Last Flashcards
(75 cards)
1
Q
_________of the ovum and the
sperm – zygote
A
Fertilization
2
Q
__________of the zygote
A
Multiplication
3
Q
Cells________to become
muscle cells, some become
multipolar neurons, some become
glial cells, and so on.
A
differentiate
4
Q
Cells_______themselves with the
cells around them to form particular
structures.
A
align
5
Q
Cells______appropriate
functional relations with other cells.
A
establish
6
Q
FIVE PHASES
OF NEURAL
DEVELOPMENT
A
induction of the neural plate
neural proliferation,
migration and aggregation,
axon growth and synapse formation,
neuron death and synapse rearrangement.
7
Q
a small patch of
ectodermal tissue on the dorsal
surface of the developing embryo.
A
neural plate
8
Q
The neural plate folds to form the
_______, and then the lips of
the neural groove fuse to form the
________. The inside of the neural
tube eventually becomes the
_____________.
A
neural groove
neural tubecerebral
ventricles and spinal canal.
9
Q
Once the lips of the neural groove
have fused to create the neural
tube, the cells of the tube begin to
_______ (increase greatly in
number).
A
Proliferate
10
Q
Most cell division in the neural tube
occurs in the __________the
region adjacent to the ventricle
(the fluid-filled center of the tube).
A
ventricular zone
11
Q
Migration
• Two major factors govern migration in the developing neural tube:
A
time and location.
12
Q
an extension grows from the developing
cell in the general direction of the migration;
A
somal translocation,
13
Q
Once the period of neural
proliferation is well underway and the walls of the neural tube are
thickening, a temporary network of glial cells, called radial glial
cells, appears in the developing neural tube. At this point, most
cells engaging in radial migration do so by moving along the radial
glial network
A
glia-mediated migration
14
Q
proceeds
from the ventricular zone in a
straight line outward toward
the outer wall of the tube;
A
Radial migration
15
Q
occurs
at a right angle to radial
migration that is, parallel to the
tube s walls.
A
Tangential migration
16
Q
Once developing neurons have migrated, they must
align themselves with other developing neurons that
have migrated to the same area to form the
structures of the nervous system.
A
Aggregation
17
Q
Both ___________ are thought to be mediated by __________
which are located on the surfaces of neurons and
other cells_______________ have the ability
to recognize molecules on other cells and adhere to
them.
A
migration and aggregation
cell-adhesion molecules (CAMs),
18
Q
Once neurons have migrated to their
appropriate positions and aggregated into
neural structures, axons and dendrites
begin to grow from them.
A
Axon Growth
19
Q
For the nervous system to function, these
projections must grow to appropriate
targets. At each growing tip of an axon or
dendrite is an amoebalike structure called
a _________, which extends and
retracts fingerlike cytoplasmic extensions
called filopodia as if searching for the
correct route
A
growth cone
20
Q
the first growth cones to travel along a
particular route in a developing nervous system are presumed to
follow the correct trail by interacting with guidance molecules
along the route. Then, subsequent growth cones embarking on the
same journey follow the routes blazed by the pioneers.
A
• Pioneer growth cones
21
Q
The tendency of developing axons to grow along the paths
established by preceding axons is called
A
fasciculation
22
Q
According to this hypothesis, axons growing
from one topographic surface (e.g., the
retina) to another (e.g., the optic tectum)
are guided to specific targets that are
arranged on the terminal surface in the
same way as the axons cell bodies are
arranged on the original surface.
• The key part of this hypothesis is that the
growing axons are guided to their
destinations by two intersecting signal
gradients (e.g., an anterior-posterior
gradient and a medial-lateral gradient).
A
Topographic Gradient Hypothesis
23
Q
• Once axons have reached their intended
sites, they must establish an appropriate
pattern of synapses. (synaptogenesis)
• A single neuron can grow an axon on its
own, but it takes coordinated activity in at
least two neurons to create a synapse
between them
• It depends on the presence of glial cells,
particularly astrocytes Retinal ganglion
cells maintained in culture formed seven
times more synapses when astrocytes were
present. Moreover, synapses formed in the
presence of astrocytes were quickly lost
when the astrocytes were removed.
