Chapter 10 (part 2)

Agonist

prime mover

it is the muscle primarily responsible for producing a particular movement

Antagonists

Opposite actions

sacromere movement

Muscle sacromeres can only contract and need help to length

Synergistic pairs

Act in the same direction

Concentric contraction

Muscle contracts with force greater than resistance and shortens

same direction

Eccentric contraction

Muscle contracts with force less than resistance and lengthens

Opposite direction

Isotonic contraction

movement

Isometric contraction

Muscle contracts but does not change lengths

Muscle tension = resistance

SO fibbers, FO fibers, FG fibers

Slow oxidation fibers = slow twitch

Fast oxidatation = intermediae

Fast glycolytic = fast twitch

Power of SO, FO and FG fibers

SO: Less powerfull

FO: more powerful

FG: more powerful

Duration of SO, FO and FG

SO: Long

FO: medium

FG: short

Myosin ATPase of SO, FO and FG

SO: slow

FO: fast

FG: fast

Capactity to make ATP of SO, FO, FG

SO: High, aerobic

FO: Moderate, aerboic

FG: Limited, anaerboic

Speed of SO, FO and FG

SO: slow

FO: fast

FG: fast

Fatigue resistance of SO, FO and FG fibers

SO: Highest

FO: high

FG: low

Primary fiber function of SO, FO and FG fibers

SO: Endurance

FO: Medium duration

FG: Short intense movements

Muscle fiber type and motor unit

All muscle fibers associated with a particular motor unit are of the same fiber type

How does excerise affect muscle

Increase in muscle cell size, not increase in cell number

Increase number of myofibrils per muscle cell, in fast fibers

Aerboic excerise

myofibril number does not increase but increase ATP support molecules and structures

Hypertrophy

Increase in fiber size

Atrophy

Loss of mass, size, tone, and power when not used

Circular fasiciles

Fascicles arranged concentrically around an opening

Acts as a sphinctor to clsoe a passageway or opening

Ex. Orbicularis oris

Parllael fascicles

fascicles are parallel to the long axis of the muscle

Body of muscle increases in diameter with contraction

High endurance, not very strong

EX. rectus abdomnis

Convergent fascicles

Triangular muscle with common attachment site

Direction of pull of muscle can be changes

Does not pull as hard as equal sized parallel muscle

Ex. Pectoralis major

Pennate

Muscle body has one or more tendons

Fascicles at oblique angle to tendon

Pulls harder than a parallel muscle of equal size

Mutiple types

Unipennate

All fasiculates on the same side of the tendon

Bipennete

Fascicles on both sides of the tendon

Multipennate

Tendon branches wihtin the muscle

4 parts of levels

1) arm = bar = bones

2) effort = force in

3) ressitance = force out

4) fulcrum = joint = pivot

First class level

Fulcrum is in the middle and resitence and effort are on the opposite sides

Ex. looking up

Second class level

Fulcum is on the end, resistnace is in the middle and effort is on the end

Ex. calf raises

Third class level

Fulcrum is on the end, effort is in the middle and resistance is on the end

Ex. elbow

Few first class levers

Applied force and resistance on opposite sides of fulcrum

Most common are third class levers

Applied force between fulcrum and resistance, have greater speed and increased distance, but sacrifice effective force

Few second levels

Resistence located between applied force and fulcrum; small force can balance larger weight but slower & shorts distance movd\ed

What do levers depend on

Diffrences in the site of muscle insertion can influence amount of force a muscle must generate to move a given load

Depends on position of 3 elements; effort, fulcrum and load

If you increase the in-lever length what happens to force out

increases

if you decrease the in-lever length what happens to force out

Decreases

If you increase the out lever length, what happens to force out

Decreases

If you decrease the out lever length, what happens to force out

Increases

If you decrease the in lever length, what happens to velocity out

Decreases

If you increase the in lever length, what happens to velocity out

Increases

If you increase the out lever length what happens to velocity out

Increases

If you decrease the out lever length, what happens to velocity out

decreases

Mechanical advantage

useful to move a heavy load; slow, stable & used when strength is a priority

• requires small effort to move load

Velocity advantage

Useful to move a laod fast; force is lost but speed and range of motion is gained

Mechanical advantage & velocity advantage

The longer the effort arm, the more load (resistance) can be moved

Inverse relationship: tarde off between force and velocity