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MCAT > Biology Ch 11. The Musculoskeletal System > Flashcards

Biology Ch 11. The Musculoskeletal System Flashcards

(103 cards)

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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
T-tubules
Transverse tubules - Connected to the sarcolemma and oriented perpendicular to the myofibrils, allowing the action potential to reach all parts of the muscle
26
Neuromuscular junction
Where muscle contraction begins, where the motor neuron releases acetylcholine binds to receptors on the sarcolemma, causing depolarization, signals from motor/efferent neurons
27
Muscle contraction
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
28
Sliding filament model
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
29
Muscle relaxation
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
30
Simple twitch
All or nothing response exhibited by muscle cells
31
Frequency summation
Addition of multiple simple twitches before the muscle has an opportunity to fully relax
32
Tetanus
A more prolonged and stronger contraction that occurs when simple twitches occurs so frequently as to not let the muscle relax at all
33
Oxygen debt
Difference between the amount of oxygen needed and the amount present, can be reduced by muscle cells that have additional energy reserves
34
Creatine phosphate
Transfers a phosphate group to ADP, forming ATP, created during periods of resting to get ATP quickly during periods of use
35
Myoglobin
A heme containing protein that is a muscular oxygen reserve
36
Tonus
A constant state of low-level contraction, seen in the blood vessels, smooth muscle is capable of it
37
Cardiac muscle myogenic activity
Starts at SA node --> AV node --> bundles of His --> purkinje fibers
38
Titin
Acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of the muscle
39
Sarcoplasm
A modified cytoplasm located just outside the sarcoplasmic reticulum
40
Motor end plate
The nerve terminal in the neuromuscular junction
41
Motor unit
The nerve terminal and its myocytes
42
Myosin-binding sites
Locations on the actin thin filaments that are made accessible when Ca2+ binds to troponin causing a change in confirmation of tropomyosin
43
Muscle powerstroke
When myosin attaches to the myosin binding site on action, ADP and Pi dissociate from the mysosin, providing energy for a powerstroke
44
Acetylcholinesterase
Degrades acetylcholine in the synapse, terminating the signal
45
Latent period
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
Simple twitch periods
Latent period, contraction period, relaxation period
47
Endoskeletons
Internal skeletons (like in humans), are not able to protect the soft tissue structures as well as exoskeletons
48
Exoskeletons
External skeletal (like in anthropods), must shed and regrown to accommodate growth
49
Human skeletal system divisions
Axial and appendicular skeleton
50
Axial skeleton
Consists of striations in the midline such as the skull, vertebral column, ribcage, and hyoid bone
51
Appendicular skeleton
Consists of the bonds of the limbs, the pectoral girdle, and the pelvis
52
Bone
Derived form the embryonic mesoderm and includes both compact and spongy types
53
Compact bone
Provides strength, is very dense, forms outmost portions of the bone
54
Spongy bone
aka cancellous bone, has a lattice like structure consisting of trabeculae, cavities are filled with bone marrow, internal core of the bone
55
Trabeculae
Bony spicules/points in spongy bone
56
Diaphyses
Cylindrical shafts within long bones that flare to form metaphases
57
Epiphyses
Where long bones terminate, contain an epipihyseal or growth plate, use spongy cores for more effective dispersion of force and pressure at joints
58
Epipihyseal plate
aka growth plate, causes linear growth of the bone, close during puberty
59
Periosteum
Layer of connective tissue that surrounds bone, site for muscle attachment, some periosteal cells capable of differentiating into bone-forming cells
60
Tendons
Attach bones to muscles
61
Ligaments
Attaches bones to each other
62
Bone matrix
Contains both organic compounds such as collagen, glycoproteins, and peptides, and inorganic compounds like hydroxyapatite, provides strength to compact bone
63
Hydroxyapatite
Inorganic components (calcium, phosphate, and hydroxide ions) that harden together and form crystals
64
Lamellae
Concentric circles of bony matrix in compact bone
65
Bone organization
Lamellae around Haversian or Volkmannn's canals
66
Osteon
aka Haversian system, structural unit of bone
67
Lacunae
Between lamellar rings, where osteocytes reside, are connected by canaliculi to allow for nutrient and waste transfer
68
Osteocytes
Mature bone cells
69
Canaliculi
Connected to lacunae, allow for nutrient and waste transfer between osteocytes and Haversian and Volksmanns canals
70
Osteoblasts
Build bone
71
Osteoclasts
Resorb bone
72
Parathyroid hormone
Peptide hormone released be parathyroid in response to low blood calcium, increases resorption of bone, increases calcium and phosphate concentrations in the blood
73
Vitamin D
Activated by parathyroid hormone, increases resorption of bone, leads to increased turnover and the production of stronger bone
74
Calcitonin
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
Cartilage
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
Chondrocytes
Secretes cartilage
77
Chondrin
Firm but elastic matrix of cartilage
78
Endochondral ossification
Process by which bones form from fetal cartilage
79
Intramembranous ossification
The process by which bones, especially those of the skull, form directly from undifferentiated tissue in fetal life
80
Mesenchyme
Undifferentiated tissue
81
Immovable joints
Fused together to form sutures or similar fibrous joints
82
Movable joints
Strengthened by ligaments and contain a synovial capsule, include hinge joints and ball and socket joints
83
Synovial capsule
Enclose the actual joint/articular cavity
84
Synovial fluid
Secreted by the synovium, aid in motion by lubricating the joint
85
Synovium
Layer of soft tissue that secretes synovial fluid
86
Articular cartilage
What each bone in a joint is coated in to aid in movement and provide cushioning
87
Antagonistic pairs
Pairs of muscles that serve opposite functions, when one muscle contracts, another lengthens
88
Red marrow
Filled with hematopoietic stem cells, responsible for the generation of all the cells in our body
89
Yellow marrow
Composed of primarily fat, is relatively inactive
90
Bone marrow
Fills cavities between trabeculae in spongy bone, can be either red or yellow
91
Long bones
Common the appendicular skeleton, characterized by diaphyses that swell into metaphases and terminate in epiphyses
92
Haversian canals
Longitudinal canals (axis parallel to the bone), contain blood vessels, nerve fibers, lymph vessels
93
Volkmanns canals
Transverse canals (axis perpendicular to the bone), contain blood vessels, nerve fibers, lymph vessels
94
Sutures
Bones that are fused together in immovable joints
95
Origin
The end of the muscle with a larger attachment to bone, usually the proximal connection
96
Insertion
The end of the muscle with the smaller attachment to bone, usually the distal connection
97
Synergistic muscles
Muscles that work together to accomplish the same function
98
Flexor
A muscle that decreases the angle across a joint
99
Extensor
A muscle that increases the angle across a joint
100
Abductor
A muscle that moves a part of the body away from the midline
101
Adductor
A muscle that moves a part of the body toward the midline
102
Medial rotation
Rotates the axis of the limb toward the midline
103
Material rotation
Rotates the axis of the limb away from the midline

MCAT (67 decks)

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