A
Synapse Formation
24
Q
________is a normal and important part of neurodevelopment. It was initially assumed to be a passive process wherein developing neurons died when they failed to get adequate nutrition.
• However, it is now clear that cell death during development is usually active. Genetic programs inside neurons are triggered and cause them to actively commit suicide.
• Passive cell death is called ______; active cell death is called _______
A
Neuron Death
necrosis and apoptosis
25
_________break apart and spill their
contents into extracellular fluid, and the
consequence is potentially harmful
inflammation.
Necrotic cells c cells
26
DNA and other internal
structures are cleaved apart and packaged in
membranes before the cell breaks apart. These
membranes contain molecules that attract
scavenger microglia and other molecules that
prevent inflammation
apoptotic cell death
27
________ removes excess neurons in a safe,
neat, and orderly way. But _________ has a dark
side as well. If genetic programs for ________ death are blocked, the consequence can be
cancer; if the programs are inappropriately
activated, the consequence can be
neurodegenerative disease
Apoptosis
apoptotic cell
28
• During the period of cell death, neurons
that have established incorrect
connections are particularly likely to die.
• As they die, the space they leave vacant
on postsynaptic membranes is filled by
the sprouting axon terminals of surviving
neurons. Thus, cell death results in a
massive rearrangement of synaptic
connections.
• This phase of synapse rearrangement
tends to focus the output of each neuron
on a smaller number of postsynaptic
cells, thus increasing the selectivity of
transmission
Synapse Rearrangement
29
__________ is a complex neurodevelopmental disorder. In almost
all cases, the disorder is apparent before the age of 3 and
does not increase in severity after that age. Despite
considerable between-patient variation in symptoms, three
are considered to be core symptoms because they are
displayed in some form in most cases of the disorder:
• (1) a reduced ability to interpret the emotions and intentions
of others,
• (2) a reduced capacity for social interaction and
communication, and
• (3) a preoccupation with a single subject or activity
• Although the diagnosis of autism is based on these three core
symptoms, all three are not present in every Also, there are
other characteristics that tend to occur in many cases of the
disorder
• 80% of those with autism are male, 50% suffer mental
retardation and 35% have seizures.
• Older mothers are more likely to give birth to a child with
autism, but the probability of a young mother (under 30) giving
birth to a child with autism increases if the father is over 40
AUTISM
30
• Aspergers syndrome, a mild _________ in which cognitive and linguistic
functions are well preserved.
• _____________ are common enough that everybody should be alert for their two main early signs:
• delayed development of language (e.g., no babbling by 12 months,
no words by 16 months, no self-initiated meaningful phrases by 24 months)
• delayed development of social interaction (e.g., no smiles or happy expressions by 9 months, no communicative gestures such as pointing or waving by 12 months).
Autism Spectrum Disorders.
31
• _______6 heterogeneous in the sense that
afflicted individuals may be severely impaired
in some respects but may be normal, or even
superior, in others.
• For example, autistic patients who suffer from
mental retardation often perform well on tests
involving, jigsaw puzzles, music, and art.
• Many individuals with autism have sizable
vocabularies, are good spellers, and can read
aloud textual material they do not understand.
• However, the same individuals are often unable
to use intonation to communicate emotion, to
coordinate facial expression with speech, and
to speak metaphorically
Autism Is a
Heterogeneous Disorder
32
• ________ are intellectually handicapped individuals
who nevertheless display amazing and specific
cognitive or artistic abilities. About 10% of
individuals with autism display some savant
abilities; conversely, about 50% of savants are
diagnosed with autism. Savant abilities can take
many forms: feats of memory, naming the day of the
week for any future or past date, identifying prime
numbers (any number divisible only by itself and 1),
drawing, and playing musical instruments
Autistic Savants
33
Siblings of people with autism have
about a 5% chance of being
diagnosed with the disorder.
• If one monozygotic twin is diagnosed
with autism, the other has a 60%
chance of receiving the same
diagnosis.
