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Phys of Domestic Animals 1 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

what is the definition of an action potential

A

brief, rapid, large changes in the distribution of charges across a membrane in a non decremental fashion

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2
Q

what are the electrical events taking place during an action potential

A

a slow depolarization till the threshold potential is reached, then an explosive depolarization takes place, the membrane repolarizes back to its resting place, finally a transient hyperpolarization occurs

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3
Q

what type of channels are responsible for the occurance of action potentials

A

voltage gated channels

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4
Q

what happens during the resting phase of an action potential

A

Na+ and K+ voltage gated channels are closed

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5
Q

what happens during the threshold potential of an action potential

A

Na+ channels open causing a depolarization then at the peak of the action potential those channels are deactivated

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6
Q

what happens at the peak of the action potential

A

K+ gates open allowing K+ ions to leave resulting in a repolarization

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7
Q

what happens after the action potential returns to the threshold potential

A

K+ continues to move out causing a hyperpolarization once the K+ channel is fully closed the resting membrane potential is returned

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8
Q

what re-establishes and maintains the concentration gradients of Na and K

A

the Na+ K+ pump

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9
Q

what is an absolute refractory period (RP)

A

when another action potential can not be generated no matter how depolarized the membrane is to avoid the offset balance of Na and K

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10
Q

what is a relative refractory period (RP)

A

when an action potential can be generated but it requires a stronger than normal stimuli due to the membrane being hyperpolarized

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11
Q

what is the propagation of unmyelinated axons

A

the charges in the membrane continues to flow to neighboring axons

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12
Q

what are schwann cells

A

neuron associated cells that have myelin sheaths wrapped around the axon- in the peripheral system

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13
Q

what is the purpose of myelin sheaths

A

to support and propagate action potentials moving down the axon

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14
Q

what type of cell does the peripheral nervous system contain

A

Schwann cells

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15
Q

what type of cell does the central nervous system contain

A

Oligodendrocyte

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16
Q

what does the layers of myelin provide the axons

A

insulated pockets

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17
Q

do nodes of roaniver have myelin sheets

A

NO

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18
Q

what is the interaction between unmyelinated axons and schwann cells

A

the schwann cell supports several axons that are separated from its neighbor by thin cytoplasmic extensions of the schwann cell

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19
Q

what is unique about an action potential occuring in myelinated cells

A

those spots of insulation provides a pocket that allows the action potential to move from one insulated spot to another allowing the rate of passage to increase

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20
Q

do myelin sheets create a distance between the ICF and the ECF fluid membrane

A

yes

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21
Q

what is saltatory propagation

A

an action potential propagation in myelinated axons

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22
Q

what determines the rate of action potentials

A

size and diameter

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23
Q

how can an myelinated cell differ from a unmyelinated one in terms of passage rate

A

an myelinated cell can be smaller but move an action potential 3.5x faster

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24
Q

does the velocity of an action potential differ between myelinated and unmyelinated cells

A

yes myelinated tend to have a faster velocity

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25
Q

are graded potentials depolarizations or hyperpolarizations

A

this is dependent on the stimulus

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26
Q

action potentials always lead to what

A

depolarization of a membrane and the reversal of the membrane potential

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27
Q

what is the amplitude of a graded potenial based off of

A

the stength of the stimulus

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28
Q

what type of amplitude do action potentials have

A

an all or nothing amplitude

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29
Q

what does the strength of stumulus change in an action potential

A

frequency

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30
Q

what size is the general amplitude of a graded potential

A

small

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31
Q

what is the general amplitude of an action potential

A

large (100mV)

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32
Q

what is the typical duration of a graded potential

A

a few milliseconds to seconds

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33
Q

what is the typical duration of an action potential

A

3-5 minutes

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34
Q

what channel is typicall responsible for graded potentials

A

ligand gated channels

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35
Q

what ions are typically involved w/ graded potentials

A

Na+, K+, or Cl-

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36
Q

what ions are typically involved w/ action potentials

A

Na+ and K+

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37
Q

is the there a refractory period w/ graded potentials

A

NO

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38
Q

is summation possible w/ graded potentials

A

yes both temporal summation and spatial summation

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39
Q

is summation possible w/ action potentials

A

NO due to them being all or nothing

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40
Q

how do graded potentials spread

A

through passive spread to neighboring membrane regions

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41
Q

how do action potentials spread

A

to neighboring membrane regions that regeneration of a new action potential at every point

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42
Q

does the amplitude of graded potentials deminish over time

A

yes the are decremental

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43
Q

how are graded potentials created

A

either by an external stimuli or by the release of neurotransmitters in synapse

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44
Q

what is the sarcoplasm

A

the cytoplasm of muscle cells

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45
Q

what is the sarcoplasmic reticulum

A

endoplasmic reticulum in muscle cells

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46
Q

what is the sacolemma

A

the cell membrane of muscle cells

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47
Q

what are myofibrils

A

what muscle cells are contained of

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48
Q

what are myofilaments

A

filaments found in muscle cells consisted of thin actin filaments and thick myosin filaments

