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MCAT > Biology Ch 11. The Musculoskeletal System > Flashcards

Biology Ch 11. The Musculoskeletal System Flashcards

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MCAT flashcards
1
Q

Three main types of muscle

A

Skeletal, smooth, and cardiac

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2
Q

Skeletal muscle

A

Often support and movement, propulsion of blood in the Venus system, and thermal regulation, it appears striated, is under voluntary control (somatic nervous system), is multinucleated, can be derived into red fibers that curiosity to phosphorylation and white fibers that rely on anaerobic metabolism

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3
Q

Stiated

A

Striped, how skeletal and cardiac muscle appears under microscope, when actin and myosin fibers arranged into repeating units

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4
Q

Red fibers

A

aka slow twitch fibers - carry out oxidative phosphorylation, high myoglobin content, high levels of mitochondria, common in muscles that contract slowly, but can sustain activity (posture)

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5
Q

White fibers

A

aka fast twitch fibers - carry out anaerobic metabolism, lower myoglobin concentration, present in muscles that contract rapidly but fatigue quickly

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6
Q

Smooth muscle

A

Is in the respiratory, reproductive, cardiovascular, and digestive systems, it appears non-striated, is under a involuntary control, and is uninucleated, it can display myogenic activity

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7
Q

Myogenic activity

A

Contraction without neural input

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8
Q

Cardiac muscle

A

Comprises the contractile tissue of the heart, appear striated, is under involuntary control, is uninucleated or sometimes binucleated, can also display myogenic activity, cells connected with intercalated discs that contain gap junctions

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9
Q

Intercalated discs

A

Connects cells in cardiac muscle, contains many gap junctions

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10
Q

Gap junctions

A

In intercalated discs, connection between the cytoplasm of adjacent cells, site of electrical synapsing or the flow of ions directly between cells, allows for efficient depolarization and contraction

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11
Q

Sarcomere

A

The basic contractile unit of striated muscle, made of thick (myosin) and thin (actin) filaments

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12
Q

Myosin in muscle

A

Thick filaments in sarcomeres

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13
Q

Actin in muscle

A

Makes up, along with troponin and tropomyosin, the thin filaments in sarcomeres

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14
Q

Troponin

A

Found on the thin (actin) filament and regulate actin-myosin interactions

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15
Q

Tropomyosin

A

Found on the thin (actin) filament and regulate actin-myosin interactions

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16
Q

Z lines

A

Define boundaries of each sarcomere

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17
Q

M-line

A

Located in the middle of the sarcomere, right through myosin filaments

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18
Q

I band

A

Contains only thin filaments

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19
Q

H zone

A

Consists of only thick filaments

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20
Q

A band

A

Contains the thick filaments in their entirety, the only part of the sarcomere that maintains a constant size during contraction

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21
Q

Myofibrils

A

Created when sarcomeres attach end-to-end, surrounded by sarcoplasmic reticulum covering

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22
Q

Myocyte

A

A muscle cell or muscle fiber, contains many myofibrils arranged in parallel

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23
Q

Sarcoplasmic reticulum

A

Surrounds myofibrils, a calcium containing modified endoplasmic reticulum

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24
Q

Sarcolemma

A

Cell membrane of a myocyte, capable to propagating an action potential and distributing the action potential to all sarcomeres using transverse tubules

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25
Q

T-tubules

A

Transverse tubules - Connected to the sarcolemma and oriented perpendicular to the myofibrils, allowing the action potential to reach all parts of the muscle

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26
Q

Neuromuscular junction

A

Where muscle contraction begins, where the motor neuron releases acetylcholine binds to receptors on the sarcolemma, causing depolarization, signals from motor/efferent neurons

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27
Q

Muscle contraction

A

Motor neuron releases acetylcholine that binds to receptors on the sarcolemma at the neuromuscular junction, this depolarization spreads down the sarcolemma to the T tubules triggering the release of calcium ions, calcium binds to troponin causing a shift in tropomyosin and exposure of the myosin binding sites on the actin thin filament, myosin heads bind the expose sites on actin forming cross bridges and pulling the actin filament along the thick filament, resulting in contraction

