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MCAT Bio > Bio #11 > Flashcards

Bio #11 Flashcards

1
Q

high calcium means ____ contractions

A

more contractions

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2
Q

what is the neurotransmitter involved at the neuromuscular junction?

A

acetylcholine

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3
Q

muscleception

A

muscle
fascicle
myocyte/muscle fiber
myofibril

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4
Q

muscleception anatomy

A

muscle
fascicle
myocyte/muscle fiber
myofibril

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5
Q

femur =

A

thigh bone

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6
Q

smooth muscle mostly in ____

A

blood vessels and hollow organ

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7
Q

muscle speed rate

A

skeletal > smooth > cardiac

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8
Q

what makes cardiac muscle easy to spot?

A

branched

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9
Q

key symptom of upper motor neuron injury is ___

A

spasm

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10
Q

muscle cells are connected via gap junctions which allows ____

A

ions to move freely among them and disperse a certain signal

allow lots of contraction at once

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11
Q

innervating muscles: somatic vs. autonomic

A

somatic: cortex and spinal cord
autonomic: brainstem

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12
Q

what are the 3 types of muscle cells and compare and contrast them

A

skeletal, smooth, cardiac muscles

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13
Q

all muscle types are capable of ____ and all muscle types are ______

A

contraction

innervated

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14
Q

muscle fibers

A

muscle cells, are formed from the fusion of developmental myoblasts in a process known as myogenesis. Muscle fibers are cylindrical and have more than one nucleus. They also have multiple mitochondria to meet energy needs. Muscle fibers are in turn composed of myofibrils.

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15
Q

myoglobin

A

an oxygen carrier that uses iron in a heme group to bind oxygen. Also contain many mitochondria to carry out oxidative phosphorylation.

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16
Q

skeletal muscle

A

responsible for voluntary movement and is therefore innervated by the somatic nervous system.
o Sarcomeres: repeating units of actin and myosin
o Striated: striped look of skeletal muscles due to sarcomeres
o Multinucleated because it is formed as individual muscle cells fuse into long rods during development.
o Types of fibers in skeletal muscle (these two types can be mixed in muscles)
 Red fibers (slow-twitch fibers): high myoglobin content and primarily derive their energy aerobically.
• Muscles that contain these contract slowly but can be sustained
 White fibers (fast-twitch fibers): contain less myoglobin.
• Muscles that contain these contract quickly but fatigue quickly

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17
Q

sarcomeres

A

repeating units of actin and myosin

exists in cardiac muscle and skeletal muscle

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18
Q

striated

A

striped look of skeletal muscles due to sarcomeres, repeating myosin and actin bands

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19
Q

what are the two types of fibers in skeletal muscle

A

red fibers and white fibers

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20
Q

compare red fibers and white fibers

A

 Red fibers (slow-twitch fibers): high myoglobin content and primarily derive their energy aerobically.
• Muscles that contain these contract slowly but can be sustained
 White fibers (fast-twitch fibers): contain less myoglobin.
• Muscles that contain these contract quickly but fatigue quickly

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21
Q

smooth muscle

A

responsible for involuntary action (ANS).
o Found in the respiratory tree, digestive tract, bladder, uterus, blood vessel walls, and many other locations.
o Single nucleus located in the center of the cell.
o Also contain actin and myosin but less organized so not really striated
o Tonus: a constant state of low-level contraction.
o Myogenic activity: smooth muscle can contract without nervous system input  muscle cells respond directly to stretch or other stimuli.

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22
Q

how many nuclei do the types of muscle have?

A

smooth: 1
cardiac: 1-2
skeletal: many per cell

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23
Q

what muscle types are striated?

A

cardiac and skeletal

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24
Q

what muscle types are somatically controlled?

A

skeletal muscle

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25
Q

tonus

A

a constant state of low-level contraction.

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26
Q

myogenic activity

A

smooth muscle can contract without nervous system input  muscle cells respond directly to stretch or other stimuli.

