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MSK Week 1 2017/18 > 2: Muscle Physiology I > Flashcards

2: Muscle Physiology I Flashcards

1
Q

What are some physiological functions of skeletal muscle?

A

Posture

Voluntary and involuntary movement (inc. respiratory movement)

Heat production

Transport of metabolites between organs (whole body metabolism)

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2
Q

What are the three types of muscle?

A

Cardiac muscle

Skeletal muscle

Smooth muscle

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3
Q

Muscle is the largest type of ___ in the body.

A

tissue

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4
Q

What function do all three types of muscle have in common?

A

Produce tension and movement through CONTRACTION

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5
Q

Which types of muscle are striated?

A

Cardiac muscle

Skeletal muscle

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6
Q

Which type of muscle is unstriated?

A

Smooth muscle

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7
Q

How is striation recognised under a microscope?

A

Alternating light (actin) and dark (myosin) bands

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8
Q

Which division of the nervous system innervates skeletal muscle?

A

Somatic nerves

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9
Q

Skeletal muscle is (voluntary / involuntary).

A

voluntary

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10
Q

Which division of the nervous system innervates involuntary cardiac and smooth muscle?

A

Autonomic nervous system

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11
Q

Initiation of contaction in skeletal muscle is ___genic.

A

neurogenic

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12
Q

Skeletal muscle is arranged into ___ units.

A

motor

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13
Q

Are skeletal muscle cells joined by gap junctions?

A

No

one neuromuscular junction between motor neuron and motor unit

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14
Q

Does skeletal muscle have gap junctions?

A

No

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15
Q

Which ion triggers contraction of skeletal and cardiac muscle?

A

Ca2+

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16
Q

What is the only source of Ca2+ in skeletal muscle?

A

Sarcoplasmic reticulum

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17
Q

What two factors control the “power” of skeletal muscle contraction?

A

Motor unit recruitment i.e how many muscle fibres are contracting?

Summation of contractions i.e are contractions being reactivated rapidly?

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18
Q

There is no continuity of ____ between nerve and skeletal muscle cells.

A

cytoplasm

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19
Q

What is the neurotransmitter found at neuromuscular junctions?

A

Acetylcholine

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20
Q

What is a motor unit?

A

A single alpha motor neuron and ALL the skeletal muscle fibres it innervates

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21
Q

The excitation of one alpha motor neuron will stimulate the contraction of (one / multiple) motor units(s).

A

multiple units

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22
Q

What affects the number of motor units served by an alpha motor neuron?

A

Function of the muscle

23
Q

Muscles which serves fine, precision movements (give examples) are have (more / fewer) muscle fibres.

A

Eye movements

Facial expression

Hand movements

FEWER FIBRES

24
Q

Muscles which have powerful functions have (more / fewer) muscle fibres.

A

more

e.g limb movements

25
Q

A muscle fibre is made up of how many cells?

A

One cell

26
Q

A motor unit encompasses all the ___ ___ supplied by an ___ ___ ___.

A

muscle fibres

alpha motor neuron

27
Q

What are the specialised contractile elements found within skeletal muscle cells?

A

Myofibrils

28
Q

What is the functional unit of a myofibril?

A

Sarcomere

29
Q

Name the two proteins found in a sarcomere, what colour they appear on microscopy and why?

A

Actin - light - thinner filaments

Myosin - dark - thicker filaments

30
Q

Skeletal muscle fibres are (parallel / divergent).

A

parallel

31
Q

By which structures are skeletal muscle fibres attached to bones?

A

Tendons

32
Q

Each muscle fibre contains many ___.

A

myofibrils

33
Q

Myofibrils have alternating segments of which two proteins?

A

Actin

Myosin

34
Q

Within myofibrils, actin and myosin filaments are arranged into ___.

A

sarcomeres

35
Q

What is the definition of an organ’s functional unit?

What is the functional unit of skeletal muscle?

A

Smallest component capable of performing all the organ’s functions

Sarcomere

36
Q

What are Z lines?

A

Boundary lines splitting up sarcomeres

37
Q

What are A bands?

A

Sections of overlapping actin and myosin filaments

38
Q

What are H zones?

A

Lighter area in the middle of A bands where actin doesn’t overlap - myosin only

39
Q

What are M lines?

A

Line extending down the centre of the A band, right in the middle of the H zone

40
Q

What are I bands?

A

Remaining area of sarcomere where only actin is found

41
Q

What is required for the sliding of myosin and actin filaments, which itself produces muscle contraction?

A

ATP

42
Q

What binds to the myosin head to trigger detachment from the actin fibre?

A

ATP

43
Q

Even if ATP is present, binding of the myosin head to a new section of actin filament will not occur without?

A

Ca2+

44
Q

Why does rigor mortis occur?

A

No ATP present, so myosin head remains attached to actin fibre

45
Q

Nerves generate an ___ ___, which travels to the ___ ___ junction and then to the skeletal muscle fibres.

A

action potential

neuromuscular junction

46
Q

What is excitation contraction coupling?

A

Process by which surface action potential triggers contraction of skeletal muscle

47
Q

In skeletal muscle, where is Ca2+ released from?

A

Sarcoplasmic reticulum

48
Q

What structures are extensions of the surface membrane and invaginate into muscle cells, allowing surface action potentials to reach the sarcoplasmic reticulum?

A

T-tubules

49
Q

Ca2+ is released by which specific part of the sarcoplasmic reticulum?

A

Lateral sacs

50
Q

The myosin-binding sites on actin filaments are covered by which protein complex?

A

Troponin-tropomyosin complex

51
Q

When Ca2+ binds to the troponin-tropomyosin complex, what happens?

A

Conformational change, complex moves and allows myosin to form cross bridge with actin

52
Q

After an action potential, Ca2+ is (passively / actively) reabsorbed into the sarcoplasmic reticulum.

A

actively

requiring ATP

ATP is also required for cross bridge detachment

53
Q

ATP is required for (contraction / relaxation) of skeletal muscle.

A

both

MSK Week 1 2017/18 (10 decks)

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