grey matter Flashcards
1
Q
what is the central nervous system made up of
A
brain
spinal cord
2
Q
what is the largest part of the brain
A
cerebrum
3
Q
what are the functions of the cerebrum
A
vision
hearing
speech
thinking
memory
4
Q
what are the 2 halves of the cerebrum
A
cerebral hemispheres
joined by a band of nerve fibres called the corpus callosum
right hemisphere controls left side of body and vice versa
5
Q
what is the thin outer layer of the cerebrum
A
cerebral cortex/ grey matter
consists of cell bodies of neurones
highly folded
increases sa
so more neurones
more neurone connections
more ability of brain to carry out complex behaviours
6
Q
what is beneath the cerebral cortex/ grey matter
A
white matter
consists of myelinated axons of neurones
7
Q
what are the functions of the hypothalamus
A
monitors blood as it flows to the brain
releases hormones/ stimulates pituitary gland to do so
regulates body temp by monitoring blood temp
osmoregulation
water balance of blood
release ADH if blood too conc
AGH increases water absorption in kidneys
regulates digestive activity
hormones that control appetite
secretion of digestive enzymes
endocrine functions
metabolism, puberty
8
Q
what are the functions of the cerebellum
A
coordinates movement
including balance which involves coordination between eyes, muscles, semicircular canals in ears
9
Q
what are the functions of the medulla oblongata aka medulla
A
contains coordination centres that control diff functions
cardiac centre- heart rate
respiratory centre- breathing rate
10
Q
what are neurones
A
specialised cells of the nervous system which carry electrical impulses around the body
11
Q
what is a nerve
A
a bundle of neurones
12
Q
what features are in all neurones
A
axon
cell body
axon terminal
13
Q
what is an axon terminal
A
has many nerve endings
allows neurones to connect and receive impulses from others
14
Q
what is a myelin sheath
A
insulates axon in myelinated cells
made of Schwann cells
uninsulated gaps between Schwann cells called nodes of Ranvier
15
Q
why do myelinated cells have faster impulse transmissions
A
electron impulses dont travel down whole axon
jump from one node to the next
in non myelinated cells, impulse travels slower cos moves down entire length of axon
16
Q
function of sensory neurone
A
carry electrical impulses from receptors to CNS
17
Q
function of relay neurone
A
found entirely within CNS
connect sensory and motor
18
Q
function of motor neurone
A
carry impulses from CNS to effector muscles or glands
19
Q
structure of motor neurone
A
large cell body at one end in spinal cord/ brain
many highly branched dendrites extending from it
20
Q
structure of sensory neurone
A
cell body that branches off in middle of axon
dendrites attached to a receptor cell
21
Q
what is a stimulus
A
a change in the environment
22
Q
what does a receptor do
A
detect stimuli
23
Q
what are effectors
A
muscles or glands
that bring about a response
24
Q
what is the pathway that nerve impulses pass along the nervous system
A
stimulus
receptor
sensory neurone
CNS
motor neurone
effector
25
what is the pathway that nerve impulses pass along the nervous system along when there is bright light
light receptors in eyes
sensory neurone
CNS
motor neurone
circular muscles in iris contracts
26
what does contraction of circular muscles cause
pupils to constrict
limits amt of light entering eye
prevents damage to retina
27
what is the pathway that nerve impulses pass along the nervous system along when there is low light
light receptors in eyes
sensory neurone
CNS
motor neurone
radial muscles in iris contracts
28
what does contraction of radial muscles cause
pupil to dilate
maximises amt of light entering eye
improving vision
29
what is the resting membrane potential
-70mV
30
what causes the potential difference across neurone membranes
diff numbers of ions
31
when is a membrane polarised
when there is a difference in charge across a membrane
32
what factors contribute to establishing and maintaining resting potential
active transport of sodium and potassium ions
difference in membrane permeability to sodium and potassium ions
33
during resting potential, does the outside or inside of an axon have a more negative electrical potential
inside
34
explain the active transport of sodium and potassium ions
carrier proteins called sodium- potassium pumps
in neurone membrane
use ATP to actively transport Na+ out
and K+ in to axon
for every 3 Na+ out, 2K+ in
creates conc grad
35
is the neurone membrane more permeable to sodium or potassium ions?
potassium
36
what does the difference in membrane permeability result in
K+ can diffuse out at a faster rate
than Na+ can diffuse back in
so more pos ions on outside
generating a neg charge inside
37
what does the neurone membrane need to be to initiate a nerve impulse?
