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Biology MCAT > Musculoskeletal System > Flashcards

Musculoskeletal System Flashcards

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1
Q

3 types of muscle tissue

A

skeletal, cardiac, smooth

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2
Q

skeletal muscle

A

responsible for voluntary movement

-innervated by the somatic nervous system

-appears striped or striated due to sarcomeres

-multinucleated Bc it is formed as individual muscle cells fuse into long rods during development

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3
Q

2 types of fibers within skeletal muscle

A

Red fibers

white fibers

these can mix in muscle as well

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4
Q

Red fibers

A

Aka Slow-twitch muscle fibers.

-They are primarily aerobic and contain many mitochondria and myoglobin.

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5
Q

Myoglobin

A

Oxygen carrier that uses iron in a heme group to bind oxygen

-in red fibers

-causes the red color in red fibers

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6
Q

White fibers

A

Aka Fast-twitch muscle fibers.

They are primarily anaerobic

-contain much less myoglobin than red

  • fatigue more easily than red fibers.
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7
Q

Muscles that contract slowly but can sustain activity (like posture) contain a predominance of _____ fiber

while muscles that contract rapidly but fatigue quickly contain mostly ____ fibers

A

Red

white

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8
Q

Smooth muscle

A

responsible for involuntary body movement

-therefore controlled by autonomic nervous system

-found in respiratory tree, digestive tract, uterus, bladder, blood vessel walls, and many other locations

-have single nucleus in center of cell

-contains actin and myosin but are unorganized so no striations

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9
Q

Compared to skeletal muscle, smooth muscle is capable of more ____ contractions

A

Sustained

-constant state of low-level contractions (ex: in blood vessels)

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10
Q

Myogenic activity

A

ability of a muscle cell to contract without input from the nervous system

found in smooth and cardiac muscle types

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11
Q

Cardiac muscle

A

Has characteristics of both smooth and skeletal muscles

-usually single nucleated but some may have 2 nuclei

-contractions are involuntary (autonomic nervous system)

-appears striated like skeletal muscle due to actin and myosin

-is unique by how each cardiac myocyte communicates

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12
Q

Cardiac muscle communication

A

Cardiac muscle cells are connected by intercalated discs which contain many gap junctions

-these gap junctions are connections btw the cytoplasm of adjacent cells , allowing for the flow of ions directly btw them

-this allows for rapid and coordinated depolarization of muscle cells and efficient contraction of cardiac muscle

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13
Q

Cardiac muscle myogenic activity

A

SA node —> depolarization spreads using conduction pathways to the AV node ->

—> depolarization spreads to the bundle of HIS and it’s branches —>the purkinje fibers

-gap junctions allow for the progressive depolarization to spread via ion flow across the gap junctions btw cells

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14
Q

How the nervous system and endocrine systems play a role in cardiac muscle contractions

A

Vagus nerve provides parasympathetic outflow to the heart and slows the heart rate

-norepinephrine ( from sympathetic neurons) or epinephrine (from the adrenal medulla) binds to adrenergic receptors in the heart

-this causes an inc in heart rate and great contractility

-does this by increasing calcium

HEART MUSCLE RELIES ON CALCIUM!!

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15
Q

All types of muscle relies on ____ to contract

A

Ca2

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16
Q

Sarcomere

A

basic contractile unit of skeletal muscle

the arrangement of actin and myosin into repeating units

-makes skeletal muscle look striped or striated

-made of thick and thin filaments

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17
Q

Thick filaments of sarcomeres

A

Bundles of myosin

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18
Q

Thin filaments of sarcomeres

A

Made of actin

-along w 2 other proteins:
———troponin and tropomyosin

these proteins help regulate the interaction btw the actin and myosin filaments

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19
Q

troponin and tropomyosin

A

Proteins that help to regulate the interaction between the actin and myosin filaments

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20
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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21
Q

Sarcomere lines, zones, and bands

A

Z-line
M-line

I-band
A-band

H-zone

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22
Q

z-line of sarcomere

A

Defines the boundaries of a single sarcomere

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23
Q

M line of sarcomere

A

runs down the center of the sarcomere, through the middle of the myosin filaments

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24
Q

I-band of sarcomere

A

Region containing exclusively thin filaments

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25
Q

H-zone of sarcomere

A

contains thick filaments only

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26
Q

A-band of sarcomere

A

Contains thick filaments in their entirety, including any overlap with thin filaments

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27
Q

Myofibrils

A

sarcomeres attached end to end

-surrounded by a covering known as sarcoplasmic reticulum (SR)

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28
Q

sarcoplasmic reticulum (SR)

A

a modified endoplasmic reticulum that contains a high concentration of Ca2+ ions

-covers myofibrils

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29
Q

Sarcoplasm

A

cytoplasm of a muscle cell

-located just outside the sarcoplasmic reticulum

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30
Q

Sarcolemma

A

Cell membrane of a muscle cell

-capable of propagating an action potential

  • can distribute the action potential to all sarcomeres in a muscle using a system of T-tubules
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31
Q

Transverse tubules (T-tubules)