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28
Q

Sliding filament model

A

Model of shortening of the sarcomere where myosin heads bind to the expose sites on actin, forming cross bridges and pulling the actin filament along the thick filament, this occurring in a repetitive manner results in contraction

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29
Q

Muscle relaxation

A

Acetylcholine is degraded by acetylcholinesterase, terminating the signal in allowing calcium to be brought into the sarcoplasmic reticulum, ATP binds to the myosin head allowing it to release from Acton

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30
Q

Simple twitch

A

All or nothing response exhibited by muscle cells

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31
Q

Frequency summation

A

Addition of multiple simple twitches before the muscle has an opportunity to fully relax

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32
Q

Tetanus

A

A more prolonged and stronger contraction that occurs when simple twitches occurs so frequently as to not let the muscle relax at all

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33
Q

Oxygen debt

A

Difference between the amount of oxygen needed and the amount present, can be reduced by muscle cells that have additional energy reserves

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34
Q

Creatine phosphate

A

Transfers a phosphate group to ADP, forming ATP, created during periods of resting to get ATP quickly during periods of use

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35
Q

Myoglobin

A

A heme containing protein that is a muscular oxygen reserve

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36
Q

Tonus

A

A constant state of low-level contraction, seen in the blood vessels, smooth muscle is capable of it

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37
Q

Cardiac muscle myogenic activity

A

Starts at SA node –> AV node –> bundles of His –> purkinje fibers

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38
Q

Titin

A

Acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of the muscle

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39
Q

Sarcoplasm

A

A modified cytoplasm located just outside the sarcoplasmic reticulum

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40
Q

Motor end plate

A

The nerve terminal in the neuromuscular junction

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41
Q

Motor unit

A

The nerve terminal and its myocytes

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42
Q

Myosin-binding sites

A

Locations on the actin thin filaments that are made accessible when Ca2+ binds to troponin causing a change in confirmation of tropomyosin

43
Q

Muscle powerstroke

A

When myosin attaches to the myosin binding site on action, ADP and Pi dissociate from the mysosin, providing energy for a powerstroke

44
Q

Acetylcholinesterase

A

Degrades acetylcholine in the synapse, terminating the signal

45
Q

Latent period

A

Time between reaching threshold and the onset of contraction, action potential spreads along the muscle and allows for calcium to be released from the sarcoplasmic reticulum

46
Q

Simple twitch periods

A

Latent period, contraction period, relaxation period

47
Q

Endoskeletons

A

Internal skeletons (like in humans), are not able to protect the soft tissue structures as well as exoskeletons

48
Q

Exoskeletons

A

External skeletal (like in anthropods), must shed and regrown to accommodate growth

49
Q

Human skeletal system divisions

A

Axial and appendicular skeleton

50
Q

Axial skeleton

A

Consists of striations in the midline such as the skull, vertebral column, ribcage, and hyoid bone

51
Q

Appendicular skeleton

A

Consists of the bonds of the limbs, the pectoral girdle, and the pelvis

52
Q

Bone

A

Derived form the embryonic mesoderm and includes both compact and spongy types

53
Q

Compact bone

A

Provides strength, is very dense, forms outmost portions of the bone

54
Q

Spongy bone

A

aka cancellous bone, has a lattice like structure consisting of trabeculae, cavities are filled with bone marrow, internal core of the bone

55
Q

Trabeculae

A

Bony spicules/points in spongy bone

56
Q

Diaphyses

A

Cylindrical shafts within long bones that flare to form metaphases

57
Q

Epiphyses

A

Where long bones terminate, contain an epipihyseal or growth plate, use spongy cores for more effective dispersion of force and pressure at joints

58
Q

Epipihyseal plate

A

aka growth plate, causes linear growth of the bone, close during puberty

59
Q

Periosteum

A

Layer of connective tissue that surrounds bone, site for muscle attachment, some periosteal cells capable of differentiating into bone-forming cells

60
Q

Tendons

A

Attach bones to muscles

61
Q

Ligaments

A

Attaches bones to each other

62
Q

Bone matrix

A

Contains both organic compounds such as collagen, glycoproteins, and peptides, and inorganic compounds like hydroxyapatite, provides strength to compact bone

