BIO MIDTERM 3 Flashcards
(209 cards)
1
Q
cells go through a program of …
A
differentiation and morphogenesis
2
Q
the fate of cells in the embryo is determined by …
A
cytoplasmic determinants
3
Q
cleavage generates…
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lots of small undifferentiated cells
4
Q
cleavage is followed by
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gastrulation
5
Q
gastrulation…
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organises these cells into 3 germ layers
6
Q
what are the 3 germ layers and what are they involved in
A
ectoderm, endoderm and mesoderm
involved in gastrulation
7
Q
germ layers develop into …
A
organs
8
Q
a single celled zygote gives rise to …
A
cells of many different types, each with a different structure and corresponding function
9
Q
during embryonic development, fertilized egg gives rise to…
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many different cell types
10
Q
gene expression orchestrates…
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the development programs of animals
11
Q
what processes transform the zygote to adult
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cell division, cell differentiation and morphogenesis
12
Q
cell differentiation is the …
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process by which cells become specialized in structure and function
13
Q
morphogenesis is
A
the physical process that gives an organism its shape
14
Q
an egg’s cytoplasm contains…
A
RNA, proteins, and other substances
15
Q
how are the contents of the unfetilized egg distributed
A
UNEVENLY
16
Q
what are cytoplasmic determinants
A
maternal substances in the egg that influence early development
17
Q
what happens when the zygote divides by mitosis
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cells contain different cytoplasmic determinants which lead to different gene expression
18
Q
what time is important for cytoplasmic determinants
A
when the zygote divides by mitosis
19
Q
other than cytoplasmic determinants what is another important source of developmental information
A
INDUCTIVE SIGNALS aka the environment around the cell especially signals from nearby embryonic cells
20
Q
what is inductive signals
A
signal molecules from embryonic cells cause transcriptional changes in nearby target cells
21
Q
interactions between cells can …….
A
INDUCE differentiation of specialized cell types
22
Q
what does determination do?
A
commits a cell to its final fate
23
Q
what is the order of differentiation and determination?
A
determination precedes differentiation
24
Q
cell differentiation is marked by…
A
the production of tissue specific PROTEINS
25
give an example of tissue specific proteins
MyoD protein in muscle cells
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myoblasts produce...
muscle specific proteins and form skeletal muscle cells
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MyoD is ....
(what does it produce?)
one of several master regulatory genes
myoblasts
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what is the function of MYoD...
they produce proteins that commit the cell to becoming skeletal muscle
29
the myoD protein does what to the actual DNA
is A TRANSCRIPTION FACTOR that binds to enhancers of various target genes
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what are the two things that describe MYOD
master regulatory gene
TRANSCRIPTION FACTOR
31
what is pattern formation
the development of spatial organization of tissues and organs
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IN ANIMALS pattern formation begins with
the establishment of the major axes
33
In drosophila, cytoplasmic determinants in the unfertilized egg do what?
determine the axes before fetilization
34
in fruit flies, after fetilization ...
the embryo develops into a segmented larava with three larval stages
35
A bicoid is what type of gene...
maternal effect gene
36
what part of the body does the bicoid gene effect
the front half of the body
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what would happen to an embryo whose mother has no functional bicoid gene
lacks the front half of its body and has duplicate posterior structures at both ends
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what is a bicoid ...
a morphogen
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the bicoid comes from the
MOTHER's genes
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the product of the mother's bicoid gene is concentrated at the
future anterior end
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what is the morphogen gradient
in which gradients morphogens establish an embryo's axes and other features
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what are morphogens
gradients of substances
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why is bicoid research important
it identifies a specific protein required for some early steps in pattern formation
it increased understanding of the mother's role in embryo development
it demonstrated a key developmental principle that a gradient of molecules can determine polarity and position in the embryo
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what are the embryonic development stages
fertilization, cleavage, gastrulation organogenesis
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what is fertilization
combination of sperm and egg nuclei and egg activation
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3 words that describe fertilization
HAPLOID TO DIPLOID
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what is cleavage
rapid cell divisions **without substantial growth** in size to generate a multicellular embryo
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what is gastrulation
mass cell movements to generate three germ layers
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what is organogenesis
localized changes in tissue and cell shape
50
cleavage splits the ....
