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UofG Medicine Question Bank 2020 > Musculoskeletal/Joints/Cartilage > Flashcards

Musculoskeletal/Joints/Cartilage Flashcards

1
Q

What surrounds muscles?

A

Epimysium

Sense, fibrous, irregular connective tissue

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2
Q

What is a fascicle?

A

A bundle of muscle fibres

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3
Q

What are fascicles surrounded by?

A

Perimysium

Dense, irregular, fibrous, connective tissue

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4
Q

What is a muscle fiber?

A

Muscle cell

Multi-nucleated and striated

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5
Q

What surrounds the muscle cells?

A

Endomysium

Areolar connective tissue

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6
Q

What is the sarcolemma?

A

The plasma membrane surrounding the muscle cells, within the endomysium

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7
Q

What is the process of bone movement following the contraction of muscle fibres?

A

Muscle contracts -> pulls on connective tissue sheath -> pulls on tendon -> pull or move bone

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8
Q

What are the two types of muscle connection to bone?

A

Direct and Indirect (more common)

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9
Q

What is a direct muscle attachment?

A

When epimysium fuses with the periosteum or periochondrium

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10
Q

What is an indirect muscle attachment?

A

When tendons attach muscles (via binding to connective tissue) to bone

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11
Q

What are benefits to indirect muscle attachments?

A

Tendons are smaller and conserve space

Tendons are more resilient than muscle

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12
Q

What fibre is found in high amounts in tendons?

A

Collagen

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13
Q

What is found within muscle cells?

A

Many myofibrils

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14
Q

What is a sarcomere?

A

The functional component of the myofibril, from Z-disc to Z-disc

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15
Q

What is titin?

A

Protein that anchors the thick filament to the Z-disc

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16
Q

What is the m-line in a muscle cell?

A

Its an accessory protein that runs perpendicular to the titin, and attaches to the titin within the thick filament, helping to further stabilize the thick filament

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17
Q

What is the m-line made of?

A

Myomesin, C proteins, creatinine kinase (functional protein)

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18
Q

What is the anisotropic band?

A

A-Band. Runs along the length to the thick filament

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19
Q

What is the I band?

A

Called ‘Isotrope band’
Runs from A-band to A-band
Covers space between intermediate filaments

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20
Q

What is the thin filament?

A

Troponin (protein that binds actin, Ca, and tropomyosin)
Nebulin (binds to Z-disc)
Tropomyosin (binds to active site of actin to prevent myosin binding)
Actin

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21
Q

What does actin consist of?

A

Polymerized G-actin that form a double helix structure

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22
Q

What does tropomyosin do?

A

Wraps around the active site of actin to prevent myosin head from binding.
Happens in resting position

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23
Q

What is troponin?

A

A protein that works to sense Ca binding.
When Ca binds to it, troponin pulls on tropomyosin which displaces tropomyosin from the active site of actin, allowing myosin to bind to actin, and causing contraction.

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24
Q

How many sections does troponin have and what binds to them?

A

3 troponin sections;
Troponin C binds to Calcium
Troponin T binds to tropomyosin
Troponin I (inhibitory) which binds to actin

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25
Q

What does myosin attach to?

A

Thick filament and troponin on the thin filament

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26
Q

What components make myosin?

A

Head- binds to actin active sites allowing for sliding of filaments. Also has enzyme ATPase activity, which cleaves ATP into ADP. Double head
Neck- has light chains (regulatory (regulate) and essential light chain (stabilize)) that support the head and regulate activity of myosin
Tail- found at thick filament end,. Double helical structure

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27
Q

What is the Z-disc

A

A long protein consisting of alpha-actinin that runs along the width of the myofibril
Helps with stabilizing thick and thin filaments

28
Q

What is the H-zone?

A

Space between two thin filaments within the same sarcomere.

29
Q

What is the purpose of dystrophin?

A

Links actin to the sarcolemma on the membrane of the myofibril adding strength

30
Q

Why is mutation of dystrophin a problem?

A 
Mutations (typically X-linked recessive disorder) means the actin isn't linked to the sarcolemma, and can lead to muscular dystrophy as the muscle cell membranes (sarcolemma) break down over time causing muscle weakness. 
Duchenne Disease (more severe) and Becker (missense mutation -> misfolded protein, less severe, 10-12 years)
31
Q

How does skeletal muscle cell appear histologically?

A

Multinucleated, striated, long, cylindrical

Produces powerful contractions

32
Q

How does cardiac muscle cell appear histologically?

A

Branching cells (allows heart to contract AROUND ventricles), one or two nuclei per cell, intercalated discs, some striations

33
Q

What are the speeds of contraction for each type of muscle?

A

Skeletal: Fast/medium
Cardiac: Medium
Skeletal: Slow

34
Q

How does smooth muscle cells appear histologically?

A

Non-striated, spindle shape with single nuclei, cells formed closely together

35
Q

In comparison with extracellular environment, are intracellular muscle concentrations of K, Na, Cl, and organic anions higher or lower?

A

K- higher (150 vs 5)
Na- Lower (12 vs 140)
Cl- Lower (10 vs 105)
Organic Anions- higher (65 vs 0)

36
Q

What is the typical resting membrane potential of human cells?

A

-40 to -90 mV in relation to extracellular environment

37
Q

What ion typically drives the resting membrane potential of cells?

A

K as it is more permeable to the cell membrane.

38
Q

What neurotransmitter is utilized at neuromuscular junctions?

A

Acetylcholine

39
Q

How does acetylcholine cause excitation? Explain the process of ACh release to muscle contraction.

