Fourth Exam Flashcards
(510 cards)
1
Q
What are the 4 extraembryonic membranes
A
amnion
chorion
yolk sac
allantoic sac
2
Q
What are the functions of these extra embryonic membranes
A
protection
nutrition
respiration
excretion
3
Q
In birds, what occurs to the ectoderm and the somatic plate mesoderm
A
laminate
4
Q
What does this lamination produce
A
a single layer of membrane
5
Q
What is the name of this membrane created by the lamination of the ectoderm and the somatic plate mesoderm
A
somatopleure
6
Q
What occurs to the endoderm and the visceral plate mesoderm in birds
A
they laminate
7
Q
What is the name of the layer that formed from the lamination of the endoderm and visceral plate mesoderm
A
splanchnopleure
8
Q
What does the somatopleure do
A
lifts up to fuse on the dorsal side of the embryo
9
Q
What does the lifting and fusing of the somatopleure produce
A
two coverings for the embryo
10
Q
What are the two coverings produced called
A
chorion and amnion
11
Q
What is the space between chorion and amnion membranes
A
extra embryonic ceolom
12
Q
What is the name of the cavity between the amnion and the epidermis
A
amniotic cavity
13
Q
What does the amniotic cavity serve as in birds
A
a shock absorber
heat capacity
avoids dehydration
14
Q
What does the splanchnopleure do
A
moves downwards to surround the yolk
15
Q
What does surrounding the yolk sac with the splanchnopleure produce
A
the yolk sac
16
Q
How does the yolk sac retain connection to the embryo
A
via the gut
17
Q
What occurs to the splanchnopleure other than surrounding the yolk sac
A
an evagination occurs of the hindgut
18
Q
What does the evagination of the hindgut form
A
the allantoic sac
19
Q
What occurs to the allantoic sac
A
grows, pushes into the extraembryonic coelom to surround the entire embryo
20
Q
Do mammals have the same membranes as birds
A
yes
21
Q
What is the difference of the membranes of mammals rather than birds
A
they have different origins
22
Q
Where does the amnion come from in mammals
A
amniotic ectoderm
23
Q
What is the final product of the amnion
A
it surrounds the entire embryo
24
Q
What creates the somatopleure in mammals
A
amniotic ectoderm and extra embryonic mesoderm
25
Why is it important for the allantoic sac to surround the bird
allows for gas exchange to occur since it doesn't have a placenta, allows for collection of metabolic wastes
26
What metabolic waste collects in the allantoic sac
uric acid
27
What are the three initial layers of cells in mammals
amniotic, epiblast, hypoblast
28
Where do extra embryonic mesoderm come from
nothing holds some mesoderm cells as the three primary germ layers are being created
29
Where do the extra embryonic mesoderm cells travel
around to the top of the amniotic ectoderm
30
What does the amniotic ectoderm and extra embryonic mesoderm create
somatopleure layer
31
What occurs to the amniotic cavity
it surrounds the embryo to bath it in fluid
32
Where does amniotic fluid come from initially
most diffuses from the endometrium
33
Where does amniotic fluid come from once the embryo's circulatory system is set up
it oozes out through the non-karotinized skin cells
34
Where does amniotic fluid come from later in develop
baby's mucous membranes
35
What mucous membranes contribute to amniotic fluid
respiratory, digestive, urinary
36
What is the importance of amniotic fluid
allows symmetrical external growth of the embryo
acts as a barrier to infection
permits fetal internal organ development
cushions the embryo
prevents adherence of amnion to the embryo
maintains constant temperature
allows fetal movement, promotes muscle development
assists in maintaining fluid and electrolytes
37
How does amniotic fluid permit fetal internal organ development
lungs inhale
digestive system swallow
urinary system filters it
organs practice on the amniotic fluid
38
What is the disease where one does not have enough amniotic fluid
olgohydramnios
39
What does olgohydramnios cause symptom wise in babies
alters facial development
40
How does the amnion maintain fluid and electrolytes
amnion is a filter between maternal and baby blood supply
41
How often is the amniotic fluid changed
every 3 hours
42
Is amniotic stationary
no, it is always moving
43
Near the end of pregnancy, how much amniotic fluid is present
700-1000ml
44
How does the artificial womb work
takes over the circulation system of an embryo, pumps fluid through amniotic cavity to keep moving the amniotic fluid, connects umbilical circulation with o2 and CO2 lines
45
Where does the chorion come from in human embryos
cytotrophoblast
46
Where does the cytotrophoblast come from
naturally surrounds the embryo, from the endometrium
47
The endometrium is made up of what two layers
cytotrophoblast and syncytiotrophoblast
48
What occurs to the cytotrophoblast layer to create the chorion
sends out fingers through the synctiotrophoblast
49
What are these fingers called
chorionic villi
50
What do the villi do for function
reach into pools of maternal blood in the endometrium
51
Where do umbilical vesicles develop from
extra embryonic mesoderm
52
Where do the umbilical vesicles form
