Chapter 3: The Nervous System's Functional Units Flashcards
1
Q
where did the theory of the neuron emerge from?
A
controversy between Golgi and Ramon y Cajal
2
Q
how did Golgi stain tissue?
A
immerse thin slice of brain tissue in solution w/ silver nitrate
3
Q
what did Golgi’s staining suggest?
A
the nervous system is an interconnected network of fibres
4
Q
Golgi thought information flowed around a ___, and so produced ___
A
nerve net (like water running thru pipes), behaviour
5
Q
Ramon y Cajal used Golgi’s stain to study
A
chick embryos’ brain tissue
6
Q
what did Cajal conclude about the nervous system?
A
- made up of discrete cells that begin life as a rather simple structure, becomes more complex w/ age
- when mature, each cell has a main body w/ many extensions projecting from it
7
Q
who’s neuron theory is now accepted?
A
Cajal’s
8
Q
the ___ neurons an animal has, the ___ complex its behaviour
A
more, more
9
Q
we can implant tiny microscopes called ___ or ___ into the brain to view the structure and activity of its ___
A
endoscopes, microendoscopes, neurons
10
Q
research has confirmed ___ nerve net, a covering called a ___ that forms around neurons as they mature
A
Golgi’s, perineuronal net
11
Q
soma
A
cell body
12
Q
what collects information from other cells?
A
dendrites
13
Q
what would carry messages to other neurons?
A
axon
14
Q
a neuron only has one ___, but may have many ___
A
axon, dendrites
15
Q
dendrites ___ info, the soma ___ info, the axon ___ info
A
collect, integrates, passes
16
Q
A
a. axon from another neuron
b. dendrites
c. soma (cell body)
d. nucleus
e. axon
f. axon collateral
g. teleodendria
h. terminal button (end foot)
i. dendrites from another neuron
17
Q
the human nervous system contains ___ neurons and ___ glial cells
A
86 billion, 87 billion
18
Q
neurons regulate body processes such as
A
breathing, heartbeat, body temperature
19
Q
functional groups of neurons called ___ connect wide areas of the ___
A
neural networks, brain & spinal cord
20
Q
in what ways are neurons “active”?
A
- making/losing branches
- making/losing connections w/ each other
21
Q
the dynamic activity of the neuron underlies both the constancies and changes in our ___
A
behaviour
22
Q
a neuron’s ___ is increased immensely by its extensions into dendrites and axon
A
surface area
23
Q
a neuron may have up to ___ dendrites
A
20
24
Q
juncture of soma + axon
A
axon hillock
25
branch of an axon
axon collaterals
26
axon collaterals may divide into multiple smaller branches called
telodendria
27
at the end of each telodendrion is a knob called a
terminal button (end foot)
28
the terminal button does not ___ a dendritic spine, this near-connection is called a
touch, synapse
29
a synapse includes
- surface of end foot
- surface of neighbouring dendritic spine
- space between
30
the general shape of a neuron suggests it works in a similar way to a
river
31
conduct information from sensory receptors in/on the body into the spinal cord + brain
sensory neurons
32
associate sensory + motor activity in CNS
interneurons
33
carry info from brain + spinal cord out to the body's muscles
motor neurons
34
sensory neurons
1. bipolar neuron (retina)
2. somatosensory neuron (skin/muscle)
a) dendrite
b) axon
35
interneurons
1. stellate cell (thalamus)
2. pyramidal cell (cortex)
3. purkinje cell (cerebellum)
36
1. motor neuron (spinal cord)
a) dendrites
b) axon
37
structurally the simplest of the 3 types of neurons
sensory neurons
38
a ___ has a single short dendrite one one side of its soma, and a single short axon on the other
bipolar neuron
39
bipolar neurons transmit ___ info from the ___ to the neurons that carry info into the brain's ___
afferent/incoming sensory, retina's light receptors, visual centres
40
brings sensory information from the body into the spinal cord
somatosensory neuron
41
the ___ dendrite connects directly to its axon, so the cell body sits to the side of this long pathway
somatosensory
42
association cells
interneurons
43
a small interneuron w/ many dendrites extending around the cell body
stellate (star-shaped) cell
44
what is one of the main reason brain sizes vary between species?
