Physiology - Skeletal Muscle

Question 1

what is the largest tissue type in the body?

Answer 1

muscle

Question 2

what are the three types of muscle?

Answer 2

skeletal
cardiac
smooth

Question 3

what muscle types are striated?

Answer 3

cardiac

skeletal

Question 4

what muscle type is not striated?

Answer 4

smooth

Question 5

what causes muscle striation?

Answer 5

alternating dark and light bands

Question 6

what are the dark bands in muscle?

Answer 6

myosin thick filaments

Question 7

what are the light bands in muscle?

Answer 7

actin thin filaments

Question 8

what nervous system innervates skeletal muscle and what does this mean?

Answer 8

somatic

voluntary control

Question 9

what nervous system innervates cardiac and smooth muscle and what does this mean?

Answer 9

autonomic

involuntary control

Question 10

what mechanism initiates contraction of skeletal muscle?

Answer 10

neurogenic

Question 11

what mechanism initiates contraction of cardiac muscle?

Answer 11

myogenic

Question 12

in which type of muscle are neuromuscular junctions present?

Answer 12

skeletal

Question 13

in which type of muscle are gap junctions present?

Answer 13

cardiac

Question 14

what is the neurotransmitter at the neuromuscular junction?

Answer 14

acetylcholine

Question 15

what are skeletal muscle fibres organised into?

Answer 15

motor units

Question 16

what is a motor unit?

Answer 16

a single alpha motor neurone and all skeletal muscle fibres it innervates

Question 17

what does the number of muscle fibres per motor unit depend on?

Answer 17

the functions served by the muscle

fine movement = less fibres

Question 18

name two types of muscles with few fibres per motor unit

Answer 18

intrinsic hand muscle

extra ocular muscles

Question 19

how are skeletal muscles organised?

Answer 19

parallel muscle fibres bundled by connective tissues

Question 20

how long are skeletal muscle fibres?

Answer 20

the length of the muscle

Question 21

what attaches skeletal muscles to the skeleton?

Answer 21

tendons

Question 22

what is the predominant structure of skeletal muscle fibres?

Answer 22

myofibrils

Question 23

what is found within each myofibril?

Answer 23

sarcomeres

Question 24

what is the functional unit of muscle?

Answer 24

sarcomeres

Question 25

what is the functional unit of an organ?

Answer 25

the smallest component capable of performing all of the organs functions

Question 26

where are sarcomeres found?

Answer 26

between two Z lines

Question 27

what are the four zones of a sarcomere?

Answer 27

A band H zone M line I band

Question 28

what makes up the A band?

Answer 28

thick filaments | thin filaments that overlap

Question 29

what is the H zone?

Answer 29

the lighter area in the middle of the A band where thin filaments don't reach

Question 30

where is the M line found?

Answer 30

the middle of the A band and the centre of the H zone

Question 31

what is the I band made of?

Answer 31

the remaining thin filaments that are not in the A band

Question 32

what produces muscle tension?

Answer 32

sliding of actin filaments on myosin filaments

Question 33

what does force generation depend on?

Answer 33

ATP dependent interactions between myosin and actin filaments

Question 34

where are calcium ions stored in skeletal muscle fibres?

Answer 34

the lateral sacs of the sarcoplasmic reticulum

Question 35

when are calcium ions released in skeletal muscle?

Answer 35

when the surface action potential spreads down the T tubules

Question 36

what are T tubules?

Answer 36

extension of the surface membrane that dip into the muscle fibre

Question 37

what two factors determine the gradation of skeletal muscle tension?

Answer 37

number of fibres contracting | the tension developed by each fibre

Question 38

what is motor unit recruitment?

Answer 38

the stimulation of more motor units in a muscle

Question 39

what is longer in skeletal muscle - the duration of the AP or the duration of the resulting twitch?

Answer 39

the twitch

Question 40

how can a stronger contraction be achieved in skeletal muscle?

Answer 40

repetitive fast stimulation of the muscle

Question 41

what is repetitive fast stimulation of muscle called?

Answer 41

tetanus

Question 42

why can cardiac muscle not be tetanised?

Answer 42

long refractory period

Question 43

how can maximal tetanic contraction be achieved?

Answer 43

when muscle is the optimal length before the onset of contraction

Question 44

what are the two types of skeletal muscle contraction?

Answer 44

isotonic | isometric

Question 45

what is isotonic contraction used for?

Answer 45

body movements | moving objects

Question 46

what is isotonic contraction?

Answer 46

when muscle tension remains constant as the muscle length changes

Question 47

what is isometric contraction used for?

Answer 47

supporting objects in fixed positions | maintaining body posture

Question 48

what is isometric contraction?

Answer 48

when muscle tension develops at constant muscle lengths