each contain more than one nucleus.

i. Biceps, triceps, and quadriceps.

Skeletal Muscle

Muscle FibersNucleus

Striations

Muscle Types

2. Smooth MuscleA. Located in the internal organs of the body:

i. Stomach, intestines, kidney, and liver.a. Movement of food through the digestive systemb. Movement of blood through blood vessels

ii. Involuntary – you don’t control them.

B. Made up of spindle-shaped cells that contain only one nucleus.

Smooth Muscle

Smooth MuscleFiber

Nucleus

Muscle Types

3. Cardiac MuscleA. Found ONLY in the heart!B. Has characteristics in common with both smooth

and skeletal muscle:i. Like smooth, it’s involuntary – no control ii. Like skeletal, it’s striated

Cardiac Muscle

CardiacMuscle Fibers

Nucleus

Striations

Muscles and Movement

• Skeletal muscles are held to bone by tendons.– Tendons allow the muscles to pull on the bones

and move the body.

• The pull of a muscle on a bone is called a contraction. – This causes the muscle to get thicker and shorter.

• Because muscles can ONLY contract they must work in pairs to complete an opposite movement, relax.

Simulation – bicep/tricep

Triceps Muscle - Contraction/Relaxation

Hinge Joint