depolarised
38
when are voltage gated channels closed
when the membrane is at rest
39
how is an action potential generated
neurone stimulated
small number of Na+ channels open
Na+ move into axon down conc grad
making inside less neg, lower pd
if pd reaches -55mV (threshold potential) more Na+ channels open (voltage gated channels)
influx of Na+
when charge reversed from -77 to around 30, membrane depolarised and action potential generated
40
what happens about 1 millisecond after action potential generated
voltage gated Na+ channels close
voltage gated K+ channels open
allowing K+ to diffuse out of axon down conc grad
so inside axon is more neg charged
this is repolarisation
41
what is hyper polarisation
short period when membrane potential is more neg than resting potential (-0.77mV)
42
what is the refractory period
membrane is hyperpolarised
membrane unresponsive to stimulation
new action potentials cant be generated
43
how are action potentials transmitted/ propagated
depolarisation at site of 1st action potential causes
Na+ to diffuse along cyto
into next axon section
depolarising membrane at this part
causing voltage gated Na+ channels to open
triggers another action potential
repeats
44
why is an action potential not generated if stimulus is weak
few Na+ channels open
membrane not sufficiently depolarised to reach threshold potential
45
what increases as stimulation intensity increases
frequency of action potentials transmitted along neurone
46
why is speed of conduction faster in myelinated neurones
myelin sheath stops depolarisation as it stops Na+ and K+ diffusion
Na+ diffuse along axon
nodes of Ranvier membrane depolarises when Na+ arrive
action potential jumps from 1 node to the next (saltatory conduction)
47
why may impulse transmission need to be prevented
painkillers
anaesthetics
48
how do some drugs prevent impulse transmission
bind to Na+ channels
prevent the opening
prevent Na+ influx when stimulation
prevent depolarisation
action potential cant be generated
49
where are synapses found
junctions between cells in nervous system
50
what is the neurone before the synapse called
presynaptic neurone
51
what is the neurone after the synapse called
postsynaptic neurone
52
eg of neurotransmitters
ACh
53
what is the gap between neurones called
synaptic cleft
54
what is the synaptic knob
rounded end of presynaptic neurone
55
where are the vesicles containing neurotransmitters
in the synaptic knob
56
what is summation
effect of multiple impulses added together
57
what is synaptic convergence
several presynaptic neurones converge to meet a single postsynaptic neurone
58
what do synapses enable
unidirectionality of impulse transmission
divergence of nerve impulses
amplification of nerve impulses by summation
59
what is the process of synaptic transmission
action potential arrives, depolarising presynaptic membrane
voltage gated Ca+ channels open, Ca+ diffuse in to synaptic knob
presynaptic vesicles fuse w membrane
ACh released into synaptic cleft by exocytosis
ACh diffuses across it and binds to receptor proteins on postsynaptic neurone
Na+ channels open, Na+ diffuses thru postsynaptic cell
post synaptic membrane depolarised
ACh broken down
60
what does the human nervous system consist of
central nervous system: brain and spinal cord
peripheral nervous system: all nerves in body
61
where are hormones produced
endocrine glands
62
where are hormones carried
blood
63
does the nervous or endocrine system have faster transmission
nervous
64
does the nervous or endocrine system have longer length of effect
endocrine
65
what is the pathway of hormone action
stimulus
receptor
hormone
effector
66
examples of stimuli that plants can respond to
light
gravity
physical objects
herbivory
water
physical touch
67
what is a phototropism
growth response to light
68
what is a geotropism
growth response to gravity
69
what is a positive tropism
growth towards a stimulus
70
what is a negative tropism
growth away from a stimulus
71
roles of plant hormone gibberellins
stem elongation
flowering
seed germination
72
role of plant hormone cytokines
cell growth and division
73
role of plant hormone abscisic acid (ABA)
leaf loss
seed dormancy
74
role of plant hormone ethene
fruit ripening
flowering
75
where are growth factors aka plant hormones produced
growing plants of a plant
76
how is IAA transported cell to cell
diffusion/ active transport
long distances in phloem
77
what type of tropism does IAA in plant shoots bring about
phototropism
78
in plant shoots, what does an increase in concentration of IAA bring about
increase in rate of cell elongation
79
what happens when light shines on one side of a plant stem
IAA transported to the shaded side
IAA gradient established
faster rate of cell elongation on shaded side
shoot bends towards source of light
80
what type of tropism does IAA in plant roots bring about
geotropism
81
in plant roots, what does an increase in concentration of IAA bring about
decrease in rate of cell elongation
82
how does IAA work in roots
