MCAT Biology Ch6: The Musculoskeletal System Flashcards
(137 cards)
1
Q
skeletal system
A
-skeleton derived from mesoderm
2
Q
two types of skeleton
A
exoskeletons and endoskeletons
3
Q
exoskeletons
A
- encase whole organism
- protect but organism growth requires shedding
4
Q
endoskeletons
A
- vertebrates
- don’t protect surfaces and organs as well as exo but don’t shed
5
Q
components of skeletal system divded into
A
axial and appendicular
both covered by other structures (muscle, conn. tissue, and vasculature)
6
Q
axial
A
-skull, vertebral column, ribcage
basic central framework
overall shape
7
Q
appendicular
A
arms, legs, and pelvic and pectoral girdle attached to axial skeleton for stability
depend on axial for attachment
8
Q
skeleton created from two major components
A
cartilage and bone
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
10
Q
chondrocytes
A
secretes chondrin
11
Q
chondrin
A
firm (but elastic) matrix that’s secreted by chondrocytes
12
Q
bone
A
-composed of conn. tissue derived from embryonic mesoderm
harder than cartilage
lightweight
vascular and innervated
13
Q
macroscopic bone structure
A
transplanted cells in hip marrow
14
Q
compact bone (macroscopic bone structure)
A
- strength from here
- strong and compact
15
Q
spongy or cancellous bone (macroscopic bone structure)
A
-lattice structure
consists of trabeculae
16
Q
trabeculae
A
spongy bone consists of this bony spicules (points)
cavities filled w/ bone marrow (red or yellow)
17
Q
bone marrow
A
filled cavities of trabculae of spongy bone
18
Q
red marrow
A
filled w/ hematopoietic stem cells
responsible for generation of all cells in our blood
19
Q
yellow marrow
A
composed primarily of fat and relatively inactive
20
Q
long bones
A
bones in appendicular skeleton typically this
characterized by diaphyses and epiphyses
21
Q
diaphyses
A
cylindrical shafts that characterize long bones
peripheries composed of compact bone
internal core full of marrow
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
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.
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
25
microscopic bone structure
bone matrix
26
bone matrix
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
27
organic components of bone matrix
collagen, glycoproteins, and other peptides
28
inorganic components of bone matrix
Ca, phosphate, OH ions => harden =? hydroxypatite crystals
29
osteons or Haversian systems
bony matrix similarly ordered into structural units
each encircles central Haversian canal
center
30
Haversian canal
each osteon encircles this
surrounded by lamellae
contain blood vessels, nerve fibers, and lump, keep bone in peak condition
31
lamellae
concentric circles of bony matrix
surround Haversian canal
rings in tree not touching
32
lacunae
spaces interspersed w/in matrix
house osteocytes
33
osteocytes
mature bone cells
housed in lacunae
34
two ways of bone formation (ossification)
endochondral ossification and membranous ossification
35
endochondral ossification
most of bones (long)
hardening of cartilage
36
intramembranous ossification
mesenchymal tissue transformed into, and replaced by bone
37
mesenchymal tissue
undifferentiated embryonic connective tissue is transformed into, and replaced by bone
38
bone remodeling
vig. eq. between construction and destruction
endocrine hormones like parathyroid and calcitonin involved in remodeling
39
two players of bone remodeling
osteoclasts and osteoblasts
both contribute to constant maintenance of bone
40
osteoclasts
destroy or resorb bone
41
osteoblasts
build bone
42
bone reformation
like Ca, Phosphate, obtained from blood
43
bone resorption (breakdown)
ions released into bloodstream
44
osteoporosis
inc. osteoclast resorption and slowing bone formation => loss of bone mass => estrogen stimulate osteoblast
45
joints
made of conn tissue
46
two major varieties of joints
movable and immovable
47
movable joints
allow bone to shift relative to another (knees, elbows)
strengthened by ligaments
consist of synovial capsule
48
ligaments
pieces of fibrous tissue the connect bones to one another
49
synovial capsule
encloses actual joint cavity (articular cavity)
50
articular cavity/joint cavity
synovial capsule encloses this
51
synovial fluid
use since all structure of joints are solid => ease movement
lubricant
52
articular cartilage
coats articular surfaces of bones => impact restricted to lubricated joint cartilage rather than bones
53
immovable joints
not want move
ex: skull
54
3 varieties of muscles
skeletal, smooth, cardiac
55
skeletal muscle
-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
somatic
skeletal muscle innervated by this
57
sarcomere
basic contract unit of a muscle
58
myofibrils
-sarcomeres put together end by end
59
sacroplasmic reticulum
myofibril surrounded by this
modified ER, containing a great deal Ca2+, tightly controls so muscle contract when necessary
60
sacroplasm
outside the sacroplasmic reticulum
modified cytoplasm in cells
61
myocyte
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
muscle
parallel arrangement of myocytes
63
sacrolemma
cell membrane
can propagate action potential
system of t-tubules connect to this and are perpendicular to myofibrils => ions flow
64
t tubules
system of this connect to sacrolemma and are perpendicular to myofibrils => ions flow
65
red fibers
have high myoglobin content
derive energy aerobically
slow twitch
mito-rich
66
myoglobin
sim. to hemoglobin
consists of single pp chain
binds to o2 more tightly
67
white fibers
fast twitch
anaerobic
less myoglobin
don't ETC => mito poor
contract more easily => easier to fatigue
