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HES 101 > Midterm 2 > Flashcards

Midterm 2 Flashcards

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1
Q

what are the types of myfilaments

A
  • thick filaments
  • thin filaments
  • elastic filaments
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2
Q

thick filaments

A

bundles of contractile protein myosin

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3
Q

myosin

A
  • have globular heads linked by intertwining tails
  • each head has a active site that binds to actin
  • myosin tails from opposite sides are attached together at the M-line
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4
Q

thin filaments

A

proteins, actins, tropomyosin, and troponin

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5
Q

actin

A
  • multiple actin subunits string together, form two intertwining strands in functional thin filaments
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6
Q

troponin

A
  • small globular regulator protein, holds tropomyosin in place, assists with turning contractions on and off
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7
Q

tropomyosin

A
  • long rope-like regulatory protein, twists around actin, covering up active sites
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8
Q

elastic filaments

A

single spring-like protein (titin)
- stabilizes the myofibril structure

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9
Q

sarcomere

A
  • the smallest functional unit of a skeletal muscle fiber
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10
Q

I band

A

contains only thin filaments

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11
Q

Z disc

A

in the middle of I band
- anchor thin filaments in place
- attachment point for elastic fibers

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12
Q

A band

A

contains a zone of overlap, with both thick and thin filaments
- generate tension during contraction

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13
Q

H zone

A

middle of A band contains only thick filaments

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14
Q

M line

A

dark like in the middle of A band
- structural proteins hold thick filaments
- anchors elastic filaments

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15
Q

filament sliding mechanics

A

myosin head attaches to actin –> pulls thin filament towards M-line –> brings Z discs closer together

  • I band and H zone narrow
  • A band doesn’t change
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16
Q

cross bridge formation

A

when myosin and actin attach

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17
Q

cross bridge cycling

A

the on/off interaction between myosin and actin

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18
Q

stages of the cross bridge cycle

A
  • ATP hydrolysis
  • cross bridge formation
  • powerstroke
  • detachment
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19
Q

ATP hydrolysis

A
  • atp cocks myosin head
  • atp turns into adp and Pi
    ATP + H2O –> ADP + Pi
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20
Q

cross bridge formation

A
  • myosin head attaches to actin
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21
Q

powerstroke

A
  • adp and pi are released from myosin
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22
Q

detachment

A
  • another atp binds to myosin
  • breaks the attachment to actin
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23
Q

contraction cycle

A

repeats as long as atp is present
- repeats 20-40 times for each myosin head (cross-bridge cycle)

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24
Q

channels definition and the types

A

transmembrane proteins allow certain substances to cross the membrane
- always open
- gated

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25
Q

always open channels

A

like pores, flow down their gradient
- leak channels

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26
Q

gated channels

A
  • mechanically: uses a physical force
  • chemically: ligand binds to a protein receptor
  • electrically: controlled by a voltage change
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27
Q

true or false
a motor unit exits the spinal cord and consists of two motor neurons and innervates one muscle fiber

A

false
a motor unit consists of one motor neuron and innervates multiple muscle fibers

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28
Q

neuromuscular junction

A

the connection between the motor neuron and a muscle fiber
- where a nerve impulse (AP) is transmitted to the sarcolemma of the muscle fiber

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29
Q

skeletal muscles

A
  • made up of long multinucleated cells arranged parallel
  • contractions are voluntary
  • striations
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30
Q

cardiac muscles

A
  • short/highly branched with one nucleus
  • intercalated discs joined together (contains gap junctions & desmosomes –> tight junctions)
  • contractions is involuntary
  • synchronous contractions
  • striations
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31
Q

smooth muscles

A
  • long/flat, single centrally located nucleus
  • involuntary contractions
  • linked by gap junctions
  • allows synchronized contractions
  • no striations
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32
Q

fasicles

A

bundles of muscle fibers within a skeltal muscle

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33
Q

types of muscle shapes

A
  • parallel
  • pennate (uni,bi, and multi)
  • convergent
  • circular
  • fusiform
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34
Q

axon terminal

A

the end of the motor neuron axon where the electrical signal is transmitted to a chemical signal
- contains voltage gated Ca2+ channels
- contains synaptic vesicles that are filled with acetylcholine (ACh)

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35
Q

neurotransmitter

A

a chemical that transmits a signal from a neuron and triggers a change

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36
Q

synaptic cleft

A

the space between the axon terminal and muscle fiber

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37
Q

motor end plate

A

specialized region of the muscle fiber sarcolemma
- folded and contains NA+ channels

