0-1 chapter 12 Nervous Tissue Flashcards

Question

Functional Types of Neurons 3

Answer 1

sensory (afferent) neurons interneurons(association) neurons motor (efferent)neuron

Answer 2

–specialized to detect stimuli –transmit information about them to the CNS •begin in almost every organ in the body and end in CNS •afferent–conducting signals toward CNS

Answer 3

conducting signals toward CNS

Answer 4

–lie entirely within the CNS –receive signals from many neurons and carry out the integrative function •process, store, and retrieve information and „make decisions‟ that determine how the body will respond to stimuli –90% of all neurons are interneurons –lie between, and interconnect the incoming sensory pathways, and the outgoing motor pathways of the CNS

Answer 5

–send signals out to muscles and gland cells (the effectors) •motor because most of them lead to muscles •efferent neurons conduct signals away from the CNS

Answer 6

neurons conduct signals away from the CNS

Answer 7

because most of them lead to muscles

Answer 8

the control center of the neuron –also called neurosoma, cell body, or perikaryon –has a single, centrally located nucleus with large nucleolus

Answer 9

cytoplasm contains mitochondria, lysosomes, a Golgi complex, numerous inclusions, and extensive rough endoplasmic reticulum and cytoskeleton

Answer 10

consists of dense mesh of microtubules and neurofibrils (bundles of actin filaments) •compartmentalizes rough ER into dark staining Nissl bodies

Answer 11

no further cell division

Answer 12

glycogen granules, lipid droplets, melanin, and lipofuscin

Answer 13

lipofuscin(golden brown pigment produced when lysosomes digest worn-out organelles) •lipofuscin accumulates with age •wear-and-tear granules •most abundant in old neurons

Answer 14

vast number of branches coming from a few thick branches from the soma –primary site for receiving signals from other neurons

Answer 15

axon(nerve fiber) –originates from a mound on one side of the soma called the axon hillock –cylindrical, relatively unbranched for most of its length

Answer 16

cytoplasm of axon

Answer 17

plasma membrane of axon | –only one axon per neuron

Answer 18

(terminal button) –little swelling that forms a junction (synapse) with the next cell •contains synaptic vesicles full of neurotransmitter

Answer 19

branches of axon

Answer 20

distal end, axon has terminal arborization –extensive complex of fine branches

Answer 21

–one axon and multiple dendrites –most common –most neurons in the brain and spinal cord

Answer 22

–one axon and one dendrite | –olfactory cells, retina, inner ear

Answer 23

–single process leading away from the soma | –sensory from skin and organs to spinal cord

Answer 24

–many dendrites but no axon | –help in visual processes

Answer 25

two-way passage of proteins, organelles, and other material along an axon

Answer 26

movement down the axon away from soma

Answer 27

movement up the axon toward the soma

Answer 28

microtubules guide materials along axon | –motor proteins (kinesin and dynein) carry materials “on their backs” while they “crawl” along microtubules

Answer 29

motor proteins in anterograde transport

Answer 30

motor proteins in retrograde transport

Answer 31

occurs at a rate of 20 –400 mm/day

Answer 32

(up to 400 mm/day) | •organelles, enzymes, synaptic vesicles and small molecules

Answer 33

•for recycled materials and pathogens -rabies, herpes simplex, tetanus, polio viruses –delay between infection and symptoms is time needed for transport up the axon

Answer 34

-0.5 to 10 mm/day –always anterograde –moves enzymes, cytoskeletal components, and new axoplasm down the axon during repair and regeneration of damaged axons –damaged nerve fibers regenerate at a speed governed by slow axonal transport

Answer 35

* about a trillion (10-12) neuronsin the nervous system | * neurogliaoutnumber the neurons by as much as 50 to 1

Answer 36

–support and protect the neurons | –bind neurons together and form framework for nervous tissue

Answer 37

oligodendrocytes ependymal cells microglia astrocytes

Answer 38

* form myelin sheaths in CNS | * each arm-like process wraps around a nerve fiber forming an insulating layer that speeds up signal conduction

Answer 39

•lines internal cavities of the brain •cuboidal epithelium with cilia on apical surface •secretes and circulates cerebrospinal fluid (CSF) –clear liquid that bathes the CNS

Answer 40

* small, wandering macrophages formed white blood cell called monocytes * thought to perform a complete checkup on the brain tissue several times a day * wander in search of cellular debris to phagocytize

Answer 41

* most abundant glial cell in CNS | * cover entire brain surface and most nonsynaptic regions of the neurons in the gray matter of the CNS

