Ch. 11: The Musculoskeletal System Flashcards
(160 cards)
1
Q
what are the 3 types of muscle?
A
- skeletal
- smooth
- cardiac
2
Q
main funcs (3): skeletal muscle
A
- supporting the body and facilitating movement
- contraction compresses venous structures and helps propel blood through the low-pressure venous system toward the hear, as well as lymph through the lymphatic system
- rapid contraction leads to shivering (thermoregulation)
3
Q
main funcs (2): smooth muscle
A
- responsible for involuntary movement (i.e. peristalsis)
- aids in the regulation of blood pressure by constricting and relaxing the vasculature
4
Q
main func: cardiac muscle
A
able to maintain rhythmic contraction of the heart without nervous system input
5
Q
what are characteristics true of all types of muscle?
A
- capable of contraction, which relies on calcium ions
- innervated (although the part of the nervous system that does the innervating and the abilities of the muscle without nervous input varies)
6
Q
what part of the nervous system is skeletal muscle innervated by?
A
the somatic nervous system
7
Q
defn: sarcomeres
A
repeating units of arranged actin and myosin
8
Q
what impact do sarcomeres have on the impact of how skeletal muscle appears?
A
its appears striped or striated when viewed microscopically
9
Q
why is skeletal muscle multinucleated?
A
it is formed as individual muscle cells fuse into long rods during development
10
Q
char (3) + aka: red fibers
A
aka: slow-twitch fibers
- high myoglobin content
- primarily derive their energy aerobically
- contain many mitochondria to carry out ox phos
11
Q
defn + impact on red fibers: myoglobin
A
an oxygen carrier that uses iron in a heme group to bind oxygen, imparting a red color
12
Q
char (3) + aka: white fibers
A
aka: fast-twitch fibers
- contain much less myoglobin
- and therefore less iron
- and therefore lighter color
13
Q
functionality in muscles: red vs. white
A
MOSTLY RED = muscles that contract slowly, but can sustain activity
MOSTLY WHITE = muscles that contract rapidly
14
Q
why is poultry a great example of the difference between red and white fibers?
A
muscles of support (the thigh) = dark meat = high concentration of red fibers
rapid use muscles (the pec, breast, used for short bursts of flight) = white meat = high concentration of white fibers
15
Q
what part of the nervous system is smooth muscle controlled by?
A
the autonomic nervous system
16
Q
where is smooth muscle located? (6)
A
- respiratory tree
- digestive tract
- bladder
- uterus
- blood vessel walls
- others
17
Q
char (3): smooth muscle
A
- have a single nucleus located in the cell’s center
- contain actin and myosin, but not as well organized, so there are no striations
- capable of more sustained contractions
18
Q
defn + example: tonus
A
a constant state of low-level contraction
may be seen in blood vessels
19
Q
defn: myogenic activity
A
smooth muscle can contract WITHOUT nervous system input
so the muscle cells contract directly in response to stretch or other stimuli
20
Q
what 2 types of muscle exhibit myogenic activity?
A
- smooth
- cardiac
they respond to nervous input, but do not require external signals to contract
21
Q
char (6): cardiac muscle
A
- has characteristics of smooth and skeletal muscle types
- primarily uninucleated, but cells MAY contain 2 nuclei
- contraction is involuntary (like smooth)
- innervated by the autonomic nervous system (like smooth)
- appears striated (like skeletal)
- able to define and maintain their own rhythm
22
Q
what is a unique characteristic of cardiac muscle? explain how this works (3)
A
how each cardiac myocyte communicates
explanation: 1. cardiac muscle cells are connected by intercalated discs, which have many gap junctions
- these gap junctions are connections between the cytoplasm of adjacent cells, allowing for the flow of ions directly between cells
- this allows for rapid and coordinated depolarization of muscle cells and efficient contraction of cardiac muscle
23
Q
explain the pathway through cardiac muscle cells (3)
A
- starting at the sinoatrial (SA) node, depolarization spreads using conduction pathways to the atrioventricular (AV) node
- the depolarization spreads to the bundle of His and its branches
- then to the Purkinje fibers
24
Q
what do gap junctions allow for in cardiac muscle cells?
