Muscles

Features of slow twitch muscle

dark coloured

high concentration of myoglobin

lots of mitochondria

aerobic respiration

why slow twitch muscle contract and fatigue slowly

it uses aerobic respiration so contracts and fatigues slowly

myoglobin

a respiratory protein found in slow twitch muscle s that has a high affinity for oxygen

features of fast twitch muscle

light coloured

contains a low concentration of myoglobin

anaerobic respiration

few mitochondria

why fast twitch muscle has a low density of mitochondria

it uses anaerobic respiration

why a high concentration of myoglobin is a benefit

more oxygen due to its high affinity so greater aerobic respiration

why fast twitch muscle is suited to rapid bursts of activity

it produces ATP much quicker (anaerobic respiration)

why slow twitch muscle is suited to endurance activity

it produces ATP more efficiently and for longer (aerobic respiration)

antagonistic pairs

the pairs muscle tissues work in to cause movement

myofibrils

bundles of muscle fibres

two types of long protein filaments

actin

myosin

sarcomeres

functional units

what joins the cell surface membrane (sarcolemma) together

neuromuscular synapse

The I (isotropic) band

light stripes containing only thin actin filaments

The A (anisotropic) band

dark stripes that contain myosin and some actin

The H-zone

lighter stripe within the A band containing only myosin filaments

The Z-line

a dark line found in the middle of the I band where actin is anchored

(end of sarcomere)

what the z line indicates

the end of the sarcomere

the boundary between sarcomeres

the Z line

the molecule which prevents the myosin head from binding

tropomyosin

ions released by an action potential which cause tropomyosin to be displaced

calcium ions

significance of tropomyosin being displaced

allows myosin head to bind to actin and form actomyosin cross bridge

what the formation of a actomyosin cross bridge releases

inorganic phosphate

power stroke

when the myosin head bends and pulls actin over myosin

molecule released when the myosin head bends

ADP

molecule which causes myosin head to detach from actin filament

new ATP molecule

what the hydrolysis of ATP allows at the myosin head

myosin can resume its normal position

movement of actin once bound with myosin head

actin moves across one and the myosin head binds to the next binding site further a long the actin filament

change in shape of A band during muscle contraction

stays the same it never changes myosin does not move

how a H zone changes during muscle contraction

it decreases in size

what I band contains

just actin

how size of I band changes during muscle contraction

it gets smaller

what happens to the z lines during muscle contraction

they get closer together