inside of the connecting stalk
53
What does the connecting stalk do
connect the embryonic circulatory system with the chorionic villi
54
In the embryonic circulatory system, how are nutrients obtained, through which route
umbilical vein
55
In the embryonic circulator system how are wastes disposed of into maternal blood
umbilical arteries
56
What happens to the cavity between the chorion and amnion
it disappears as the embryo grows
57
As the embryo grows, what occurs
it bulges out of the endometrium into the uterine cavity
58
As the embryo bulges into the uterine cavity, it remains in contact with what
the chorionic villi and endometrium on one side
59
What does the contact with the chorionic villi and endometrium on one side form
placenta
60
What do many people think the yolk sac is
a junk sac
61
In mammals what is the yolk sac known as
umbilical vesicle
62
What are functions of the umbilical vesicle
transfers nutrients
blood initially develops here
contributes to buds and branches of gut
primordial germ cells originate
63
What eventually occurs to the umbilical vesicle in mammals
it shrivels up
64
Where do the nutrients come from that the umbilical vesicle transfers
endometrium into the embryo's gut
65
How is blood initially developed by the umbilical vesicle
EE mesoderm on the outside of the umbilical vesicle
66
What part of the umbilical vesicle contributes to the buds and branches of gut
endoderm
67
After the primordial germ cells are made in the umbilical vesicle, what occurs
they move up to the mesonephros
68
Where does the allantoic sac come from in mammals
evagination of the hindgut
69
Does the allantoic sac in mammals expand as it does in mammals
no
70
Why does the allantoic sac in mammals not expand
respiratory and excretory functions are performed by the placenta
71
How is the umbilical cord created
ventral closure squeezes all EE membranes and umbilical vessels into the cord
72
In a cross section of the umbilical cord, what things can be seen
```
ectoderm on edge
mesoderm on inner
vein in middle
two arteries
allantoic stalk
leftover yolk of umbilical vesicle
```
73
In regards to sex, how do all embryos start out
the same
74
Most vertebrate species will develop to what kind of sex
look, act quite differently, sexually dimorphic
75
In many invertebrate species what will develop in regards to sex
males and females are less obviously different, some are both male and female
76
What are organisms that are both male and female called
hemaphrodites
77
Why do organisms begin developing differently at some stage
the environment or its the
| genes they inherent
78
How does the environment contribute to sex determination
temperature, nutrient level, bacterial infection, population density
79
In a dense population, what sex is not common
females
80
Why are there more males in a dense population
no need to reproduce
81
How does temperature develop sex
alligators make one sex in cold water and the other in warm water
82
How do genes influence sex determination
determining what genes you have determines sex
83
In mammals what genes determine sex
XY male
| XX female
84
In birds, what determines sex
zz male
zw female
one has same gene the other has two different
85
For some animals what part of the gene determines sex
autosome, locus on a chromosome that if you are heterozygous you are male and homozygous is female
86
insects that are haploid are what sex
male
87
insects that are diploid are what sex
female
88
In mammals is it the X or the Y gene that leads to male
Y gene, two XX don't make you a female automatically
89
What chromosomes do Klinefelter syndrome individuals have
XXY
90
What anatomical sex do individuals with Klinefelter syndrome have
sterile male
91
What chromosomes do Turners syndrome individuals have
XO
92
What anatomical sex do individuals with Turners syndrome have
sterile female
93
In the beginning you develop as what
both genders
94
At some point, what occurs
differentiation into final gender
95
What is the default pathway for gender differentiation
female unless you have a Y chromosome
96
At the indifferent sex stage, what is present in the embryo
mesonephric duct
mesonephros
mullerian ducts
97
What forms from the mesonephric duct
the vas deferens
98
What forms from the mesonephros
gonads are occurring, indifferent gonads
99
What do the mullerian ducts connect with
the cloaca
100
What do the mullerian ducts become
ovaducts
101
In males, what does the gonads become
testes
102
What occurs to the nephric duct in males
becomes vas deferens
103
What occurs to the mullerian ducts in males
they disassemble
104
If you inherit one Y chromosome, what do you become
male
105
If you lack a Y chromosome, what do you become
female
106
In females, what happens to the mullerian ducts part way
they fuse
107
What does the Y chromosome contain
a gene called TDF or SRY
108
What is TDF
testis determining factor
109
What is SRY
sex determining region of the Y chromosome
110
In females, what occurs to the nephric ducts
they disassemble
111
What do the gonads in females become
ovaries
112
If the mullerian ducts don't completely fuse into one, what is caused