• These findings suggest that autism is
triggered by several genes interacting
with the environment, and several
genes have already been implicated
Genetic Basis
of Autism
34
• The heterogeneity of the symptoms of autism
spectrum disorders that is, severe deficits in some
behavioral functions but not others suggest
underlying damage to some neural structures but
not others.
Neural
Mechanisms of
Autism
35
_______(meaning spindle-shaped face area) is a part of the human visual system (while also activated in people blind from birth) that is specialized for facial recognition.
fusiform face area (FFA,
36
• A ________ is a neuron that fires both
when an organism acts and when the
organism observes the same action
performed by anoth
mirror neuron
37
• _________________, like autism, is a neurodevelopmental disorder associated with mental retardation and a heterogeneous pattern of abilities and disabilities, However, in contrast to the withdrawn, emotionally insensitive, uncommunicative individuals who have autism, people with ________ are sociable, empathetic, and talkative.
• Although they display a delay in language development and language deficits in adulthood their language skills are remarkable considering their characteristically low IQs which average around 60.
• Persons with _________ display many severe
cognitive deficits. Spatial Abilities
Williams Syndrome
38
Biological Basis of
• People with _______ show a general thinning of the cortex and underlying white matter. The cortical thinning is greatest in two areas: at the boundary of parietal and occipital cortex and in the orbitofrontal
cortex.
• Profound impairment of spatial cognition and remarkable hypersociability
• Conversely, the thickness of the cortex in one area in people with _________ is often normal: the superior temporal gyrus,
William’s Syndrome
39
• A ________, or neoplasm (literally, new growth ), is a mass of cells that grows independently of the rest of the body.
• About 20% of tumors found in the human brain are meningiomas tumors that grow between the meninges, the three membranes that cover the central nervous system.
• All meningiomas are encapsulated _______ - _______ that grow within their own membrane. As a result, they are particularly easy to identify on a CT scan, they can influence the function of the brain only by the pressure they exert on surrounding tissue, and they are almost always _______ - tumors that are surgically removable with little risk of further growth in the body
Tumor
Benign
40
• Aside from meningiomas, most brain tumors are __________. ________ are those that grow diffusely through surrounding tissue. As a result, they are usually ___________; that is, it is difficult to remove or destroy them completely, and any cancerous tissue that remains after surgery continues to grow.
• About 10% of brain tumors do not originate in the brain. They grow from infiltrating cells that are carried to the brain by the bloodstream from some other part of the body. These tumors are called _________; metastasis refers to the transmission of disease from one organ to
another. Many metastatic brain tumors originate as cancers of the lungs.
Infiltrating tumors
malignant tumors
metastatic tumors
41
• ______ are sudden-onset cerebrovascular disorders that cause
brain damage.
• The symptoms _________ depend on the area of the brain that is
affected, but common consequences of _________ are amnesia,
aphasia (language difficulties), paralysis, and coma
• The area of dead or dying tissue produced by a ______ is called an
infarct. Surrounding the infarct is a dysfunctional area called the
penumbra. The tissue in the penumbra may recover or die,
depending on a variety of factors, and the goal of treatment
following stroke is to save it
Stroke
42
• occurs when a cerebral blood vessel ruptures and blood seeps into the surrounding neural tissue and damages it.
• ________ is a pathological balloonlike dilation that forms in the wall of an artery at a point where the elasticity of the artery wall is defective
• It can be congenital (present at birth) or can result from exposure to vascular poisons or infection
Cerebral Hemorrhage
Aneurysm
43
• ______ is a disruption of the blood supply to an area of the brain. The three main causes of cerebral ischemia are :
• ________ - a plug called a thrombus is formed and blocks blood flow at the site of its formation.
• _______ –a plug called an embolus in this case, is carried by the blood from a larger vessel, where it was formed, to a smaller one, where it becomes lodged;
• ________ – the walls of blood vessels thicken and the channels narrow, usually as the result of fat deposits
Cerebral Ischemia
Thrombosis
Embolism
Arteriosclerosis
44
• ________are closed-head injuries that involve damage to the cerebral circulatory system. Such damage produces internal hemorrhaging, which results in a ________.