Answer 42

–form a supportive framework of nervous tissue –have extensions (perivascular feet) that contact blood capillaries that stimulate them to form a tight seal called the blood-brain barrier –convert blood glucose to lactate and supply this to the neurons for nourishment

Answer 43

secreted by astrocytes promote neuron growth and synapse formation

Answer 44

when neuron is damaged, astrocytes form hardened scar tissue and fill space formerly occupied by the neuron SCAR TISSUE

Answer 45

Schwann cells | satellite cells

Answer 46

* envelop nerve fibers in PNS * wind repeatedly around a nerve fiber * produces a myelin sheath similar to the ones produced by oligodendrocytes in CNS * assist in the regeneration of damaged fibers

Answer 47

Schwann cells

Answer 48

* surround the neurosomas in ganglia of the PNS * provide electrical insulation around the soma * regulate the chemical environment of the neurons

Answer 49

masses of rapidly dividing cells | –mature neurons have little or no capacity for mitosis and seldom form tumors

Answer 50

–meninges (protective membranes of CNS) –by metastasis from non-neuronal tumors in other organs –most come from glial cells that are mitotically active throughout life

Answer 51

gliomas grow rapidly and are highly malignant –blood-brain barrier decreases effectiveness of chemotherapy –treatment consists of radiation or surgery

Answer 52

an insulating layer around a nerve fiber –formed by oligodendrocytes in CNS and Schwann cells in PNS –consists of the plasma membrane of glial cells •20% protein and 80 % lipid

Answer 53

production of the myelin sheath –begins the 14thweek of fetal development –proceeds rapidly during infancy –completed in late adolescence –dietary fat is important to nervous system development

Answer 54

in PNS, Schwann cell spirals repeatedly around a single nerve fiber –lays down as many as a hundred layers of its own membrane –no cytoplasm between the membranes

Answer 55

thick outermost coil of myelin sheath | •contains nucleus and most of its cytoplasm

Answer 56

external to neurilemma is basal lamina and a thin layer of fibrous connective tissue

Answer 57

in CNS –oligodendrocytes reaches out to myelinate several nerve fibers in its immediate vicinity –anchored to multiple nerve fibers –cannot migrate around any one of them like Schwann cells –must push newer layers of myelin under the older ones •so myelination spirals inward toward nerve fiber –nerve fibers in CNS have no neurilemma or endoneurium

Answer 58

segmented nodes of Ranvier internodes

Answer 59

gap between segments

Answer 60

myelin covered segments from one gap to the next

Answer 61

short section of nerve fiber between the axon hillock and the first glial cell

Answer 62

the axon hillock and the initial segment | •play an important role in initiating a nerve signal

Answer 63

multiple sclerosis | Tay-Sachs disease

Answer 64

* oligodendrocytes and myelin sheaths in the CNS deteriorate * myelin replaced by hardened scar tissue * nerve conduction disrupted (double vision, tremors, numbness, speech defects) * onset between 20 and 40 and fatal from 25 to 30 years after diagnosis * cause may be autoimmune triggered by virus

Answer 65

a hereditary disorder of infants of Eastern European Jewish ancestry •abnormal accumulation of glycolipid called GM2in the myelin sheath –blindness, loss of coordination, and dementia •fatal before age 4

Answer 66

neurilemma wrapping of unmyelinated nerve fibers

Answer 67

–diameter of fiber | –presence or absence of myelin

Answer 68

–small, unmyelinated fibers -0.5 -2.0 m/sec –small, myelinated fibers -3 -15.0 m/sec –large, myelinated fibers -up to 120 m/sec –slow signals supply the stomach and dilate pupil where speed is less of an issue –fast signals supply skeletal muscles and transport sensorysignals for vision and balance

Answer 69

regeneration of a damaged peripheral nerve fiber can occur if: –its soma is intact –at least some neurilemma remains

Answer 70

formed by Schwann cells, basal lamina, and the neurilemma near the injury –regeneration tube guides the growing sprout back to the original target cells and reestablishes synaptic contact

Answer 71

of muscle due to loss of nerve contact by damaged nerve

Answer 72

cellular mechanisms for producing electrical potentials and currents –basis for neural communication and muscle contraction

Answer 73

a difference in the concentration of charged particles between one point and another

Answer 74

a flow of charged particles from one point to another

Answer 75

RMP exists because of unequal electrolyte distribution between extracellular fluid (ECF) and intracellular fluid (ICF)

Answer 76

–ions diffuse down their concentration gradient through the membrane –plasma membrane is selectively permeable and allows some ions to pass easier than others –electrical attraction of cations and anions to each other

Answer 77

have the greatest influence on RMP –plasma membrane is more permeable to K+ than any other ion –leaks out until electrical charge of cytoplasmic anions attracts it back in and equilibrium is reached and net diffusion of K+ stops –K+ is about 40 times as concentrated in the ICF as in the ECF