didephys uterus
113
What is didephys uterus
split uterus with a wall between
114
The gonads are made from at least how many kinds of cells
two different
115
What two kinds of cells make up the gonads
intermediate mesoderm
| germ cells
116
What region of the intermediate mesoderm contributes to gonads
mesonephros
117
What does the intermediate mesoderm form for the gonad structure
body of the organ
118
The intermediate mesoderm is also the what of the organ
somatic cells or permanent framework
119
In opposition of the germ cells that become gametes and leave, what does the intermediate mesoderm do
never leave
120
Where do the primordial germ cells come from
migrates from the umbilical vesicle via the gut tube
121
What do the germ cells form as part of the gonad
arrange themselves in rows and cords
122
What are these rows or cords called
primitive sex cords
123
What other cells do the intermediate mesoderm create
supporting cells
steroidal cells
connective tissue cells
124
What are the two steroidal cells/ gender
male=interstitial
| female=granulosa
125
What are the two supporting cells/gender
sertoli=male
| follicle cells=female
126
What do the connective tissue cells make up
scaffold of the organ
127
At the arrangement of the sex cords, has sex differentiation occurred
no
128
What causes the differentiation of the gonads
if the supporting cells have Y chromosomes or not
129
If the supporting cells have Y chromosomes, what occurs
the supporting cells express the TDF gene
130
What does expressing TDF gene cause
neighboring cells to develop in certain ways that could have gone either way
131
What occurs to the primitive sex cords when TDF gene is expressed
the cords on the edges of the gonad disappear, leaving only those in the middle
132
What do the sex cords in the middle of the gonad develop into
seminiferous tubules
133
How do the cells on the edge of the gonad disappear
cell suicide
134
What do the primordial germ cells become when TDF is expressed
spermatogonia
135
What do the steroidal cells produce when TDF is expressed
testosterone
136
What does testosterone do
influence many other cells near and far
137
What do the supporting cells produce when TDF is expressed
anti-Mullerian duct hormone
138
What does the anti-Mullerian duct hormone do
kills mullerian duct cells
139
Where do the testis initially form
abdominal cavity
140
What occurs to the testes shortly before birth
descend to their eventual location
141
what occurs to the edges of the gonads when TDF is expressed
it gets a thick capsule
142
What is the thick capsule called
tunica albuginea
143
If there is a mutation for the anti-mullerian duct hormone or the receptor what occurs
genetic male, anatomic male with ova-ducts
144
If the supporting cells do not have a y chromosome what pathway is taken
the default pathway to become female
145
What occurs to the sex cords when no y chrom is present
the middle sex cords disappear, leaving only the ones on the edges
146
What is the edge of the gonad called
cortex
147
What is the middle of the gonad called
medulla
148
What do the sex cords on the edges of the gonads do
break up into primordial follicles
149
What occurs to the primordial germ cells right away
they enter into meiosis
150
What week of development do the germ cells enter meiosis
before the 12th week of development
151
What do the steroidal cells produce in females
estrogen
152
What occurs to the mullerian ducts
persist to become oviducts which merge at far end of the uterus
153
Where do the ovaries initially develop
abdominal cavity
154
What occurs in development to the ovaries in placement within the body
descend to the pelvic cavity
155
How could an XY female persist
if TDF gene or the promotor is mutated, TF is mutated
156
At the most fundamental level, what three things determine sex
genetics
embryology
choice
157
How does genetics determine sex
testosterone vs estrogen genes. Combo of genes not just one
158
How does embryology determine sex
the way things develop if primordial germ cells don't make it
159
How does choice determine sex
freedom/nature, worldview, person gets to decide
160
What is the ratio for the number of individuals that the anatomy does not match the genes
1/4500
161
In males vs females, how could the sex chromosomes lead to differences in gene products
more products could be produced from X chromosome in females than in males
162
How many genes on X chromosomes
1606
163
What could the extra doses of gene products of the X chromosome lead to
disease and or death
164
If the X chromosome had a growth factor, how could double of X products be a problem
twice the urge to have cells proliferate, 2x chance of cancer
165
How is this double dosage problem in females solved
inactivation of one of the chromosomes
166
When is the one chromosome entirely inactivated
in each cell of the epiblast layer, shortly after cell mass is formed
167
How many cells are present when an X is inactivated
a few hundred cells at this stage
168
Is this a random or scheduled inactivation process. Are the paternal or maternal ones inactivated?
