OC2 - musculoskeletal system Flashcards
what are tendons?
tendons attach muscle to bone
what are ligaments?
ligaments attach bone to bone
what are the properties of muscles?
excitable - can receive and respond to signals from the nervous system
contractible - can respond to signals by contracting
extensible - can be stretched without damage
elastic - can return to original shape after stretching/contraction
adaptable - can be changed in response to how it is used
what are the major muscles in the ‘front’?
deltoids
biceps
quadriceps
pectorals
abdominals
what are the major muscles in the ‘back’?
trapezius
triceps
Latissimus Dorsi
Gluteus Maximus
hamstrings
what are the type of muscles?
voluntary - skeletal muscle
involuntary - smooth muscle
cardiac muscle
what are the divisions of the structure of a muscle?
whole muscle > fasicle > muscle cell (myocyte, muscle fibre) > myofibril > sacromere
what is contained within the myofibril?
titin, myosin and actin
M line, A line and Z line
what is the structure of the myofibril?
sarcomeres are arranged end to end to form myofibrils suspended in a fluid called the sarcoplasm
the sarcoplasm is surrounded in a membrane called the sarcolemma
what is the sarcomere?
the shortest unit of muscle contraction
what is contained within the sarcomere?
thin filament - actin, troponin, tropomyosin
thick filament - myosin
elastic filament - titin
what is the mode of action of the neuromuscular junction?
action potential from motor neuron reaches motor end plate. Acetylcholine is released and diffuses across the synaptic cleft and binds to receptors opening ligand-gated cation channels, allowing Na+ ions to enter and K+ ions to exit the muscle fibre increasing the membrane potential. The action potential travels along the sarcolemma and its transverse tubules once the threshold potential is reached, this releases Ca2+ ions from the sarcoplasmic reticulum into the sarcoplasm.
what is the mode of action of the sliding filament theory?
troponin and tropomyosin form a protein complex that at low Ca2+ ion concentration binds to actin blocking the myosin-actin binding site. When calcium is present, troponin is released revealing the myosin-actin binding site. calcium is released.
ATP binds to the myosin head before dissociating into ADP and Pi, activating the myosin head by forming the activated myosin and ADP complex. The energy released from ATP hydrolysis is used to allow the myosin head to cock and bind to the binding site on actin. ADP and Pi is released from the myosin head initiating a power stroke to pull the actin inwards, shortening the sarcomere. Myosin then binds to ATP and releases from actin, this ATP also hydrolyses to ADP and Pi to reactivate the myosin head so it can bind to actin once again.
what are isotonic muscle contractions?
change muscle fibre length
eccentric and concentric
used to move skeletal muscle
what are eccentric muscle contractions?
lengthen the muscle fibre
e.g. lowering the bicep following bicep curl