there are many more interneurons in larger brains than smaller, giving a correlation between interneuron # and behavioural complexity
45
- long axon
- pyramid-shaped cell body
- two sets of dendrites
pyramidal cell
46
distinctive interneuron w/ extremely branched dendrites that form a fan shape
purkinje cell
47
- extensive dendritic networks
- large cell bodies
- long axons that connect to muscle
motor neurons
48
all efferent/outgoing neural info must pass thru ___ to reach muscles
motor neurons
49
3 functions/features of neuronal networks
input, association, output
50
___ carry info to distant parts of the nervous system, while ___ are engaged in local processing
long extensions, short extensions
51
somatosensory neurons can send information over more than ___
2 metres
52
pyramidal neurons must reach from the cortex to the lower spinal cord, which can be as long as ___
1 metre
53
each neuron receives up to ___ of excitatory + inhibitory signals every second
thousands
54
how does a neuron pick which input to use?
it sums them all up, follows whichever input exceeds the other
55
AI is based on the principles of
nervous system function
56
Barbara Webb constructed a
cricket robot
57
___ parts are constructed to mimic parts of a human body
anthropomimetic robots
58
glial cells help neurons by
- binding them together
- providing support, nutrients, protection
59
5 types of glial cells
1. ependymal cell
2. astrocyte
3. microglial cell
4. oligodendroglial cell
5. schwann cell
60
small ovoid, secretes CSF
ependymal cell
61
- star-shaped
contributes to
- neuronal nutrition, support + repair
- forming blood-brain barrier
- healing scarring after injury
astrocyte
62
small, derived from blood, defensive function to remove dead tissue
microglial cell
63
forms myelin around CNS axons in brain + spinal cord
oligodendroglial cell
64
wraps around peripheral nerves to form myelin
schwann cell
65
errors in ___ replication are a main source of ___
glial cell, brain tumors/abnormal growths
66
an uncontrolled growth of new tissue that is independent of surrounding structures
tumor
67
incidence of brain tumors in the US is ___ according to CBTR
20 per 100,000
68
in adults, brain tumors grow from ___, but in infants they may grow from ___
glia/supporting cells, developing neurons
69
___ are not likely to recur after removal
benign tumors
70
___ are likely to progress + invade other tissue, and apt to recur after removal
malignant tumors
71
3 major types of brain tumors
1. gliomas (from glial cells)
2. meningiomas (attached to meninges)
3. metastatic tumors (cells transfer regions)
72
- found on the walls of ventricles
- produce/secrete CSF
ependymal cells
73
functions of CSF
- shock absorber for brain
- carries away waste products
- assist constant brain temperature
- source of nutrients for parts of brain
74
hydrocephalus is the buildup of fluid pressure in the brain and, in infant, swelling of the head, due to the ___; can cause severe intellectual impairment
flow of CSF being blocked
75
- provide structural support to CNS
- extensions attach to blood vessels + brain's lining, forming a scaffolding that holds neurons in place
- provide pathways for nutrients to move between blood vessels + neurons
- secrete chemical that keep neurons healthy + help them heal if injured
- contribute to blood-brain barrier
astrocytes
76
protective partition between blood vessels + the brain formed by tight junctions between the cells that compose blood vessels in the brain, prohibits entry of certain substances like toxins into the brain
blood-brain barrier
77
a. astrocyte
b. blood vessel
c. blood vessel cells
d. astrocyte end feet
e. tight junctions
f. myelinated axon
g. neuron
78
why are brain infections difficult to treat?
many useful drugs cannot pass thru the blood-brain barrier
79
how do astrocytes enhance brain activity?
pass along signals from neurons to blood vessels to increase blood flow + fuel supply in response to a behaviour
80
how do astrocytes contribute to the healing of damaged brain tissue?
form a scar to seal off the damaged area
81
- originate in the blood as an offshoot of immune system
- migrate thru nervous system
- make up 20% of all glial cells
microglia
82
how do microglia play an important role in monitoring/maintaining the health of brain tissue?
- identify + attack foreign tissue
- invade damaged areas to provide growth factors that aid in repair
83
___ engulf any foreign tissue + dead brain cells, an immune process called ___
microglia, phagocytosis
84
a characteristic of Alzheimer disease, a degenerative brain disorder commonly associated w/ aging, is:
the deposit of distinctive bodies called plaques in regions of damage
85
microglia may play a harmful role in Alzheimers by
consuming inflamed tissue rather than protecting it
86
___ interact w/ astrocytes in brain healing
microglia
87
which 2 glial cells insulate neuronal axons?