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27
Q

cardiac muscle

A

has characteristics of both smooth and skeletal types.
o Cells are uninucleated or some contain two nuclei, striated, controlled by ANS.
o Cardiac muscle cells are connected by intercalated discs, which contain many gap junctions.
 Gap junction: connection between the cytoplasm of adjacent cells which allows direct transfer of material  ion flow, rapid depolarization of muscle cells and efficient contraction.
o Myogenic activity: can define and maintain their own rhythm
o Starting at the Sinoatrial (SA) node, depolarization spreads using conduction pathways to the atrioventricular (AV) node. It then spreads to the bundle of His and its branches and then to the Purkinje fibers.
o Cardiac muscle contractions can also be influenced by the nervous and endocrine systems
 Nervous: vagus nerve can slow heart rate
 Endocrine: norepinephrine and epinephrine can cause increased heart rate and greater contractility.

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28
Q

how are cardiac muscle cells connected?

A

are connected by intercalated discs, which contain many gap junctions.
 Gap junction: connection between the cytoplasm of adjacent cells which allows direct transfer of material  ion flow, rapid depolarization of muscle cells and efficient contraction.

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29
Q

cardiac muscle is also under ____ and can control and maintain its own rhythm

A

myogenic activity

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30
Q

how does cardiac muscle contraction work?

A

Starting at the Sinoatrial (SA) node, depolarization spreads using conduction pathways to the atrioventricular (AV) node. It then spreads to the bundle of His and its branches and then to the Purkinje fibers.

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31
Q

how can cardiac muscle contractions be influenced by the nervous and endocrine systems?

A

 Nervous: vagus nerve can slow heart rate

 Endocrine: norepinephrine and epinephrine can cause increased heart rate and greater contractility.

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32
Q

which muscle type ABSOLUTELY NEEDS central nervous system activity?

A

skeletal muscle

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33
Q

sarcomere

A

skeletal muscle
the basic contractile unit of skeletal muscle
o Consist of thin and thick filaments
o Thick filaments: myosin
o Thin filaments; actin + troponin + tropomyosin
o Titin: acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of muscle.
o Each sarcomere is divided into bands.
o Z-lines: define the boundaries of each sarcomere.
o M-lines: run down the middle of the sarcomere through the middle of the myosin filaments
o I-band: contains exclusively thin filaments
o H-zone: only thick filaments
o A-band: thick filaments in their entirety (including overlap with thin filaments)
o During contraction, the H-zone, I-band, distance between Z lines, and the distance between M lines become smaller but the A-band stays the same size.

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34
Q

what are the thick filaments in skeletal muscle?

A

myosin

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35
Q

what are the thin filaments in skeletal muscle?

A

actin, troponin, tropomyosin

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36
Q

skeletal muscle: titin

A

acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of muscle.

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37
Q

skeletal muscle: Z-lines

A

define the boundaries of each sarcomere.

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38
Q

skeletal muscle: M-lines

A

run down the middle of the sarcomere through the middle of the myosin filaments

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39
Q

skeletal muscle: I-band

A

contains exclusively thin filaments

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40
Q

skeletal muscle: H-zone

A

only thick filaments

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41
Q

skeletal muscle: A-band

A

thick filaments in their entirety (including overlap with thin filaments)

doesn’t change length during contraction

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42
Q

skeletal muscle: what happens to bands during contraction?

A

o During contraction, the H-zone, I-band, distance between Z lines, and the distance between M lines become smaller but the A-band stays the same size.

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43
Q

describe the structure of myocytes

A

o Myofibrils: sarcomeres attached end to end
o Sarcoplasmic Reticulum (SR): covering that surrounds the myofibrils. It is a modified ER that contains high concentration of Ca+2 ions.
o Sarcoplasm: modified cytoplasm just outside the SR
o Sarcolemma: cell membrane of a myocyte
 Capable of propagating an action potential and can distribute it to all sarcomeres in a muscle system using a system of transverse tubules (T-tubules) that are oriented perpendicularly to the myofibrils.
o Terms:
 Myofibril: arrangement of many sarcomeres in series
 Muscle fiber = muscle cell = myocyte: contains many myofibrils in parallel
 Muscle: parallel muscle fibers
 A muscle is composed of parallel myocytes (muscle fibers), which are composed of parallel myofibrils.

