Skeletal Muscle Physiology 2

Question 1

4 causes of impaired skeletal muscle

Answer 1

intrinsic disease of muscle, problem with NMJ, problem with lower motor neurons, problem with upper motor neurons

Question 2

name the 2 factors influencing skeletal muscle tension?

Answer 2

number of muscle fibres contracting within the muscle, tension developed by each contracting muscle fibre

Question 3

what allows the simultaneous contraction of muscle fibres

Answer 3

motor units

Question 4

what would make contraction of muscle fibres stronger?

Answer 4

stimulation of more motor units

Question 5

is the action potential shorter or longer in duration than the resulting contraction?

Answer 5

shorter

Question 6

what aspect of the skeletal muscle action potential prevents tetanic contraction?

Answer 6

a long refractory period

Question 7

describe the relationship developed by skeletal muscle tension and frequency of stimulation

Answer 7

skeletal muscle tension increases with increasing frequency of stimulation

Question 8

when is skeletal muscle at its optimum length?

Answer 8

at resting conditions

Question 9

when is cardiac muscle at its optimum length?

Answer 9

when stretched

Question 10

name the contractile component of skeletal muscle

Answer 10

cross bridge cycling via sarcomeres

Question 11

name the elastic component of skeletal muscle

Answer 11

stretching and tightening of muscle connective tissue and tendon

Question 12

name the 2 types of skeletal muscle contraction

Answer 12

isotonic

isometric

Question 13

which type of skeletal muscle contraction changes its length but not its tension

Answer 13

isotonic contraction

Question 14

give an example of isotonic contraction

Answer 14

moving objects

body movements

Question 15

which type of skeletal muscle contraction changes its tension but not its length

Answer 15

isometric contraction

Question 16

give an example of isometric contraction

Answer 16

supporting objects

maintaining body posture

Question 17

name the main differences between different types of skeletal muscle?

Answer 17

methods of ATP synthesis
resistance to fatigue
myosin ATPase activity

Question 18

what effect does myosin ATPase have on skeletal muscle?

Answer 18

increases speed of muscle contraction as it makes ADP more readily available for cross bridging

Question 19

name the different methods of ATP production in muscle

Answer 19

creatinine phosphate to ADP, oxidative phosphorylation, glycolysis

Question 20

which pathway provides the main source of ATP when oxygen isnt present

Answer 20

glycolysis

Question 21

which pathway provides the main source of ATP when oxygen is present

Answer 21

oxidative phosphorylation

Question 22

name the 3 types of skeletal muscle

Answer 22

type 1, 2 and 2x

Question 23

which skeletal muscle type has a slow contraction speed and a high resistance to fatigue

Answer 23

type 1

Question 24

which skeletal muscle type has a high contraction speed and large number of mitochondria

Answer 24

2a

Question 25

which skeletal muscle type depends on anaerobic activity?

Answer 25

2x

Question 26

which skeletal type is white?

Answer 26

white

Question 27

through what kind of activity is type 1 skeletal muscle used?

Answer 27

walking, posture maintenance

Question 28

through what kind of activity is type 2a skeletal muscle used?

Answer 28

jogging, moderate activity

Question 29

through what kind of activity is type 2x skeletal muscle used?

Answer 29

short term high intensity eg jumping

Question 30

why are type 2 skeletal muscles very fast?

Answer 30

high myosin ATPase activity

Question 31

what is a reflex action?

Answer 31

a stereotyped response to a specific stimulus

Question 32

is the stretch reflex a negative or positive feedback mechanism?

Answer 32

negative

Question 33

what structure is the sensory receptor in the stretch reflex?

Answer 33

muscle spindle

Question 34

what is the sensory receptor activated by in the stretch reflex?

Answer 34

muscle stretch

Question 35

what causes contraction of muscle in the stretch reflex?

Answer 35

stretching of the muscle stimulates firing of afferent neurons, these synapse in the spinal cord with the alpha motor neurons that innervate muscle

Question 36

what nerve levels and overall nerve are tested in the knee jerk test?

Answer 36

L3, L4; femoral

Question 37

what are muscle spindles?

Answer 37

collection of specialised muscle fibres

Question 38

where muscle spindles found?

Answer 38

in the belly of muscles parallel to normal muscle fibres

Question 39

what is an extrafusal fibre?

Answer 39

normal muscle fibre

Question 40

what are the sensory nerve endings of muscle spindles called?

Answer 40

annulospiral fibres

Question 41

what are the efferent neurons that supply muscle spindles called?

Answer 41

gamma motor neurons

Question 42

what do gamma motor neurons do?

Answer 42

adjust tension levels in skeletal muscle to maintain sensitivity

Question 43

does the contraction of muscle spindles contribute to overall muscle contraction?

Answer 43

no

Question 44

give an example of an inflammatory acquired myopathy

Answer 44

polymyositis

Question 45

give an example of a non-inflammatory acquired myopathy

Answer 45

fibromyalgia

Question 46

give an example of an endocrine acquired myopathy

Answer 46

cushings syndrome, thyroid disease

Question 47

investigations for neuromuscular disease?

Answer 47

electromyography nerve conduction study creatine kinase CRP