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MSK > Physiology 1 and 2 > Flashcards

Physiology 1 and 2 Flashcards

1
Q

What are the striated muscles

A

Skeletal and cardiac

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2
Q

What makes the muscles striated?

A

Alternating dark thick myosin bands and light thin actin bands

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3
Q

What are skeletal muscles innervated by

A

the somatic nervous system - subject to voluntary control

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4
Q

What are cardiac and smooth muscles innervated by

A

Autonomic nervous system - involuntary

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5
Q

How does initation of contraction come about in skeletal and cardiac muscle

A

Neurogenic by skeletal muscle, and myogenic by cardiac

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6
Q

How does calcium enter cells in skeletal and cardiac muscle

A

In skeletal muscle, entirely from SR - in cardiac muscle from ECF and SR (Calcium induced Ca release)

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7
Q

What is the transmitter at the neuromuscular junction

A

Acetylcholine

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8
Q

What is a motor unit

A

A single alpha motor neurone and all the skeletal muscle fibres it innervates

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9
Q

Where is precision more important than power

A

Extra ocular muscles, few muscle fibres per motor unit

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10
Q

What exists inside a muscle fibre (one cell)

A

Myofibril and sarcomere

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11
Q

How are skeletal muscles usually attached to bones

A

by tendons

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12
Q

What are the functional units of muscle

A

Sarcomeres

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13
Q

What are myofibrils

A

Specialised contractile intracellular structures

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14
Q

What is a functional unit of any organ defined as

A

the smallest componenet capable of performing all the functions of that organ

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15
Q

Where is the sarcomere found

A

between two Z lines

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16
Q

What is the A band

A

made up of thick filaments along with portions of thin that overlap in both ends of thick filaments

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17
Q

What is the H Zone

A

lighter area within middle of A band where thin filaments don’t reach

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18
Q

What is the M line

A

Extends vertically down middle of A band within the centre of H zone

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19
Q

What is the I Band

A

Consists of remaining portion of thin filaments that do not project in A Band

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20
Q

How is muscle tension produced

A

By sliding of actin filaments on myosin filaments

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21
Q

What is force generation dependent upon

A

ATP dependent interaction between thick and thin filaments

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22
Q

What is ATP required for

A

both contraction (to power cross bridges) and relaxation (release cross bridges and pump calcium back into SR) of muscle

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23
Q

What is Calcium required for

A

to switch on cross bridge formation

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24
Q

What is excitation contraction coupling

A

the process whereby the surface action potential results in activation of contractile structures of the muscle fibre

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25
Q

Where is calcium released from in skeletal muscle fibres

A

Lateral sacs of the sarcoplasmic reticulum

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26
Q

When is calcium released from skeletal muscle fibres

A

When the surface action potential spreads down the transverse T tubules

27
Q

What are T tubules

A

Invaginations of the surface membrane that dip into the muscle fibre

28
Q

What is motor unit recruitment

A

a stronger contraction achieved by stimulation of more motor units

29
Q

What are the two primary factors which changes the gradation of skeletal muscle tension

A

Number of muscle fibres contracting within the muscle and tension developed by each contracting muscle fibre

30
Q

In skeletal muscle, what relation does the duration of the action potential have to the resulting twitch

A

the duration of the action potential is much shorter than the duration of resulting twitch

31
Q

Why can cardiac muscle not be tetanised

A

The long refractory period prevents generation of tetanic contraction

32
Q

What is tetanus

A

A maximal sustained contraction achieved by summation of action potentials

33
Q

Is a single twitch useful in bringing about meaningful muscle activity

A

No its not

34
Q

How can maximal tetanic contraction be achieved

A

When the muscle is at its optimal length before the onset of contraction

35
Q

When in the body are skeletal muscles at their optimal length

A

At their resting length

36
Q

What are the two types of skeletal muscle contraction

A

Isotonic and isometric

37
Q

What is isotonic contraction used for and what is it

A

Body movements and moving objects, muscle tension remains constant as the muscle length changes

38
Q

What is isometric contraction and whats it used for

A

Muscle tension develops at a constant muscle length, used for supporting objects in fixed position and maintaining body posture

39
Q

What happens to the velocity of muscle shortening as the load increases

A

It decreases

40
Q

What are the 3 main metabolic pathways that supply ATP in muscle fibre

A

Transfer of high energy phosphate from creatine phosphate to ADP, oxidative phosphorylation, glycolysis

41
Q

What is an immediate source for ATP

A

Transfer of high energy phosphate from creatine phosphate to ADP

42
Q

What is the main source for ATP when oxygen is present

A

oxidative phosphorylation

43
Q

What is the main source for ATP when oxygen is not present

A

Glycolysis

44
Q

What are the 3 types of skeletal muscle fibres

A

Slow-oxidative, fast-oxidative, fast glycolytic

45
Q

What are slow oxidative type 1 fibres (slow twitch) used for

A

prolonged relatively low work aerobic activities eg. posture, walking

46
Q

What are fast oxidative type 2a (intermed twitch) fibres used for

A

prolonged relatively moderate work activities eg jogging (use both aerobic and anaerobic)

47
Q

What are fast glycolytic type 2x fibres (fast twitch) used for

A

anaerobic metabolism, short term high intensity activities eg. jumping

48
Q

What is a reflex action

A

a stereotyped response to a specific stimulus - the simplest form of coordinated movement

49
Q

What is the simplest monosynaptic spinal reflex

A

Stretch reflex

50
Q

Sum up a stretch reflex

A

Serves as a negative feedback that resists passive change in muscle length to maintain optimal resting length of muscle

51
Q

Where is the sensory receptor located in musc;e

A

in the muscle spindle, activated by muscle stretch

52
Q

What effect does stretching the muscle spindle have

A

increases firing in the afferent neurones, which synapse in the spinal cord with alpha motor neurones (efferent) - activation of the reflex results in contraction of stretched muscle

53
Q

What are muscle spindles

A

the sensory receptors for stretch reflex, collection of specialised muscle fibres

54
Q

What are muscle spindles also known as

A

intrafusal fibres

55
Q

what can ordinary muscle fibres be known as

A

extrafusal fibres

56
Q

Where are intrafusal fibres found in the muscle

A

The belly

57
Q

What are annulospiral fibres

A

the sensory nerve endings on muscle spindles

58
Q

What is the efferent motor nerve supply to muscle spindles called

A

gamma motor neurones

59
Q

does the contraction of intrafusal fibres contribute to the overall strength of muscle contraction

A

no

60
Q

What is the role of gamma motor neurones

A

They adjust the level of tension in the muscle spindles to maintain their sensitivity when the muscle shorten during muscle contraction

61
Q

Some useful investigations in neuromuscular disease

A

Electromyography, nerve conduction studies, muscle enzymes CK, inflammatory markers, muscle biopsy

62
Q

What is myalgia

A

muscle pain

63
Q

What is myotonia

A

Delayed relaxation after voluntary contraction

64
Q

What are two main causes of intrinsic muscle disease

A

Genetically determined, acquired

MSK (14 decks)

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