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44
Q

myofibrils

A

Myofibrils: sarcomeres attached end to end

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45
Q

sarcoplasmic reticulum

A

covering that surrounds the myofibrils. It is a modified ER that contains high concentration of Ca+2 ions.

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46
Q

sarcoplasm

A

modified cytoplasm just outside the SR

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47
Q

sarcolemma

A

cell membrane of a myocyte
 Capable of propagating an action potential and can distribute it to all sarcomeres in a muscle system using a system of transverse tubules (T-tubules) that are oriented perpendicularly to the myofibrils.

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48
Q

T (transverse) tubules

A

The sarcolemma is capable of propagating an action potential and can distribute it to all sarcomeres in a muscle system using a system of transverse tubules (T-tubules) that are oriented perpendicularly to the myofibrils.

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49
Q

what are the two things muscle contraction relies on?

A

ATP and calcium

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50
Q

describe the process of initiation of muscle contraction

A

Part 1
Initiation
o Contraction starts at the neuromuscular junction, where the NS communicates with muscles via motor (efferent) neurons.
o Signal travels down the neuron until it reaches the nerve terminal (synaptic bouton), where acetylcholine is released into the synapse. The nerve terminal can also be called the motor end plate with regard to the neuromuscular junction.
o Acetylcholine binds to receptors on the sarcolemma which causes a depolarization.
o Each nerve terminal controls a group of myocytes and the nerve terminal + motor sites = motor unit.
o Depolarization triggers an action potential, spreads down the sarcolemma to T-tubules, travels down T-tubules into the muscle tissues in the SR, Ca+2 is then released.
o Calcium binds to troponin, leading to a conformational change in tropomyosin, which exposes the myosin binding sites of actin.

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51
Q

describe the process of shortening of sarcomere of muscle contraction

A

Part 2

Myosin molecules move toward and bind with exposed sites on actin. Myosin can then pull on the actin, draws the actin toward the M-line.
o The Actin-Myosin Cross-Bridge Cycle
 1. Resting stage: myosin carrying hydrolyzed ATP (ADP + P)
 2. Ca+2 binds to troponin, tropomyosin changes confirmation, myosin carrying hydrolyzed ATP (ADP + P) is able to bind with the myosin binding site
 3. Power stroke occurs, sarcomere contracts, ADP and P dissociate from myosin. ADP and P dissociation allows energy for power stroke to occur.
 4. ATP binds to myosin, myosin detaches from actin, hydrolysis of ATP to ADP+P causes recocking of myosin head.
o Sliding filament model: the repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along the thick filament.

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52
Q

describe the process of relaxation of muscle contraction

A

Part 3
o Acetylcholine is degraded in the synapse by the enzyme acetylcholinesterase. Results in termination of signal at the neuromuscular junction and the sarcolemma can repolarize.
o Calcium release ceases, SR takes up calcium from the sarcoplasm, ATP binds to myosin heads, freeing them from actin, sarcomeres return to original width, myosin binding sites on actin become covered again.

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53
Q

where does contraction start?

A

neuromuscular junction

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54
Q

acetylcholine binds to the sarcolemma and causes ______

A

depolarization

o Depolarization triggers an action potential, spreads down the sarcolemma to T-tubules, travels down T-tubules into the muscle tissues in the SR, Ca+2 is then released.

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55
Q

motor unit

A

nerve terminal + motor sites

o Each nerve terminal controls a group of myocytes and the nerve terminal + motor sites = motor unit.

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56
Q

calcium binds to _______ , leading to a conformational change in _____, which exposes the _______

A

troponin
tropomyosin
myosin binding sites of actin (so myosin binds to actin)

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57
Q

describe the myosin movement on actin

A

Actin-Myosin Cross-Bridge Cycle
 1. Resting stage: myosin carrying hydrolyzed ATP (ADP + P)
 2. Ca+2 binds to troponin, tropomyosin changes confirmation, myosin carrying hydrolyzed ATP (ADP + P) is able to bind with the myosin binding site
 3. Power stroke occurs, sarcomere contracts, ADP and P dissociate from myosin. ADP and P dissociation allows energy for power stroke to occur.
 4. ATP binds to myosin, myosin detaches from actin, hydrolysis of ATP to ADP+P causes recocking of myosin head.