some are paternal, some are maternal, random
169
What causes the inactivation of an X chromosome
accumulation of the produce XIST
170
Where is the XIST gene located
on a locus on the chromosomes
171
What occurs to produce XIST
gets transcribed into RNA, never gets translated, RNA attaches to rest of chromosome
172
What occurs as the RNA coats the chromosome
it gets inactivated
173
How does the RNA coating the chromosome lead to inactivation
RNA attracts methylation enzymes that cause methyl groups to be put everywhere and inactivate it
174
What happens to the inactivated chromosome
it forms into a Barr body
175
When does the Barr body unfold
only for replication prior to mitosis
176
What does the random inactivation lead to
chimerism
177
What is an example of X linked chimerism
calico cats
178
What is the most obvious example of pattern formation in development
limb development
179
How is a pattern seen in limb development
humans have the similar structures in the same pattern
180
This pattern develops from what
the same embryonic structure
181
What causes the patterns to develop
```
cells dividing at different speed
cell aggregation
cell growth
programmed cell death
embryonic induction
expression of certain genes
```
182
How does cells dividing at different speeds contribute to patterns
cells with faster speed make greater amount of cells
183
How does cell aggregation contribute to patterns
cells aggregate in certain areas and don't in other areas
184
How does cell growth contribute to patterns
elongation, esp, muscle cells
185
How does programmed cell death lead to patterns
occurs at certain points to get rid of cells
186
How does embryonic induction lead to patterns
chemical morphogens lead to ends and gradients of chemicals, concentration is proportional to distance, cells respond differently to different concentrations
187
How do genes contribute to patterns
specify regional differences in the anteroposterior body pattern during embryonic development
188
What are pattern forming genes
homeotic genes
189
homeotic genes are expressed in what motion across the embryo
anterior to posterior
190
When homeotic genes get mutated what occurs to the patterns
they get disrupted
191
If the wingless gene in flies gets mutated, what happens
flies don't have wings and instead have more legs
192
Homeotic genes are how long
1000bp
193
of the 1000bp a certain region codes for what
consensous sequence
194
How long is the region that codes for the consensous sequence
180bp
195
What does the consensous region code for
homeobox
196
What is the homeobox
HOX genes
197
How are the HOX genes arranged on a chromosome
in order and clustered together to be expressed in bunches
198
the 180bp region codes for what
homeodomain
199
How big is the homeodomain
60 AA
200
What is the function of the homeodomain
bind to DNA, making the products of homeotic genes, transcription factors
201
some of the HOX genes are what kind of genes
master control genes
202
What are the three axis of limb development
proximal-distal
dorsal-ventral
anterior-posterior
203
All limbs begin as what
a limb field
204
What is a limb field
limb fate map
205
What occurs within the limb fate map on a cellular level
limb forming cells + limb inducing cells
206
What type of interaction occurs between limb forming and limb inducing cells
reciprocal interaction
207
What type of development is limb development
regulative, very flexible, not fixed
208
The limb forming and inducing cells form in what
concentric circles
209
Where are the limb forming cells in the concentric circles
anterior edge of circle
210
Where are the limb inducing cells in the concentric circle
in the middle
211
What does the concentric circle produce
one limb on each side
212
If a concentric circle splits on one side what occurs
two limbs form on one side
213
What week of development do limb buds start forming
5th week of human development
214
The limb bud has what covering
ectoderm
215
What occurs following the production of the initial bud
mesenchyme cells condense in the forming bud
216
Where do the mesenchyme cells come from
the hypaxial myotome of the somite
217
What do the mesenchyme cells form in the limb bud
muscles on the outside of the bones
218
Once the hypaxial myotome cells aggregate, what occurs
they secrete FGF10
219
Does the FGF10 make them aggregate
no they aggregate in response to something else
220
What is the thing that makes them aggregate
unknown
221
What dictates what limb is formed
concentration gradient and expression of HOX genes
222
What dictates formation of an arm
noggin and OTX2 expression
223
What dictates formation of a leg
BFGF production on the posterior end
224
What does equal concentrations of noggin OTX2 and BFGF produce
flank
225
What is a flank
no limb formation, flat layer of skin
226
What HOX genes code for a flank
b9 =c9 production
227
What HOX genes code for a leg bone production
d9=c9>b9
228
What HOX genes code for an arm
d9>b9>c9
229
What forms the bone in limbs
somatic plate mesoderm starts cartilage
230
In the proximodistal axis, the mesenchyme cells induce the formation of what
apical ectodermal ridge
231
What is the apical ectodermal ridge
ridge of elongated cells along the anterio-posterior axis
232
What does the apical ectodermal ridge correspond with
finger tips
233
what does the ridge induce
mesencyme cels to proliferate
234
As the mesenchyme cells proliferate, what occurs
they push AER outward
235
The cells that are proliferating are in what area of the limb bud
the progress zone
236
The AER and the progress zone are always on what end of the limb
the distal end
237
The first mesenchyme cells are on what axis
proximal axis
238
What parts of the bone are formed first
proximal bones
239
What is the last portion of bone finished
distal end bones and muscles
240
How are joints formed
unknown mechanism
241
All of cell proliferation requires what
blood supply
242
What is needed to provide the blood supply
angiogenesis
243
How does angiogenesis occur
branches of dorsal aorta
244
If no blood vessels what occurs
no limbs are formed
245
What drug was used in teh 1960s for morning sickness
thalidimide
246
What was a side effect of the thalidimide drug
blocks angiogenesis=blocked limb formation
247
What did children of mothers that took thalidimide have instead of limbs
flippers, hand attached to the shoulder, no limb
248
When is limb formation initiated along the dorsoventral axis
before the limb bud is formed
249
What occurs to the ectoderm for limb formation
it becomes dorsalized
250