A
progressive depolarizations to spread via ion flow across the gap junctions between cells
25
how do the nervous and endocrine systems also play a role in the regulation of cardiac muscle contraction? (3)
1. the vagus nerve provides parasympathetic outflow to the heart and slows the heart rate
2. norepinephrine from sympathetic neurons or epinephrine from the adrenal medulla binds to adrenergic receptors in the heart, causing an increased heart rate and greater contractility
3. epinephrine does this by increasing intracellular calcium levels within cardiac myocytes
26
table: main characteristics of each type of muscle
27
defn + char: sarcomere
the basic contractile unit of skeletal muscle
char: made of thick and thin filaments
28
defn: thick filaments
organized bundles of myosin
29
defn: thin filaments
made of actin along with 2 other proteins (troponin and tropomyosin)
30
func: troponin and tropomyosin
help to regulate the interaction between the actin and myosin filaments
31
defn + func: titin
a protein
acts as a spring and anchors the actin and myosin filaments together, preventing excessive muscle stretching
32
mnemonic: which filament is associated with troponin and tropomyosin
actin has a T in it
33
what are the segments of each sarcomere? (5) + diagram
1. Z-lines
2. M-line
3. I-band
4. H-zone
5. A-band
34
defn: Z-lines
define the boundaries of each sarcomere
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defn: M-line
runs down the center of the sarcomere, through the middle of myosin filaments
36
defn: I-band
the region containing exclusively thin filaments
37
defn: H-zone
contains only thick filaments
38
defn: A-band
contains the thick filaments in their entirety, including any overlap with thin filaments
39
what happens to each of the segments of the sarcomere during contraction?
the H-zone, I-band, the distance between the Z-lines, and the distance between M-lines all become smaller
A-band's size is constant
40
mnemonic: which is the thin and thick filament
acthin --> actin filaments are thin
myosin filaments are thick
41
defn: myofibrils
sarcomeres attached end to end
42
defn + func: sarcoplasmic reticulum (SR)
func: surrounds myofibrils
a modified endoplasmic reticulum that contains a high concentration of Ca2+ ions
43
defn: sarcoplasm
a modified cytoplasm located just outside the sarcoplasmic reticulum
44
defn + func: sarcolemma
the cell membrane of a myocyte
func: capable of propagating an action potential and can distribute the action potential to all sarcomeres in a muscle
45
how is the sarcolemma capable of distributing the action potential to all sarcomeres?
using a system of transverse tubules (T-tubules) that are oriented perpendicularly to the myofibrils
46
char + aka: myocyte
each myocyte (muscle cell) contains many myofibrils arranged in parallel and can also be called a muscle fiber
the nuclei (many) are usually at the periphery of the cell
47
what forms a muscle?
many myocytes in parallel
48
diagram + summary: architecture of skeletal muscle
a muscle is composed of parallel myocytes (muscle fibers), which are composed of parallel myofibrils
49
mnemonic: parts of the sarcomere
Z - Z is the end of the alphabet, and the end of the sarcomere
M - Middle of the Myosin filaments
I - I is a thin letter (thin filaments only)
H - H is a thick letter (thick filaments only)
A - All of the thick filament, whether or not it is overlapping
50
what 2 things does muscle contraction depend on?
1. ATP
2. calcium
51
explain the initiation steps of muscle contraction (8) + diagram
1. contraction starts at the neuromuscular junction, where the nervous system communicates with muscles via motor (efferent) neurons
2. this signal travels down the neuron until it reaches the nerve terminal (synaptic bouton), where ACh is released into the synapse
3. ACh binds to receptors on the sarcolemma, causing depolarization
4. depolarization triggers an action potential, which spreads down the sarcolemma to the T-tubules
5. the action potential travels down the T-tubules into the muscle tissues to the sarcoplasmic reticulum
6. when the action potential reaches the SR, Ca2+ is ultimately released
7. the calcium ions bind to a regulatory subunit in troponin, triggering a change in the confirmation of tropomyosin, to which troponin is bound
8. this change exposes the myosin-binding sites on the actin thin filament
52
defn: motor end plate
in the case of the neuromuscular junction, this is what the nerve terminal is called
53
each nerve terminal controls what?
a group of myocytes
54
defn: motor unit
the nerve terminal and its myocytes together
55
explain the shortening of the sarcomere steps of muscle contraction (2 summary steps)
1. the free globular heads of the myosin molecules move toward and bind with the exposed sites on actin
2. the newly formed actin-myosin cross bridges then allow myosin to pull on actin, which draws the thin filaments toward the M-line, resulting in sarcomere shortening
56
explain the actin-myosin cross-bridge cycle of sarcomere shortening of muscle contraction + diagram (the sliding filament model) (5)
1. myosin carrying hydrolyzed ATP (ADP and an inorganic phosphate, Pi) is able to bind with the myosin-binding site
2. the release of the inorganic phosphate and ADP in rapid succession provides the energy for the powerstroke and results in sliding of the actin filament over the myosin filament
3. then ATP binds to the myosin head, releasing it from actin
4. this ATP is hydrolyzed to ADP and Pi, which recocks the myosin head so that it is in position to initiate another cross-bridge cycle
5. the repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along the thick filament, causing sequential sarcomere shortening
57
diagram: sarcomere contraction
58
what is responsible for the powerstroke? what is NOT responsible for the powerstroke?
