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MCAT > MCAT Biology Muscular and Skeletal Systems > Flashcards

MCAT Biology Muscular and Skeletal Systems Flashcards

1
Q

The band of the sarcomere that extends the full length of the thick filament

A

A band

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2
Q

The __ includes regions of thick and thin filament overlap, as well as regions of thick only filament

A

A band

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3
Q

The __ alternates with the I band to give skeletal and cardiac muscle tissue a striated appearance

A

A band

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4
Q

___ does NOT shorten during muscle contraction

A

A band

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5
Q

A contractile protein, in skeletal muscles __ form the thin filaments

A

Actin

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6
Q

A hormone produced from vitamin D that acts to INCREASE serum calcium levels

A

Calcitriol

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7
Q

___ is produced by C-cells of the thyroid gland that decreases serum calcium levels. It targets bones to stimulate osteoblasts and the kidney to REDUCE calcium reabsorption

A

Calcitonin

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8
Q

A cytoplasmic Ca2+- binding protein. __ is important in smooth muscle cells, where binding of Ca2+ allows __ to activate myosin light-chain kinase, the first step in smooth muscle cell contraction

A

Calmodulin

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9
Q

A strong connective tissue with varying degrees of flexibility.__

A

Cartilage

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10
Q

The hollow center of an osteon, known as the Haversian canal

A

Central canal

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11
Q

The __ contains blood vessels, lymphatic vessels, and nerves, bone is laid around this in concentric rings called lamellae

A

Central canal

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12
Q

Bone is laid around the central (haversian) canal in concentric rings called__

A

Lamellae

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13
Q

A protein fiber with a unique triple-helix structure that gives it great strength

A

Collagen

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14
Q

Tissues with a lot of __ are typically very strong such as bone, tendon, ligaments etc.

A

Collagen

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15
Q

___ forms the diaphysis of the long bones, and the outer shell of the epiphysis and all other bones

A

Compact bone

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16
Q

What are the four basic tissue types in the body?

A
  • epithelial
  • connective
  • muscle
  • nervous
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17
Q

An energy storage molecule used by muscle tissue

A

Creatine phosphate

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18
Q

The phosphate from __ can be removed and attached to an ADP to generate ATP quickly in muscle tissue

A

Creatine phosphate

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19
Q

The connection of a myosin head group to an actin filament during muscle contraction (the sliding filament theory)

A

Cross bridge

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20
Q

The shaft of a long bone is termed__

A

Diaphysis

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21
Q

__ is hollow and made entirely of compact bone

A

Diaphysis

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22
Q

The fraction of the end-diastolic volume ejected from the ventricles in a single contraction of the heart

A

Ejection fraction

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23
Q

The __ is normally around 60% of the end-diastolic volume

A

Ejection fraction

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24
Q

__ is found in great amounts in lung tissue, arterial tissue, skin, and the epiglottis

A

Elastin

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25
Q

The depolarization of the motor end plate on a muscle cell

A

End plate potential

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26
Q

A band of cartilage (hyaline) found between the diaphysis and the epiphysis of long bones during childhood and adolescence

A

Epiphyseal plate

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27
Q

Cell proliferation in the middle of the __ is essentially forces the diaphysis and epiphysis further apart, while the older cartilage at the edges of the plate is replaced with bone.

A

Epiphyseal plate

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28
Q

The __ gets thinner and thinner the older a person gets, until finally it fuses (the diaphysis and epiphysis connect) in late adolescence, preventing further elongation of the bones

A

Epiphyseal plate

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29
Q

A bundle of skeletal muscle cells. __ group together to form skeletal muscles

A

Fascicle

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30
Q

The region at the center of an A band of a sarcomere that is made up of myosin only. The __ gets shorter ( and may disappear) during muscle contraction

A

H zone

31
Q

The region of a sarcomere made up only of thin filaments. The ___ is bisected by a Z line.

A

I band

32
Q

The __ alternates with A bands to give skeletal and cardiac muscle a striated appearance. The ___ gets shorter and may disappear completely, during muscle contraction

A

I band

33
Q

Small cavities in bone or cartilage that hold individual bone or cartilage cells

A

Lacunae

34
Q 
The relationship of muscle length to its ability to generate strong contractions.
Maximum tension (contraction strength) is achieved at sarcomere lengths between 2.0 and 2.2 microns. Tension decreases outside of this range
A

Length-tension relationship

35
Q

A strong band of connective tissue that connects bone to one another

A

Ligament

36
Q

The most common class of bone in the body, __ have a well-defined shaft (diaphysis) and two well-defined ends (epiphyses)

A

Long bone

37
Q

The portion of the muscle cell membrane at the neuromuscular junction; essentially the postsynaptic membrane at this synapse

A

Motor end plate

38
Q

A motor and all the skeletal muscle cells it innervates

A

Motor unit

39
Q

Larger __ are tpically found in large muscles (thighs, buttocks) and produce gross movement

A

Motor unit

40
Q

A mechanism for increasing tension (contractile strength) in a muscle by activating more motor units.