What is dorsalized ectoderm
cells are induced to end up on the dorsal side
251
Dorsalized ectoderm expresses what
Wnt-7a
252
What causes the dorsal ectoderm to move on the dorsal side
as limb bud grows it pulls it to the dorsal side
253
What occurs to other cells on the ectoderm
they are induced to be ventral side cells
254
What is the space between the dorsal and ventral cells of the ectoderm
future AER
255
Due to the concentration gradient of Wnt-7a, what does the dorsal side develop
knuckles, nails,
256
What causes knuckles and nails to form
expression of radical fringe TF
257
On the ventral side how much WNT7a is there
very little to none
258
What do the cells that do not get WNT7a express
transcription factors engrailed 1
259
What does engrailed 1 produce
palms and pads
260
without WNT-7a, what would occur to the dorsal and ventral sides
they would both be ventral and express pads
261
The anterior posterior axis of the limb distinguishes what
thumb vs pinky
262
In the posterior edge of the limb bud, what occurs
zone of polarizing activity
263
What does the zone of polarizing activity do
polarize the pole
264
What is causing this polarization
SHH is being secreted by the cells in the region
265
What does SHH being secreted on one end create
a concentration gradient
266
This causes the limb to be divided into what
5 concentration sections
267
In each section what occurs
HOX genes are expressed in varying degrees
268
In the highest concentration on the posterior end what HOX genes are expressed
HOX d9/10/11/12/13
269
What does the highest concentration end produce
pinky and everything on edge of arm
270
What does the second highest concentration have for HOX genes expressed
HOX d9/10/11/12
271
What does the second highest concentration produce
the ring finger
272
What does the mid concentraiton have for HOX gene expression
HOX d9/10/11
273
What does the mid concentration produce
middle finger
274
What does second lowest concentration have for HOX genes
HOX d9/10
275
What does the second lowest concentration produce
index finger
276
What does lowest concentration produce
thumb
277
What HOX genes make thumb
HOX d9
278
The concentration and finger formation initially forms what
a solid hand
279
What defines each finger
apoptosis of cells between
280
What are conjoined fingers or toes called
webbed, syndactyly
281
Initially, how do all limbs begin
outward, no bending ventrally or dorsally
282
What occurs to the upper limbs after formation
rotate 90 degrees to have elbows point backwards
283
What occurs to the lower limbs after formation
rotate 90 in the opposite direction to point bend ventrally
284
What two things produce neurons
neural tube, neural crest cells
285
How do neurons generally reach specific target cells
elongate
286
What are the two typical target cells
muscle or another neuron
287
Why is it best for the neurons to connect to their target cells in an embryo stage
neurons are close to their targets as the embryo is small
288
What is constructed between the neuron and its target
synapse
289
Throughout life, what occurs to synapses
the number and strength are adjusted
290
What is the rate at which neurons are produced
250,000 per minute
291
In total, how many neurons are produced during the embryo stage
2 billion
292
In comparison to the adult, 2 billion neurons is what
2x as many as the neurons the adults have
293
Why does the embryo produce 2x the number of needed neurons
body errs on the side of having too many, rather than too few as some cell will not make it, they will be defected, or commit suicide and be pruned
294
What is the mechanism towards which neurons extend
unknown
295
What is the length per day that neurons extend to
1mm a day
296
Does nerve regeneration occur in adults
yes, but it takes a lot of time
297
Where does outgrowth of neurites toward target cells occur
axon or dendrite growth is at the tip
298
What is the area on the axon or dendrite that extends called
growth cone
299
What is the growth cone/ what shape
a slightly enlarged area shaped like a hand
300
What does the hand shaped growth cone also have
cytoplasmic extensions
301
What are the cytoplasmic extensions on the growth cone called
microspikes or filopodia
302
What is the function of microspikes
transient feelers that probe the growth cone's environemnet
303
What are the microspikes probing for
adhesive molecules on cell or substrate surfaces
304
What are the adhesive molecules that the microspikes are probing for
CAMs and SAMs
305
What occurs when the microspike encounters a non-adhesive or repellant molecule
the microspike rapidly withdraws
306
When an adhesive molecule is contacted, what does the microspike do
attaches and a new growth cone is set up at the location
307
In vivo, what serves as barriers for neuron extensions
ECM with collagen, ect. that it must break through
308
What path does the growth cone follow
path of greatest adhesion
309
How does the neuron get through collagen and ECM
secretes proteases
310
What are axons packed with that also aid in the breaking through of collagen and movement
microtubules
311
How do microtubules aid in moving through ECm
generate a ton of force to allow axons to "punch" through
312
What forms the path of adhesive molecules which a growth cone follows
a continuous pathway of ECM molecules
guidepost cells
contact guidance
chemotaxis
313
Neurons that follow a continuous pathway of ECM molecules will require what
SAMs
314
What is another name for the continuous pathway of ECM molecules
pathway guidance
315
1 neuron will attach to what
1 target cell
316
What is the basis for neural pathology
if a neuron does not reach its target cell and the affect this has on a disease
317
The pathway guidance is around for how long
transient pathway, available only for a short time
318
Is only one molecule used for the pathway guidance for one neuron
no, the ECM molecules may be used repeatedly at different locations and times to lead a series of neurons to targts
319
What gene regulates migration and GABA production
HOX genes
320
What is the pathway that involves guidepost cells
spots of adhesive ECM are secreted by guidepost cells
321
Are the guidepost cells secreting a continuous pathway
no, it is spots
322
How does the growth cone find the guidepost cells
extremely long microspikes are sent out in all directions
323
In the guidepost cell method what occurs when one microspike binds to a substrate
the other microspikes collapse and the one that binds is maintained
324
Once the neuron is filled in to a guidepost, what occurs
