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anatomy 2401 > lecture anatomy exam 3 > Flashcards

lecture anatomy exam 3 Flashcards

1
Q

what characteristics define skeletal muscle tissue?

A

voluntary; striated, long, multi-nucleated.

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2
Q

what characteristics define cardiac muscle tissue?

A

involuntary; long-ish, branching, intercalated discs.

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3
Q

what characteristics define smooth muscle tissue?

A

involuntary; smooth fibers with spindle shaped cells.

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4
Q

what are the layers of connective tissue that enclose the structural components of skeletal muscle?

A

epimysium (superficial; encloses entire muscle), perimysium (middle; encloses muscle fascicle [bundle]), endomysium (deepest; muscle fiber).

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5
Q

what is a tendon?

A

band of connective tissue that extends beyond the muscle to attach it to bone.

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6
Q

what are the regulatory proteins of the thin myofilaments?

A

tropomyosin and troponin.

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7
Q

what are the components of the thin filaments of striated muscle?

A

composed of the fibrous protein actin, which is made of globular subunits that have a myosin- binding site. two actin strands twist together to form the thin filament.

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8
Q

the repeated segments of a myofibril are called?

A

sarcomeres

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9
Q

what is a motor unit?

A

a motor neuron and all the muscle fibers it innervates.

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10
Q

what are the sarcolemma’s folds called within a synaptic cleft?

A

junctional folds

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11
Q

what would happen to a muscle if a poison inhibited the activity of acetylcholinesterase?

A

first: function of acetylcholinesterase is to remove acetylcholine from synaptic cleft.
second: the presence of acetylcholine in the synaptic cleft causes the ach receptors to open the Na+ gates allowing an influx of N into cell.
third: if no acetylcholinesterase removes acetylcholine, and Na+ constantly goes into cell, then the muscle is constantly contracted, and this leads to muscle fatigue.

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12
Q

what are muscle fibers and neurons termed?

A

they’re termed excitable because their cell membranes show signs of voltage changes as a result of stimulation.

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13
Q

what type of ions do muscle fibers and neurons have an excess of surrounding them and inside of them?

A

Na+ and K+

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14
Q

what is depolarization?

A

a rapid voltage change in which a plasma membrane briefly reverses electrical polarity.

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15
Q

what is the function of T-tubules?

A

propagate the action potential deep into the muscle fiber, where voltage- sensitive proteins will open to allow Ca+ to be released from the sarcoplasmic reticulum.

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16
Q

what is the sliding-filament theory of muscle contraction?

A

actin and myosin filaments slide past each other to produce a contraction.

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17
Q

can muscle move a bone by either pushing or pulling during contraction?

A

muscle can pull a bone when it contracts (shortens) and the tendon (attached to the bone) is also pulled.

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18
Q

what causes rigor mortis (stiffening of muscles after death)?

A

intracellular calcium levels increase becuase ATP is no longer synthesized, so calcium can’t be pumped back into the sarcoplasmic reticulum. thus, a cross bridge is formed and can’t detach because ATP is needed for detachment. muscles stay contracted until proteins in the muscle break down, which causes myosin to release.

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19
Q

in a relaxed muscle fiber, what blocks the active sites of actin?

A

tropomyosin

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20
Q

how is ATP used in muscle contraction and relaxation?

A

move and detach cross bridges (myosin head), pump calcium back into sarcoplasmic reticulum, and pump sodium out of and potassium back into the cell after excitation contraction coupling.

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21
Q

what can muscles store large amounts of in molecules?

A

glycogen

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22
Q

when there is not enough oxygen to create ATP by aerobic respiration, a muscle fiber can produce ATP by borrowing phosphate groups from?

A

creatine phosphate

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23
Q

what is the function of creatine kinase?

A

an enzyme that transfers the phosphate group to ADP to create ATP.

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24
Q

after a muscle fiber has exhausted all of its immediate sources of ATP what does it switch to as the only source of ATP?

A

lactic acid

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25
Q

a “stair step” increase in muscle contraction strength believed to be due to an increase in heat and enzyme activity, during a warm-up is what?