• A _________ is a localized collection of clotted blood in an organ or tissue in other words, a bruise.
Contusions
hematoma
45
• a disturbance of consciousness following a blow to the head and there is no evidence of a contusion or other structural damage
• entails a temporary disruption of normal cerebral function with no long-term damage.
Concussions
46
• is the dementia (general intellectual
deterioration) and cerebral scarring
observed in boxers and other individuals
who experience repeated concussions.
Punch-drunk syndrome
47
• When ________ the brain, they often lead to the formation of cerebral abscesses pockets of pus in the brain.
• Bacteria are also the major cause of __________ (inflammation of the
meninges), which is fatal in 25% of adults (Nau & Brück, 2002).
Penicillin and other antibiotics sometimes eliminate bacterial
infections of the brain, but they cannot reverse brain damage that has
already been produced.
• _________ are passed from infected to noninfected individuals through contact with genital sores. The infecting bacteria then go into a dormant stage for several years before they become virulent and attack many parts of the body, including the brain. The syndrome of insanity and dementia that results from a syphilitic infection is called ___________.
bacteria infect
meningitis
Syphilis
general paresis.
48
• _______ is a well-known example of a virus that has a particular affinity for the nervous system. The fits of rage caused by the virus’ effects on the brain increase the probability that rabid animals that normally attack by biting will spread the disorder. However, It does not usually attack the brain for at least a month after it has been contracted, thus allowing time for a preventive vaccination.
• The ________ viruses are common examples of viruses that can attack the nervous system but have no special affinity for it. Although these viruses sometimes spread into the brain, they
typically attack other tissues of the body
Viral infection
Rabies,
mumps and herpes
49
• The nervous system can be damaged by exposure to any one of a variety of toxic chemicals, which can enter general circulation from the gastrointestinal tract, from the lungs, or through the skin.
• For example, heavy metals such as mercury and lead can accumulate in the brain and permanently damage it, producing a toxic psychosis (chronic insanity produced by a neurotoxin).
• Many of the patients developed a motor disorder termed __________. Its primary symptoms are involuntary smacking and sucking movements of the lips, thrusting and rolling of the tongue, lateral jaw movements, and puffing of the cheeks.
• Some neurotoxins are endogenous (produced by the patients own body). For example, the body can produce antibodies that attack, particularly components of the nervous system
Neurotoxins
tardive dyskinesia (TD).
50
is a brain disease where nerve cells don't signal properly, which causes seizures. Seizures are uncontrolled bursts of electrical activities that change sensations, behaviors, awareness and muscle movements. Although epilepsy can't be cured, many treatment options are available
Epilepsy
51
• The primary symptom of epilepsy is the _______, but not all persons who suffer seizures are considered to have epilepsy.
• __________ (motor seizures); these often involve tremors (clonus), rigidity (tonus), and loss of both balance and consciousness.
• But many seizures do not take this form; instead, they involve subtle changes of thought, mood, or behavior that are not easily distinguishable from normal ongoing activity
epileptic seizure,
Convulsions
52
Causes of Epilepsy
• Indeed, all of the causes of brain damage including
viruses, neurotoxins, tumors, and blows to the
head can cause epilepsy, and over 70 different
faulty genes have been linked to it
• Many cases of epilepsy appear to be associated
with faults at inhibitory synapses (e.g., GABAergic
synapses) that cause many neurons in a particular
area to fire in synchronous bursts , a pattern of
firing that is rare in the normal brain
• The diagnosis of epilepsy rests heavily on evidence
from electroencephalography (EEG). Epileptic
seizures are associated with bursts of highamplitude EEG spikes, which are often apparent in
the scalp EEG during an attack, and from the fact
that individual spikes often punctuate the scalp
EEGs of epileptics between attacks
53
• A _________ is a seizure that does not involve the entire brain.
The epileptic neurons at a focus begin to discharge together in
bursts, and it is this synchronous bursting of neurons that produces
epileptic spiking in the EEG.
• There are two major categories of ________: _______ and ________.