a new growth cone is set up to search for the next guidepost cell
325
The first neuron to use a guidepost cell method is called what
pioneer cell
326
Different combinations of guidepost cells can do what
direct axons toward different targets
327
How do neurons use contact guidance to get to a target cell
axons going to the same region as a pioneer cell show high affinity towards them
328
What mediates contact guidance pathway
CAMs or cadherins
329
Cams or cadherins allow for what
cell to cell adhesion
330
How long does the contact guidance pathway work for
until the axon of the pioneer cell is myelinated
331
What about myelin prevents contact guidance pathway
NOGO protein
332
What does the NOGO protein do
blocks regeneration of neurons and their ability to follow pioneer cells
333
What is the name of the neurons that follow pioneer cells
secondary cells
334
At some point during the contact guidance pathway what occurs to secondary cells
the secondary cells veer off
335
What causes the secondary cells to veer off
BMP lures it away
336
What is an example of contact guidance pathway
autonomic nervous system
337
Organs are innervated by both what
parasympathetic and sympathetic neurons
338
What is the pioneer cell between parasympathetic and sympathetic neurons
sympathetic
339
What direction do sympathetic neurons send signals
from the spinal cord to the organ
340
What direction does the parasympathetic neuron travel
from organ to spinal cord
341
How does the parasympathetic neuron innervate the spinal cord
follows the sympathetic neuron using contact guidance
342
What is a nerve
a bundle of axons
343
What method creates a nerve
pioneer cells followed by secondary cells
344
Failed connections between neurons would lead to what of the neuron
apoptosis, as it is not being used and the cell trims any pathway not being used
345
What is the fourth mechanism that takes over as a growth cone approaches its target
chemotaxis
346
How do cells move in chemotaxis
movement is towards the direction of highest concentration of some soluble signaling molecule
347
What secretes the soluble signaling molecule
a target cell
348
What is the general name for a soluble signaling molecule
chemotactic factor
349
Since the chemotactic factor is referencing for neurons, what is the name of the soluble signaling molecule
neurotrophic factor
350
What is an example of neurotrophic factors forming specific neurons
interneuron formation in the spinal cord
351
what does the word neurotrophic factors mean
feeding neurons
352
What is the meaning of determined
fate is set
353
What is the meaning of differentiated
cell is acting out its fate
354
What attracts growth cone from interneuron to move towards the motor neuron
the neurotrophic factor netrin
355
What produces netrin
floor plate cells
356
netrin is not only a neurotrophic factor but also what
growth factor
357
What are the functions of netrin
support the neuron, keeps it alive
358
In mice, what neurotrophic factor contributes to Alzhiemers disease
reelin
359
If neurons are not kept alive, what occurs
they die and are removed
360
What other cell do neurotrophic factors stimulate
oligodendrocytes
361
Whern oligodendrocytes are signaled, what occurs
they myelinate the axons
362
If there is not enough neurotrophic factor to stimulate oligodendrocytes, what occurs
not enough myelin
363
What causes the establishmet of a synapse between the axon and its target cell
reciprocal interaction, exchange of signals between pre and post synaptic membranes
364
When the target cells secrete NTF, what occurs to the neuron
it attaches to the surface of the neuron to put in calcium channels
365
What is the function of the calcium channels in the membrane
when an AP comes down the neuron it opens the calcium channels to open and allow neurotransmitter vesicle release
366
How does the target cell respond to the release of neurotransmitters
clusters NT receptors on the side of the cell exposed to the highest concentration of NT
367
How were the receptors for the neurotransmitters prior in the membrane
distributed more or less ecenly over the whole cell
368
Why were the NTRs spread evenly over the whole cell
target cell did not know which direction its axon would come from
369
Once the growth cone and the target come into contact, what occurs to the growth cone
it become the nerve terminal
370
What is joined between the target cell and nerve terminal
junctional complex
371
What is the junctional complex
an ECM pad
372
What function does the ECM pad
both cells adhere to maintain a connection without the two synaptic membranes having to come into contact
373
What are the components of the ECM pad
Dok-7 and agrin procteins
374
What does the neuron membrane have to connect to the ECM pad
neurexin
375
What do target cells have to connect to the ECM pad
neuroligin
376
What does mutant neuroligin cause in mice
autism like cells
377
In strengthening the synapse with more receptors, where are NTRs sent
directly to the synapse rather than to the other membranes of the cell and moving later
378
What is pruning of synapses do
activity-dependent synapse elimination
379
Why is pruning of synapses activity dependent
inactive synapses are disconnected, while more used ones are maintained
380
Synapses used frequently undergo what
strengthening
381
Strengthening and Pruning of synapses forms the basis for what
memory formation and memory loss
382
How are synapses strengthened
more agrin in ECM
increase in neurotransmitter concentration
nerve terminal can expand and split into boutons
formation of ECm net arround synapse
383
How does more agrin in ECM strengthen synapse
stronger pad between
384
How does an increase in neurotransmitter concentration strengthen synapse
strong response by a target cells, more channels opened
385
How does nerve terminal expanding and splitting into more boutons strengthen the synapse
more surface area for more areas of contact
386
How does the formation of ECM net arround synapse strengthen the synapse
holds synapse together so the synapse is retained
387
What is the level of genetic variation among neurons
enormous diversity
388
When looking at the neurons within a brain what is observed
the brain is a mosaic of neurons, huge areas in the brain are different from other areas
389
Most of the variation is in what part of the chromosome
heterochromatin
390
What is heterochromatin
non-coding regulatory regions of the chromosome
391
While the gene looks normal, if the heterochromatin is off what occurs
expression regulation is off and does not work properly.