IAA transported to lower side of plant roots
inhibits cell elongation there
lower side grows at a slower rate
root bends downwards
83
what stimulus controls flowering in plants
night length
84
how can night length be detected by plants
determines quantities of diff forms of phytochrome pigment in leaf
85
what is Pr form of phytochrome
inactive form
absorbs light from red wavelength part of spectrum
660 nm
86
what is Pfr form of phytochrome
active form
absorbs light from far red wavelength part of spectrum
730 nm
87
what happens when Pr absorbs red light
converted to Pfr
88
what happens when Pfr absorbs far red light
converted to Pr
89
what happens to phytochrome in the absence of red light
unstable Pfr gradually converts back into Pr
90
what happens to phytochrome during the day
high levels of Pfr
sunlight contains more 660nm than 730
more Pr being converted to Pfr
91
what happens to phytochrome during the night
high levels of Pr
red light wavelengths not available in dark
Pfr converts gradually to Pr
92
what does light enter the eye thru
pupil
93
where is light focused
fovea
(region of retina)
94
what controls amount of light entering eye
iris muscles
95
how is the shape of the lens controlled
ciliary muscles attached to lens by suspensory ligaments
96
what focuses light
lens
97
where are rod cells found
around outer retina
98
where are cone cells found
fovea
99
what are rod cells sensitive to
light intensity
100
what are cone cells sensitive to
diff wavelengths of visible light
101
what type of images are generated from rod cells
back and white
102
what type of images are generated from cone cells
coloured
103
how are action potentials generated in photoreceptors transmitted to brain
via optic nerve
104
where does optic nerve leave back of eye
blind spot
has no photoreceptors
105
what is rhodopsin
a light sensitive pigment in rod cells
106
what happens when light hits rhodopsin
breaks apart into
retinal, opsin
107
what is the breaking apart of light sensitive pigments called
bleaching
108
what does bleaching cause
chemical change in photoreceptor
generation of nerve impulse
travels along a bipolar neurone
to optic nerve
109
what happens in rod cells in the dark
Na+ pumped out
diffuse back in
membrane depolarised
inhibitory neurotransmitter released
action potential in bipolar neurone inhibited
110
what happens in rod cells in the light
rhodopsin bleached
Na+ pumped out
Na+ channels closed
Na+ cant diffuse back in
membrane hyper polarised
no inhibitory neurotransmitter released
action potential generated in bipolar neurone
111
what type of images do CT scans produce
cross section
112
what does CT scan stand for
computerised tomography
113
how do CT scans work
x ray beams aimed at patient from all angles around body
digital x ray scanners pick up beams as they exit body
denser tissues absorb more radiation so show up lighter
114
do CT scans show brain structure and function
no
j structure
115
who are CT scans not recommended for and why
pregnant women
children
radiation risk
116
what does MRI stand for
magnetic resonance imaging
117
what do MRIs use
magnetic field
radio waves
118
does CT or MRI have higher resolution
MRI
119
do MRI scans show brain structure and function
no
j structure
120
are CT or MRI scans more expensive
MRI
121
who cant have MRIs and why
patients w medical devices such as pacemakers and insulin pumps
122
what must patients do during MRIs
remain still
123
what do functional MRIs use
magnetic field
radio waves
124
do functional MRI scans show brain structure and function
yes
125
how do functional MRIs show brain function
show location of oxygenated and deoxygenated blood
so which brain regions active
measures ratio of oxygenated to deoxygenated haemoglobin
126
what does PET scan stand for
position emission tomography
127
what do PET scans use
radioactive tracers
128
in PET scans, where do the radioactive tracers collect
areas w increased blood flow, metabolism, neurotransmitters
129
in PET scans, what does the amount of tracer present in the brain region indicate
if region is active/ inactive
130
do PET scans show brain structure and function
yes
131
what is the visual cortex
region of cerebral cortex where visual info is processed
132
what is the cerebral cortex
outer layer of cerebrum
133
what happens in the visual cortex after birth
synapses form
critical period
134
why do both eyes need to be visually stimulated after birth
so neurones in visual cortex can be organised correctly
135
what happens to synapses that pass on nerve impulses during the critical period
strengthened
become permanent part of structure of visual cortex
136
what happens to synapses that don't receive nerve impulses during the critical period
lost/ cant be reformed
can cause blindness
137
what did Hubel and Wiesel study
the long term impact of depriving animals of vision in 1 eye
138
what animals did Hubel and Wiesel test on
kittens
monkeys
139
what did Hubel and Wiesel do to the animals straight after birth
and what happened due to that
stitch 1 eye closed