Partial Seizure
54
• ________ are partial seizures whose symptoms are primarily sensory or motor or both; they are sometimes called Jacksonian seizures after the
famous 19th-century neurologist Hughlings Jackson. As the epileptic discharges spread through the sensory or motor areas of the brain, the symptoms spread systematically through the body.
Simple partial seizures
55
• __________ are often restricted to the temporal lobes, and those who experience them are often said to have temporal lobe epilepsy. During
a complex partial seizure, the patient engages in compulsive,
repetitive, simple behaviors commonly referred to as automatisms (e.g., doing and undoing a button) and in more complex behaviors that appear almost normal.
Complex partial seizures
56
• _________6 begin as focal discharges that gradually spread
through the entire brain.
• In other cases, the discharges seem to begin almost simultaneously in all parts of the brain.
• Such sudden-onset generalized seizures may result from diffuse
pathology or may begin focally in a structure, such as the thalamus, that projects to many parts of the brain
Generalized seizures
57
• The primary symptoms of a ___________are loss of consciousness, loss of equilibrium, and a violent tonic-clonic convulsion a convulsion
involving both tonus and clonus.
• Tongue biting, urinary incontinence, and cyanosis (turning blue from
excessive extraction of oxygen from the blood during the convulsion) are common manifestations of grand mal convulsions.
• The hypoxia (shortage of oxygen supply to tissue, for example, to the
brain) that accompanies a ______ can itself cause brain damage.
grand mal seizure
58
• A second major category of generalized seizure is the _______
(literally, small trouble ).
• _________ are not associated with convulsions; their primary behavioral symptom is the ____ absence - a disruption of consciousness that is associated with a cessation of ongoing behavior,
a vacant look, and sometimes fluttering eyelids.
• _________ are most common in children, and they frequently cease at puberty. They often go undiagnosed
petit mal seizure.
59
Management of
Epilepsy
• Although there is no cure
for epilepsy, the
frequency and severity of
seizures can often be
reduced by antiepileptic
medication
Unfortunately, these
drugs often have adverse
side effects
• Brain surgery is
sometimes performed,
but only in grave
situations
60
• _________ is a movement disorder of middle and old age that affects 1 2% of the elderly population
• It is about 2.5 times more prevalent in males than in females
• Although _______ patients often display cognitive deficits, dementia
is not typically associated with the disorder. In essence, Parkinson’s
disease victims are thinking people trapped inside bodies they cannot
control
Parkinson’s disease
61
Symptoms of
Parkinson’s Disease
• The initial symptoms of Parkinson s disease are
mild perhaps no more than a slight stiffness or
tremor of the fingers, but they inevitably
increase in severity with advancing years.
• The most common symptoms of the full-blown
disorder are a tremor that is pronounced during
inactivity but not during voluntary movement or
sleep, muscular rigidity, difficulty initiating
movement, slowness of movement, and a
masklike face.
• Pain and depression often develop before the
motor symptoms become severe.
62
Biological Basis of Parkinson’s Disease
• Parkinson’s disease seems to have no single cause; faulty genes, brain infections, strokes, tumors, traumatic brain injury, and neurotoxins have all been implicated in specific cases.
• It is particularly severe in the __________ the midbrain nucleus
• There is little dopamine in the substantia nigra and striatum of long-term Parkinson s patients.
• Autopsy often reveals clumps of proteins in the surviving dopaminergic neurons of the substantia nigra the clumps are
called _______
substantia nigra
Lewy bodies
63
Management of Parkinson’s Disease
• The symptoms of Parkinson’s disease can be alleviated by
injections of L-dopa the chemical from which the body
synthesizes dopamine. However, it typically becomes less
and less effective with continued use, until its side effects
(e.g., involuntary movements) outweigh its benefits
• One of the most controversial treatments for Parkinsons
disease is deep brain stimulation, a treatment in which lowintensity electrical stimulation is continually applied to an
area of the brain through a stereotaxically implanted
electrode
• The treatment of Parkinson’s disease by this method usually
involves chronic bilateral electrical stimulation of a nucleus
that lies just beneath the thalamus and is connected to the
basal ganglia: the subthalamic nucleus.