392
What is the last stage of development
senescence
393
What is senescence
deterioration of the body leading to natural death
394
What causes senescence
cell malfunction, deterioration, or death
395
What does senescence cause
changes visible on the outside of the body mirrors the changes happening on the inside
396
What are symptoms of senescence
```
gray hair
skin cracked and leathery
cataracts form
muscles atrophy
osteoarthritis
menopause
atherosclerosis
osteoporosis
hearing loss
slowed would healing and immune response
diabetes
nervous system problems
increased risk of cancer
```
397
What cell gives pigment to the hair
melanocytes
398
What replaces melancytes when they die out
melanocyte stem cells
399
Once melanocyte stem cells are gone and melanocytes are gone what occurs
no pigment
400
What leads to cracked and leathery skin
elastin fibers are being replaced with collagen
401
What causes collagen to form on the skin
UV radiation and sunburn damage the skin and lead to "scar tissue formation"
402
What causes cataracts
cells on the interior of the lens die
403
What causes muscle atrophy
myoblast and sattelite cells are being removed
404
What causes osteoarthritis
articular cartilage has worm out
405
What typically replaces articular cartilage
chondrocytes stem cells
406
Once chodrocytes are gone what occurs
cartilage cannot be replaced
407
What causes menopause
oogonia stem cells are gone
408
What does the removal of oogonia cause
no more follicles, no more estrogen
409
What causes atherosclerosis
collagen replaces elastin in the arteries
| phospholipids are replaced with cholesterol
410
What occurs to cholesterol to cause damage in the arteries
leads to damage, inflammation, swelling, blocking and scar tissue buildup
411
What effects does inflammation and scar tissue have on arteries
decreased vesicle radis
412
How does decreased vesicla radius affect MAP
increases arterial pressure
413
What is the #2 cause of death if you include abortion
coronary artery disease
414
What is the #1 cause of death if you do not include abortion
coronary artery disease
415
What is the #3 cause of death
stroke
416
What causes osteoporosis
the balance between osteoblast and osteoclast is heavily weighted towards osteoclast activity
417
In middle age what is the relationship between osteoblast and osteoclast activity
equal
418
In development what is the relationship between osteoblast and osteoclast activity
heavy on the osteoblast activity
419
What causes hearing loss
ear drum hardens
| graying of hair in cochlea
420
How does the ear drum harden
less elastic, doesn't stretch or vibrate as much
421
How does graying of hair in cochlea lead to hearing loss
once out of hair stem cells, no new hair you can't hear
422
What is the hair in the ears
cilia
423
What is the #8 leading cause of death
pneumonia and influenza
424
What is the #6 cause of death
type 2 diabetes
425
What causes type 2 diabetes in elderly individuals
impaired glucose regulation, no longer store glucose
426
Why can someone no longer store glucose
ran out of adipose cells
427
Type II diabetes is what kind of diabetes
non-insulin dependent
428
What is the #2 leading cause of death
cancer
429
What is the #7 leading cause of death
alzheimers and parkinsons
430
Most of the top deaths are what age related
old age
431
Why do christians believe senescence happens
the curse, the wages of sin is death, eat from the tree and you will die
432
What are suggested secondary causes to senescence (hypothesis)
mutation accumulation hypothesis
antagonistic pleiotrophy hypothesis
disposable soma hypothesis
433
What is the mutation accumulation hypothesis
random mutation accumulate throughout life and are passed on to daughter cells
434
Where do the random mutations come from
environmental factors and errors in DNA replication and repair
435
What does the accumulation of these mutations cause
stem cells die off or cause cancer development
436
What is the antagonistic pleiotrophy hypothesis
genes that promote reproduction early in life have the side effect of contributing to senescence later in life
437
What is the side effect of reproduction
senescence
438
What is pleiotrophy
a single gene leads to multiple conflicting effects
439
How is testosterone pleiotrophy
promotes sperm reproduction to build strong muscles, but also contributes to prostate cancer
440
How is estrogen pleiotrophy
promotes reproduction, enhances immune system to protect offspring but also leads to autoimmune diseases
441
What is the disposable soma hypothesis
bodies exist to produce germ cells, once the job is done the body serves no purpose
442
What does evolution not save
useless things
443
What does evolution save
only those things which confer a reproductive advantage
444
Why is an old body useless
maintaining and repairing an old body would take too much energy
445
Prior to the flood, how long did people live
1000 years
446
After the flood, humans live how long
120 years
447
Who was the last oldest person
Joseph
448
How old did joseph live to be
124 years
449
What genes are responsible for mutations to accumulate
DNA, RNA, and protein repair genes
450