68
sarcomere structure
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
thick filaments
organized bundle of myosin
70
thin filaments
made up of actin along w/ two other proteins, troponin and tropomyosin
71
myosin
thick filaments organized bundle of this
72
actin
thin filaments made up of this
73
troponin and tropomyosin
along w/ actin, make up thin filaments
74
Z lines (sarcomere)
boundaries of each sarcomere
responsible for striated nature of skeletal and cardiac muscles)
75
M lines (sarcomere)
runs down sarcomere
76
I band (sarcomere)
region of thin filaments
77
H zone
contains thick filaments
78
A band
thick filaments in entirety, including any overlap w/ thin filaments
79
sarcomere contraction
series of coordinated steps repeated to induce further shortening
80
sarcomere contraction: initiation
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
motor neuron
nervous system send signal via a motor neuron to nerve terminal
82
nerve terminal (synaptic button)
receives signal from nervous system send signal via a motor neuron
releases neurotransmitter (acetylcholine) into synapse
83
synapse
releases neurotransmitter (acetylcholine) into synapse from nerve terminal (synaptic button)
binding neurotransmitter to receptor on muscle => contraction
84
neuromuscular junction
connection between nerve and muscle
85
sarcomere contraction: shortening of sarcomere
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
myosin-binding sites
exposed when Ca binds to troponin => tropomyosin shift
87
sarcomere contraction: relaxation
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
ATP
used for both contraction and release of muscle fibers
89
Muscle Response
stimulus coupled to
90
stimulus intensity
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
all or none
innevated by neurons whose basic signal is an action potential => response of muscle cells, completely or not at all
92
threshold value
stimuli must reach this
93
tonus
muscles in constant state of low-level contraction
essential for voluntary and involuntary muscles
94
simple twitch
response of single muscle fiber to brief stimulus at or above the threshold
consists of latent, contraction, and relaxation period
95
3 period of simple twitch
consists of latent, contraction, and relaxation period
96
latent period
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
refractory period
after period, muscle will be unresponsive stimuli following Ca released from SR
98
two types of refractory period
absolute and relative
99
absolute refractory period
no amount of stimulus (sister poking) will give response since muscle is restoring its resting potential
100
relative refractory period
muscle can be activated but w/ higher stimulus
101
summation and tetanus
muscle fiber freq. and prolonged stimulation => not relax => contractions combine => stronger and prolonged => tetanus
102
frequency summation
contractions combine => stronger and prolonged
103
tetanus
contraction so freq => no time relax
stronger than simple muscle fiber twitch
prolonged => muscle fatigue
104
smooth muscle
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
autonomic nervous system
smooth muscle controlled by this
106
myogenic activity
muscles can contract w/o nervous system, will respond, but not require external signals to contract
107
cardiac muscle
prop of both smooth and skeletal
involuntary
striated
Ca
may myogenic activity
108
Energy reserves
creatine phosphate and myoglobin
109
creatine phosphate
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
myoglobin
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
connective tissue
bind and support other tissues
holds body together
sparsely scattered population of cells in amorphous ground substance may be liquid, jellylike, or solid
112
two types of connective tissue
loose and dense
113
loose connective tissue
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
proteinaceous fibers of 3 types:
collagenous, elastic, and reticular fibers
115
collagenous fiber
composed of collagen
great tensile strength
116
elastic fiber
composed of elastin
give conn. tissue w/ resilience
117
reticular fiber
branched, tightly woven fibers that join conn. tissue to adjoining tissue
118
two cell types of loose conn. tissue
fibroblasts and macrophages
119
fibroblast
secrete components of extracellular fibers
120
macrophage
engulf bacteria and dea cells via phagocytosis
121
dense conn. tissue
high prop. of collagenous fibers => organized into parallel bundles => great tensile strength
forms tendons and ligaments
122
tendons
attach muscle to bone
123
ligaments
holds bones together at joints
124
muscle-bone interaction
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
origin
end of muscle attached to stationary bone called this
limb muscles => proximal end
126
proximal end
in limb muscles, this is origin
127
insertion
end of muscle attached to bone that moves during contraction
limb muscles => distal end
128
distal end
in limb muscles, this is insertion
129
synergistic muscle
assist principal muscles during movement
130
flexor
muscle contract => dec. angle of joint
131
extensor
muscle contract => straight joint
132
abductor
moves part of body away from body's midline
133
adductor
moves part of body away toward body's midline
134
osteoblasts
bone cells involved in secretion of bone matrix
135
osteoclasts
large, multinucleated cells involved in bone resorption
136
osteocytes
mature osteoblasts that eventually became surrounded by matrix and primary role in bone maintenance
137
intramembraneous ossification
where mesenchymal cells directly create bone matrix
