exam 1 Flashcards

(178 cards)

1
Q

scientific method

A
  • observation
  • replication
  • interpretation
  • verification
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2
Q

what drives the scientific method?

A

hypothesis but discovery research also needed

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3
Q

egypt (5000 years ago)

A
  • knew about the brain but it was not important

- heart was the key to the soul and where memories were stored

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4
Q

hippocrates

A

brain is the center of sensation and intelligence and epilepsy=brain damage

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5
Q

alcmaion of crotona

A

described the optic nerve in 500 BC

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6
Q

plato (387 BC)

A

believes brain is the center of mental processes

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7
Q

aristole (384-322 BC)

A

thought heart was the center of intelligence and the brain simply cooled the blood

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8
Q

galen (AD 130-200)

A

a doctor to gladiators that studied the structure of the brain
* had a similar view to hippocrates

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9
Q

what were galen’s beliefs?

A
  • cerebrum felt soft, so sensations and memory formed here
  • cerebellum felt hard, so it controlled muscles
  • the brain received sensory info
  • nerves were tubes
  • humors (vital fluids) flowed to the brain ventricles
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10
Q

leonardo da vinci

A

produced wax cast of ventricles in 1504

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11
Q

andreas vesalius (1514-1264)

A

produced detailed drawings of the brain

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12
Q

decartes (1596-1650)

A

believed in fluid-mechanical theory but that humans abilities came from the “mind” which communicated to the brain via the pineal gland

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13
Q

history of neuroscience in the 17th and 18th century

A
  • distinguished gray matter from white matter
  • peripheral and central divisions
  • every brain has the same pattern GYRI (bumps) and SUCLI & FISSURES (grooves)
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14
Q

grey matter

A

cell bodies of neurons

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15
Q

white matter

A

axons of neurons

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16
Q

19th century views of the brain

A
  • brain generates electricity
  • nerves are made of bundles of fibers
  • each fiber transmission is one way
  • sensory and motor nerves in same bundle
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17
Q

Galvani and du Bois-Reymond

A

showed that electricity can stimulate muscle movement

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18
Q

Bell and Magendie

A

nerves as bundles, motor and sensory nerves in same bundle

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19
Q

bell (1811)

A

proposed that motor fibers come from cerebellum and sensory fibers GO TO cerebellum

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20
Q

flourens (1823)

A
  • used experimental ablation to show bell was correct

- though that all parts of the cerebrum contribute to all functions… WRONG

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21
Q

gall (1809)

A
  • phrenology

- brain divided into 35 regions (language, color, hope) shown to be WRONG

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22
Q

broca

A

believed that different functions localized to different areas

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23
Q

fritsch and hitzig

A

used dogs and frogs in 1870 to show specific region of the brain controlled movement

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24
Q

ferrier

A

1881 showed the same thing as fritsch and hitzig with monkeys; removal caused paralysis