after 3 months, blind in that eye
140
what are ocular dominance columns
groups of neurones in visual cortex
respond to light input from 1 eye
right ocular dominance columns receive info from right eye and vice versa
141
what did Hubel and Wiesel discover when they studied neurone activity in the visual cortex
ocular dominance columns corresponding to the stitched eye were smaller than normal
and the other eyes were larger
so concluded that ocular dominance columns for blind eye redistributed to correspond to normal eye- switched dominance
142
what is habituation
if a stimulus is repeated many times w no neg outcome, animal learns to not respond to it
143
why is habituation important
process of detecting and responding to stimuli requires energy
important animals don't waste energy responding to non threatening stimuli
144
what is the process of habituation
less Ca2+ move into presynaptic neurone on arrival of a nerve impulse
less neurotransmitter released, less binds to post synaptic membrane receptors
less Na+ channels open, less move into axon, axon still neg charged, threshold potential not reached
action potential less likely generated in post synaptic neurone
nerve impulse doesn't reach effector
145
symptoms of Parkinson's disease
tremor to specific body parts
slow movement
stiff muscles
difficulty w balance
changes to speech
146
what is Parkinson's disease caused by
loss of neurones that produce neurotransmitter dopamine
147
what is dopamine involved in
muscle control
148
what drugs can treat Parkinson's disease
dopamine agonists
dopamine precursors
enzyme inhibitors
149
how do dopamine agonists work in the treatment of Parkinson's disease
bind to and activate dopamine receptors on post synaptic membrane
produce same effect as dopamine
150
what are dopamine precursors in the treatment of Parkinson's disease
chemicals that can be converted to dopamine in the neurones
151
what is an example of a dopamine precursor in the treatment of Parkinson's disease
L- dopa
152
how do enzyme inhibitors work in the treatment of Parkinson's disease
inhibit activity of enzymes that break down dopamine in synaptic cleft
so more dopamine present in brain
153
how could gene therapy be used in the treatment of Parkinson's disease
add genes to affected brain cells
to increase dopamine production
or prevent destruction of dopamine producing cells
154
how could stem cell therapy work in the treatment of Parkinson's disease
stem cells replace lost dopamine producing cells
155
what is depression linked to
low levels of neurotransmitter serotonin
156
what is the function of serotonin
transmits nerve impulses through areas of brain that control mood
157
what are some types of antidepressants
SSRIs
TCAs
MAOB inhibitors
158
how do SSRIs work in the treatment of depression
prevent uptake of serotonin at synapses
so increases overall brain serotonin levels
159
how do TCAs work in the treatment of depression
increase serotonin and noadrenaline in brain
160
how do MAOB inhibitors work in the treatment of depression
inhibit enzymes that break down neurotransmitters in synaptic clefts in brain
161
what are some ways that drugs can increase transmission of impulses at a synapse by
cause more neurotransmitters to be produced in synaptic knob
cause more neurotransmitters to be released at presynaptic membrane
imitate effect of neurotransmitter by binding to and activating receptors on post synaptic membrane
preventing breakdown of neurotransmitters by enzymes
preventing reuptake of neurotransmitters by presynaptic cell
162
what are some ways that drugs can decrease transmission of impulses at a synapse by
preventing production of neurotransmitter in presynaptic knob
preventing release of neurotransmitter at presynaptic membrane
enabling neurotransmitter to gradually leak out of presynaptic knob (then broken down by enzymes) so little will be left when action potential arrives
binding to receptors on post synaptic membrane to prevent neurotransmitters from binding
163
what symptoms does taking MDMA cause
affects mood, anxiety, sleep
164
what does MDMA do to serotonin
inhibits reuptake of serotonin into presynaptic neurone
by binding to proteins that enable serotonin reuptake
so more serotonin present in brain
also triggers release of further serotonin from presynaptic neurones
165
how does L- dopa work
transported from the blood to the brain
converted into dopamine
catalysed by dopa decarboxylase
so more dopamine in brain
166
why cant people with Parkinson's disease directly be given dopamine
dopamine cant cross the barrier between the blood and the brain
167
what is personalised medicine
development of targeted drugs to treat diseases in ppl w diff genotypes
168
what can personalised medicine be tested on
synthetic tissues genetically identical to patients
169
how can the human genome project be used to develop genomic medicine
sequenced entire human genome
so genes that code for certain proteins can be found and analysed
knowing structure of proteins involved in disease allows development of drugs that target specific proteins