IS: the dissociation of ADP and Pi from myosin
NOT: the hydrolysis of ATP
59
what is required for releasing the myosin head from the actin filament?
the binding of ATP
60
explain the relaxation steps of muscle contraaction (5)
1. ACh is degraded in the synapse by enzyme acetylcholinesterase
2. this results in termination of the signal at the neuromuscular junction and allows the sarcolemma to repolarize
3. As the signal decays, calcium releases ceases and the SR takes up calcium from the sarcoplasm
4. ATP binds to the myosin heads, freeing them from actin
5. once the myosin and actin disconnect, the sarcomere can return to its original width
61
why does the SR tightly control intracellular calcium concentrations?
so that muscles are contracted only when necessary
62
what happens without calcium? (2)
1. the myosin-binding sites are covered by tropomyosin
2. contraction is prevented
63
what causes rigor mortis? (2)
1. After death, ATP production ceases
2. Myosin heads cannot detach from actin, making it impossible for muscles to relax and lengthen
64
do muscle cells exhibit an all-or-nothing response? can the strength of a response from one muscle cell be changed?
yes! either they respond completely to a stimulus or not at all
the strength of a response from one muscle cell cannot be changed because the only options are all or nothing
65
what must be true for muscle cells to respond?
stimuli must reach a threshold value
66
how do nerves control overall force of muscle contraction?
by the number of motor units they recruit to respond
67
when does maximal muscle response occur?
when all fibers within a muscle are stimulated to contract simultaneously
68
WHY do muscle fibers contract in an all or nothing fashion?
they are innervated by neurons that deliver signals using action potentials, which are all-or-nothing phenomena as well
69
defn: simple twitch
the response of a single muscle fiber to a brief stimulus at or above threshold
70
what are the 3 periods of a simple twitch?
1. latent period
2. contraction period
3. relaxation period
71
defn + what happens during this time (3): latent period
the time between reaching threshold and the onset of contraction
1. during this time, the action potential spreads along the muscle and allows for calcium to be released from the sarcoplasmic reticulum
2. the muscle then contracts, and 3. assuming calcium is cleared from the sarcoplasm, it then relaxes
72
defn (2): frequency summation
1. if a muscle fiber is exposed to frequent and prolonged stimulation, it will have insufficient time to relax
2. the contractions will combine, become stronger and more prolonged
73
defn: tetanus
if the contractions from frequency summation become so frequent that the muscle is unable to relax at all
74
what does prolonged tetanus result in?
muscle fatigue
75
does tetanic physiology only occur with tetanus the disease?
no, tetanus the disease includes tetanus the physiological phenomenon but tetanic physio also occurs under normal circumstances with multiple switch twitches in succession
76
diagram: force of muscle contraction due to a simple twitch vs. tetanus
77
what are the 2 supplemental energy reserves in muscle?
1. creatine phosphate
2. myoglobin
78
how is creatine phosphate created? how does this come into use during muscle use?
by transferring a phosphate group from ATP to creatine during times of rest
this reaction can then be reversed during muscle use to quickly generate ATP from ADP
79
func: myoglobin
binds oxygen with high affinity
as exercising muscles run out of oxygen, they use myoglobin reserves to keep aerobic metabolism going
80
what do fast-twitch (white) muscles fibers use to make ATP under most circumstances? why?
glycolysis and fermentation
because they have fewer mitochondria
81
what happens when a person exercises? (4)
1. heart rate and respiratory rate increase in order to move more oxygen to actively respiring muscles
2. the oxyhemoglobin dissociation curve undergoes a right shift the presence of increased CO2 concentration, increased hydrogen ion concentration (decreased pH) and increased temperature
3. even with these adaptations, muscle use can quickly overwhelm the ability of the body to deliver oxygen
4. then, even red muscle fibers must switch to anaerobic metabolism and produce lactic acid, at which point the muscle begins to fatigue
82
defn: oxygen debt
the difference between the amount of oxygen needed by the muscles and the actual amount present
83
what happens after strenuous exercise stops?
