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MCAT - Biology > MCAT Biology Ch6: The Musculoskeletal System > Flashcards

MCAT Biology Ch6: The Musculoskeletal System Flashcards

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1
Q

skeletal system

A

-skeleton derived from mesoderm

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2
Q

two types of skeleton

A

exoskeletons and endoskeletons

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3
Q

exoskeletons

A
  • encase whole organism

- protect but organism growth requires shedding

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4
Q

endoskeletons

A
  • vertebrates

- don’t protect surfaces and organs as well as exo but don’t shed

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5
Q

components of skeletal system divded into

A

axial and appendicular

both covered by other structures (muscle, conn. tissue, and vasculature)

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6
Q

axial

A

-skull, vertebral column, ribcage

basic central framework

overall shape

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7
Q

appendicular

A

arms, legs, and pelvic and pectoral girdle attached to axial skeleton for stability

depend on axial for attachment

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8
Q

skeleton created from two major components

A

cartilage and bone

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9
Q

cartilage

A

softer and more flexible than bone

consists of chondrin, that’s secreted by chondrocytes

much fetal skeleton made out of this => calcify to bone => adult have only body parts that need little extra flexibility (external ear, nose, walls of larnyx and trachea, and joints) => degradation (old age) => lack of cartilage in joints => bones rub against each other => arthritis

relatively avascular (w/o blood and lymphatic vessels) and no innervated

nonarticular kind can grow and repair throughout life

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10
Q

chondrocytes

A

secretes chondrin

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11
Q

chondrin

A

firm (but elastic) matrix that’s secreted by chondrocytes

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12
Q

bone

A

-composed of conn. tissue derived from embryonic mesoderm

harder than cartilage

lightweight

vascular and innervated

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13
Q

macroscopic bone structure

A

transplanted cells in hip marrow

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14
Q

compact bone (macroscopic bone structure)

A
  • strength from here

- strong and compact

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15
Q

spongy or cancellous bone (macroscopic bone structure)

A

-lattice structure

consists of trabeculae

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16
Q

trabeculae

A

spongy bone consists of this bony spicules (points)

cavities filled w/ bone marrow (red or yellow)

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17
Q

bone marrow

A

filled cavities of trabculae of spongy bone

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18
Q

red marrow

A

filled w/ hematopoietic stem cells

responsible for generation of all cells in our blood

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19
Q

yellow marrow

A

composed primarily of fat and relatively inactive

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20
Q

long bones

A

bones in appendicular skeleton typically this

characterized by diaphyses and epiphyses

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21
Q

diaphyses

A

cylindrical shafts that characterize long bones

peripheries composed of compact bone

internal core full of marrow

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22
Q

epiphyses

A

dilated ends of long bones

peripheries composed of compact bone

internal core have spony bone core inside compact bone for dispersion of force at joints

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23
Q

epiphyseal plate

A

seperating diaphyses and epiphyses

cartilaginous structure and site of long. growth

seal due to sex hormone effects => growth continues through puberty until 25, although most down between onset of puberty and 18.

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24
Q

periosteum

A

fibrous sheath

surrounds long bone to protect and serve as muscle attachment

some able to differentiate into bone-forming cells

healthy one necessary for bone growth and repair

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25
Q

microscopic bone structure

A

bone matrix

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26
Q

bone matrix

A

strength of compact bone comes from here

organic and inorganic components

minerals like Na, Mg and K also stored in bone

strong bones require uniform dist’n of inorganic material (Haversian, lamellae, etc)

ordered into osteons or Haversian systems

interspersed w/in matrix are lacunae

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27
Q

organic components of bone matrix

A

collagen, glycoproteins, and other peptides

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28
Q

inorganic components of bone matrix

A

Ca, phosphate, OH ions => harden =? hydroxypatite crystals

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29
Q

osteons or Haversian systems

A

bony matrix similarly ordered into structural units

each encircles central Haversian canal

center

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30
Q

Haversian canal

A

each osteon encircles this

surrounded by lamellae

contain blood vessels, nerve fibers, and lump, keep bone in peak condition

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31
Q

lamellae

A

concentric circles of bony matrix

surround Haversian canal

rings in tree not touching

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32
Q

lacunae

A

spaces interspersed w/in matrix

house osteocytes

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33
Q

osteocytes

A

mature bone cells

housed in lacunae

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34
Q

two ways of bone formation (ossification)