Answer 78

can not escape due to size or charge (phosphates, sulfates, small organic acids, proteins, ATP, and RNA)

Answer 79

3 Na+ for every 2 K+ it brings in

Answer 80

* Na+ concentrated outside of cell (ECF) | * K+ concentrated inside cell (ICF)

Answer 81

disturbances in membrane potential when a neuron is stimulated

Answer 82

case in which membrane voltage shifts to a less negative value

Answer 83

are graded decremental reversible either excitatory or inhibitory

Answer 84

vary in magnitude with stimulus strength | •stronger stimuli open more Na+gates

Answer 85

get weaker the farther they spread from the point of stimulation •voltage shift caused by Na+ inflow diminishes rapidly with distance

Answer 86

when stimulation ceases, K+ diffusion out of cell returns the cell to its normal resting potential

Answer 87

some neurotransmitters (glycine) make the membrane potential more negative –hyperpolarize it –becomes less sensitive and less likely to produce an action potential

Answer 88

more dramatic change produced by voltage-regulated ion gates in the plasma membrane –only occur where there is a high enough density of voltage-regulated gates

Answer 89

soma (50 -75 gates per m2 ) -cannot generate an action potential

Answer 90

(350 –500 gates per m2 ) –where action potential is generated

Answer 91

critical voltage to which local potentials must rise to open the voltage-regulated gates •-55mV

Answer 92

look at slides

Answer 93

action potential is often called a spike–happens so fast

Answer 94

–follows an all-or-none law •if threshold is reached, neuron fires at its maximum voltage •if threshold is not reached it does not fire –nondecremental-do not get weaker with distance –irreversible-once started goes to completion and can not be stopped

Answer 95

the period of resistance to stimulatio

Answer 96

–absolute refractory period •no stimulus of any strength will trigger AP •as long as Na+gates are open •from action potential to RMP –relative refractory period •only especially strong stimulus will trigger new AP –K+gates are still open and any effect of incoming Na+ is opposed by the outgoing K+

Answer 97

has voltage-regulated ion gates along its entire length

Answer 98

the nerve signal seems to jump from node to node(

Answer 99

1st neuron in the signal path is the presynaptic neuron | •releases neurotransmitter

Answer 100

2nd neuron is postsynaptic neuron | •responds to neurotransmitter

Answer 101

a dendrite, soma, or axon of postsynaptic neuron to form axodendritic, axosomaticor axoaxonic synapses

Answer 102

gap between neurons was discovered by Ramón y Cajal through histological observations

Answer 103

Otto Loewi, in 1921, demonstrated that neurons communicate by releasing chemicals later renamed acetylcholine, the first known neurotransmitter

Answer 104

–some neurons, neuroglia, and cardiac and single-unit smooth muscle –gap junctions join adjacent cells •ions diffuse through the gap junctions from one cell to the next

Answer 105

advantage of quick transmission •no delay for release and binding of neurotransmitter •cardiac and smooth muscle and some neurons –disadvantage is they cannot integrate information and make decisions •ability reserved for chemical synapses in which neurons communicate by releasing neurotransmitters

Answer 106

* synaptic knob of presynaptic neuron contains synaptic vesicles containing neurotransmitter * postsynaptic neuron membrane contains proteins that function as receptors and ligand-regulated ion gates