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38
Q

myosin and actin attachment steps
(4 steps)

A
  1. Ca2+ (stored in the SR) binds to troponin
  2. troponin changes shape and pulls tropomyosin
  3. binding site on actin is exposed
  4. myosin binds to actin (ATP present)
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39
Q

true or false
muscle fibers are excitable cells

A

true

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40
Q

excitable cells

A
  • produce action potential
  • defined by a rapid/ temporary change in membrane potential
  • generated by opening/closing of Na+/K+ channels (active transporters)
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41
Q

membrane potential

A

the electrical potential difference across the plasma membrane
- mainly Na+ and K+
- rest at -90mV

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42
Q

resting membrane potential (RMP)

A
  • at -90mV
  • Na+ and K+ channels closed
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43
Q

depolarization

A
  • Na+ channels open (Na+ enters cell)
  • K+ channels closed
  • makes less negative
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44
Q

repolarization

A
  • Na+ channels closed
  • K+ channels open (K+ exits cell)
  • makes more negative
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45
Q

myofibrils

A

made up of contractile proteins

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46
Q

sarcoplasmic reticulum (SR)

A
  • surrounds myofibrils
  • stores and releases Ca2+
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47
Q

transverse tubules (t-tubules)

A
  • deep inward extensions of sarcolemma
  • surrounds each myofibrils
  • tunnel-like network
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48
Q

terminal cisternae

A
  • enlarged sections of the SR
  • two terminal cisternae plus the corresponding t-tubule form a triad
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49
Q

how many mitochondria in a muscle fiber

A

many

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50
Q

how many nuclei in a muscle fiber

A

multiple

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51
Q

steps of skeletal muscle contractions
(4 steps)

A
  1. Ca2+ is released from the SR at the terminal cisternae
  2. Ca2+ binds to troponin
  3. tropomyosin moves
  4. myosin binding sites on actin becomes exposed
52
Q

prerequisites of muscle relaxation

A
  • no more acetylcholine is released into the synaptic cleft (motor neuron AP stops)
  • acetylcholine is present in the synaptic cleft but is broken down by acetylcholinesterase
  • Ca2+ ions pumped back into the SR
53
Q

steps of muscle relaxation
(5 steps)

A
  1. AP down the motor neuron stops
  2. Acetylcholinesterase breaks down ACh
  3. sarcolemma returns to RMP due to K+ exiting its channels
  4. Ca2+ pumped back into the SR
  5. active sites on actin are blocked
54
Q

muscle fiber twitch

A

the response of 1 isolated muscle fiber to a single AP in a motor neuron

55
Q

whats the RMP for motor neurons and muscle fibers

A

motor neuron: -70 mV
muscle fiber: -90 mV

56
Q

myogram

A

records tension produced over time

57
Q

what are the three phases of a muscle twitch

A
  • latent period
  • contraction period
  • relaxation period
58
Q

latent period

A

the time it takes the AP to propagate across the sarcolemma

59
Q

contraction period

A

cross bridge cycling generates muscle tension

60
Q

relaxation period

A

Ca2+ ions pumped back into the SR and muscle tension returns to resting state

61
Q

muscle fatigue and what are the types

A

the inability of a muscle to maintain a given level of tension during activity
- central fatigue
- peripheral fatigue

62
Q

central fatigue

A

arises from the CNS

63
Q

peripheral fatigue

A

arises anywhere from the neuromuscular junction and/or within the muscle fiber

64
Q

what does muscle fiber tension depend on

A
  • the frequency of the AP firing by the motor neuron (wave summation)
  • the length of the muscle fiber at rest (length-tension relationship)
65
Q

length tension relationship and whats the optimal length of a sarcomere

A
  • short enough to allow enough zone of overlap between thick and thin filaments
  • long enough for thick filaments toward the M-line without running into the z-disc
  • 100-120% of its resting length
66
Q

wave summation and the types

A

repeated stimulation of the muscle fiber by the motor neuron results in greater tension production if the stimulus are close enough in time
- unfused tetanus
- fused tetanus

67
Q

unfused tetanus

A

muscle fiber has time to partially relax between stimuli
- can get up to 80% of max

68
Q

fused tetanus

A

muscle fiber doesn’t have to time to relax
- can get up to 100% of max

69
Q

fine motor control

A

smaller motor units

70
Q

less control but higher power generation

A

larger motor units

71
Q

true or false
as the force required for contraction decreases, the number of motor units recruited for that muscle increase

