Muscle fibres and structures

Question 1

what are the functions of the muscular system?

Answer 1

maintain body's temperature 
movement 
support (maintain posture)

Question 2

what is the breakdown of a muscle?

Answer 2

Epimysium 
fasciculi 
muscle cell fibre 
myofibril 
sarcomere

Question 3

what is a fasciculi?

Answer 3

bundles of muscle fibres that make up muscle belly

Question 4

what is Epimysium?

Answer 4

connective tissue that surrounds the muscle belly, fasciculi and muscle fibres respectively

Question 5

what is actin?

Answer 5

the thin protein filament found in muscle cells that together with myosin form sarcomeres

Question 6

what is myosin ?

Answer 6

the thick protein filament that together with actin form sarcomeres

Question 7

what is a sarcomere?

Answer 7

the contractile units of skeletal muscle

Question 8

what are the different types of muscle fibres?

Answer 8

type 1 slow
type 2 a fast
type 2 b fast

Question 9

what are the characteristics of a type 1 slow twitch muscle?

Answer 9

red
high in everything
small fibre size
10-180 fibres/ motor neurons

Question 10

what are the characteristics of a type 2 a fast twitch muscle?

Answer 10

pink
medium
300-800 fibres

Question 11

what are the characteristics of a type 2b fast twitch muscle?

Answer 11

white
low
300-800

Question 12

what are the effects of endurance training on muscle fibres?

Answer 12

capillary content increase
myoglobin content increase
increase resistance to fatigue
more efficient use of aerobic system

Question 13

what are the effects of strength training on the muscle fibres?

Answer 13

increase force of contraction
increased size of muscle fibres
muscle mass increase
cap and myo don’t change

Question 14

what is a motor unit?

Answer 14

is a motor neuron attached to a muscle fibre

Question 15

what is a summary of the sliding filament theory?

Answer 15

during a contraction thin actin filaments slide inwards over thicker myosin filaments causing a shortening of each sarcomere along the entire length of the myofibril, this causing shortening over the muscle and the entire muscle

Question 16

what happens at stage 1 ?

Answer 16

actin potential reaches the axon terminal and acetylcholine is released, this causes the depolarization of the motor end and is transmitted down the T tubules into the muscle fibres , choline is released

Question 17

what happens at stage 2 ?

Answer 17

the actin filament has active sites surrounded by troponintropomyosin , the calcium ions bind to this, revealing active binding sites and myosin heads attach to the actin to form a cross bridge.

Question 18

what happens at stage 3 ?

Answer 18

ATPase enzyme catalyzes the breakdown to ATP, energizing the myosin cross bridge , the myosin pulls the actin inwards , shortening the muscle

Question 19

what happens at stage 4 ?

Answer 19

when an ATP molecule binds to its head, the myosin detaches from the actin, ATP can be broken down again and again as long as there are enough calcium ions

Question 20

what happens at stage 5 ?

Answer 20

the impulse stops , calcium ions are pumped back into the sarcoplasmic reticulum , the myosin no longer pulls on the actin so it moves back to its position at rest and the muscle relaxes

Question 21

what are calcium ions?

Answer 21

released from sarcoplasmic reticulum and binds to troponin

Question 22

what is actin?

Answer 22

component of thin filament

Question 23

what is myosin?

Answer 23

component of thick filament

Question 24

what is troponin?

Answer 24

calcium ions bind to this to help move tropomyosin strands from the binding sites

Question 25

what is tropomyosin ?

Answer 25

a protein molecule, part of the thin filament; covers binding sight

Question 26

what is cross bridges ?

Answer 26

formed by myosin heads attaching to the actin

Question 27

what is the ratchet mechanism?

Answer 27

alternate use of myosin cross bridges to produce a contraction