1. the body must metabolize all of the lactic acid it has produced
2. most lactic acid is converted back into pyruvate, which can enter the TCA cycle
3. this process requires oxygen and the amount of oxygen required to recover from strenuous exercise is equal to the oxygen debt
84
char: endoskeleton (4) vs. exoskeletons (3)
EXOSKELETONS:
1. encase whole organisms
2. usually found in arthropods (crustaceans, insects)
3. must be shed and regrown to accommodate growth
ENDOSKELETONS:
1. found in vertebrates, including humans
2. internal
3. not able to protect the soft tissue structures as well as exoskeletons
4. much better able to accommodate the growth of a larger organism
85
components (4) + func: axial skeleton
1. skull
2. vertebral column
3. rib cage
4. hyoid bone (a small bone in the anterior neck used for swallowing)
func: provides the basic central framework for the body
86
components (bone groups: 3): appendicular skeleton
1. bones of the limbs (humerus, radius and ulna, carpals, metacarpals, and phalanges in the upper limb; femur, tibia, fibula, tarsals, metatarsals, and phalanges in the lower land)
2. pectoral girdle (scapula and clavicle)
3. pelvis
87
what 3 other structures are both skeleton types covered by?
1. muscle
2. connective tissue
3. vasculature
88
how many bones does an adult human have?
206
89
how many bones are there in the hands and feet?
over 100
90
what are the 2 major components that the skeleton is created from?
1. bone
2. cartilage
91
defn: bone
a connective tissue derived from embryonic mesoderm
92
what are the 2 types of bone?
1. compact bone
2. spongy (cancellous) bone
93
where does bone's characteristic strength come from?
compact bone
94
char (3): compact bone
1. dense
2. strong
3. composes the outermost portions of bone
95
char (3): spongy bone
1. lattice structure visible under microscopy
2. consists of bony spicules (points) known as trabeculae
3. composes the internal core of bones
96
what fills the cavities between trabeculae?
bone marrow
97
composition + function: red marrow vs. yellow marrow
RED MARROW: filled with hematopoietic stem cells --> responsible for the generation of all cells in our blood
YELLOW MARROW: composed primarily of fat --> relatively inactive
98
what types of bones are typically in the appendicular skeleton?
long bones
99
defn: long bones
cylindrical shafts called diaphyses that swell at each end to form metaphyses and that terminate in epiphyses
100
what is inside long bone diaphyses and metaphyses vs. epiphyses
diaphyses and metaphyses: full of bone marrow
epiphyses: spongy cores
101
what is the function of the spongy cores of long bone epiphyses?
for more effective dispersion of force and pressure at the joints
102
diagram: anatomy of a long bone
103
defn + location: epiphyseal (growth) plate
a cartilaginous structure and the site of longitudinal growth
at the internal edge of the epiphysis
104
what happens to the epiphyseal growth plate prior to adulthood? during puberty?
prior to adulthood: it is filled with mitotic cells that contribute to growth
during puberty: they close and vertical growth is halted
105
defn: periosteum
a fibrous sheath that surrounds the long bone to protect it as well as serve as a site for muscle attachment
106
what are some periosteal cells capable of differentiating into?
bone-forming cells
107
what is a healthy periosteum needed for?
necessary for bone growth and repair
108
what are the 2 types of dense connective tissue and what is their function in the musculoskeletal system (overall + individual)?
1. tendons (attach muscle to bone)
2. ligaments (hold bones together at joints to stabilize joints)
hold together structures in the musculoskeletal system
109
what does the strength of compact bone come from?
the bone matrix
110
what are the organic components of the bone matrix? (3)
what are the inorganic components of the bone matrix? (3)
ORGANIC: 1. collagen
2. glycoproteins
3. other peptides
INORGANIC: 1. calcium ions
2. phosphate ions
3. hydroxide ions
111
what do calcium, phosphate, hydroxide ions harden together to form?
hydroxyapatite crystals (Ca10(PO4)6(OH)2)
112
what 3 minerals are also stored in bones?
1. sodium
2. magnesium
3. potassium
113
what does strong bone require in terms of its structure?
uniform distribution of organic and inorganic materials
114
defn: osteons or Haversian systems
structural units that the bony matrix is ordered into
115
structure: osteon
each osteon contains concentric circles of bony matrix called lamellae surrounding a central microscopic channel
116
defn: Haversian canals vs. Volkmann's canals
Haversian: longitudinal channels (those with an axis parallel to the bone)
Volkmann's: transverse channels (those with an axis perpendicular to the bone)
117
what do the bone's canals contain? (3)
the blood vessels, nerve fibers, and lymph vessels that maintain the health of the bone
118
defn + func: lacunae
defn: small spaces between lamellar rings
func: house mature bone cells (osteocytes)
119
defn + func: canaliculi
tiny channels that interconnect lacunae
func: allow for the exchange of nutrient and wastes between osteocytes and the Haversian and Volkmann's canals
120
diagram: bone matrix showing haversian systems
121
explain how bone is actually quite dynamic (3)
1. it is vascular
2. it is innervated (which is why it hurts so much to break a bone)
3. it remains in a vigorous equilibrium between construction and destruction (bone remodeling)
122
what group of cell type do osteoblasts and osteoclasts fit into?
the cells that are largely responsible for building and maintaining strong bones
123
defn: osteoblasts vs. osteoclasts
osteoBLASTS: build bone
osteoCLASTS: resorb bone
124
defn: osteoclasts
polynucleated resident macrophages of bone
125
what happens to calcium and phosphate ions during bone formation? during bone resorption?