A

false
as the force required for contraction increase, the number of motor units recruited for that muscle increase

72
Q

true or false
smaller motor units generally recruited first and as force decreases, larger motor units are not recruited

A

false
smaller motor units generally recruited first and as force increases, larger motor units are recruited

73
Q

isotonic contractions and the types

A

constant tension produced, muscle length changes
- concentric
- eccentric

74
Q

concentric contractions

A

muscles shorten (external force<muscle force)

75
Q

eccentric contractions

A

muscles lengthen (external force>muscle force)

76
Q

isometric contractions

A

muscle length remains constant (external force=muscle force)

77
Q

true or false
skeletal muscle function = contraction/relaxation –>requires ATP

A

true

78
Q

skeletal muscle functions

A
  • contraction/relaxation
  • pumping Ca2+ back into the SR
  • power the Na+/K+ pumps to maintain gradients
79
Q

types to generate energy for skeletal muscles and what it produces

A
  • immediately
  • rapidly
  • sustained
    all produce ATP
80
Q

immediate energy

A

reaction with creatine phosphate in the cytosol
- stored ATP provides ATP for use (2-3 sec worth of muscle contractions)
- ADP + CP –> ATP + Creatine (10 sec worth of ms contr.)
- hydrolysis of 1 CP molecule produces 1 molecule of ATP

81
Q

rapid energy

A

anaerobic metabolism in the cytosol (no oxygen) –> glycolysis

82
Q

glycolysis

A

produces enough ATP for 30-40 sec of sustained muscle contractions

83
Q

sustained energy

A

aerobic metabolism in the mitochondria (oxygen) –> oxidative metabolism
- cellular respiration

84
Q

oxidative metabolism and the sources

A

continues to produce ATP as long as oxygen and nutrients are available
- glucose (preferred)
- fatty acids
- amino acids (if necessary)

85
Q

how many ATP are produced by glycolysis and oxidative metabolism

A

1 glucose molecule produces:
2 ATP via glycolysis (anaerobic)
30 ATP via oxidative metabolism (aerobic)

in total 32 ATP

86
Q

myoplasticity

A

the change in muscle structure as a result of physical training

87
Q

types of training

A
  • endurance (aerobic)
  • resistance (strength)
88
Q

endurance training

A
  • aerobic
  • large increase in frequency of a motor unit activation and moderate increase in force production
  • causes biochemical changes
89
Q

what are the effects of endurance training

A
  • increased oxidative enzymes, mitochondria and associated proteins
  • increasing blood vessel in network supplying muscles
  • increasing fatigue resistance
  • more efficient use of fatty acids and non-glucose fuels for ATP production
90
Q

resistance training

A
  • strength
  • moderate increase in frequency of motor unit activation, large increase in force production
  • causes primer anatomical changes both number of myofibrils and diameter of muscle fibres increase (hypertrophy)
91
Q

hypertrophy

A

Decrease proportion of mitochondrial proteins and blood supply to muscle because of fiber enlargement

92
Q

muscle metabolism at rest

A
93
Q

muscle metabolism at moderate activity

A
94
Q

muscle metabolism at peak activity

A
95
Q

VO2

A

oxygen consumption
- the amount of oxygen taken in and used by the body per min

96
Q

VO2 max

A

the max amount of O2 that an individual can use during max exercise

97
Q

classes of skeletal muscle

A
  • type I: slow
  • type II: fast (IIa and IIx)
  • classified based on myosin ATPase activity (speed of powerstroke) and the predominant energy source
98
Q

myosin ATPase

A

a part of myosin is an enzyme (-ase) that catalyzes the hydrolysis of ATP –> ADP + Pi in cross bridge cycling

99
Q

central nervous system (CNS)

A

brain and spinal cord

100
Q

peripheral nervous system (PNS)

A
  • 12 cranial nerves
  • 31 spinal nerves
101
Q

nervous system actions

A
  • sensory input
  • integration
  • motor output
102
Q

parts of the CNS

A

sensory (afferent):
- somatic sensory division: muscles/bones/joints and skin
- visceral sensory division: organs
motor (efferent):
- somatic motor division: muscles
- autonomic nervous system (ANS): smooth/cardiac muscles and glands

103
Q

nervous tissue

A

made up of neurons and neuroglia
- neurons: are excitable cells (conduct electrical signals to transmit)
- neuroglia: provide structural support and protection for neurons