A

Transmit action potential btw sarcomeres in muscle

Allow entire muscle fiber to contract simultaneously

-they are oriented perpendicularly to the myofibrils (shown in pic)

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32
Q

Myocyte

A

muscle cell

-each one contains many myofibrils arranged in parallel and can be called a muscle fiber

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33
Q

Parts of sarcomere mnemonic

A

Z: end of alphabet = ends of sarcomere

M= middle of myosin

I is a Thin letter

H is a Thick letter

A is in All of the thick filaments whether or not it’s overlapping

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34
Q

Muscle fiber versus muscle

A

Muscle fiber contains many myofibrils within it, arranged in parallel

Muscle: made up of parallel muscle fibers

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35
Q

muscle contraction steps

A

1) Initiation
2) shortening of sarcomere
3) relaxation
4) stimulation, summation, and muscle fatigue

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36
Q

Initiation of muscle contraction

A

1) starts at the neuromuscular junction where the nervous system communicated with muscles via motor (efferent) neurons

2) signal travels down neuron to nerve terminal (synaptic bouton)

3) acetylcholine is released into synapse

4)this binds to receptors on the sacrolemma causing depolarization

5) this triggers an action potential which spreads to T-tubules

6) travels to sarcoplasmic reticulum

7) Ca2+ is released Which triggers troponin to change the conformation of tropomyosin

8) this exposes myosin-binding sites

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37
Q

Motor unit

A

A nerve terminal and it’s myocytes

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38
Q

Motor end plate

A

The nerve terminal of a neuromuscular junction can be called this

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39
Q

Shortening of the sarcomere during contraction

A

1) Free globular heads of the myosin molecules bind with exposed sites on actin (from initiation)

2) this actin-myosin bridge allows myosin to pull on actin

3) this draws thin filaments toward the M-line resulting tin a shortening of sarcomere

4) diagram shows actin-myosin bridge cycle

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40
Q

Actin-myosin bridge cycle

A

1) myosin carrying hydolyzed ATP (ADP and an inorganic phosphate) binds to myosin-binding site

2) release of inorganic phosphate and ADP rapidly provides energy for the power stroke an results in sliding of actin over myosin

3) ATP binds to myosin head releasing it from actin

4) ATP is hydolyzed back to ADP and Pi which recooks the myosin head back

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41
Q

Sliding filament model

A

states that the thick and thin filaments slide past each other so that their degree of overlap increases.

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42
Q

Relaxation step of contraction of muscle

A

Acetylcholine is degraded in synapse by enzyme : acetylcholinesterase

2) results in termination of the signal

3) sarcolemma is depolarizer

4) Ca2+ release ceases and SR takes up calcium from sarcoplasm

5) ATP binds to myosin heads releasing them from actin

43
Q

Simple twitch of muscle

A

Response of a single muscle fiber to a brief stimulus at or above threshold

-consists of: a latent period, contraction period, and relaxation period

44
Q

Latent period of simple twitch

A

-The time between reaching threshold and onset of contraction

-when action potential spreads along the muscle and allow for calcium to be released from the sarcoplasmic reticulum

45
Q

Frequency summation

A

When a muscle fiber is exposed to frequent and prolonged stimulation, it cannot relax. The contractions combine and become stronger and more prolonged.

46
Q

Tetanus

A

When the muscles have contacted so frequent that the muscle is unable to relax at all

-prolonged tetanus results in muscle fatigue

47
Q

2 supplemental energy reserves in muscle

A
  1. creatine phosphate
  2. myoglobin
48
Q

Creatine phosphate in muscle energy

A

Creatine phosphate is created by transferring a phosphate group from ATP to creatine during times of rest

-reaction can then be reserved during muscle use

49
Q

Myoglobin for energy reserve in muscles

A

Myosin binds oxygen with high affinity

-as exercising muscles run out of oxygen, myoglobin reserves are used to keep aerobic metabolism going

50
Q

When a person exercises, heart rate and respiratory rate increase in order to more more oxygen to active muscles. But the muscles still get overwhelmed and :

A

Even the red fibers must switch to anaerobic metabolism and begin to make lactic acid at which point the muscles begin to fatigue

51
Q

Oxygen debt

A

The difference between the amount of oxygen needed by the muscles and the actual amount present

52
Q

After the cessation of strenuous exercise, the body must

A

Metabolize all of the lactic acid it has produced

53
Q

Two types of skeletons

A

exoskeleton and endoskeleton

54
Q

Exoskeletons

A

encase whole organisms and are usually found in arthropods, such as crustaceans and insects

55
Q

Endoskeletons

A

Internal skeletons that all vertebrae’s have

-do not protect the soft tissue structures like the exoskeleton does

-much better at accommodating growth of larger organisms

56
Q

Our skeletal structure is divided into

A

Axial and appendicular skeletons

57
Q

Axial skeleton

A

consists of the skull, vertebral column, rib cage, and hyoid bone (small bone used for swallowing)

58
Q

Appendicular skeleton

A

consists of the bones of the limbs, the pectoral girdle, and the pelvis

59
Q

Anatomy of the human skeleton

A
60
Q

Bone

A

A connective tissue

-derived from the mesoderm

61
Q

Structure of the bone

A
62
Q

Compact bone

A

dense, hard layers of bone tissue that lie underneath the periosteum

63
Q

spongy or cancellous bone

A

has a lattice-like structure consisting of bony spicules known as trabeculae.