A

endochondral ossification and membranous ossification

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35
Q

endochondral ossification

A

most of bones (long)

hardening of cartilage

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36
Q

intramembranous ossification

A

mesenchymal tissue transformed into, and replaced by bone

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37
Q

mesenchymal tissue

A

undifferentiated embryonic connective tissue is transformed into, and replaced by bone

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38
Q

bone remodeling

A

vig. eq. between construction and destruction

endocrine hormones like parathyroid and calcitonin involved in remodeling

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39
Q

two players of bone remodeling

A

osteoclasts and osteoblasts

both contribute to constant maintenance of bone

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40
Q

osteoclasts

A

destroy or resorb bone

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41
Q

osteoblasts

A

build bone

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42
Q

bone reformation

A

like Ca, Phosphate, obtained from blood

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43
Q

bone resorption (breakdown)

A

ions released into bloodstream

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44
Q

osteoporosis

A

inc. osteoclast resorption and slowing bone formation => loss of bone mass => estrogen stimulate osteoblast

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45
Q

joints

A

made of conn tissue

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46
Q

two major varieties of joints

A

movable and immovable

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47
Q

movable joints

A

allow bone to shift relative to another (knees, elbows)

strengthened by ligaments

consist of synovial capsule

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48
Q

ligaments

A

pieces of fibrous tissue the connect bones to one another

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49
Q

synovial capsule

A

encloses actual joint cavity (articular cavity)

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50
Q

articular cavity/joint cavity

A

synovial capsule encloses this

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51
Q

synovial fluid

A

use since all structure of joints are solid => ease movement

lubricant

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52
Q

articular cartilage

A

coats articular surfaces of bones => impact restricted to lubricated joint cartilage rather than bones

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53
Q

immovable joints

A

not want move

ex: skull

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54
Q

3 varieties of muscles

A

skeletal, smooth, cardiac

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55
Q

skeletal muscle

A

-innervated by somatic nervous sytem

striated, from alignment of Z-lines and inc. density to other structures

consist of red and white fibers

Ca

56
Q

somatic

A

skeletal muscle innervated by this

57
Q

sarcomere

A

basic contract unit of a muscle

58
Q

myofibrils

A

-sarcomeres put together end by end

59
Q

sacroplasmic reticulum

A

myofibril surrounded by this

modified ER, containing a great deal Ca2+, tightly controls so muscle contract when necessary

60
Q

sacroplasm

A

outside the sacroplasmic reticulum

modified cytoplasm in cells

61
Q

myocyte

A

muscle cell

many myofibrils contained w/in

most cells are multinucleate due to fusion of several embryonic uninucleate cells; nucleus usually found in periphery

62
Q

muscle

A

parallel arrangement of myocytes

63
Q

sacrolemma

A

cell membrane

can propagate action potential

system of t-tubules connect to this and are perpendicular to myofibrils => ions flow

64
Q

t tubules

A

system of this connect to sacrolemma and are perpendicular to myofibrils => ions flow

65
Q

red fibers

A

have high myoglobin content

derive energy aerobically

slow twitch

mito-rich

66
Q

myoglobin

A

sim. to hemoglobin

consists of single pp chain

binds to o2 more tightly

67
Q

white fibers

A

fast twitch

anaerobic

less myoglobin

don’t ETC => mito poor

contract more easily => easier to fatigue

68
Q

sarcomere structure

A

made thick and thin filaments

contraction => Hzone, I band, and distance between Z line become smaller, A band remains constant (defined as total length fibers)

