Musculo-skeletal systemMusculo-skeletal system

ObjectivesObjectives

• UnderstandUnderstand: : the the histologyhistology of striated muscle of striated muscleThe The structurestructure and role of fast and slow and role of fast and slow

twitch muscle fibrestwitch muscle fibresMuscle Muscle contractioncontraction (role of actin, myosin, (role of actin, myosin,

Ca ions and ATP).Ca ions and ATP).The structure and role of The structure and role of neuromuscularneuromuscular

junctions.junctions.The The structurestructure of of compact bonecompact bone and a and a

synovialsynovial jointjoint..

Muscle structureMuscle structure

Muscle structureMuscle structurehttp://www.life.uiuc.edu/crofts/bioph354/lect16&17.htmlhttp://www.life.uiuc.edu/crofts/bioph354/lect16&17.html

Neuromuscular junctionNeuromuscular junction

http://www.blackwellpublishing.com/matthews/myosin.html

Motor neurone end plateMotor neurone end plate

Cross bridge structure.Cross bridge structure.http://www.univie.ac.at/cga/courses/be522/emg/http://www.univie.ac.at/cga/courses/be522/emg/scroll down to see units working togetherscroll down to see units working together

Actin structureActin structure

Muscle contractionMuscle contraction

Muscle movementMuscle movement

AUDIOAUDIO• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__breakdown_of_atp_and_cross-bridge_movement_during_muscle_contraction.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__breakdown_of_atp_and_cross-bridge_movement_during_muscle_contraction.htmlTROPININ MOVEMENTTROPININ MOVEMENT• http://http://www.sci.sdsu.edu/movies/actin_myosin_gif.htmlwww.sci.sdsu.edu/movies/actin_myosin_gif.html

After a muscle contraction After a muscle contraction

• Calcium ions are actively reabsorbed into Calcium ions are actively reabsorbed into the sarcoplasmic recticulum.the sarcoplasmic recticulum.

• In a resting muscle there is only enough In a resting muscle there is only enough ATP for 8-10 muscle twitches (60 m race).ATP for 8-10 muscle twitches (60 m race).

• ATP stores need to be replenished.ATP stores need to be replenished.

Muscle contraction can also be Muscle contraction can also be stimulated by muscle spindles stimulated by muscle spindles (2 - 12 modified fibres)(2 - 12 modified fibres)..• Intrafusal fibresIntrafusal fibres

• Arranged in parallel to Arranged in parallel to surrounding muscle fibres surrounding muscle fibres (exrafusal fibers).(exrafusal fibers).

• Associated to sensory Associated to sensory receptors (such as receptors (such as annulospiral endings.annulospiral endings.

• Provide feedback on Provide feedback on contraction, length, contraction, length, position and rate.position and rate.

2 types of muscle fibre2 types of muscle fibre

Fast/twitch fibres Slow/tonic Fast/twitch fibres Slow/tonic fibresfibres

- Myoglobin -Myoglobin -- Colour –Colour –

- Sarcoplasm -Sarcoplasm --- Nucleus - Nucleus -- Fibrils -Fibrils -- Size -Size -

- Conduction velocity -Conduction velocity -- Speed of response –Speed of response –

All or nothing - Type of response - summationAll or nothing - Type of response - summation- Use -Use -