A

treppe effect

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26
Q

a state of smooth, sustained contraction of a muscle fiber is called.

A

tetanus

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27
Q

when a muscle develops increased tension, but does not shorten, it is said to exhibit what kind of contraction?

A

isometric

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28
Q

red slow-twitch muscle fibers get their name from the fact that they contain more of what?

A

myoglobin

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29
Q

what is the function of myoglobin?

A

binds oxygen to muscle fibers.

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30
Q

what kind of fiber maintains posture?

A

slow oxidative

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31
Q

do muscle cells increase in the number after following a routine exercise program?

A

they can increase in size, mitochondria, strength, etc., but can’t increase in number.

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32
Q

smooth muscle fibers that act like skeletal muscle fibers, that is they are not connected by gap junctions, but are controlled by autonomic nerves and hormones are called what?

A

multiunit

33
Q

the site of calcium regulation for a muscle contraction within a smooth muscle cell is.

A

the extracellular space

34
Q

distinguish single-unit smooth muscle from multiunit smooth muscle.

A

single unit exhibits spontaneous depolarization and movement is caused by alternating muscle layers contracting. multi-unit muscle rarely exhibits spontaneous depolarization and contains independent muscle fibers innervated by ANS.

35
Q

list and understand the brief summary of steps involved in a smooth muscle contraction.

A

calcium, mostly coming from the extracellular space, binds to calmodulin. activated calmodulin activates myosin kinase which activates the myosin head, forming a crossbridge with actin.

36
Q

what functions are performed by the nervous system?

A

sensory input, processing information, responding with motor output.

37
Q

what is an effector?

A

the organ/muscle/gland that receives a motor neuron. somatic nerve fibers innervate skeletal muscles, and visceral motor fibers innervate smooth/cardiac muscle and glands.

38
Q

what constitutes the central nervous system?

A

brain and spinal cord

39
Q

what carries brain and spinal cord signals to other organs?

A

motor (efferent) nervous system.

40
Q

what functions are performed by the autonomic nervous system?

A

regulates smooth/cardiac muscle, and glands.

41
Q

what are the subdivisions of the autonomic nervous system?

A

sympathetic and parasympathetic.

42
Q

what are nissl bodies? where are they located?

A

chromatophilic substances found in the rough er of a neuron cell body.

43
Q

what is the soma of a neuron?

A

the cell body

44
Q

how are axons and dendrites alike? how are they different?

A

they both carry signals within the neuron, but dendrites receive the signal to give to the cell body, and axons send the signal away from the cell body.

45
Q

what is the trigger zone of a neuron? where is it located?

A

the axon hillock, it is found where the cell body narrows and leads to the axon.

46
Q

though the synaptic cleft is not a structure on a neuron, it plays an important role in nerve function. what the function of the synaptic cleft and where is it located?

A

the synaptic cleft is found between an axon terminal of a neuron and whatever it is synapsing with; its function is to provide a medium for neurotransmitter to diffuse through, as well as hold ions that aid in maintaining the polarized resting membrane potential.

47
Q

what is typically short, abundantly branched, slender processes of the cell body that receive stimuli and send impulses toward the cell body.

A

dendrites

48
Q

what are astrocytes and what are their functions?

A

neuroglial cells in the CNS that support neurons, control the chemical environment surrounding a neuron, and help with information processing in the brain.

49
Q

what type of neuroglia line the ventricles of the brain?

A

ependymal cells

50
Q

what is the function of oligodendrocytes?

A

neuroglia in the CNS that wrap axons to form an insulating myelin sheath.

51
Q

what wraps around axons to produce insulating myelin sheathes in the peripheral nervous system?

A

schwann cells

52
Q

what are microglia; what is their function; where are they found?

A

neuroglia found in the CNS that help repair injured neurons and phagocytize debris.

53
Q

what are ganglia and where are they found?

A

clusters of neuron cell bodies in the PNS.

54
Q

what are nuclei and where are they found?

A

clusters of neuron cell bodies in the CNS.

