muscles

Question 1

outline the structure and features of myosin

Answer 1

fiborous protein
forms thick filaments
has heads
heads lie in bundles at each end

Question 2

outline the structure and features of actin

Answer 2

globular protein
thin filaments
2 actin chains twist around each other
tropmyosin lines inbetween the actin chains
troponin globular protien binds regularlary to the actin chains

Question 3

outline fast twitch fibres

Answer 3

contract faster
more powerful
work for shrort periods
intense

Question 4

outline the adaptations of fast twitch fibres

Answer 4

thicker myosin
more glycogen
more anaerobic enzymes
more phosphocreatin which converts ADP to ATP in anaerobic conditions

Question 5

outline slow twitch fibres

Answer 5

contract slower
less powerul
work for longer periods
endurance

Question 6

what are the adaptations of slow twitch fibres for aerobic respiration

Answer 6

more myoglobin
greater blood supply
more mitochondria

Question 7

what happens to muscles when they are relaxed

Answer 7

Actin has myosin binding sites

when relaxed these sites are blocked by tropomyosin

Question 8

what are the similarties between neuromuscular junctions and cholingeric synapses

Answer 8

neurotransmitters that are transported by diffusion
use of enzymes to break down neurotransmitter
use of a sodium potassium pump to repolarise the axon
have receptors on binding with neurotransmitter cause sodium ion influx

Question 9

what are the three types of muscle

Answer 9

cardiac muscle
skeletal muscle
smooth muscle

Question 10

what is cardiac muscle

Answer 10

muscle that contracts without conscious control

only found in the heart

Question 11

what is skeletal muscle

Answer 11

muscle that you use to move

Question 12

what is smooth muscle

Answer 12

muscle that contracts without conscious control found in walls of internal organs

Question 13

what are antagonistic pairs

Answer 13

muscles that work together to move a bone
contracting muscle agonist
relaxing muscle antagonist

Question 14

what do myosin filaments have on them

Answer 14

hinged globular heads

each head has binding site for actin and binding site for ATP

Question 15

what do actin filaments have on them

Answer 15

binding sites of myosin heads

tropomyosin found between actin filaments

Question 16

outline the arrival of an action potential in muscle contraction

Answer 16

action potential depolarises sarcloemma
slowing down T-tubulus casuing release of Ca2+ ions
into sarcosplam
Ca2+ ions bind to tropomyosin causing it to change shape
This pulls tropomyosin out of binding site on acting filament allowing myosin head to bind to exposed binding site
actin-myosin cross bridge forms

Question 17

out line the movement of the actin filament in muscle contraction

Answer 17

Ca 2+ ions actiavate ATPase which hydrolyses ATP
to release energy needed for muscle contraction
energy released from ATP causes mysoing head to bend pulling actin filament along

Question 18

outline the breaking of the cross-bridge

Answer 18

another ATP molecule provides energy to break cross bridge
mysoin head detaches from actin filament after it’s moved and reattaches to a new binding site further along actin filament.
new cross bridge forms and cycle is repeated

Question 19

outline the process of muscle relaxtion

Answer 19

nervous stimulation stops
Ca2+ ions reabsorbed into sarcoplasmoc reticulum by A/T
tropomyosin moves back
myofibrils relax

Question 20

what is ATP needed for in muscles

Answer 20

movement of myosin head back to the normal

reabsoprtion of Ca2+ into the sarcoplasmic reticulum

Question 21

what do muscles store to help produce ATP

Answer 21

phosphocreatine

it converts ADP to ATP

Question 22

what is the reaction of phosphocreatine and ADP

Answer 22

ADP + phosphocreatine – ATP + creatine

Question 23

where is excess phosphocreatine broken down

Answer 23

it is broken down in the kidneys

Question 24

what are the four pieces of evidence for the sliding filament theory

Answer 24

A band stays the same
I band becomes narrower
Z lines move closer together
H band narrows

Question 25

what is the evidence for the I band becoming narrower

Answer 25

the actin moves

Question 26

what is the evidence for the Z lines moving closer together

Answer 26

The whole sarcomere shortens

Question 27

what is the evidence for the H band narrowing

Answer 27

Actin slides over mysoin

Question 28

what is the evidence for the A band staying the same

Answer 28

Myosin filaments do not shorten