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49
Q

what is the relationship between actin filaments and myosin filaments in muscle cells

A

the actin and myosin filaments slide across each other which is what causes contractions and relaxations

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50
Q

what is the I band

A

actin filaments w/ in a myofibril w/ some myosin

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51
Q

what is the A band

A

myosin filaments w/ in a myofibril w/ some actin on the outer parts

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52
Q

what is the H zone

A

region in the middle of the A band where there is only myosin

53
Q

what does a small H zone equal for a muscle

A

it means the muscle is fully contracted

54
Q

what is the M line

A

a protein called myozenin that marks the centre of the sarcomere, primarily role is structurally keeping everything spaced properly

55
Q

what is the Z disc

A

an anchor point where actin are anchored to each other on both sides of the I band

56
Q

what is a T tubule

A

an extension of the sarcolemma that extends down in the cell membrane that wraps around myofibrils to relay an action potential

57
Q

what ion allows the SR to be extremely extensive for contraction

A

Ca

58
Q

what is the terminal cisternae of SR

A

where the sarcoplasmic reticulum and T tubule meet physically

59
Q

what is the triad in skeletal muscle cells

A

T tubule, sarcoplasmic reticulum, and terminal cisternae

60
Q

what is tropomyosin

A

it prevents myosin from binding to actin in the absence of Ca

61
Q

what is troponin

A

it shifts the position of tropomyosin on the actin filaments, exposing myosin binding sites on actin

62
Q

where are actin filaments oriented w/ their plus end

A

Z disc

63
Q

where are actin filaments oriented w/ their minus end

A

the center of the sacromere

64
Q

what is ATP critical for in muscle

A

both contraction and relaxation

65
Q

what is the difference between channels and gap junctions

A

channels are material specific while gap junctions will allow anything through that can fit

66
Q

how many nuclei are in each cardiomyocyte

A

one or two large ones located centrally surrounding the numerous mitochondria

67
Q

how are cardiac muscle cells arranged

A

distinctly aligned w/ one another

68
Q

what type of muscle cells are striated

A

cardiac and skeletal

69
Q

does cardiac muscle require a signal for contraction

A

no

70
Q

what purpose does intercalated disks have for cardiac muscle cells

A

they join them w/ adjacent cells as well as allowing passage of electrical activity throughout creating a conduit from one cell to the next

71
Q

how are sepearate cardiomyocytes connected

A

by desmosomes and adherin junctions

72
Q

where in individual cardiomyocytes is the nuclei

A

in the center of the cell

73
Q

how many nuclei does smooth muscle cells have

A

one

74
Q

are smooth muscle cells straited

A

NO

75
Q

what are smooth muscle cells modulated by

A

autonomic nervous system

76
Q

what do gap junctions in smooth muscle cells do

A

they allow for coordination of contraction

77
Q

what are actin filaments attached to in the cytoplasm of smooth muscle

A

dense bodies

78
Q

what are actin filaments attached to in the membrane of smooth muscle

A

attachment plaques

79
Q

what is the caveolae

A

folds in the cell membrane that contain aggregates of receptors and ion channels responsible for conveying signals into the cell

80
Q

what is a single unit smooth muscle cell

A

a buncle or sheet of hundreds to thousands of smooth muscle fibers that contract together as a single unit

81
Q

how are neurotransmitters distributed to both a single unit smooth muscle cell and a multi unit smooth muscle cell

A

via varicosities

82
Q

what are multi unit smooth muscle cells

A

these are capable of contracting independently of one another and often are innervated by a single nerve ending

83
Q

what type of contraction does multi unit smooth muscle cells have

A

spontaneous

84
Q

what type of contraction does single unit smooth muscle cells have

A

synchronous due to action potentials flowing from one fiber to another thru gap junctions

85
Q

how are action potentials communicated to skeletal muscles

A

from a motor neuron extending from the ventral root of the spinal cord

86
Q

what is the only way skeletal muscle can be induced for contraction

A

after interacting with motor neurons

87
Q

what is neurogenic mean for SM

A

that is when smooth muscle contracts in response to stimulation from neurons, typically w/ multi unit muscles

88
Q

what is myogenic for SM

A

when the muscle itself generates its own rhythmic contractions, typically w/ single unit muscles

89
Q

where is an action potential initated in skeletal muscle

A

at a neuromuscular junction

90
Q

what is a dihypropyridine recepors (DHPR)

A

a voltage dependent Ca channel that acts like a voltage gated sensor that is present in the T tubule

91
Q

what is excitation contraction coupling

A

idea that an action potential will inevitably lead to contraction that stems from DHPR

92
Q

what is a ryanodine receptor (RYR)

A

a Ca channel in the sarcoplasmic reticulum that is opened due to depolarization caused conformational change in DHPR, this is initally causes the cross bridge cycle

93
Q

what happens after repolarization of the sarcolemma

A

DHPR and RYR return to their original conformation, Ca channels close, ATP dependent Ca pumps return Ca to the SR, Ca levels in the sarcoplasm declines, Ca dissociates from troponin, and tropomyosin returns to its “blocking” position on actin