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58
Q

sliding filament model

A

the repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along the thick filament.

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59
Q

what happens to sarcomeres after Ca+2 is no longer available?

A

they return to normal length

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60
Q

describe the process from neurotransmitter release to mysosin binding to actin

A

• Release of acetylcholine from motor neuron  activation of acetylcholine receptors in sarcolemma  depolarization of sarcolemma  spreading of signal using T-tubules  release of calcium from sarcoplasmic reticulum  binding of calcium to troponin  conformational shift in tropomyosin  exposure of myosin binding sites  myosin binds to actin.

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61
Q

muscle cells, like neurons, exhibit _______

A

all or nothing response

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62
Q

nerves control overall force by number of ______ they recruit to responsd

A

motor units

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63
Q

simple twitch

A

the response of a single muscle fiber to a brief stimulus at or above threshold.
o Consists of a latent period, contraction period, and relaxation period.
o Latent period: the time between reaching threshold and the onset of contraction. This is the time in which the action potential spreads along the muscle and calcium is released…

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64
Q

frequency summation

A

contractions combine, become stronger, and more prolonged due to frequent and prolong stimulus.
 Summation: period where the force is building and can’t return to relaxation.

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65
Q

summation and tetanus

A

o Frequency summation: contractions combine, become stronger, and more prolonged due to frequent and prolong stimulus.
 Summation: period where the force is building and can’t return to relaxation.
o Tetanus: the contractions are so frequent and the muscle is unable to relax at all.
 Prolonged tetanus results in muscle fatigue.

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66
Q

tetanus

A

the contractions are so frequent and the muscle is unable to relax at all.
 Prolonged tetanus results in muscle fatigue.

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67
Q

what are the two supplemental energy reserves in muscle?

A

o Creatine phosphate: created by transferring a phosphate group from ATP to creatine during times of rest.  this can then be reversed to quickly generate ATP from ADP during muscle use.
o Myoglobin: as exercising muscles run out of oxygen, then use myoglobin reserves of oxygen to keep aerobic metabolism going.

68
Q

creatine phosphate

A

created by transferring a phosphate group from ATP to creatine during times of rest.  this can then be reversed to quickly generate ATP from ADP during muscle use.

69
Q

myoglobin in exercise

A

as exercising muscles run out of oxygen, then use myoglobin reserves of oxygen to keep aerobic metabolism going.

70
Q

______ rely on glycolysis and fermentation to make ATP under most circumstances.

A

Fast twitch white muscle fibers

71
Q

what occurs during exercise?

A

o Heart rate and respiratory rate increase, oxyhemoglobin dissociation curve shifts right in presence of increased CO2, increased H+, and increased Temp. Even with this, the body still becomes overwhelmed. Even red muscle fibers much switch to anaerobic metabolism.

72
Q

oxygen debt

A

the difference between the amount of oxygen needed by the muscles and the actual amount present OR the amount of oxygen required to recover from exercise.

73
Q

what are the functions of our skeleton?

A
  1. supports us and is framework for movement
  2. protects vital organs
  3. physiological roles: stores Ca+ and hematopoiesis
74
Q

lacunae

A

empty spaces in bone

75
Q

resporption of bone =

A

osteoclast ==> breaking it down

76
Q

Parathyroid hormone activates vitamin ____

A

D

77
Q

collagen and elastin give cartilage ____

A

strength and flexibility

78
Q

cartilage is not ______ and it is ____

A

not innervated: does not have nerve cells

avasculature: no arteries and veins

79
Q

ligaments connect ___

A

bone to other bone

80
Q

tendons _____

A

connect muscle to bone

81
Q

joint

A

one bone meets up with another

82
Q

joint

A

one bone meets up with another

83
Q

what are the two types of skeletons for different animals?

A

exoskeleton and endoskeleton

84
Q

exoskeleton

A

encase whole organisms and are usually found in arthropods, crustaceans, and insects.
 Must be shed and regrown to accommodate growth

lady bug

85
Q

endoskeleton

A

internal but are not able to protect the soft tissue structures as well as exoskeletons.
 Vertebrates, including humans.
 Accommodate growth much better

86
Q

what are the two components of our skeletal system?

