the muscular system

Question 1

involuntary muscle tissue

Answer 1

not controlled consciously

bodily functions such as digestion, urination, circulation

Question 2

voluntary muscle tissue

Answer 2

under conscious control

also referred to as ‘skeletal muscles’ - via levers and joints can produce movement

Question 3

skeletal muscles

Answer 3

'striated muscles'
some are flat and sheet-like
some are short and fat 
some are long and slender
75% water, 20% protein 5% salts

Question 4

functions of skeletal muscles

Answer 4

movement 
circulation 
energy storage
shape and structure
upright posture
heat production

Question 5

structure of skeletal muscle

Answer 5

external wall = fascia (sheath) ~ surrounding entire muscle is layer of connective tissue called ‘epimysium’
‘bundles of muscle fibres’ = bound together by fascia
‘myofibrils’/’myofilament’ = smaller fibres in each individual muscle fibre
‘sarcomeres’ = what each myofibril is made up of - form contractile units of the muscle

Question 6

sarcomere

Answer 6

formed by 2 types of protein filament called actin and myosin
actin - thinner and lighter filament
myosin - thicker and darker
their overlapping nature allows sarcomeres to shorten - how muscles contract
when muscle is relaxed has a striped appearance

Question 7

tendon

Answer 7

referred to as an ‘origin’ or ‘insertion’
when the muscle shortens the insertion moves towards the origin
when it lengthens the insertion moves away from the origin
connects muscle to the bone - sometimes also attach to other connective tissues

Question 8

ligaments

Answer 8

connect bone to bone - provide stability

made from densely packed inelastic regular collagen fibres

Question 9

the motor unit

Answer 9

made from a nerve or neuron and all of the muscle fibres of that nerve
when the muscles need to generate large forces (eg heavy strength training) the brain signals the muscles to recruit more motor units

Question 10

all or nothing principle

Answer 10

when a muscle fibre is stimulated, every contractile unit within that fibre will contract

Question 11

types of muscle fibre

Answer 11

fast twitch = larger, stronger more explosive fibres

slow twitch = slender and more enduring fibres

Question 12

mitochondria

Answer 12

located inbetween muscle fibres - predominantly slow twitch
possess the unique ability to burn oxygen with other nutrients - generate energy in form of ATP
‘aerobic power house’ of the muscle cell
regular cardiovascular and endurance exercise stimulates increase in these cells = more aerobic energy

Question 13

myoglobin

Answer 13

oxygen carrying protein located within muscle tissue
moves oxygen from blood vessel to mitochondria
primary oxygen carrier
regular cardiovascular and endurance exercise stimulates increase in these cells = more oxygen transported

Question 14

muscle glycogen

Answer 14

formed from chains of glucose - in muscle and liver for energy
glycogen is broken down and deposited into blood as glucose - then used for energy - esp brain
combination of regular endurance and high level of carbs enhances muscles ability to store glycogen

Question 15

when a muscle contracts, movement will occur if

Answer 15

1) the muscle crosses a joint

2) the opposing muscle relaxes

Question 16

isotonic contractions

Answer 16

most common 
2 phases = concentric, eccentric 
concentric = usually first stage, occurs when muscle becomes shorter and fatter 
insertion moves towards origin
eccentric = muscles lengthens and is under tension 
'negative phase' 
insertion moves away from origin
eg leg extension, bench press

Question 17

DOMS

Answer 17

delayed onset muscle soreness
linked with eccentric muscles
results in microscopic tears along length of the muscle fibre - repaired by protein during the hypertrophy process

Question 18

advantages of isotonic contractions

Answer 18

develops strength or endurance through the joints
more relevant to daily activities
can develop motor skills
develops oxygen delivery mechanisms within the muscle

Question 19

isometric contractions

Answer 19

the length of the muscle does not alter - distance between insertion and origin remains constant
eg - isometric contraction of bicep = holding a weight in the hands with elbow at a 90 degree angle
exert a ‘Valsalva effect’ because of their effect on internal pressure, esp blood pressure - done with caution

Question 20

advantages of isometric contractions

Answer 20

requires little or no equipment/space
good in rehabilitation when only a small ROM is permitted
can be functional in things like developing strength of joint stabilisers

Question 21

disadvantages of isometric contractions

Answer 21

not suitable for those with primary heart disease risk factors - rapid increase in blood pressure
only strengthens the joint at angle held - limits crossover benefits
can be tedious and boring

Question 22

prime mover

Answer 22

muscle(s) responsible for creating the movement

eg pectorals for bench press

Question 23

fixator

Answer 23

the muscle contracts isometrically to resist movement

eg medial and posterior deltoids, and latissimus dorsi during bench press

Question 24

synergist

Answer 24

assistant muscle working with prime mover

eg in bench press - triceps assist pecs by extending elbow, anterior deltoid assists by flexing the shoulders

Question 25

antagonist

Answer 25

the muscle(s) that must relax for the movement to take place
for one muscle to contract the opposing one must relax
eg during barbell curl triceps relax so biceps can flex

Question 26

muscle contractions are governed by 2 factors

Answer 26

1) energy availability

2) nervous impulses

Question 27

momentary muscle failure

Answer 27

when there is insufficient energy to fuel contraction. in the latter stages of heavy resistance training when muscles become exhausted - prevents contraction from continuing