94
Q

what depolarization cause in the sarcoplasm

A

it causes a conformational change in DHPR that opens the RYR Ca channel on the SR, Myosin/Actin cross bridges which induces sliding of actin filaments

95
Q

what is the Ca induced Ca release seen in the contraction of cardiac muscles

A

An action potential enters from adjacent cells, voltage gated Ca channels open allowing Ca to enter the cell, Ca induces Ca release through RYR channels which causes Ca spark which create a Ca signal, Ca ions bind to troponin to initate contraction

96
Q

what happens when the cardiac muscle relaxes

A

Ca unbinds from troponin Ca is pumped back into the sarcoplasmic reticulum for storage, Ca is exchanged w/ Na. The Na gradient is maintained by the Na K ATPase

97
Q

what is the propagation of myelinated axon potentials

A

Slatatory propagation which is when the ions jump from one insulated pocket to another

98
Q

what type of neurotransmitter is released in muscle cells

A

acetylcholine

99
Q

describe the cross bridge cycle

A

ATP binds w/ myosin, after Ca is released from the voltage gated channels Ca binds to troponin pulling tropomyosin from actin allowing myosin binded w/ ADPase to bind to actin, the ADPase then unbinds from the myosin leaving room for another ATP to bind to the myosin to relax and detach from the actin

100
Q

what type of neuron releases norepinephrine

A

somatic

101
Q

what is the connective tissue surrounding each myofibril

A

endomysium

102
Q

what connective tissue is surrounding each fascicle

A

perimysium

103
Q

what connective tissue is surrounding groups of fascicles

A

epimysium

104
Q

what type of cycle is the cross bridge cycle and how long does it contiune

A

it is the contractile cycle and it contiunes as long as the Ca and ATP is present

105
Q

how does contraction in a skeletal muscle ends

A

Ca ATP pumps returns Ca to the sarcoplasmic reticulum resting the membrane polarity

106
Q

what type of stimulus contracts smooth muscle

A

mechanical, electrical, or chemical

107
Q

what does depolarization cause in smooth muscle cells

A

contractions from the opening of voltage dependent calcium channel causing an increase of the intracellular concentration of Ca

108
Q

what are neurogenic smooth muscle

A

smooth muscle that is initated by the stimulus from neurons

109
Q

what is myogenic smooth muscle

A

smooth muscle that self generates rhythmic contractions

110
Q

what is phasic contractions

A

rapid alternating contractions and relaxations

111
Q

what is tonic contractions

A

a degree of tension or tone is maintained at all times

112
Q

describe the release of neurotransmitter at a varicosity

A

the action potential arrives at the varicosity causing a depolarization opening the voltage gated Ca channels allowing Ca to trigger exocytosis of synaptic vesicles NE then binds to the adrenergic recptor of the target once NE diffuses away from the synapses the activity stops

113
Q

what happens after the snyapses of contraction stops in a smooth muscle cell

A

the NE is transported back into the axon placed back into the synaptic vesicles to be metabolized by monamine oxidase (MAO)

114
Q

what connects adjacent fibers in smooth muscle

A

gap junctions

115
Q

how is myosin different in terms of contraction of smooth muscle

A

in SM the movement of myosin heads is mediated by two small protein chains associated w/ the neck of the myosin molecule

116
Q

what is the role light chains have in smooth muscle contraction

A

once they are phosphorylated they allow the myosin head to bind to actin

117
Q

what is kinases

A

enzymes that add phosphate groups

118
Q

what is phosphatases

A

enzymes that remove phosphate groups

119
Q

what is calmodulin

A

a Ca binding protein that stimulates SM contraction

120
Q

what is the myosin light chain kinase (MLCK)

A

it regulates the myosin and actin interaction by binding phosphate to myosin in the presence of calmodulin and Ca allowing it to bind w/ actin

121
Q

where does most Ca come from for SM contraction

A

the ECF

122
Q

how can cytosolic Ca levels be increased in SM cells

A

either by voltage dependent activation processes or by receptor mediated processes

123
Q

what is the mechanism for SM contraction

A

intracellular Ca concentrations increases when Ca enters the cell and is released from sarcoplasmic reticulum then Ca binds to calmodulin activating the MLCK this phosphorylates light chains in myosin increasing myosin ATPase activity inacting the cross bridge slide along actin creating muscle tension

124
Q

how does SM contraction end

A

Ca decreases and the phosphate unbinds from the light chain of the myosin head through myosin light chain phosphatase (MLCP)

125
Q

what are satellite cells

A

a ganglia cell that regulates O2, CO2, nutrient, and neurotransmitter levels in the peripheral nervous system specifical the afferent side

126
Q

what are astrocytes cells

A

they maintain blood brain barrier providing structural support, regulating ion, nutrient, and dissolved gas concentrations while absorbing and recycling neurotransmitters in the central nervous system

127
Q

what are ependymal cells

A

line ventricles and central canal and assists in producing, circulating, and monitoring of cerebrospinal fluid

128
Q

what are microglia cells

A

they remove cell debris wastes, and pathogens by phagocytosis

Phys of Domestic Animals 1 (4 decks)

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