Muscular System Anatomy

Skeletal

found in limbs

striated, multinucleated

voluntary, regulated by CNS

Cardiac

found in heart

striated, 1 nucleus

involuntary, regulated by ANS

Smooth

found in viscera

not striated, 1 nucleus

involuntary, regulated by ANS

Produces movement

maintains posture

stabilizes joints

generates heat

1. All cross at least 1 joint

2. bulk lies proximal to joint crossed

3. All have at least 2 attachments: origin & insertion

4. Muscles can only pull, they never push

5. During contraction, the insertion moves towards origin

Triangular

shoulder, neck

Spindle

arms, legs

Flat

diaphragm, forehead

Circular

mouth, eyes

1. Size

2. Location

3. Movement/action it causes

4. Number of origins

5. Location of origin and insertion

6. shape

7. Direction of muscle fibers

Graded Responses

how skeletal muscles react to stimuli

a. speed or b. number of cells stimulated

Twitch

single, brief contraction

not normal function

Tetanus

one contraction immediately followed by another

muscle never completely returns to a relaxed state

effects are compounded

does not use oxygen

produces 2 molecules of glucose

Shortcoming: uses a lot of glucose and produces little ATP

increases strength

uses oxygen

produces 36 molecules of ATP

Shortcoming: requires continuous supply of oxygen and fuels

makes body more flexible and resistant to fatigue

muscles shorten

movement occurs

normal exercise

tension in muscles increases

no movement occurs

pushing against concrete wall

increases size of muscles

movement occurs

weightlifting