the cytoplasm of one large cell into many smaller cells called blastomeres
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what is the blastula
ball of cells with fluid like cavity in the center
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what is the fluid-filled cavity in the blastula called
blastocoel
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what is the yolk
stored nutrients
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what is a key factor influencing the pattern of cleavage?
the distribution of yolk
55
describe the amount of yolk at each pole
vegetal pole has more yolk
animal pole has less yolk
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the difference in yolk distibution results in
animal and vegetal hemispheres that differ in appearance
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when do animal embryos complete cleavage
when the ratio of material in the nucleus relative to the cytoplasm is sufficiently large
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what happens after cleavage
the rate of cell divisions slows and the normal cell cycle is restored
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morphogenesis in animals involves
specific changes in cell shape, position and survival
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what are the two types of morphogenesis
gastrulation and organogenesis
61
how does frog gastrulation begin
when a group of cells on the dorsal side of the blastula begins to invaginate (be turned inside out)
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the beginning of gastrulation causes
a crease along the region where the gray cresent formed in the zygote
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the part above the crease is called
the dorsal lip of the blastopore
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how do the cells move from the embryo surface into the embryo
by involution (inward movement)
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the cells on the inside form the
endoderm and the mesoderm
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the cells on the embryo surface will form the
ectoderm
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the ectoderm is the
outer layer
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the mesoderm is the
middle layer
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the endoderm is the
inner layer
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the ectoderm forms the
epidermis of the skin and its derivatives, nervous and sensory systems, was. and teeth, pituitary glands
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the mesoderm forms the
skeletal and muscular systems
circulatory and lymohatic systems
excretory and reproductive systems
dermis of skin
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the endoderm forms the
epithelial ining of digestive trats
epethilial lining of respiratory, excretory and reproductive tracts
thymus , thyroid, parathyroid
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in early vertebrate organogenesis, ....
the notochord forms from mesoderm
neural plate forms from ectoderm
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the neural tube will become the
central nervous system
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the neural crest cells develop along the
neural tube of vertebrates and form various part of the embryo
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the neural plate curves inward forming the ...
neural tube
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What is the dorsal lip?
tissue
its cells commit to invaginate into the blastula --> initiates gastrulation and forms the notochord
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What is the notochord?
main axial skeletal element
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information is processed by ...
neurons organised into the brain
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what are the three types of neuronal types
sensory neurons, interneurons and motor neurons
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how do neurons transmit information?
through propagated changes in the membrane known as ACTION POTENTIALS
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action potentials are the result of ...
opening and closing of voltage gates sodium and potassium channels
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neurons are ...
nerve cells that transfer information within the body
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what are the two signals that neurons use to communicate
electrical and chemical
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what is the difference between electrical and chemical signals
electrical is LONG DISTANCE
chemical is SHORT DISTANCE
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WHAT does the central nervous system include
brain and spinal cord
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what does the peripheral nervous system include
cranial nerves, ganglia outside CNS, and spinal nerves
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where does processing of information take place>
ganglia or brain
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what is a brain
complex organization of neurons
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what are the three stages of information processing
sensory input
integration
motor output
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which part of the information processing happens in the CNS? PNS?
sensory input and motor output take place in the PNS
integration happens in the CNS
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synapse?
a junction between an axon and another cell
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synaptic terminal?
passes information across the synapse in the form of chemical messengers called neurotransmitters
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what are the chemical messengers in neurons
neurotransmitters
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describe the pathway of information in a neuron
a neuron receives information, transmits it along an axon, and transmits the information to other cells via synapse
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what is something neurons cannot do
go through cell cycle/ divide
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the cell body houses
the nucleus + organelles+ ALL DNA
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dendrites?
receive information and pass it to cell body
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what happens at the Axon Hillick
where axon is attached to the cell body
generates electrical signals
WHERE ACTION POTENTIAL IS GENERATED
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where does chemical signaling occur
at the synapse
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where does electrical signaling happen
along the axon
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in how many directions can electrical impulses travel in
ONEE
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an electrical impulse is ______ but the _________ _ ______ varies
identical
frequency of signaling
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sensory neurons do what
receive sensory information
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what do interneurons do?