69
Q

thick filaments

A

organized bundle of myosin

70
Q

thin filaments

A

made up of actin along w/ two other proteins, troponin and tropomyosin

71
Q

myosin

A

thick filaments organized bundle of this

72
Q

actin

A

thin filaments made up of this

73
Q

troponin and tropomyosin

A

along w/ actin, make up thin filaments

74
Q

Z lines (sarcomere)

A

boundaries of each sarcomere

responsible for striated nature of skeletal and cardiac muscles)

75
Q

M lines (sarcomere)

A

runs down sarcomere

76
Q

I band (sarcomere)

A

region of thin filaments

77
Q

H zone

A

contains thick filaments

78
Q

A band

A

thick filaments in entirety, including any overlap w/ thin filaments

79
Q

sarcomere contraction

A

series of coordinated steps repeated to induce further shortening

80
Q

sarcomere contraction: initiation

A

nervous system send signal via a motor neuron => signal down neuron until reaches nerve terminal (synaptic bouton) => release neurotransmitter (acetylcholine) into synapse => binding neurotransmitter to receptor on muscle => contraction

enough acetylcholine bind to muscle cell => muscle depolarize (action potential generation) => sarcolemma’s permeability will inc.

81
Q

motor neuron

A

nervous system send signal via a motor neuron to nerve terminal

82
Q

nerve terminal (synaptic button)

A

receives signal from nervous system send signal via a motor neuron

releases neurotransmitter (acetylcholine) into synapse

83
Q

synapse

A

releases neurotransmitter (acetylcholine) into synapse from nerve terminal (synaptic button)

binding neurotransmitter to receptor on muscle => contraction

84
Q

neuromuscular junction

A

connection between nerve and muscle

85
Q

sarcomere contraction: shortening of sarcomere

A

action potential along sarcolemma and T system => muscle fiber => massive release of Ca ions from SR => Ca binds to troponin => tropomyosin shift => expose myosin-binding sites on actin => free globular head myosin move and bind to exposed action => cross bridge allow action pull myosin => thin filaments to center of H zone => shorten sarcomere => ATPase activity in myosin give energy for power stroke => disso. of actin from myosin => myosin resets by binding to another molecule of ATP and free to bind another actin

86
Q

myosin-binding sites

A

exposed when Ca binds to troponin => tropomyosin shift

87
Q

sarcomere contraction: relaxation

A

when SR receptors not stimulated => Ca fall

product of ATP hydrolysis release from myosin during power stroke => new ATP molecule to bind => disso. of myosin from thin filament => sacromere original width

after death => ATP not produced =>myosin can’t detach from actin => muscle can’t relax = rigor mortis

88
Q

ATP

A

used for both contraction and release of muscle fibers

89
Q

Muscle Response

A

stimulus coupled to

90
Q

stimulus intensity

A

strength of indie response by muscle fiber can’t be adjusted, but muscle control overall force by # of fibers they recruit to respond => all fibers stimulated to contract same time => max response

91
Q

all or none

A

innevated by neurons whose basic signal is an action potential => response of muscle cells, completely or not at all

92
Q

threshold value

A

stimuli must reach this

93
Q

tonus

A

muscles in constant state of low-level contraction

essential for voluntary and involuntary muscles

94
Q

simple twitch

A

response of single muscle fiber to brief stimulus at or above the threshold

consists of latent, contraction, and relaxation period

95
Q

3 period of simple twitch

A

consists of latent, contraction, and relaxation period

96
Q

latent period

A

time between reaching threshold (enough pokes) and onset of contraction (getting punched)

this time => action potential spread along muscle => Ca released from SR => after period, muscle will be unresponsive stimuli

97
Q

refractory period

A

after period, muscle will be unresponsive stimuli following Ca released from SR

98
Q

two types of refractory period

A

absolute and relative

99
Q

absolute refractory period

A

no amount of stimulus (sister poking) will give response since muscle is restoring its resting potential

100
Q

relative refractory period

A

muscle can be activated but w/ higher stimulus

101
Q

summation and tetanus

A

muscle fiber freq. and prolonged stimulation => not relax => contractions combine => stronger and prolonged => tetanus