A

Motor unit recruitment

41
Q

A skeletal muscle cell, also known as a muscle fiber. Skeletal muscle cells are formed from the fusion of many smaller cells (during development) consequently they are very long and are multinucleate.

A

Myofiber

42
Q

A string of sarcomeres within a skeletal muscle cell. Each muscle cell contains hundreds of __

A

Myofibril

43
Q

One of the contractile proteins in muscle tissues. IN skeletal and cardiac muscle, __ forms the thick filaments.

A

Myosin

44
Q

__ has intrinsic ATPase activity and can exist in two conformations, either high energy or low energy

A

Myosin

45
Q

A kinase in smooth muscle cells activated by calmodulin in the presence of Ca2+. As its name implies this phosphorylates myosin, activating it so that muscle contraction can occur

A

Myosin light-chain kinase (MLCK)

46
Q

A hormone produced and secreted by the parathyroid glands that increases serum calcium levels

A

Parathyroid hormone (PTH)

47
Q

___ targets bones (stimulates osteoclast), the kidneys (increases calcium reabsorption), and the small intestine (increases calcium absorption)

A

Parathyroid hormone (PTH)

48
Q

The step in the sliding filament theory during which myosin undergoes a conformational change to its low energy state, in the process dragging the thin filaments (and the attached Z lines) toward the center of the sarcomere.

A

Power stroke

49
Q

__ requires ATP only indirectly: to set the myosin molecule in its high-energy conformation during a different step of the sliding filament theory

A

Power stroke

50
Q

Skeletal muscle cells that contract slowly but are fatigue resistant due to high concentrations of myoglobin and a good blood supply

A

Red slow twitch fibers

51
Q

The plasma membrane of a muscle cell

A

Sarcolemma

52
Q

The unit of muscle contraction

A

Sarcomere

53
Q

__ are bounded by Z lines, to which thin filaments attach. Thick filaments are found in the center of them, overlapped by thin filaments

A

Sarcomere

54
Q

Sliding of thin and thick filaments over one another during contraction reduces the distance between Z lines, shortening the __

A

sarcomere

55
Q

The smooth ER of a muscle cell, enlarged and specialized to act as a Ca2+ reservoir. The __ widens around each myofibril in the muscle cell

A

Sarcoplasmic reticulum (SR)

56
Q

Explain four steps of sliding filament theory

A
  1. Myosin binds actin
  2. Myosin pulls actin towards the center of the sarcomere
  3. Myosin releases actin
  4. Myosin resets to its high-energy conformaton
57
Q

Muscle tissue that is non-striated, uninucleate, and under involuntary control (controlled by the ANS)

A

Smooth muscle

58
Q

A looser, more porous type of bone tissue found at the inner core of the epiphyses in long bones and all other bone types

A

Spongy bone

59
Q

__ is filled with red bone marrow, important in blood cell formation

A

Spongy bone

60
Q

A lubricating, nourishing fluid found in joint capsules

A

Synovial fluid

61
Q

Strong bands of connective tissue that connect skeletal muscle to bone

A

Tendon

62
Q

A smooth sustained muscle contraction, such as occurs in skeleletal muscle when stimulation frequency is high enough (this is the normal type of contraction exhibited by skeletal muscle)

A

Tetanus

63
Q

In skeletal and cardiac muscle tissue a filament composed of bundles of myosin molecules. The myosin head groups attach to the thin filaments during muscle contraction and pull toward the center of the sarcomere

A

Thick filament

64
Q

In skeletal and cardiac muscle tissue, a filament composed of actin, tropomyosin, and troponin. __ are attached to the Z lines of the sarcomeres and slide over thick filaments during muscle contraction

A

Thin filament

65
Q

A helical protein that winds around actin helices in skeletal and cardiac muscle cells to from the thin filament of the sarcomere.

A

Tropomyosin

66
Q

In the absence of Ca2+___ covers the myosin-binding sites on actin and prevents muscle contraction. When calcium is present, a conformational change in __ occurs so that the mysoin-binding sites are exposed and muscle contraction can occur.

A

Tropomyosin

67
Q

A globular protein that associates with tropomyosin a part of the thin filament of the sarcomere`

A

Troponin

68
Q

__ is the protein that binds Ca2+, which causes the conformational change in tropomyosin required to expose the myosin-binding sites on actin and initiate muscle contraction

A

Troponin

69
Q

Also called transverse tubules, these are deep invaginations of the plasma membrane found in skeletal and cardiac muscle cells. These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell

A

T-tubules

70
Q

Also known as red slow twitch or red oxidative fibers, these are skeletal muscle cells that contract slowly and are extremely resistant to fatigue

A

Type 1 fibers

71
Q

Also known as fast twitch oxidative fibers, these are skeletal muscle cells that contract quickly and are somewhat resistant to fatigue

A

Type 2A fibers

72
Q

Also known as white fast twitch fibers, these are skeletal muscle cells that contract quickly and fatigue quickly

A

Type 2B fibers

73
Q

The ends of a sarcomere are its__

A

Z-line

MCAT (45 decks)

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