process information
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what do motor neurons do?
control muscles, gland
carry out physical response
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what do glands do in response to stimulus
secrete things
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what is the name given to the cell from where information is transmitted from
presynaptic cell
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what is the name of the cell where the information is received?
postsynaptic cell
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most neurons are nourished or insulated by cells called
glia
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what are the types of glia cells
astrocytes
ependymal cells
microglia
oligodendrocytes and schwann cells
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astrocytes?
support neurons and form the blood-brain barrier
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ependymal cells?
promote circulation of cerebrospinal fluid
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microglia?
protect the nervous system from microogranisms
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oligodendrocytes and schwann cells
form the myelin sheath around axons
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difference between Schwann cells and oligodendrocytes
schwann found in peripheral nervous system
oligodendrocytes in cns
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what is a membrane potential
voltage (Difference in electrical charge) across its plasma membrane
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(electrical) how are messages transmitted in TWO WORDS
membrane potential
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resting potential ?
membrane potential of a neuron not sending signals
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what is the resting potential in humans
-70mv
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what maintains the resting potential of a neuron
ion pumps and ion channels
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in mammalian neuron at resting potential, the concentration of K+ is.... NA+??`
greater inside the cell for K+
greater outside the cell NA+
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sodium-potassium pumps use
the energy of ATP to maintain these K+ and Na+ gradient across the plasma membrane
123
the concentration gradients of k and na represent
chemical potential energy
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leak channels?
allow K+ to leak outside the cell
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what type of membrane ion channel is most likely to be open when a neuron is not transmitting an electrical signal
those channels that admit K+ ions
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resting neurons are most permeable to
K+ ions
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what can contribute to the negative charge within the neuron
anions trapped inside the cell
128
the opening of ion channels in the plasma membrane converts...
chemical potential to electrical potential
129
a neuron at resting potential contains...
many open K+ channels (leak channels ) and fewer open NA+ channels
130
voltage gated ion channels?
open or close in response to stimuli
131
when do leak potassium channels open?
always open
132
why are leak potassium channels good?
they help set the resting potential
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why are voltage-gated potassium channels important
for restoring membrane potential following depolarization
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how do voltage gated potassium channels open?
open slowly causing delayed efflux (movement out of neuron) of potassium
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why are gated sodium channels important
for depolarizing membrane (making more positive) during action potential
136
how does the voltage gates sodium channels open
opens rapidly allowing influx of sodium`
137
voltage gates calcium channels open when?
when membrane depolarises and lets calcium flow into cell
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why are voltage gates calcium channels important
for synaptic release
139
at resting potential voltage gated NA+ channels are --> open/ closed?
closed
140
when the membrane is depolarised the voltage gated NA channels are ...
open
141
in depolarization the membrane potential becomes ...
less negative
142
what is the action potential threshold
-55mv
143
action potential is an ___ or ___ response
ALL OR NONE response
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the action potential carries info across ...
axon
145
how many actions potentials can a neuron produce
hundreds of action potential
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what reflects the strength of a stimulus
the frequency of action potential
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what are the stages of an action potential
1) resting state
2) depolarization ( some NA channels open)
3) rising phase of the action potential
4) falling phase of the action potential( gates NA channels close and most gates K channels open)
5) undershoot
148
different regions of the brain are responsible for ...
different function
149
imbalances in neurotransmitters are associated with ...
neurological/psyhchological disorders
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different neurons use different...
neurotransmitters
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temporal and spatial summation lead to
action potential generation
152
neurotransmitters binding to receptors on the postsynaptic membrane generate ...
a postsynaptic potential
153
refractory period?
after an action potential a second action potential cannot be initiated
154
the refractory period is a result of a
temporary inactivation of NA + channels
155
how can an action potential travel long distances
by regenerating itself along the axon
156
at the axon hillock...
an electrical current depolarizes the neighboring region of the axon membrane
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what prevents the action potential from traveling backward
inactivated NA+ channels behind the zone of depolarization
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what location do action potentials travel to
toward the synaptic terminals
159
the speed of an action potential....
increases with the axon's diameter
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in vertebrates axons are insulated by...
myelin sheath
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what is the effect of the myelin sheath?
causes an action potential's speed to increase.