1. oligodendroglia
2. schwann cells
88
myelinated neurons send information ___ than neurons without myelin
much faster
89
neurons that send messages over long distances quickly, like __, are ___ to increase their messaging speed
sensory and motor neurons, heavily myelinated
90
oligodendroglia myelinate axons in the brain + spinal cord by
sending out large, flat branches that enclose + separate adjacent axons
91
schwann cells myelinate axons in the PNS by
wrapping itself repeatedly around a part of an axon, forming a structure somewhat like beads on a string
92
in addition to myelination, schwann cells and oligodendroglia contribute to a neuron's nutrition + functioning by
- absorbing chemicals the neuron releases
- releasing chemicals the neuron absorbs
93
multiple sclerosis (MS) is associated w/ damage to the ___ that leaves a _, rather than myelin, on neurons in nervous system pathways, resulting in ___ , producing ___
oligodendroglia, scar, information flow impairment, impaired movement + cognitive function
94
loss of both movement + sensation
paralysis
95
___ participate in repairing damage to the peripheral nervous system
microglia + schwann cells
96
neuron repair
1. when peripheral axon is cut, the axon dies
2. schwann cells shrink, then divide, forming glial cells along the axon's former path
3. neuron sends out axon sprouts, one of which finds the schwann cell path + becomes a new axon
4. schwann cells envelop the new axon, forming new myelin
97
when the CNS is damaged, does regrowth and repair occur?
no
98
why may regrowth/repair in CNS not occur?
as neural circuits mature, they become finely tuned to mediate individualized behaviour + develop chemical strategies that prevent the proliferation of new cells or regrowth of existing cells
99
a cell's ___ determine its characteristics + functions
proteins
100
a cell's ___ separates the cell from its surroundings + allows it to regulate what enters/leaves its domain
cell membrane
101
nerve cell
a. dendrite
b. dendritic spine
c. nucleus
d. nuclear membrane
e. mitochondrion
f. endoplasmic reticulum
g. intracellular fluid
h. tubule
I. cell membrane
j. axon
k. golgi body
l. lysosomes
m. microfilaments
102
very few substance can enter/leave a cell spontaneously because
the cell membrane is virtually impermeable
103
proteins embedded in the cell membrane facilitate:
transport of substances in/out of the cell
104
what happens inside the nucleus?
genetic blueprints for proteins are stored, copied, and sent to the ER
105
structure that gathers, stores, and releases energy
mitochondrion
106
folded layers of membrane where proteins are assembled
endoplasmic reticulum
107
tiny tube that transports molecules + helps give the cell its shape
tubule
108
membranous structure that packages protein molecules for transport
golgi body
109
sacs containing enzymes that break down wastes
lysosomes
110
threadlike fibres making up much of the cell's "skeleton"
microfilaments
111
more ___ are found in old cells vs. new ones
lysosomes
112
the cell membrane regulates the differing concentrations of ___ on its inner/outer sides
salts + other chemicals
113
what allows cell membranes to regulate water + salt concentrations?
phospholipids
114
phospholipid heads are ___, and the lipid tails are ___
polar + hydrophilic, hydrophobic
115
what can traverse a phospholipid bilayer?
small molecules such as
- oxygen
- CO2
- sugar glucose
116
segments of DNA that encode the synthesis of particular proteins
genes
117
genes are contained within ___, which are ___
chromosomes, double-helix structures that hold an organism's DNA library
118
what happens when chromosomes change shape to occupy the best location in the nucleus?
they expose different genes to the surrounding fluid, allowing the gene to begin the process of making a protein
119
a human somatic/body cell has __ of chromosomes, or ___ in all
23 pairs, 46
120
each chromosome is a double-stranded molecule of
deoxyribonucleic acid (DNA)
121
4 nucleotide bases
(A) adenine
(T) thymine
(G) guanine
(C) cytosine
122
_ always pairs with T, _ always pairs with C
A; G
123
how are the 2 strand of the DNA helix bound together?
by the attraction between the 2 bases in each pair
124
sequences of ___ within the chromosomes spell out the genetic code
hundreds of nucleotide bases
125
the sequence of base pairs spell out the order in which ___ should be assembled to construct a certain ___
amino acids (the constituent molecules of protein); protein
126
2 steps of transcription
1. DNA uncoils to expose a gene, a sequence of nucleotide bases that encodes a protein
2. 1 strand of the gene serves as a template for transcribing a molecule of mRNA
127
what is different about RNA vs. DNA?