63
Q

Hydroxyapatite

A

Inorganic components (calcium, phosphate, and hydroxide ions) that harden together and form crystals

64
Q

Lamellae

A

Concentric circles of bony matrix in compact bone

65
Q

Bone organization

A

Lamellae around Haversian or Volkmannn’s canals

66
Q

Osteon

A

aka Haversian system, structural unit of bone

67
Q

Lacunae

A

Between lamellar rings, where osteocytes reside, are connected by canaliculi to allow for nutrient and waste transfer

68
Q

Osteocytes

A

Mature bone cells

69
Q

Canaliculi

A

Connected to lacunae, allow for nutrient and waste transfer between osteocytes and Haversian and Volksmanns canals

70
Q

Osteoblasts

A

Build bone

71
Q

Osteoclasts

A

Resorb bone

72
Q

Parathyroid hormone

A

Peptide hormone released be parathyroid in response to low blood calcium, increases resorption of bone, increases calcium and phosphate concentrations in the blood

73
Q

Vitamin D

A

Activated by parathyroid hormone, increases resorption of bone, leads to increased turnover and the production of stronger bone

74
Q

Calcitonin

A

Peptide hormone released by parafollicular cells of the thyroid in response to high blood calcium, increases bone formation, decreases calcium concentration in the blood

75
Q

Cartilage

A

Firm, elastic material secreted by chondrocytes, matrix is the chondrin, usually found in areas that require more flexibility or cushioning, avascular and not innervated

76
Q

Chondrocytes

A

Secretes cartilage

77
Q

Chondrin

A

Firm but elastic matrix of cartilage

78
Q

Endochondral ossification

A

Process by which bones form from fetal cartilage

79
Q

Intramembranous ossification

A

The process by which bones, especially those of the skull, form directly from undifferentiated tissue in fetal life

80
Q

Mesenchyme

A

Undifferentiated tissue

81
Q

Immovable joints

A

Fused together to form sutures or similar fibrous joints

82
Q

Movable joints

A

Strengthened by ligaments and contain a synovial capsule, include hinge joints and ball and socket joints

83
Q

Synovial capsule

A

Enclose the actual joint/articular cavity

84
Q

Synovial fluid

A

Secreted by the synovium, aid in motion by lubricating the joint

85
Q

Synovium

A

Layer of soft tissue that secretes synovial fluid

86
Q

Articular cartilage

A

What each bone in a joint is coated in to aid in movement and provide cushioning

87
Q

Antagonistic pairs

A

Pairs of muscles that serve opposite functions, when one muscle contracts, another lengthens

88
Q

Red marrow

A

Filled with hematopoietic stem cells, responsible for the generation of all the cells in our body

89
Q

Yellow marrow

A

Composed of primarily fat, is relatively inactive

90
Q

Bone marrow

A

Fills cavities between trabeculae in spongy bone, can be either red or yellow

91
Q

Long bones

A

Common the appendicular skeleton, characterized by diaphyses that swell into metaphases and terminate in epiphyses

92
Q

Haversian canals

A

Longitudinal canals (axis parallel to the bone), contain blood vessels, nerve fibers, lymph vessels

93
Q

Volkmanns canals

A

Transverse canals (axis perpendicular to the bone), contain blood vessels, nerve fibers, lymph vessels

94
Q

Sutures

A

Bones that are fused together in immovable joints

95
Q

Origin

A

The end of the muscle with a larger attachment to bone, usually the proximal connection

96
Q

Insertion

A

The end of the muscle with the smaller attachment to bone, usually the distal connection

97
Q

Synergistic muscles

A

Muscles that work together to accomplish the same function

98
Q

Flexor

A

A muscle that decreases the angle across a joint

99
Q

Extensor

A

A muscle that increases the angle across a joint

100
Q

Abductor

A

A muscle that moves a part of the body away from the midline

101
Q

Adductor

A

A muscle that moves a part of the body toward the midline

102
Q

Medial rotation

A

Rotates the axis of the limb toward the midline

103
Q

Material rotation

A

Rotates the axis of the limb away from the midline

MCAT (67 decks)

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