162
what is the depolarized region of the axon
node of ranvier
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where are action potentials formed only ?
at nodes of ranvier
164
nodes of ranvier?
gaps in the myelin sheath where voltage gated NA+ channels are found
165
saltatory conduction?
the way action potentials in myelinated axons jump between the nodes of ranvier
166
most synapses are...
chemical
167
chemical synapse order ...
1. Arrival of action potential at synaptic
terminal depolarizes membrane, opening
voltage-gated channels that allow Ca2+ to
diffuse into the terminal.
2. This triggers vesicles to fuse with
membrane and release neurotransmitter.
3. The neurotransmitter diffuses across the
synaptic cleft, binds to ligand-gated ion
channels in the post-synaptic membrane,
opening the channels.
168
direct synaptic transmission involves...
binding of neurotransmitters to ligand-gated ion channel in post synaptic cells
169
neurotransmitters binding causes...
ion channels to open, generating a post synaptic potential
170
neurotransmitters can be...
excitatory or inhibitory
(cause firing or prevent firing)
171
a single excitatory post synaptic potential is ....
not sufficient to trigger an action potential in a postsynaptic neuron
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a postsynaptic potential is a change...
in the membrane potential of the postsynaptic neuron
173
temporal summation?
two EPSP (excitatory postsynaptic potential) are produced in rapid sucession
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a single EPSP is usually..
too small to trigger an action potential in a postsynaptic neuron
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spatial summation?
EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron ass together
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the combo of EPSPs through spatial and temporal summation can ....
can result in depolarization of the membrane and trigger an action potential
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what are the three options after the release of the neurotransmitter
1) may diffuse out of the synaptic cleft
2) may be taken up by surrounding cells
3) may be degraded by enzymes
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the same neurotransmitter can produce...
different effects in different types of cells
179
what are the 5 major classes of neurotransmitters
acetylcholine, biogenic amines, amino acids, neuropeptides, and gases
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what are some amino acid neurotransmitters?
glutamate
GABA
GLYCINE
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what are some examples of biogenic amines
norepinephrine
dopamine
serotonin
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what is acetylcholine involved in
muscle stimulation, memory formation and learning
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what disrupts acetylcholine neurotransmitiion
a number of toxins
including nerve gas, serin, botulism
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what is botulism
a severe form of food poising
produced by certain bacteria
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where is acetylcholine common in?
vertebrate and invertebrates
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what are the two major classes of acetylcholine receptor?
ligand gates
metabotropic
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cholinergic neurons ....
release acytlcholine
188
the neurotransmitters biogenic amines are derived from
amino acids
189
most common biogenic amines
serotonin
dopamine
epinephrine
norepinephrine
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how can be depression treated
with drugs that block the reuptake of serotonin
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parkinson;s disease is associated with
lack of dopamine in the brain
192
how do biogenic amines affect the body
affect sleep, mood, attention, learning and memory
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psychoative drugs like LSD and mescaline produce ____ by _________
produce hallucinatory effect by binding receptors for serotonin and dopamine
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dopaminergic neurons release
DOPAMINE
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what does the motor cortex control
control of skeletal muscles
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prefrontal cortex controls
decision making, planning
197
broca's area?
forming speech
198
somatosensory cortex?
sense of touch
199
sensory association cortex?
integration of sensory information
200
visual association cortex
combining images and object recognition
201
visual cortex?
processing visual stimuli and pattern recognition
202
wernicke's area
comprehending language
203
cerebellum
coordinating movement and balance
204
frontal lobe?
control over many abilities, including the way you think, how you move and how you remember things.
205
pariental lobe ?
responsible for receiving and processing sensory input such as touch, pressure, heat, cold, and pain
206
temporal lobe?
managing your emotions, processing information from your senses, storing and retrieving memories, and understanding language.
207
occipital lobe?
responsible for visual perception, including colour, form and motion.
208
why must neurotransmitters be terminated ASAP
so that the action potential doesn't stay continuous
