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Human Physiology > W9 - The Muscular System > Flashcards

W9 - The Muscular System Flashcards

1
Q

What are the primary functions of smooth muscle?

A

Digestion

Breathing

Circulation

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2
Q

What shape are smooth muscles?

A

Fusiform shaped

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3
Q

What do intercalated discs do for cardiac muscle?

A

Support synchronised contraction

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4
Q

What are cardiac muscle cells also known as?

A

Cardiomyocytes

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5
Q

What is the function of fascia adherens in a muscle fibre?

A

Mechanical support

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6
Q

What are desmosomes?

A

Specialised adhesive protein complexes.

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7
Q

What are desmosomes responsible for?

A

Maintaining mechanical integrity of tissues

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8
Q

What 4 characteristics define the skeletal muscle?

A

Excitability

Contractility

Extensibility

Elasticity

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9
Q

What does Titin do?

A

Keeps thick + thin filaments aligned.

Prevents muscle from overstretching.

Recoils muscle to resting length after stretching.

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10
Q

What does Nebulin do?

A

Anchors actin to Z disc

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11
Q

What is dystrophin?

A

Anchoring protein

Links actin filaments to other support proteins on the inner surface of each sarcolemma.

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12
Q

What is muscular dystrophy?

A

Weakening + breakdown of skeletal muscle

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13
Q

What are the 2 components of the motor unit?

A

A-motorneurone

Muscle fibres innervated by the AMN

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14
Q

HENNEMANS SIZE PRINCIPLE

What is recruitment based on?

A

Force req, not the velocity of the movement.

Slow units are ALWAYS recruited, regardless of velocity.

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15
Q

What are myogenic stem cells known as?

A

Satellite cells

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16
Q

Satellite cells

A

Incorporation of satellite cell nuclei into existing muscle fibres seems a likely explanation for exercise-induced muscle fibre hypertrophy.

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17
Q

Muscles Chemical composition

A

H20 ~75%

Protein ~20%

Salts + other substances ~5%

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18
Q

What are the most abundant muscle proteins?

A

Titin

Myosin

Actin

Tropomyosin

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19
Q

What does each 100g of muscle tissue contain in relation to myoglobin?

A

~700mg of myoglobin.

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20
Q

A band, lighter or darker area?

A

Darker

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21
Q

I band, lighter or darker area?

A

Lighter

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22
Q

What is the z line made from?

A

a-actin

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23
Q

What are the connection called between 2 sarcomeres from adjacent myofibrils?

24
Q

What is the M band made of?

A

M protein

Myomesin

M creatine kinase (M-CK)

25
Q

What protein are the elastic filaments made from?

26
Q

What proteins come under the thin filament?

A

Actin

Tropomyosin

Troponin

Nebulin

27
Q

What 2 structures come under the thick filaments?

A

C stripes

M line

28
Q

What proteins comes under the C stripes in the thick filaments?

A

Myosin

C protein

29
Q

What proteins are found in the z line?

A

a-actinin

Desmin

30
Q

What does M-CK do?

A

Provides ATP from PC

31
Q

What does myomesin do?

A

Provides strong anchoring point for Titin

32
Q

What does an unusually large pennation angle of 30 degrees result in?

A

13% loss in an ind fibres force capacity.

33
Q

Do pennate muscles generate considerable power?

34
Q

At what angle do muscle fibres lie to the tendon when in a unipennate fibre arrangement?

A

At an oblique angle to the tendon.

35
Q

What are the 3 ways in which pennate muscles differ from fusiform fibres?

A

Generally contain shorter fibres

More ind fibres

Less range of motion

36
Q

What are the purposes of the intracellular cytoskeleton?

A

Structural integrity in the inactive muscle cell

Lateral force transmission to adjacent sarcomeres

Connections to the cells surface membrane

37
Q

In what direction do T-tubules system run to the myofibril?

A

Perpendicular

38
Q

What does the term triad describe?

A

Repeating pattern of 2 terminal cisterns + 1 T tubule in each Z line region

39
Q

How many triads does each sarcomere contain?

40
Q

What is the purpose of the triad + the T-tubule system?

A

Function as a MICROTRANSPORTATION NETWORK.

By spreading the AP/wave of depolarisation from fibres outer membrane inward to the deeper cell region.

41
Q

What does propagation of the AP stimulate the triad sacs to do?

A

Release Ca2+ to “activate” actin filaments.

42
Q

What is the optimal sarcomere length in which there’s the greatest interaction between actin + myosin filaments?

A

2.0 - 2.25 micrometers

43
Q

Formula showing the dissociation of actomyosin

A

Actomyosin + ATP –> Actin + Myosin-ATP

44
Q

What happens to the energy from ATP hydrolysis in the dissociation of actomyosin?

A

Transduces into mechanical force when ADP + inorganic phosphate end products form.

45
Q

Major storage fuel for Type 1 fibres

A

Triacylglycerol

46
Q

Major storage fuel for Type 2a fibres

A

Creatine phosphate

Glycogen

47
Q

Major storage fuel for Type 2x fibres

A

Creatine phosphate

Glycogen

48
Q

Major storage fuel for Type 2b fibres

A

Creatine phosphate

Glycogen

49
Q

What receptor can be found on T-tubules?

A

Dihydropyridine receptor (DHP)

50
Q

Ryanodine receptors

A

Intracellular Ca2+ channels

51
Q

What is calsequestrin?

What does it do?

A

Most abundant Ca2+ binding protein.

Allows Ca2+ req. for contraction to be stored at total conc of up to 20mM while the free Ca2+ conc remain at ~1mM.

52
Q

Where can calsequestrin be found?

A

Sarcoplasmic reticulum of skeletal + cardiac muscle

53
Q

What is calmodulin?

A

Calcium modulated protein

54
Q

What binds to calmodulin?

55
Q

What does Ca2+-calmodulin activate?

A

Myosin Light-Chain Kinase (MLCK)

56
Q

What does MLCK do?

A

Phosphorylates light chains in myosin heads + ⬆️ myosin ATPase activity

57
Q

What do Na+ + K+ do to the activation of RyR?

A

Decrease it

Human Physiology (16 decks)

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