55
Q

an interneuron is associated especially with what functions of the nervous system?

A

integration

56
Q

what neuron has its primary function of sending signals away from the CNS, and what neuron has its primary function of receiving signals from the PNS.

A

motor and interneuron

57
Q

what are bipolar, multipolar, unipolar neurons and where do they normally occur?

A

multipolar neurons have one axon and many dendrites and are mostly found in the CNS. Bipolar neurons have 1 axon and 1 dendrite and are found in retina and olfactory mucosa. unipolar neurons have a single process and are associated with sensory receptors.

58
Q

what substance comprises myelin?

A

mostly lipids

59
Q

what is the difference in the neurilemma and axolemma?

A

neurilemma is the cell membrane of the cell body, and axolemma is the cell membrane of the axon.

60
Q

what is a synapse?

A

an electrically coupled junction, either between neuron cells or nervous to muscle cells.

61
Q

what are nodes of ranvier?

A

gaps between myelin sheaths on an axon, they serve as a location for ions to move in/out of the neuron to propagate the signal down the axon.

62
Q

how might one measure the membrane potential of a neuron using electrodes?

A

with a voltmeter, see video on blackboard for visual demonstration.

63
Q

in what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environmental?

A

inside of a cell is negatively charged with more potassium ions compared to the outside of the cell being more positive and with more sodium ions.

64
Q

which ions are needed to establish a resting potential in a cell?

A

sodium and potassium

65
Q

what are sodium-potassium pumps, and how do they work?

A

allow the movement of sodium and potassium along the cell membrane to maintain the resting membrane potential. three sodium ions enter the cell for every two potassium ions that leave the cell.

66
Q

when does a neuron fire?

A

when threshold is reached, at -55mv.

67
Q

what is the all-or-nothing phenomenon?

A

either an action potential happens completely or it doesn’t happen at all.

68
Q

during a nerve impulse, what events take place when the mV is at -70 millivolts, about -55mV, 0 mV, about +30mV, about -71mV or -72 millivolts?

A

-70 mV is resting membrane potential with all gated channels closed. Depolarization occurs when Na+ gates open and allow influx of sodium, and an action potential is sent once threshold is met, -55mV. Depolarization peak at +30mV which triggers Na+ gates to close and K+ gates to open, and repolarization starts. Hyperpolarization occurs when the K+ gates close and conditions reset, and the mV dips slightly below RMP -70mV.

69
Q

what happens when a neuron is depolarized to threshold?

A

an action potential is generated.

70
Q

the period after an initial stimulus when a neuron is not sensitive to another stimulus is what?

A

refractory period.

71
Q

compare and contrast continuous conduction and saltatory conduction.

A

continuous conduction is slower and occurs in unmyelinated fibers; saltatory conduction is faster and occurs in myelinated fibers as the AP is generated at gaps between myelin sheaths.

72
Q

what type of axons do nerve impulses travel down?

A

thick and myelinated

73
Q

why do demyelinated axons fail to function normally?

A

large gaps without Na+ gates, so AP can’t regenerate along the membrane.

74
Q

what are the events that occur when a nerve signal reaches a synaptic knob?

A

neurotransmitter is released and binds to receptors on post-synaptic membrane, which allows NA+ to flood into post-synaptic cell. this causes depolarization, then Na+ gates close and K+ gates open to cause repolarization, then K+ gates close and everything resets during hyperpolarization.

75
Q

what specific event will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane?

A

depolarization

76
Q

what is an inhibitory postsynaptic potential (IPSP)?

A

when a neurotransmitter binds to K+ or CL- channels to allow ion movements that cause hyperpolarization (further from threshold).

77
Q

what happens in summation?

A

when many EPSP’s from one or more presynaptic neurons occurring in a short period of time depolarize a neuron to threshold.

78
Q

which neurotransmitter is secreted by motor neurons onto skeletal muscle?

A

acetylcholine (ACH)

79
Q

what is acetylcholinesterase and where is it found?

A

enzyme that degrades ACH, it is found in the synaptic cleft.

anatomy 2401 (12 decks)

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