FORMATION: they are obtained from the blood
RESORPTION: they are released back into the bloodstream
126
what does bone remodeling occur in response to?
stress
bone remodels in such a way as to accommodate the repetitive stresses faced by the body
127
what 3 endocrine hormones affect bone metabolism?
1. parathyroid hormone
2. vitamin D
3. calcitonin
128
defn + role in bone metabolism: parathyroid hormone
a peptide hormone released by the parathyroid glands in response to low blood calcium, promotes resorption of bone, increasing the concentration of calcium and phosphate in the blood
129
role in bone metabolism: vitamin D
activated by parathyroid hormone
promotes bone resorption (which encourages the growth of new, stronger bone, overcompensating for the effect of resorbing bone in the first place)
130
defn + role in bone metabolism: calcintonin
a peptide hormone released by the parafollicular cells of the thyroid in response to high blood calcium, promotes bone formation, lowering blood calcium levels
131
diagram: bone remodeling
132
what is the cause of osteoporosis?
it is the result of increased osteoclast resorption and some concomitant slowing of bone formation, both of which leads to loss of bone mass
133
why is estrogen believed to help prevent osteroporosis?
by stimulating osteoblast activity
134
mnemonic: osteoblasts vs. osteoclasts
osteoBlasts Build bone
osteoClasts Chew bone
135
defn: chondrin
a firm but elastic matrix that makes up cartilage
136
defn: chondrocytes
cells that secrete chondrin
137
why is it advantageous that fetal skeletons are mostly made up of cartilage?
because fetuses must grow and develop in a confined environment and then traverse the birth canal
138
what parts of the body do adults have cartilage? (group + 5 individual)
body parts that need extra flexibility or cushioning
1. external ear
2. nose
3. walls of the larynx and trachea
4. intervertebral discs
5. joints
139
how else does cartilage differ from bone?
it is avascular (without blood and lymphatic vessels) and is not innervated
140
defn + func: endochondral ossification
the hardening of cartilage into bone
func: responsible for the formation of most of the long bones of the body
141
defn + what bones does this occur with: intramembranous ossification
another way of forming bones
undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into and replaced by bone
occurs in bones of the skull
142
what are joints made of?
connective tissue
143
what are the 2 types of joints?
immovable
movable
144
defn + location + func: immovable joints
consist of bones that are fused together to form sutures or similar fibrous joints
found primarily in the head
anchor bones of the skull together
145
what are 2 types of movable joints + what joints fall into this?
1. hinge joints (elbow, knee)
2. ball-and-socket joints (shoulder, hip)
146
char (3): movable joints
1. permit bones to shift relative to one another
2. strengthened by ligaments
3. consists of a synovial capsule (which encloses the actual joint cavity (articular cavity)
147
defn + func: synovium
defn: a layer of soft tissue
func: secretes synovial fluid
148
func: synovial fluid
lubricates the movement of structures in the joint space
149
func: articular cartilage
contributes to the joint by coating the articular surfaces of the bones so that impact is restricted to the lubricated joint cartilage rather than to the bones
150
diagram: structures of a movable joint
151
what happens when a muscle that is attached to 2 bones contracts?
it will cause one of the bones to move
152
defn: origin vs. insertion
ORIGIN = the end of the muscle with a larger attachment to bone (usually the proximal connection)
INSERTION = the end of the muscle with a smaller attachment to bone (usually the distal connection)
153
what does it mean that our muscles often work in antagonistic pairs? + example
one relaxes while the other contracts
example:
bicep contracts, tricep relaxes: elbow is flexed
tricep contracts, bicep relaxes: elbow is extended
154
defn: synergistic muscles
they work together to accomplish the same function
155
defn: flexor muscle
decreases the angle across the joint
156
defn: extensor muscle
increases or straightens the angle across the joint
157
defn: abductor
moves a part of the body away from the midline
158
defn: adductor
moves a part of the body toward the midline
159
defn: medial rotator
rotates the axis of the limb toward the midline
160
defn: lateral rotator
rotates the axis of the limb away from the midline
