PHY2011 Lecture Notes - Lecture 26: Titin, Gastrocnemius Muscle, Delayed Onset Muscle Soreness
20 Jun 2018
School
Department
Course
Professor
Week 10 L1 (T5AL3) -Mechanisms of muscle contraction
Types of contractions:
oIsotonic – muscle changes length while maintaining tension
oIsometric – muscle develops tension without changing length
oWhat happens at a molecular level?
Cross bridge cycling always occurs
If no lengthening occurs, cross bridges simply rebind in the same place
oConcentric contraction -The muscle shortening while contracting
oEccentric contraction -the muscle lengthening while contracting
oMuscular contraction – generating tension
Skeletal muscles and the skeleton
oSkeletal muscles are attached to bones of the skeleton by tendons
oMuscles themselves can only exert pulling forces
oFor movement of limbs, you need at least two muscles pulling in opposite directions
Ie Biceps -contracts and Triceps -extends
oMuscles with opposing actions at a joint -antagonist muscles
oMuscles doing the same action -agonist muscles
ie. Quadriceps and Gastrocnemius muscles (Front of thigh, back of calf)
-Quad relaxed, Gastroc contracted -knee bends
-Both quads and gastric contract -leg straight, toe points
oHolding weight -force exerted is larger than weight of object
Ie. weight 10kg, 35cm from elbow, 5cm width of bicep muscle
= 10 x 35 / 5 = 70kg
oLever function when lifting an object
Every 1cm of bicep shortening = 7cm of hand moving upwards
-hand velocity = 7 x muscle contraction velocity
oLength-force relation of muscle
-Note: tension = force
Passive force
-Observed when a resting muscle is stretched.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Week 10 l1 (t5al3) -mechanisms of muscle contraction. If no lengthening occurs, cross bridges simply rebind in the same place: concentric contraction -the muscle shortening while contracting, eccentric contraction -the muscle lengthening while contracting, muscular contraction generating tension. Skeletal muscles and the skeleton: skeletal muscles are attached to bones of the skeleton by tendons, muscles themselves can only exert pulling forces, for movement of limbs, you need at least two muscles pulling in opposite directions. Ie biceps -contracts and triceps -extends: muscles with opposing actions at a joint -antagonist muscles, muscles doing the same action -agonist muscles ie. quadriceps and gastrocnemius muscles (front of thigh, back of calf) Both quads and gastric contract -leg straight, toe points: holding weight -force exerted is larger than weight of object. Ie. weight 10kg, 35cm from elbow, 5cm width of bicep muscle. = 10 x 35 / 5 = 70kg: lever function when lifting an object.