The cavities are filled with bone marrow

64
Q

Two types of bone marrow

A

red and yellow

65
Q

red bone marrow

A

filled with hematopoietic stem cells Which are responsible for the generation of all the cells in our blood

66
Q

Yellow bone marrow

A

composed primarily of fat and is relatively inactive

67
Q

Long bones

A

Typically in the appendicular skeleton

-characterized by cylindrical shafts called diaphyses

-outer portion: compact bond

-inner portion: spongy bone

68
Q

Diaphyses

A

cylindrical shafts that characterize long bones

-they swell at each end to form metaphyses and that terminate in epiphyses

-diaphyses and metaphyses have bone marrow

69
Q

Epiphyses

A

ends of long bone

-efffective in dispersion of force and pressure at joints

70
Q

epiphyseal plate

A

Growth plates

-at end of epiphyses

71
Q

Periosteum

A

Double-layered connective tissue that covers and nourishes the bone.

72
Q

Tendons

A

attach muscle to bone

73
Q

Ligaments

A

hold bones together at joints

74
Q

Bone matrix

A

-gives compact bone its strength

-has both organic components (ex: collagen, glycoproteins, and other peptides)

-and inorganic components (ex: hydroxyapatite crystals)

-ordered into units of osteons

75
Q

Osteons or Haversian systems

A

bony matrix are ordered into these structural units

-each contain concentric circles of bony matrix called lamellae

each encircles central Haversian canal

76
Q

Haversian canals

A

longitudinal channels (those with an axis parallel to the bone)

-contain blood vessels , nerve fibers, and lymph vessels that maintain health of bone

77
Q

Volkmann’s canals

A

transverse channels (those with an axis perpendicular to the bone)

-contain blood vessels , nerve fibers, and lymph vessels that maintain health of bone

78
Q

Lacunae

A

Space that House mature bone cells (osteocytes)

-between the lamellar rings

79
Q

Canaliculi

A

Tiny channels that allow for the exchange of nutrients and wastes btw osteocytes and Haversian and Volkmanns canals

80
Q

Two types of cells involved in bone remodeling

A

Osteoblasts and osteoclasts

81
Q

Osteoblasts

A

build bone

82
Q

Osteoclasts

A

reabsorb bone

83
Q

Bone formation

A

calcium and phosphate are obtained from blood

-done by osteoblasts

84
Q

Bone reabsorption

A

Ions (calcium and phosphate) are released back into the blood stream

-done by osteoclasts

85
Q

Hormones that effect bone remodeling

A

Parathyroid hormone: responds to low blood calcium, promotes reabsorption of bone, increasing concentration on calcium and phosphate in the blood

Vitamin D: activated by parathyroid hormone , promotes reabsorption , encourages growth of new stronger bone

calcitonin: responds to high blood calcium , promotes bone formation, lowering calcium levels

86
Q

Cartilage

A

Softer and more flexible than bone

-consists of a firm but elastic matrix called chondrin

-is avascular

found in adults in ear, nose, walls of larynx and trachea, intervertebral discs, and joints

87
Q

Fetal skeletons are made of

A

Cartilage

88
Q

Most bones in the body are made by hardening ____

A

Cartilage into bone

known as endochondral ossification

89
Q

endochondral ossification

A

Process of transforming cartilage into bone.

-forms most long bones

90
Q

intermembranous ossification

A

Undifferentiated embryonic connective tissue is transformed into bone

-occurs in skull

91
Q

Joints

A

Made of connective tissue

2 types: immovable and movable

92
Q

Immovable joints

A

Consist of bones that are fused together to form sutures or similar fibrous joints

Found primarily in the head, where they anchor bones of the skull together.

93
Q

Movable joints

A

include hinge joints, ball-and-socket joints, pivot joints, and gliding joints

-permit bones to shift relative to another

94
Q

Moveable joints are strengthened by _____ and _____ lubricates the movement of the structures in the space

A

Ligaments

synovial fluid (which is secreted by synovium)

95
Q

Ligaments

A

Piece of fibrous tissue that connects the bones to one another

-consists of synovial capsule that encloses joint cavity

96
Q

Articulate cartilage

A

Contributes to the joint by coating the articulate surfaces of the bones so that impact is restricted to the lubricated joint cartilage rather than to the bones

97
Q

The end of the muscle with the larger attachment to the bone is called the _____

which the end with the smaller attachment to bone is called _____

A

Origin

the insertion

98
Q

Antagonistic pairs of muscles

A

When one contracts the other relaxes

99
Q

Flexor muscle

A

Decreases the angle across a joint

100
Q

Extensor muscle

A

increases or straightens the angle across the joint
ex) triceps brachii

101
Q

Abductor muscles

A

moves a part of the body away from the midline

102
Q

Adductor muscle

A

moves a part of the body toward the midline

103
Q

Medial rotation

A

Rotation toward the midline

104
Q

lateral rotation

A

rotation away from the midline

Biology MCAT (12 decks)

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