RNA has the base uracil (U) instead of thymine (T)
128
the transcribed strand of RNA is called ___ because ___
messenger RNA (mRNA); it carries the protein code (message) out of the nucleus to the ER
129
a distinguishing feature of the ER is that it may be studded with ___, which are ___
ribosomes; protein structures that act as catalysts to facilitate the building of proteins
130
when mRNA reaches the ER, it passes thru a ___, where its ___
ribosome; genetic code is read
131
2 steps of translation
3. the mRNA leaves the nucleus + comes into contact w/ ribosomes in the ER
4. as a ribosome moves along the mRNA, it translates the bases -> amino acid chain = protein
132
what does transfer RNA (tRNA) do?
assists in translating nucelotide bases into amino acids
133
___ encodes one particular amino acid
each group of 3 consecutive nucleotide bases along an mRNA
134
what 3 bases encode the amino acid tryptophan (Trp)?
UGG
135
what 3 bases encode the amino acid phenylalanine (Phe)?
UUU
136
the sequence of ___ determines the sequence of the resulting amino acid chain
codons on the mRNA strand
137
a. template strand
b. DNA
c. mRNA
d. codon
e. polypeptide chain
f. amino acids
138
humans utilize __ different amino acids
20
139
amino acid chemical structure
a central carbon (C), bound to:
- a hydrogen atom (H)
- an amino group (NH3+)
- a carboxyl group (COO-)
- a side chain (R)
140
each amino group is bound to the carboxyl group (COO-) by a ___, which gives the amino acid chain the alt name of ___
peptide bond; polypeptide chain
141
summary of info flow driven by the genetic code
gene transcribed into mRNA -> ribosomes translate it into a chain of amino acids (polypeptide chain) = forms a protein
142
folded-up polypeptide chain that serves a particular function in the body
protein
143
primary structure
amino acid chain
144
secondary structure
pleated sheet or helix
145
tertiary structure
protein
146
quaternary structure
complex protein
147
a. primary
b. secondary
c. tertiary
d. quaternary
148
any one neuron contains up to ___ genes, and they can produce as many as ___ different protein molecules
20,000; 20,000
149
the # of proteins that can ultimately be made by a neuron is far ___ than the # of its genes
larger
150
a protein's ___ and ___ are central to its function
shape; its ability to change shape/combine w/ other proteins
151
2 steps of protein export
1. proteins formed in ER enter Golgi bodies, then wrapped in a membrane + given a shipping address
2. each protein package is attached to a motor molecule + moves along a microtubule to its destination
152
3 membrane proteins
1. channels
2. gates
3. pumps
153
a protein's ability to change shape is analogous to
a lock in a door - needs the right key
154
small molecules can bind to a protein's ___ and cause the protein to change shape
receptors
155
changes in shape allow the proteins to ___
serve a new function
156
how does a protein channel work?
an opening lets specific ions thru based on size
157
how does a protein gate work?
it changes shape to allow the passage of substances when the gates are open, and prevents passage when they are closed
158
how does a protein pump work?
the pump transporter changes shape to carry substances across the membrane
159
whose research led to the concept of the gene?
Gregor Mendel
160
what is the objective of epigenetics?
to study how the environment influences gene expression
161
chromosome pairs are numbered from 1-23, according to ___, with chromosome 1 being the ___
size; largest
162
chromosome pairs 1-22 are called ___ because ___
autosomes; they contain the genes that contribute most to our physical appearance + behaviour
163
the 23rd pair of chromosomes are called the ___ which ___
sex chromosomes; contribute to our physical/behavioural sexual characteristics
164
the Y chromosome contains the ___, which triggers ___
SRY (sex-determining region) gene; testes development
165
two copies of a gene
alleles
166
two identical nucleotide sequences in a pair of alleles
homozygous
167
two different nucleotide sequences in a pair of alleles
heterozygous
168
the nucleotide sequence most common in a population is called the ___, while a less frequently occurring sequence is called a ___
wild-type allele; mutation
169
if both alleles are homozygous, they encode ___
the same protein
170
if both alleles are heterozygous, they encode ___
somewhat different proteins
171
3 possible outcomes from the heterozygous condition when their proteins express a physical/behavioural trait
1. only the allele from mother may be expressed
2. only the allele from father may be expressed
3. both alleles may be expressed simultaneously
172
an member of a gene pair that is routinely expressed
dominant allele
173
an unexpressed allele
recessive allele
174
in complete dominance, ___ is expressed in the phenotype
only the allele's own trait
175
in incomplete dominance, ___ expressed
the allele's own trait is partially
176
in codominance, ___ expressed
both the allele's own train + that of the other allele is completely
177
a mutation may be as small as
a change in 1 single nucleotide base = single nucleotide polymorphism (SNP)
178
more than ___ mutations of the breast cancer gene (BRCA1) have been found
1000
179
is a mutation always bad?
a mutation can be beneficial, disruptive, or both
180
what is the most common genetic blood disease, affecting 80,000 US citizens
sickle-cell anemia
181
what causes sickle-cell anemia?
a SNP on chromosome 11 where T is substituted for an A base in the HBB (hemoglobin) gene
182
why does it make sense that neurons can get mutations?
most neurons are with us/are metabolically active for life!