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25
munk
showed that occipital lobe was required for vision
26
evolution of nervous system
1859 Darwin published ON THE ORIGIN OF SPECIES - nervous systems have evolved and were related - some animals are better at specific functions
27
squid and snail
- basic biology of neurons - synaptic transmission - plasticity
28
cats and primates
visual system
29
rats and mice
neuropharmacological and behavioral studies
30
alzheimer's disease
degeneration of cholinergic neurons, dementia, fatal
31
parkinson's disease
degeneration of dopaminergic neurons, loss of voluntary movement
32
depression
15 million experience, major cause of suicide
33
schizophrenia
2 million affected, severe psychotic illness. delusions, hallucinations, and bizarre behavior
34
stroke
loss of blood supply can lead to permanent loss of function
35
epilepsy
seizures due to disruption of normal brain electrical activity
36
multiple sclerosis
loss of nerve conduction
37
nervous system uses large amount of...
oxygen and glucose
38
neurons
- only 10-20% of cells | - 0.01-0.05 mm in diameter
39
microtome
small slices of neurons needed to study the brain
40
nissil stain
labels nuclei of ALL cells but also the nissil bodies (rough endoreticulum) of neurons *franz nissil in 1894
41
golgi stain
stains ALL parts of neurons but NOT all neurons | - only stains 5%
42
cajal
neurites not continuous, communicate by contact
43
is the nervous system an exception to the cell theory?
NO
44
soma
- cell body of a neuron - 20 um in size - the nucleus is 5-10 um
45
mitochondria
widespread throughout the cytoplasm, presynaptic region
46
neural membrane
- 5 nm thick - many proteins embedded in the membrane - protein composition varies from soma, axons, and dendrites
47
microtubules
- 20 um in diameter - polymer of tubulin - not static - associated with other proteins (MAPS) * tau found in paired helical filaments seen in alzheimer's - involved in axoplasmic transport
48
microfilaments
- 5 um in diameter - numerous in neurites - two thin strands of actin polymers - not static - closely associated with membrane - often seen at synaptic terminals - dendritic spines
49
neurofilaments
- 10 um in diameter - also called intermediate filaments - strong - maintains neuronal shape - form tangle in alzheimer's
50
axons
- unique to neurons - NO rough ER, few ribosomes - proteins in membrane differ from those in the soma - 1 mm to over a 1 m long - form branches or collaterals (some recurrent) - diameter varies from 1-25 um
51
speed of nerve impulse depends on..?
diameter, thicker = faster
52
axon hillock
- beginning of axon | - NO ribosomes or most organelles
53
terminal
- end of axon - NO microtubules - many synaptic vesicles - protein rich - many mitochondria
54
synapse
- two sides (pre and post) - many drugs and chemicals act here - malfunctions here are responsible for many mental disorders
55
synaptic cleft
in-between pre and post synapse sides, no direct contact
56
synaptic transmission
mediated by chemical neurotransmitters
57
wallerian degeneration
after axons cut, death distal to injury
58
axonal transport
- fast axoplasmic (1000 mm/day) | - slow axoplasmic (1-10 mm/day)
59
anterograde axonal transport
walked down microtubules by kinesin, uses ATP
60
retrograde axonal transport
dyeing used along microtubules | - fast 50-250 mm/day
61
dendrites
- come in different shapes and sizes - covered with thousands of synapses - some covered with spines; can change structure depending on type - polyribosomes often under spines - contain microtubules, fewer mictofilaments
62
dendritic tree
collection of all branches that extend from the soma
63
unipolar or pseudounipolar
single process with peripheral branch and central branch | - found in sensory ganglia
64
bipolar
found in sensory structures
65
multipolar
many dendrites, single axon
66
spiny dendrite
ALL pyramidal cells and some stellate cells
67
aspinous dendrite
some stellate cells
68
golgi type 1 neurons (projection)
- extend between brain regions - long axons - many pyramidal cells
69
golgi type 2 neurons (local circuit)
- connect to neurons in vicinity - short axons - stellate cells
70
glia
- most of the cells in the brain - supportive of neuronal function - support synapse formation - vasculature
71
astrocytes
- most numerous glia - between neurons - express neurotransmitter receptors - regulate contents of extracellular space - remove NTs from synaptic cleft - regulate extracellular ion levels - can divide - source of the majority of brain tumors
72
myelinating glia
- oligodendrocytes | - schwann cells
73
ependymal cells
line ventricles, direct cell migration during development
74
microglia
- remove debris (phagocytosis) - release cytokines - may be activated in response to stroke or brain trauma - may also be involved in pruning or refining circuits
75
protoplasmic astrocytes
in gray matter close to neurons, involved in blood-brain barrier and metabolism
76
fibrous astrocytes
repair damaged tissue, may form scars. found primarily in white matter
77
muller astrocytes
found in retina
78
oligodendroglia
found in brain and spinal cord; myelinate several axons
79
schwann cells
found in peripheral nervous system; myelinates single axons, every internode region by one of these
80
neural membrane at rest
- passive conduction of signal only works for short distance - need resting potential to generate action potential - varies between different types of neurons
81
action potential
conduct signal without loss of strength
82
excitable cells
- can generate action potentials (nerve impulse) | - at rest have a resting membrane potential (inside negative compared to outside)
83
how do cells generate a charge difference across the membrane
