muscular contraction

muscular system

• 600+ muscles in the body

• 40-50% of total body weight

3 types of muscle

• skeletal muscle

• smooth muscle

• cardiac muscle

smooth muscles

• lines walls of blood vessels and hollow organs

• striated appearance

• involuntary

Skeletal muscle

• voluntary control

• striated appearance

• tendons that attach to bone

• move the skeleton

cardiac muscle

• involuntary control

• striated appearance

• tendons that attach to bone

• ex: heart

properties of muscle tissues

• contractility

• extensibility

• elasticity

motor neurons - efferent system

the nerves that carry info from CNS to the muscles to create contraction and relaxion

structure of a neuron

• nucleus surrounded by cell body with cell membrane, dendrites branch off cell membrane

• axon inside myelin sheath that goes to axon terminal which branches to synaptic end bulbs

motor unit

• single motor neuron with it’s muscle fibres

innenation ratio

• 10-20,000 muscle fibres could connect to a motor neuron

fast twitch muscle fibres

• short bursts of speed

• fatigue quickly

• anaerobic metabolism

slow twitch fibres

• high endurance

• oxygen for fuel (aerobic metabolism)

• continuous energy

type 1 motor units

• slow twitch muscle fibres

• slow nerve transmission speeds

• smaller forces generated

• fatigue resistant

type 2a motor units

• fast twitch muscle fibres

• fast nerve transmission

• stronger forces generated

• decently fatigue resistant

type 2b motor units

• fast twitch muscle fibres

• fastest contraction times with largest force

• fatigue very quickly

hypertrophy

significant development of a muscle over time

atrophy

loss of muscle size, mass, or body tissue due to disuse

muscular contraction types

• isometric

• isotonic eccentric

• isotonic concentric

• isokinetic

isometric

tightening (contractions) of a specific muscle or group of muscles

isotonic eccentric

involves the muscle lengthening whilst it is under tension

isotonic concentric

involves the muscle shortening

isokinetic

Muscles contract at a constant speed in isokinetic contraction

agonist

muscle who’s contraction is responsible for producing movement

antagonist

muscle that opposes the action of an agonist

synergist

muscle who’s contraction helps an agonist in an action

fixator

muscle that assists an agonist by preventing or reducing movement at a diff joint

reciprocal inhibition

the stretch of one muscle inhibits the action of the opposite muscle