physiology - muscle contraction Flashcards
a defect in the signalling from nerve to muscle at the neruo muscular junction causes which condition
a. MS
b. marfans
c. myasthenia gravis
c.myasthenia gravis
muscle weakness in the muscles of the eyes, eyelids and face is the symptom of which autoimmune condition
a. MS
b. marfans
c. myasthenia gravis
c.myasthenia gravis
what does myasthenic crisis refer to?
a. heart problems due to myasthenia gravis
b. lack of oxygen to the brain due to myasthenia gravis
c. breathing difficulties due to myasthenia gravis
c.breathing difficulties due to myasthenia gravis
many muscle fibres are held within a …
a. connective tissue
b. tendon
c. fascicle
c.fascicle
whats the correct order of skeletal muscle organisation from largest to smallest
a. muscle, fasiculus, fibre/cell, myofibril, sarcomere, filaments
b. filaments, sarcomere, myofibril, fibre/cell,fasiculus, muscle
a.muscle, fasiculus, fibre/cell, myofibril, sarcomere, filaments
what happens to actin filaments in the contracted state?
a. ends of actin filaments from z discs barely overlap
b. actin filaments are pulled inward and overlap to max extent
b. actin filaments are pulled inward and overlap to max extent
a double stranded F actin molecule is formed from polymerised ……………… molecules
a. A actin
b. F actin
c. B actin
d. G actin
d. G actin
how many strnds of tropomyosin molecules are found bound to an actin filament
a. 1
b. 2
c. 3
d. 4
b.2
what binds ca2+
a. actin
b. tropomyosin
c. troponin
c.troponin
what type of proteins are troponin and tropomyosin
a. contractile
b. regulatory
c. structural
b. regulatory
what does binding of calcium ions to troponin cause
a. muscle relaxation
b. muscle contraction
b.muscle contraction
what causes the myosin head to be reorientated and energised
a. ATP binding
b. ADP released
c. ATP hydrolysis
c.ATP hydrolysis
what happens when the myosin head attaches to the myosin binding site on actin
a. ATP binding
b. ADP released
c. ATP hydrolysis
d. pi released
d.pi released
cross bridge formation and power stroke changes the angle of the myosin head from 90 - what?
a.30 degrees
b.35
degrees
c.40 degrees
d.45 degrees
d.45 degrees
halves
the cross bridge remains attached to actin until what occurs?
a. ATP binding
b. ADP released
c. ATP hydrolysis
d. pi released
a.ATP binding
myosin head then dettaches
the length tension relationships depends on sarcomere length …………….. contraction
a. before
b. during
c. after
a.before
what type of receptors on the t tubule membrane sense AP voltage
a. dihydropiyridine
b. ryanodine
c. voltage gated sodium channels
a. dihydropiyridine
what type of receptors on the sarcoplasmic reticulum open and release ca2+ into the sarcoplasm
a. dihydropiyridine
b. ryanodine
c. voltage gated sodium channels
b. ryanodine
active pumping of what substance causes muscle relaxation
a. Ach
b. na
c. ca
c. ca
rigor mortis is due to leaking of which substance into the cell
a. sodium
b. pottasium
c. ach
d. calcium
d.calcium
ATP no longer synthesised so cross bridges cannot dettach from actin