A

axial skeleton and appendicular skeleton

87
Q

axial skeleton

A

consists of the skull, vertebral column, ribcage, and hyoid bone (a small bone in the anterior neck used for swallowing).
 Provides the basic central framework for the body.

88
Q

appendicular skeleton

A

the bones of the limbs (humerus, radius and ulna, carpals, metacarpals, and phalanges in the lower limb), the pectoral girdle (scapula and clavicle), and pelvis.

89
Q

what is the skeleton created of?

A

bone and cartilage

90
Q

what is bone composed of?

A

• Connective tissue derived from embryonic mesoderm, Much harder than cartilage but still pretty light weight.

91
Q

is bone from endoderm, mesoderm, or ectoderm?

A

mesoderm

92
Q

compact bone

A

where bone strength comes from
o Dense and strong
o Outermost part of the bone.

93
Q

spong or cancellous bone

A

lattice structure is visible under microscopy and consists of bony points called trabeculae. The cavities between trabeculae are filled with bone marrow which can be yellow or red.
o Internal core of the bone.

94
Q

red bone marrow

A

filled with hematopoietic stem cells  generate all of the cells in our blood

95
Q

yellow bone marrow

A

composed of fat and is relatively inactive.

96
Q

Bones in the appendicular skeleton are typically _____: characterized by cylindrical shafts called _____. The diaphysis swell at each end to form _____ and then terminate in _____

A

long bones
diaphysis
metaphysis
epiphyses

97
Q

what parts of long bone have bone marrow?

A

Long bone metaphysis and diaphysis are full of bone marrow.

98
Q

epiphysis

A

 Use spongy cores for more effective dispersion of force and pressure at the joints.
 At the internal edge is the epiphyseal (growth) plate: a cartilaginous structure and site of longitudinal growth.
 The plate is filled with mitotic cells that contribute to growth, proliferating during puberty and then stopping. The plates then close and vertical growth is halted.

99
Q

ligaments

A

hold bone together at joints

100
Q

bone matrix

A

• Compact bone strength comes from the bone matrix: has both organic and inorganic contents.
o Organic: collagen, glycoproteins, and other peptides
o Inorganic: calcium, phosphate, hydroxide ions. These sometimes combine to form hydroxyapatite crystals. Sodium, magnesium, and potassium. (most inorganic bone is composed of this)

101
Q

hydroxyapatite crystals

A

calcium, phosphate, hydroxide ions

102
Q

organic part of bone matric

A

collagen, glycoproteins, and other peptides

103
Q

inorganic part of bone matrix

A

calcium, phosphate, hydroxide ions. These sometimes combine to form hydroxyapatite crystals. Sodium, magnesium, and potassium. (most inorganic bone is composed of this)

104
Q

osteons or haversian systems

A

structural units of the bony matrix.
o Lamellae: concentric circles of bone matrix that surround central microscopic channels.
o Haversian canals: longitudinal channels.
o Volkmann’s canals: transverse channels
 Haversian and Volkmann canals contain the blood vessels, nerve fibers, and lymph vessels that maintain the health of the bone.
o Lacunae: located between lamellar rings that house mature bone cells called osteocytes.
 Interconnected by tiny channels called canaliculi: allow for exchange of nutrients and wastes between osteocytes and the Haversian and Volkmann’s canals.

105
Q

lamellae

A

osteons

concentric circles of bone matrix that surround central microscopic channels.

106
Q

haversian canals

A

osteons
transverse channels
 Haversian and Volkmann canals contain the blood vessels, nerve fibers, and lymph vessels that maintain the health of the bone.

107
Q

lacunae

A

located between lamellar rings that house mature bone cells called osteocytes.
 Interconnected by tiny channels called canaliculi: allow for exchange of nutrients and wastes between osteocytes and the Haversian and Volkmann’s canals.