A

Released from neural cells at neuromuscular junctions, it opens a channel that is permeable to sodium, and allows positive Na charges into the cell, increasing the cellular membrane potential (to around +40). Depolarization is propagated along sarcolemma of cell, down T-Tubules, and action potential signals release of Ca from cisternae of Sarcoplasmic Reticulum, to sustain the charge. Calcium then binds troponin, causing troponin to unblock actin active site by moving tropomyosin, which allows myosin to bind to actin, and initiate contraction using ATP.

40
Q

How is action potential achieved in the different muscle types?

A

In skeletal, ACh release from neuromuscular junctions will depolarize and initiate contraction.
In cardiac muscle, the sinoatrial node contains sodium channels that will spontaneously open to allow sodium entry and initiate depolarization (small levels of Na leak through to help initiate this)
In smooth muscle, sodium entry can be triggered by hormonal release leading to depolarization.

41
Q

What is the sarcoplasmic reticulum?

A

It is an specialized endoplasmic reticulum organelle in muscle that stores calcium

42
Q

How can a given motor neuron cause different stimulation?

A

There are different branches within the motor neurons that can stimulate different parts of the muscle through acetylcholine release at different neuromuscular junctions

43
Q

Why are motor ratios useful?

A

Closer rations (i.e. eye is 1:1) allows for very specific muscular control.
Hand : 1:10
Back: 1:100

44
Q

What is muscle tonus?

A

Continual tightness of muscle

Muscle held in steady, partially contracted state

45
Q

What is muscle tetanus?

A

Sustained contraction of muscle

Only in skeletal muscle.

46
Q

What are striations formed of?

A

Arrangement of proteins, particularly actin and myosin filaments, within the myofibril

47
Q

How is the myosin head movement related to other heads?

A

They move in unison to create smooth movement

48
Q

What allows for the lack of phosphate related fatigue to occur within myofibrils?

A

Excess phosphate and creatine build up cause muscle fatigue, as well as lactate is anaerobic respiration is utilized.
Fatigue will be reached with extended muscle use though

49
Q

How is calcium released from the sarcoplasmic reticulum?

A

Influx of sodium caused by Ach activates the Voltage-sensitive dihydropyridine receptors (L-type Ca channel) within the sarcolemma, linked to the Ryanodine Receptors on the SR, and Ca is released from the sarcoplasmic reticulum.

50
Q

How is creatine important?

A

We use it to store energy when muscles are at rest (in the form of ADP and creatine phosphate) and when energy is needed for muscle activation, we create ATP and creatine, so we can use ATP for contraction

51
Q

What is isometric contraction?

A

Contraction that produces no movement, i.e. standing, sitting, and posture

52
Q

What is isotonic movement?

A

Contraction that produced movement

53
Q

What is isokinetic movement?

A

Muscle shortens at a constant speed, and exerts maximum tension over the full range of movement. This is only fully achieved with specially designed weight training equipment,

54
Q

What are the 3 types of joints?

A

Fibrous, Cartilage, Synovial

55
Q

What are the 3 basic structural classifications of joints?

A

Synarthrosis, Amphiarthrosis, Diarthrosis

56
Q

What are the types of Synarthrosis joints and what kind of movement does this joint permit?

A

Extremely strong joints that prevent movement between bones.

Fibrous suture, Gomphosis, Cartilaginous Synchondrosis, Bony Fusion Syndesmosis

57
Q

Give a brief example of a fibrous suture joint as well as an example.

A

Bones are interlocked and bound together by dense fibrous tissue.
Only in bones of skull

58
Q

Give a brief description of a gomphosis joint as well as an example.

A

Fibrous connection between tooth and alveolar canal forms a periodontal ligament.
Teeth and socket

59
Q

Give a brief example of a cartilaginous synchondrosis joint as well as an example.

A

Syn=together, chondro= cartilage
Rigid, cartilaginous bridge between two articulating bones.
Between the ends of first 2 ribs and sternum.

60
Q

Give a brief description of a bony fusion synostosis joint as well as an example.

A

Rigid, immovable joint created when bones fuse together.

Epiphyseal lines of long bones, and frontal suture of frontal bone

61
Q

What are types of amphiarthrosis joints and what movement does this kind of joint permit?

A

Permits more movement than synarthrosis joints, but is more secure than diarthrosis joints. Articulating bones are joined by cartilage or collagen fibres.
Fibrous Syndesmosis
Cartilaginous symphysis

62
Q

Give a brief example of a Fibrous Syndesmosis joint as well as an example.

A

desmos= band or ligament
Bones are connected by a ligament
Distal articulation between the tibia and fibulla

63
Q

Give a brief description of a cartilaginous symphysis joint as well as an example.

A

Articulating bones are attached/separated by a wedge of fibrous cartilage
Pubic symphysis

64
Q

What is a diarthrosis joint and what movement does this kind of joint permit?

A

A free moving joint

Consists of synovial joints

65
Q

What are the 6 types of muscle shape?

A

Flat (parallel fibers often with aponeurosis), Pennate (feather-like), Fusiform (spindle shape with round thick belly), Convergent (start at broad area and converge to single tendon), Quadrate (4 equal sides), Circular (surround opening)

66
Q

How can pennate muscles within the body differ?

A

Can be uni/bi/multi pennate, meaning the fibers of the muscle may move in different directions.
i.e. deltoid is multipennate, rectus femoris is bipennate, extensor digitorum longus in unipennate)

67
Q

What separates the intrinsic back muscles from the superficial back muscles?

A

Thoracolumbar Fascia

UofG Medicine Question Bank 2020 (42 decks)

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