Muscles

Question 1

Neuromuscular junction

Answer 1

Ap arrives her which triggers release of Ca triggering Ach release which binds to receptors on sarcolemma opening Na+ channels

Question 2

Depolarisation of sarcolemma

Answer 2

Depol travels down t tubule in contact w sarcoplasmic reticulum
Sr contains Ca+ which open Ca binds to troponin

Question 3

Contract muscle

Answer 3

Ca+ binds to troponin which pulls tropomyosin away from the site

Question 4

Stage 1

Answer 4

Cocked myosin hydrolyses atp
Ready to bind in cocked position

Question 5

Stage 2

Answer 5

Attach
Myosin heads bind to actin forming cross bridge

Question 6

Stage 3

Answer 6

Power stroke
Myosin head flexes pulling actin along
Adp and p dissociate

Question 7

Stage 4

Answer 7

Release
Cross bridge still in place
Atp bind to myosin detach from actin

Question 8

Energy for contraction

Answer 8

Aerobic respiration
Anaerobic respiration
Creatine phosphate store if phosphate used up rapidly

Question 9

Types of muscle

Answer 9

Skeletal
Cardiac
Involuntary

Question 10

Skeletal muscle

Answer 10

Striated
Voluntary
Regularly arranged - unidirectional contraction
Rapid contraction
Short contraction
Tubular and multinucleated fibres

Question 11

Cardiac

Answer 11

Specialised striated
Involuntary
Branch and interconnected strands simultaneously contract
Intermediate contraction speed and length
Branched uninucleate fibres

Question 12

Involuntary

Answer 12

Non striated
Involuntary
No regular arrangement contract different directions
Slow contractions
Can be contracted for long time
Spindle shaped and uninucleate

Question 13

Sarcolemma

Answer 13

Plasma membrane which encloses bundles of muscle fibres

Question 14

Sarcoplasm

Answer 14

Shared cytoplasm within a muscle fibre

Question 15

T tubules

Answer 15

Parts of sarcolemma that fold inwards to help spread electrical impulses ensures whole of fibre receives impulse

Question 16

Sarcoplasmic reticulum

Answer 16

Modified version of endo plastic reticulum
Extends through fibre and contains calcium ions required for muscle contraction

Question 17

Myofibrils

Answer 17

Long cylindrical organelles made of protein lined up in parallel
Made up of actin and myosin

Question 18

Actin

Answer 18

Thinner filament 2 twisted strands

Question 19

Myosin

Answer 19

Thicker filament
Rod shaped fibres w bulbous heads

Question 20

Light bands

Answer 20

Appear light as region where actin and myosin do not overlap ( only actin present)

Question 21

Dark bands

Answer 21

Presence of thick myosin as well as overlapping actin

Question 22

Z line & H zone

Answer 22

Z line - centre of each z line ( distance between 2 = sarcomere)
H zone - lighter coloured region in middle only myosin ( reduce when muscle contracts)

Question 23

Slow twitch

Answer 23

Fatigue resistant
Lots of aerobic resp
Lots of mitochondria
Slower contraction
Good blood supply high amounts of myoglobin
Appear darker

Question 24

Fast twitch

Answer 24

Rapid contraction large amount of calcium ions required
Anaerobic resp
Fewer blood vessels than slow twitch
Eg human eyelids
Low myoglobin