102
Q

frequency summation

A

contractions combine => stronger and prolonged

103
Q

tetanus

A

contraction so freq => no time relax

stronger than simple muscle fiber twitch

prolonged => muscle fatigue

104
Q

smooth muscle

A

responsible for involuntary action

controlled by ANS

digestive tract, bladder, uterus, blood vessels walls, and others

actin and myosin, not striated fashion

contract like skeletal, but can longer and more sustained contractions; myogenic activity

single centrally placed nuclei

Ca

105
Q

autonomic nervous system

A

smooth muscle controlled by this

106
Q

myogenic activity

A

muscles can contract w/o nervous system, will respond, but not require external signals to contract

107
Q

cardiac muscle

A

prop of both smooth and skeletal

involuntary

striated

Ca

may myogenic activity

108
Q

Energy reserves

A

creatine phosphate and myoglobin

109
Q

creatine phosphate

A

energy can be derived from this high-energy compound

time of plenty => store away by transfering phosphate from ATP to creatine; reverse during muscle use (ATP from ADP)

advantageous = immediate ATP making (otherwise from glycolysis or TCA)

110
Q

myoglobin

A

generate more energy aerobically => require oxygen

myoglobin in muscle binds o2 tight => when exercise, use if muscles run out of oxygen => exhaust, then ferment remaining pyruvate to regenerate NAD+ and start glycolysis again

lactic acid and fermentation converted back into energy producing intermediates once sufficient O2 available => cori cycle in liver

111
Q

connective tissue

A

bind and support other tissues

holds body together

sparsely scattered population of cells in amorphous ground substance may be liquid, jellylike, or solid

112
Q

two types of connective tissue

A

loose and dense

113
Q

loose connective tissue

A

throughout body

attaches epithelium to underlying tissue

material that holds organs in place

contain proteinaceous fibers of 3 types: collagenous, elastic, and reticular fibers

114
Q

proteinaceous fibers of 3 types:

A

collagenous, elastic, and reticular fibers

115
Q

collagenous fiber

A

composed of collagen

great tensile strength

116
Q

elastic fiber

A

composed of elastin

give conn. tissue w/ resilience

117
Q

reticular fiber

A

branched, tightly woven fibers that join conn. tissue to adjoining tissue

118
Q

two cell types of loose conn. tissue

A

fibroblasts and macrophages

119
Q

fibroblast

A

secrete components of extracellular fibers

120
Q

macrophage

A

engulf bacteria and dea cells via phagocytosis

121
Q

dense conn. tissue

A

high prop. of collagenous fibers => organized into parallel bundles => great tensile strength

forms tendons and ligaments

122
Q

tendons

A

attach muscle to bone

123
Q

ligaments

A

holds bones together at joints

124
Q

muscle-bone interaction

A

locomotion interactions

muscle (w/ asso. joints) attached two bones => contractiion => one of two bones move

one relax, one contracts

contraction of antagonistic muscle lengthen paired muscle => muscle elongation

125
Q

origin

A

end of muscle attached to stationary bone called this

limb muscles => proximal end

126
Q

proximal end

A

in limb muscles, this is origin

127
Q

insertion

A

end of muscle attached to bone that moves during contraction

limb muscles => distal end

128
Q

distal end

A

in limb muscles, this is insertion

129
Q

synergistic muscle

A

assist principal muscles during movement

130
Q

flexor

A

muscle contract => dec. angle of joint

131
Q

extensor

A

muscle contract => straight joint

132
Q

abductor

A

moves part of body away from body’s midline

133
Q

adductor

A

moves part of body away toward body’s midline

134
Q

osteoblasts

A

bone cells involved in secretion of bone matrix

135
Q

osteoclasts

A

large, multinucleated cells involved in bone resorption

136
Q

osteocytes

A

mature osteoblasts that eventually became surrounded by matrix and primary role in bone maintenance

137
Q

intramembraneous ossification

A

where mesenchymal cells directly create bone matrix

MCAT - Biology (16 decks)

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