183
at 1 year of age, a neuron may have up to ___ mutations, but by 80 it may have as many as ___ mutations
300-900; 2000
184
despite our genome being inherited from our parents, it actually ___ as we develop and age
gets modified a lot
185
Gregor Mendel introduced dominant + recessive alleles thru the use of
pea plants
186
what is Tay-Sachs disease?
inherited birth defect, appears 4-6 months after birth, results in intellectual disability, physical changes, and death by age 5
187
what causes Tay-Sachs disease?
dysfunction in the HEXA gene on chromosome 15 = lipids accumulate in brain cells = cell damage
188
to have Tay Sach's disease, ___ must carry the mutation
both parents
189
hereditary disease characterized by chorea (ceaseless involuntary jerky movements) and progressive dementia, ending in death
Huntington disease
190
how does Huntington disease work?
buildup of an abnormal version of the huntingtin protein kills brain cells, esp in basal ganglia + cortex
191
to get Huntington disease, __ must carry the allele
only one parent
192
the HTT (huntingtin) gene is found on chromosome _, where part of the gene contains repeats of the base sequence ___
4; CAG
193
aberrations in a part of a chromosome/an entire chromosome
copy number variation
194
copy number variations are related to disorders such as
- autism
- schizophrenia
- learning disabilities
195
chromosomal abnormality resulting in intellectual impairment + other abnormalities, usually caused by an extra chromosome 21
Down syndrome
196
how does one get Down syndrome?
one parent (usually mom) passes on 2 copies of chromosome 21 - this combined with 1 from dad = trisomy
197
3 techniques of genetic engineering
1. selective breeding
2. cloning
3. transgenics
198
how has selective breeding influenced the dog brain?
- made it smaller than a wolf's
- larger # of cortical neurons
199
how do scientists clone animals like Dolly the sheep?
- cell nucleus w/ DNA is placed in an egg cell that had its nucleus removed
- egg stimulated to start dividing
- implant new embryo in uterus of a female
200
transgenic technology allows scientists to
introduce genes into an embryo OR remove genes from it
201
___ is used when 1+ genes from one species is added to the genome of another species, passed along, and expressed in subsequent generations, creating ___
knock-in technology; transgenic animals
202
___ is used to inactivate a gene so that a line of lab animals fail to express it
knockout technology
203
our phenotypic plasticity is due to
- the genome's capacity to express a large # of phenotypes
- epigenetics/the influence of environment + experience on phenotypic expression
204
incidence of similar behavioural traits
concordance
205
the concordance rate between identical twins for an array of diseases such as ___, is between ___
schizophrenia, Alzheimer's, MS, Chron's, asthma, diabetes, prostate cancer; 30-60%
206
epigenetic mechanisms create ___ without ___
phenotypic variation; altering the base pair nucleotide sequence of the genes
207
chromosomes are wrapped around supporting molecules of a protein called
histone
208
for any gene to be transcribed into mRNA, its DNA must be ___, then the gene must be ___, then the mRNA must be ___
unspooled from the histone, instructed to transcribe mRNA, translated into an amino acid chain that forms the protein
209
3 epigenetic mechanisms
1. histone modification
2. gene (DNA) methylation
3. mRNA modification
210
histone modification
a methyl group/other molecules bind to the tail of histones, either blocking them from opening or allowing them to open for transcription
211
gene (DNA) methylation
methyl groups bind to CG base pairs to block transcription
212
mRNA modification
ncRNA (noncoding) binds to mRNA, preventing translation
213
a. histone modification
b. gene (DNA) methylation
c. mRNA modification
214
who found that individuals' nutritional experiences can affect their offspring's health?
Lars Olov Bygren
215
what was interesting about Bygren's findings?
the descendants of individuals who have plenty of food had higher rates of cardiovascular disease, diabetes, and a life expectancy of 7 years shorter vs. the famine group
216
what scan is used for MS?
MRI
217
in the 1950's, what microscope was used for synapse discovery?
electron microscope
218
easiest tumor to remove
meningiomas
219
Huntington vs. Parkinson disease
Huntington: more jerky movement + cognitive/psychological symptoms
Parkinson: rigidity/slowed movements