104
Q

neuron sturcture

A
  • cell body: soma (cell organelles)
  • dendrites: receives input from other neurons
  • Axon: generates/ conducts AP
  • axon hillock
  • axon collaterals
  • axon terminals
  • axolemma and axoplasm
    structure:
  • multipolar
  • bipolar
  • pseudounipolar
    function:
  • sensory/motor
  • interneurons
105
Q

types of neuroglia and the roles in the CNS

A
  • astrocytes: anchor neurons and blood vessels, blood brain barrier
  • oligodendrocytes: myelinated certain axons in the CNS
  • microglial cell: phagocytes (immune cell)
  • ependymal cell: lines cavities, cilia circulate fluid
106
Q

types of neuroglia and roles in the PNS

A
  • schwann cell: myelinates axons in the PNS
  • satellite cells: surrounds and supports cell bodies
107
Q

disuse

A

leads to anatomical and biochemical changes including decrease in number of myofibrils and size of fibre and decrease in oxidative enzymes (atrophy)

108
Q

myelin sheath

A
  • multiple layers of schwann cells (PNS) and oligodendrocytes (CNS) that wrap the axon
  • provides insulation
109
Q

true or false
Myelinated axons conduct action potentials about 15 to 25 times faster than unmyelinated axons

A

false
Myelinated axons conduct action potentials about 15 to 20 times faster than unmyelinated axons

110
Q

RMP of a neuron and why

A
  • K+ channels always leaking out (more)
  • Na+ channels always leaking in (less)
    results in -70 mV
111
Q

local potentials and what are the parts

A
  • smaller, local changes in the MP
  • depolarization & hyperpolarization
  • strength depends on the length of stimulation and number of ion channels
  • weaken as they spread from source (decremental)
  • multiple consume together in time and space as they spread through the cell body (neural integration)
112
Q

depolarization and an example

A

Positive charges entered the cytosol (MP becomes less negative)
- eg. -70 to -60 mV

113
Q

hyperpolarization

A

Either positive charges exit or negative charges enter the cytosol (MP becomes more negative)
- eg. -70 to -80 mV

114
Q

action potentials

A
  • large, uniform in magnitude changes in MP
  • “all or none”
  • depolarization –> repolarization–> RMP
  • generated in the trigger zone (at the axon hillock) then regenerated and propagated along the axon length due to Na+/K+ channels in the axolemma
  • requires threshold depolarization to be initiated
115
Q

steps of action potential
(5 steps)

A
  1. a local potential depolarizes the axolemma of the tigger zone to threshold
  2. Na+ channels activate and enters the axon (depolarization)
  3. Na+ channels inactivate, K+ channels open and exits the cell (repolarization)
  4. Na+ channels return to resting state, repolarization continues
  5. the axolemma may hyperpolarize before K+ channels return to resting state, axolemma returns to RMP
116
Q

refractory period definition and the types

A

neurons are limited to how quickly they can fire another AP
- absolute refractory period
- relative refractory period

117
Q

absolute refractory period

A

no amount of stimulus can produce another AP
- Na+ channels are activated then temporarily inactivated when K+ channels are activated

118
Q

relative refractory period

A

only a strong stimulus can produce another AP
- K+ channels are still open

119
Q

Action potential propagation steps
(4 steps)

A
  1. the axolemma depolarizes to threshold due to local potentials
  2. as Na+ channels activate, an AP is triggered and spreads down the axon
  3. the next section of the axolemma depolarizes to the threshold and fires another AP as the previous section repolarizes
  4. the current continues to move down the axon
120
Q

continues conduction

A

in unmyelinated axons, every section of the axolemma from the trigger zone to the axon terminal must propagate an AP
- slower conduction speed as the axon depolarizes

121
Q

types of action potential propagation

A
  • continuous conduction
  • saltatory conduction
122
Q

saltatory conduction

A

in myelinated axons where insulating properties of myelin sheath increase efficiency and speed of signal conduction
- AP only at the nodes of ranvier
- jumps from one node to the next

123
Q

what are two things that influence the speed of AP propagation

A
  • myelinated axons: myelination lowers resistance to conduction by insulating the membrane
  • axon diameter: axons with larger diameter have faster conduction speeds (larger axons have lower resistance to conduction)
124
Q

what are the steps of action potentials down the axon
(3 steps)

A
  1. local potential: soma
  2. action potential: trigger zone (axon hillock)
  3. action potential propagation: axon
125
Q

where does a presynaptic neuron synapse with

A
  • post synaptic neuron
  • other target cells
126
Q

termination of the synaptic transmission at the chemical synapse

A

the neurotransmitter must be removed

HES 101 (2 decks)

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