Answer 107

acetylcholine amino acid neurotransmitters monoamines neuropeptides

Answer 108

``` in a class by itself •formed from acetic acid and choline ```

Answer 109

•include glycine, glutamate, aspartate, and -aminobutyric acid (GABA)

Answer 110

•synthesized from amino acids by removal of the –COOH group •retaining the –NH2(amino) group •major monoamines are: –epinephrine, norepinephrine, dopamine(catecholamines) –histamine and serotonin

Answer 111

chains of 2 to 40 amino acids –beta-endorphin and substance P •act at lower concentrations than other neurotransmitters •longer lasting effects

Answer 112

* they are synthesized by the presynaptic neuron * they are released in response to stimulation * they bind to specific receptors on the postsynaptic cell * they alter the physiology of that cell

Answer 113

•a given neurotransmitter does not have the same effect everywhere in the body •multiple receptor types exist for a particular neurotransmitter –14 receptor types for serotonin •receptor governs the effect the neurotransmitter has on the target cell

Answer 114

–some excitatory –some inhibitory –some the effect depends on what kind of receptor the postsynaptic cell has –some open ligand-regulated ion gates –some act through second-messenger systems

Answer 115

time from the arrival of a signal at the axon terminal of a presynaptic cell to the beginning of an action potential in the postsynaptic cell –0.5 msec for all the complex sequence of events to occur

Answer 116

–excitatory cholinergic synapse –inhibitory GABA-ergic synapse –excitatory adrenergic synapse

Answer 117

cholinergic synapse –employs acetylcholine (ACh) as its neurotransmitter –ACh excites some postsynaptic cells •skeletal muscle –inhibits others

Answer 118

* GABA-ergic synapse employs -aminobutyric acid as its neurotransmitter * nerve signal triggers release of GABA into synaptic cleft * GABA receptors are chloride channels * Cl-enters cell and makes the inside more negative than the resting membrane potential * postsynaptic neuron is inhibited, and less likely to fire

Answer 119

* adrenergic synapse employs the neurotransmitter norepinephrine(NE) also called noradrenaline * NE and other monoamines, and neuropeptides acts through second messenger systems such as cyclic AMP (cAMP) * receptor is not an ion gate, but a transmembrane protein associated with a G protein

Answer 120

stop adding neurotransmitter and get rid of that which is already there –stop signals in the presynaptic nerve fiber –getting rid of neurotransmitter

Answer 121

* diffusion * reuptake * degradation in the synaptic cleft

Answer 122

hormones, neuropeptides, and other messengers that modify synaptic transmission –may stimulate a neuron to install more receptors in the postsynaptic membrane adjusting its sensitivity to the neurotransmitter –may alter the rate of neurotransmitter synthesis, release, reuptake, or breakdown

Answer 123

the ability of your neurons to process information, store and recall it, and make decisions

Answer 124

the postsynaptic potentials produced by neurotransmitters

Answer 125

excitatory postsynaptic potentials (EPSP) –any voltage change in the direction of threshold that makes a neuron more likely to fire glutamate and aspartate

Answer 126

any voltage change away from threshold that makes a neuron less likely to fire glycine and GABA produce IPSPs and are inhibitory

Answer 127

excitatory to some cells and inhibitory to others

Answer 128

the process of adding up postsynaptic potentials and responding to their net effect –occurs in the trigger zone

Answer 129

occurs when a single synapse generates EPSPs so quickly that each is generated before the previous one fades –allows EPSPs to add up over time to a threshold voltage that triggers an action potential

Answer 130

occurs when EPSPs from several different synapses add up to threshold at an axon hillock. –several synapses admit enough Na+ to reach threshold –presynaptic neurons cooperate to induce the postsynaptic neuron to fire

Answer 131

a process in which one neuron enhances the effect of another one –combined effort of several neurons facilitates firing of postsynaptic neuron

Answer 132

process in which one presynaptic neuron suppresses another one –the opposite of facilitation

Answer 133

the way in which the nervous system converts information to a meaningful pattern of action potentials

Answer 134

depends upon which neurons fire –labeled line code –each nerve fiber to the brain leads from a receptor that specifically recognizes a particular stimulus type

Answer 135

information about the intensity of a stimulus is encoded in two ways: –one depends on the fact that different neurons have different thresholds of excitation –other way depends on the fact that the more strongly a neuron is stimulated, the more frequently it fires

Answer 136

diverging circuit converging circuit reverberating circuits parallel after-discharge circuits

Answer 137

–one nerve fiber branches and synapses with several postsynaptic cells –one neuron may produce output through hundreds of neurons

Answer 138

–input from many different nerve fibers can be funneled to one neuron or neural pool –opposite of diverging circuit

Answer 139

–neurons stimulate each other in linear sequence but one cell restimulates the first cell to start the process all over –diaphragm and intercostal muscles

Answer 140

physical basis of memory is a pathway through the brain called a memory trace or engram

Answer 141

the ability of synapses to change

Answer 142

the process of making transmission easier

Answer 143

immediate, short-and long-term memory

Answer 144

the ability to hold something in your thoughts for just a few seconds –essential for reading ability

Answer 145

lasts from a few seconds to several hours –quickly forgotten if distracted –calling a phone number we just looked up –reverberating circuits

Answer 146

declarative | procedural

Answer 147

retention of events that you can put into words

Answer 148

retention of motor skills

Answer 149

memory loss for recent events, moody, combative, lose ability to talk, walk, and eat •show deficiencies of acetylcholine (ACh) and nerve growth factor (NGF)

Answer 150

progressive loss of motor function beginning in 50‟s or 60‟s -no recovery –degeneration of dopamine-releasing neurons in substantia nigra •dopamine normally prevents excessive activity in motor centers (basal nuclei) •involuntary muscle contractions

0-1 chapter 12 Nervous Tissue Flashcards

(174 cards)