What does mutations in the DNA, RNA, and protein repair genes lead to
proteins not being repaired
451
What occurs when proteins are not repaired
they accumulate inside cells and lead to cell death
452
What diseases feature proteins aggregating
Alzheimers and Parkinsons
453
What is one gene known to be involved in aging
WRN gene
454
What is the WRN gene named for
Werner's syndrome
455
What is werner's syndrome
people visibly age at an accelerated rate
456
People with werner's syndrome typically die at what age
47
457
What does the WRN gene code for
helicase enzyme
458
If the helicase gene is mutated what occurs
DNA doesn't unwind, no proteins no repair, less replication of stem cells
459
What role does helicase function as
unwinds DNA, reproduction
460
What is another accelerated aging disease
progerias
461
Who is affected by progerias
children
462
When do children with progerias die
within their teens
463
Children with progeria have a mutation in what
insulin signaling gene
464
This gene produces a mutated what
lamin
465
What is lamin
a protein that lines the inside of the nuclei
466
If lamin is mutated, what occurs
disorganized chromosomes
467
What is the most impressive and easily reproducible way of extendin the life spand of mice, rats, and hamsters
calorie restriction
468
What is calorie restriction
reduction in calories of an otherwise complete and balanced diet
469
What did calorie restriction lead to health problems wise
less frequenct atherosclerosis, auto-immunity and cancer
470
Calorie restriction idea has caused people to form what
calorie restriction society
471
because calorie restriction how is energy diverted
distributed towards survival rather than reproducing
472
In humans what does calorie restriction lead to
delayed menstruation
473
What shows correlations with calorie restriction
insulin levels and concentration are dependent upon calories
474
What genes prodect us from starvation
starvation avoidance genes
475
How do starvation avoidance genes contribute to senescence
when these genes are damaged or underexpressed
476
What is hormesis
minor stressors that get you cell's guard up against other stressors
477
How is calorie restriction hormesis
under eating is a slight stress that promotes longevity
478
What are the mechanisms of senescence
accumulation of mutations
over-eating
oxidative stress
replicative arrest
479
How does ATP generation lead to senescence
oxidative phosphorylation generates some nasty by-products
480
What are the byproducts of oxidative phosphorylation
reactive oxidation species
481
What are the reactive oxidation species
superoxide ions O2-
hydrogen peroxide H2O2
hydroxyl radicals OH
482
What are strong reactive oxidation species affects
strong oxidizing agents that attack DNA, lipids, and proteins
483
When strong reactive oxidation species attack DNA, lipids, and proteins, what occurs
break bonds and alter their functions
484
What does breaking bonds and altering a cell's function lead to
cell death
485
Hydroxyl radicals can lead to the formation of what chemical group
carbonyls
486
What is the affect of forming carbonyls rather than hydroxyl groups
cannot make hydrogen bonds to form protein structures
487
What proteins exist to neutralize the ROS
superoxide dismutase
catalast
peroxidase
488
What percent of all proteins are damaged by ROS forming carbonyls
40%
489
In fruit flies, extra superoxide dismutase causes what
increased longevity by 35%
490
What component do dietary supplements have
anti-oxidant actity
491
What dietary supplements are antioxidant activity
vitamin C, vitamin E, beta carotene
492
Do dietary supplements reduce risk of disease
no, they actually increase the risk of disease
493
What is necessary to replace worn-out, damaged and lost cells
replication and cell division
494
What are the 3 sources to replace damage
some cells are permanent
stable cells
adult stem cells
495
What cells are permanent
neurons and muscles
496
What are stable cells
liver, pancreas, kidney that can dedifferentiate
497
What does dedifferentiation lead to
regress and divide to serve as a replacement
498
How many times can stale cells divide
50X
499
What does the amount of division stable cells can undergo make them
a stable source, but limited
500
How many times can adult stem cells divide
unlimited
501
Why are stable cells limited to 50X division
every time a cell divides, part of the telomere gene is cleaved off
502
After 50X division, what occurs to the telomere gene
the telomere gene is gone and cannot acquire
503
fetal cells in culture will replicate how many times
50X
504
cells from and 80yo will replicate how many times
28 X
505
cells from someone with werners syndrome will replicate how many times
20X
506
how are adult stem cells able to replicate unlimitedly
they experess telomerase
507
What is the function of telomerase
replaces the tips of chromosomes to protect telomere gene
508
What other cells express telomerase
cancer cells
509
Even if cancer cells do not express telomerase, what can occur
still get a big cancer
510
In mice that had a knockout of telomerase, what occurred
they died prematurely, showed spleen atrophy and slow wound healing