108
Q

osteocytes

A

mature bone cells

109
Q

bones are filled with ____ and are _____

A

vasculature

innervated

110
Q

bone remodeling

A

equilibrium between bone construction and destruction
o There are two cell types responsible for building and maintaining strong bones:
 Osteoblasts: build bone  secrete matrix proteins and transport minerals into the matrix
 Osteoclasts: resident macrophages, resorb bone.
o During this process, essential ingredients such as calcium and phosphate are taken from the blood and put in bone and then released from bone into the blood.
o Bone remodeling is based on repeated stresses to the body.
o Endocrine hormones may also affect bone metabolism:
 Parathyroid hormone: released by the parathyroid glands in response to low blood calcium promotes resorption of bone.
• Vitamin D: also activated by the parathyroid hormone promotes the resorption of bone.  stronger bone results when more vitamin D because new, stronger bone is created in place of the old bone.
 Calcitonin: released by parafollicular cells of the thyroid in response to high blood calcium promotes bone formation.

111
Q

osteoblasts

A

build bone  secrete matrix proteins and transport minerals into the matrix

112
Q

osteoclasts

A

resident macrophages, resorb bone.

113
Q

o Endocrine hormones may also affect bone metabolism

A

 Parathyroid hormone: released by the parathyroid glands in response to low blood calcium promotes resorption of bone.
• Vitamin D: also activated by the parathyroid hormone promotes the resorption of bone.  stronger bone results when more vitamin D because new, stronger bone is created in place of the old bone.
 Calcitonin: released by parafollicular cells of the thyroid in response to high blood calcium promotes bone formation.

114
Q

cartilage

A

• Softer and more flexible than bone.

115
Q

chondrin

A

• Chondrin: firm but elastic matrix secreted by chondrocytes that makes up most of cartilage.

116
Q

what are some body parts made of cartilage

A

• Some body parts that consist of cartilage are external ear, nose, walls of the pharynx and trachea, intervertebral discs, and joints.

117
Q

how is bone made?

A

o Endochondral ossification: hardening of cartilage into bone (most bone is made this way), especially formation of long bones.
o Intramembranous ossification: undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into and replaced by bone (bones in the skull).

118
Q

immovable joints

A

o Endochondral ossification: hardening of cartilage into bone (most bone is made this way), especially formation of long bones.
o Intramembranous ossification: undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into and replaced by bone (bones in the skull).

119
Q

immovable joints

A

o Endochondral ossification: hardening of cartilage into bone (most bone is made this way), especially formation of long bones.
o Intramembranous ossification: undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into and replaced by bone (bones in the skull).

120
Q

movable joints

A

: hinge joints (elbow and knee), ball and socket joints (shoulder or hip) and others.
 Allow bones to shift relative to each other.
 Movable joints are strengthened by ligaments: pieces of fibrous tissue that connect bones to one another.
 Consist of a synovial capsule, which encloses the actual joint cavity (articular cavity).
 A layer of soft tissue called the synovium secretes synovial fluid, which lubricates the movement of structures in the joint space.
 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.

121
Q

what are hinge joints

A

elbow and knee

122
Q

what are ball and socket joints

A

shoulder and hip

123
Q

synovial capsule

A

encloses the actual joint cavity (articular cavity).

124
Q

synovium

A

 A layer of soft tissue called the synovium secretes synovial fluid, which lubricates the movement of structures in the joint space.

125
Q

articular cartilage

A

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.

126
Q

some muscles are connected to two bones

A

o Origin: end of the muscle with larger attachment to bine (usually the proximal connection).
o Insertion: end with the smaller attachment to bone (usually the distal connection).

127
Q

antagonistic pairs

A

how our muscles normally work, one relaxes while the other contracts.
o Ex: arm:
 Biceps brachii and triceps brachii work antagonistically

128
Q

synergistic muscles

A

work together to accomplish the same function.