170
how can genome information be used along with clinical information
to identify pattens to determine risk of developing disease
also work out how well person might respond to specific treatments
171
what can be used to identify ppl w high risk of a disease
genetic screening
172
what are some social moral and ethical issues around personalised medicine
increased research costs for drug companies leads to increased price of new meds so only wealthy ppl have access to personalised medicine
patients cld be refused personalised medicine if predicted ineffective
knowing that the only medicine available may not work is distressing
173
what is genetic engineering
deliberately modifying a specific characteristic of an organism
174
what type of DNA is a GMO said to have
recombinant DNA
175
what does GMO stand for
genetically modifies organism
176
what are examples of drugs produced by genetically modified micro organisms
human insulin
blood clotting factors
177
what are examples of drugs produced by genetically modified plants
human insulin
cholera vaccine
178
what are examples of drugs produced by genetically modified animals
human blood clotting proteins from milk
179
what is the process of genetically engineering a micro organism
restriction enzymes remove gene coding for desired protein
many copies of gene made from PCR
copies inserted into plasmids (catalysed by DNA ligase) which transfer copies into microorganisms
GM micro organism grown in large fermenters containing nutrients so they can multiply and produce large quantities of new protein
protein can be isolated and purified before it's packaged and distributed
180
what are DNA vectors when genetically engineering micro organisms
plasmids
181
what is the process of genetically engineering a plant
same start as microorganisms so gene inserted into plasmid then transferred to microorganism
bac infects plant cells
gene transferred from bac to plant cell nucleus
plant cell stimulated to multiply and grow into adult plant (each plant cell contains a copy of the gene)
protein purified from plant tissue/ plant eaten
182
what is the gene gun method of genetically engineering a plant
tiny pellets are coated with the desired DNA and then fired into the plant cells
183
what is the process of genetically engineering an animal
gene injected into zygote nucleus
zygote implanted into surrogate nucleus, develops into adult (each cell contains a copy of gene)
protein purified
184
what are the benefits of genetically engineering crops
modify to have higher yield, decrease famine
modify to be resistant to pests, decrease production costs
185
what is the benefit of treating diseases w human proteins from GMOs
decrease allergic reactions
increase effectiveness
186
what is the benefit of producing vaccines from GM plants
dont need refrigeration
accessible for ppl in rural areas
187
what are the risks of eating GM food
long term impacts on human health
188
what are the risks of genetically engineering crops
pests cld develop resistance to crop defences
increase pesticide use
189
what are the benefits of genetically engineering animals
unethical to do it just to benefit humans
190
what is brain development
growth of the brain and formation of neurone connections
191
what factors can be measured to determine brain development
brain size
number of neurones
level at which brain is functioning
192
what is 'nature' on the development of the brain
impact of genetic factors
193
what is 'nurture' on the development of the brain
impact of environmental factors
194
how are animal experiments used to investigate nature vs nurture on brain development
same species (similar genes) put in different environments
differences in brain development likely to be nurture
use genetic modification to switch off genes, same environment
differences likely to be nature
195
how are twin studies used to investigate nature vs nurture on brain development
identical twins (genetically identical) raised in diff environments
diffs due to nurture
similarities nature
identical and non identical twins raised in the same environment
diffs due to nature
196
how are cross cultural studies used to investigate nature vs nurture on brain development
large groups of children of similar age from diff cultural backgrounds
diffs due to nurture
similarities nature
197
how are newborn studies used to investigate nature vs nurture on brain development
environment outside womb doesn't impact brain development
so level of brain development is due to nature
eg cant speak so nurture
can cry so nature
198
how are brain damage studies used to investigate nature vs nurture on brain development
compare a particular characteristic in kids born w and without brain damage
if brain damage kids have development of characteristic, due to nurture
if dont, nature
199
why cant the effects of brain damage on development be studies in adults
Brain damage in adults cannot be easily repaired as the brain is fully developed
however a child's brain is still developing