64
• _______ is a progressive motor disorder of middle and old age;
but, unlike Parkinsons disease, it is rare (1 in 10,000), it has a strong genetic basis, and it is associated with severe dementia.
Huntington s disease
65
Symptoms of Huntington’s Disease
• The first sign of Huntingtons’ disease
is often increased fidgetiness.
• As the disorder develops, rapid,
complex, jerky movements of entire
limbs (rather than individual
muscles) begin to predominate.
• Eventually, motor and intellectual
deterioration become so severe that
sufferers are incapable of feeding
themselves, controlling their bowels,
or recognizing their own children
66
Biological Basis of
Huntington’s
Disease
• Huntingtons disease is passed from
generation to generation by a single
dominant gene, called huntingtin.
• The protein it codes for is known as the
huntingtin protein.
• Because the gene is dominant, all
individuals carrying thgene develop the
disorder, as do about half their
offspring.
67
Management of Huntington’s Disease
•There is no cure; death
typically occurs about 15
years after the appearance
of the first symptoms.
68
• _________ is a progressive disease that attacks the myelin of axons in
the CNS.
• First, there are microscopic areas of degeneration on myelin sheaths; but but eventually damage the myelin is so severe that the associated axons become dysfunctional and degenerate Ultimately, many areas of hard scar tissue develop in the CNS (sclerosis means hardening ).
• It is an __________ a disorder in which the body s immune system attacks part of the body, as if it were a foreign substance.
Multiple sclerosis (MS)
autoimmune disorder
69
Symptoms of Multiple
Scleriosis
• Common symptoms of advanced
multiple sclerosis are visual
disturbances, muscular weakness,
numbness, tremor, and ataxia (loss
of motor coordination).
• In addition, cognitive deficits and
emotional changes occur in some
patients
70
Biological Basis of
Multiple Scleriosis
• Although epidemiological evidence has
implicated genetic factors in the etiology
of multiple sclerosis, the effects are
weak the concordance rate in identical
twins is only 25%
• One good example of such research is
the study of the role of vitamin D in
multiple sclerosis: The incidence of
multiple sclerosis is highest in regions far
from the equator, which are exposed to
little strong sunshine, a major source of
vitamin D
71
Treatment of
Multiple Scleriosis
• A number of treatments have
been shown to be effective
with the animal model of
multiple sclerosis, and some
of these have proven
beneficial to human patients
• Corticosteroids, such as
intravenous (infused into a
vein) methylprednisolone,
are prescribed over the
course of three to five days.
72
• _________ is the most common cause of dementia. It sometimes appears in individuals as young as 40, but the likelihood of its development becomes greater with advancing years
• Because Alzheimer s disease is not the only cause of dementia, it
cannot be diagnosed with certainty on the basis of its behavioral
symptoms-definitive diagnosis of ______ must await
autopsy
Alzheimers disease
73
•_____________ are threadlike tangles of protein in the neural cytoplasm,
• __________ are clumps of scar tissue composed of degenerating
neurons and a protein called amyloid, which is present in normal brains in only very small amounts. In addition, there is substantial neuron loss.
Neurofibrillary tanglesAmyloid plaques
74
Biological Basis of
Alzheimer’s
• People with an Alzheimer s victim
in their immediate family have a
50% chance of being stricken by
the disease if they survive into their
80s
• The amyloid hypothesis is view
proposes that amyloid plaques are
the primary symptom of the
disorder and cause all the other
symptoms
75
Treatment of
Alzheimer’s
• The first efforts to develop treatments
for Alzheimers disease focused on the
fact that declines in acetylcholine
levels were among the earliest
neurochemical changes appearing in
patients.
• Cholinergic agonists are still
sometimes prescribed, but, except for
a few minor benefits early in the
disorder, they have proven ineffective.
Several other treatments are currently
under development.
• Arguably, the most promising of these
is the immunotherapeutic approach
(which involves administering an
amyloid vaccine to reduce plaque
deposits. This vaccine initially proved
effective in tests on transgenic mice
carrying human Alzhe