129
Q

• Muscles can also be classified by the types of movements they coordinate:

A

o Flexor: muscle decrease the angle across a joint (like the biceps brachii)
o Extensor: increases or straightens this angle (triceps brachii)
o Abductor: moves a part of the body away from the midline (deltoid)
o Adductor: moves part of the body toward the midline (pectoralis major)
o Medial and Lateral Rotation: describe motions that occur in limbs
 Medial rotator rotates the axis of the limb toward the midline (subscapularis)
 Lateral rotator rotates the axis of the limb away from the midline (infraspinatus)

130
Q

muscle: flexor

A

muscle decrease the angle across a joint (like the biceps brachii)

131
Q

muscle: extensor

A

increases or straightens this angle (triceps brachii)

132
Q

muscle: abductor

A

moves a part of the body away from the midline (deltoid)

133
Q

muscle: adductor

A

moves part of the body toward the midline (pectoralis major)

134
Q

muscle: medial and lateral rotation

A

describe motions that occur in limbs
 Medial rotator rotates the axis of the limb toward the midline (subscapularis)
 Lateral rotator rotates the axis of the limb away from the midline (infraspinatus)

135
Q

what type of muscle is capable of contraction?

A

all 3 types

136
Q

of the 3 types of muscle, which participate in myogenic activity?

A

smooth and cardiac muscle

137
Q

what connects cardiac muscle cells and what is a special feature about them?

A

intercalated discs
have a lot of gap junctions: allows for flow of ions directly between cells ==> allows for rapid and coordinated depolarization of muscle cells.

138
Q

how can the nervous and endocrine systems alter heart rate?

A

vagus nerve provides parasympathetic outflow which decreases heart rate
norepinephrine from sympathetic neurons or epinephrine from the adrenal medulla binds to adrenergic receptors in the heart which increases heart rate

139
Q

are troponin and tropomyosin associated with actin or myosin

A

actin

140
Q

sarcomeres attached end to end into _____

A

myofibrils

141
Q

muscle contraction: what provides the energy for the powerstroke?

A

release of the ADP and inorganic phosphate in rapid succession

142
Q

muscle contraction: what leads to myosin unbinding from actin?

A

binding of ATP

143
Q

muscle contraction: what leads the myosin head to be recocked?

A

ATP hydrolysis

144
Q

what does acetylcholinesterase do?

A

degrades acetylcholine in the synapse

145
Q

why do muscle fibers contract in an all or nothing fashion?

A

because they are innervated by neurons that deliver signals using action potentials

146
Q

since muscle contraction is all or nothing, how do nerves control overall force?

A

control it by the number of motor units they recruit to respond. Maximal response occurs when all fibers within a muscle are stimulated to contract simultaneously.

147
Q

what are two ways muscles get extra ATP/oxygen during oxygen debt

A

creatine phosphate donates phosphate to ADP to make ATP

myoglobin in muscle cells has oxygen that it donates

148
Q

what type of tissue is bone?

A

connective

149
Q

where is bone derived from?

A

mesoderm

150
Q

is bone or cartilage harder?

A

bone

151
Q

what is another name for spongey bone?

A

cancellous bone

152
Q

where are osteocytes housed?

A

lacunae

153
Q

what interconnects lacunae?

A

canaliculi: allow for exchange of nutrients and wastes between osteocytes and the haversian and volkmann’s canals.

154
Q

how does vitamin D affect bone remodeling?

A

promotes bone resorption which actually allows stronger bone to take its place

155
Q

what type of hormones are parathyroid hormone and calcitonin?

A

peptide hormones

156
Q

endochondral ossification

A

the hardening of cartilage into bone

157
Q

origin vs. insertion

A

origin: the end of a contracting muscle with a larger attachment to bone
insertion: the end with the smaller attachment to bone (usually the distal connection)

158
Q

compact bone vs. spongy bone

A

Compact bone is dense and is used for strength; it forms most of the outer layers of bone. Spongy (cancellous) bone has many spaces between bony spicules called trabeculae and is the site of marrow production. It is found in the interior core of the bone and also helps distribute forces or pressures on the bone

159
Q

most inorganic bone is composed of _____

A

hydroxyapatite crystals

160
Q

what type of fluid lubricates movable joints and what produces it?

A

synovial fluid produced by the synovium

161
Q

what is the only section of the sarcomere that maintains a constant size during contraction?

A

A band

162
Q

what do the Z lines anchor in the sarcomere?

A

the thin filaments (actin)

163
Q

____ secrete bone matrix

A

osteoblasts

164
Q

what do osteocytes do?

A

maintain bone

165
Q

T/F: Some periosteum cells are capable of differentiating into bone-forming cells called osteoblasts

A

true

MCAT Bio (12 decks)

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