voltage gated channels
84
what do you need to generate the resting potential?
- cytosol - plasma membrane - membrane proteins
85
cytosol and extracellular fluid
water is the major component | - polar molecules dissolve in water bc its polar
86
ions in the cytosol and extracellular fluid
- major charge carrier - surrounded by clouds of water called spheres of hydration - Ca2+, K+, Na+, and Cl- are important for neurophysiology
87
hydrophilic
ions and polar molecules
88
hydrophobic
molecules with non polar covalent bonds (oils, lipids)
89
phospholipid membrane
- barrier to water and ions, allows membrane potentials to form - in the bilayer, hydrophilic head towards water while hydrophobic tail inside towards membrane
90
amino acids
- 20, properties determined by R group | - chains of these are held together by peptide bonds
91
ion channels
- have both hydrophobic and hydrophilic regions - selective - can be controlled
92
pumps
transport ions across membranes against concentration gradients using ATP as the energy source
93
diffusion
random movement from region of high concentration to one of low (concentration gradient) temperature dependent=must have a path through the lipid bilayer (a channel)
94
electrical current (I)
movement of charge; positive in the direction of positive charge movement
95
how much current flows depends on...
- electrical potential (voltage, V) | - electrical conductance
96
voltage
the measure of the difference in charge between anode and cathode. more difference=more current
97
conductance (g, siemens)
relative ability for a charge to move from one place to another, depends on the number of particles available to carry the charge and how easily these can travel
98
resistance (R, ohms)
the relative inability of an electric charge to migrate R=1/g
99
ohm's law
I=gV
100
membrane potential (Vm)
- voltage across a membrane - typical = -65 Mv - inside of cell is MORE negative relative to outside
101
equilibrium state
occurs when diffusional and electrical forces are equal and opposite
102
ionic equilibrium potential
the potential difference that balances the ionic concentration gradient *voltage that balances diffusion*
103
large changes in membrane potential are produced by..
tiny changes in ionic concentration (0.00001mM)
104
net difference
occurs at the inside and outside surfaces of the membrane (5nm thick), the membrane acts like a capacitor (stores charge)
105
rules for generating a electrical potential difference
ions move across the membrane at a rate proportional to the difference between the membrane potential and the equilibrium potential (Vm-Eion). for each different ion is the ionic driving force, move in the direction that moves the cell toward the Eion
106
nernst equation
- ions have their own equilibrium potential - charge and concentration difference determines whether inside of cell is positive or negative at equilibrium for each ion
107
what is the equilibrium potential of potassium, K+?
-80 mV
108
what is the equilibrium potential of sodium, Na+?
+62 mV
109
what is the equilibrium potential of calcium, Ca2+?
+123 mV
110
what is the equilibrium potential of chloride, Cl-?
-65 mV
111
ion pumps
work against the concentration gradient
112
sodium-potassium pump
uses ATP for energy source, exchanges internal Na+ for external K+, used 70% of brain ATP
113
calcium pump
transfers Ca2+ out of the cell, other proteins and channels help as well
114
goldman equation
relative permeability to multiple ions can be factored in | *if cell 40x more permeable to K+ than Na+, then Vm= -65mV
115
K+ channels
- key to determining a neurons resting Vm - first cloned in fruit fly - mutations here lead to severe neurological problems or death
116
external K+ must be carefully regulated
- membrane potential close to K+ due to high permeability of the cell - changing K+ outside can change membrane potential - can cause cell to depolarize - blood-brain barrier - death by lethal injection
117
hodgkin and katz (1949)
used manipulation of the external K+ concentration to show that resting potential is mostly set by K+ permeability of neuron
118
other names of action potential
spike, discharge, or nerve impulse
119
stages of action potentials
- resting - rising - overshoot - falling - undershoot
120
generator potential produced by...
entry of positive charge into cell
121
properties of action potentials
- all or none mechanism | - firing frequency can reflect size of inout current
122
absolute refractory period
- Na+ channels inactived, can't be deinactivated until Vm is more negative - maximum rate 1000Hz, 1 msec
123
relative refractory period
- Vm hyperpolarized until K+ channels close | - more current required to fire action potential
124
what controls the firing frequency of action potential?
amount of depolarization | *more stimulation=more firing
125
hodgkin and huxley
- used voltage clamp to determine ionic permeability changes during the AP - early inward current is carried by Na+ - late outward current carried by K+ - membrane voltage changes are time and voltage dependent
126
action potential theory
- depolarization caused by influx of Na+ ions - depolarization by efflux of K+ ions - rising phase due to inward Na+ current - falling phase due to outward K+ current I=g(Vm-Eion)
127
change in Na+ channel
-65mV closed to -40mV opened
128
voltage-gated sodium channels
- open and closed by changes in membrane potential Vm - one long protein - 4 domains of 6 transmembrane helixes - association with water important for selectivity - segment S4 contains voltage sensor
129
tetrodotoxin (TTX)
from puffer fish, blocks channel
130
saxitoxin
from dinoflagellate, occurs in clams, shellfish, mussels
131
bactrachotoxin
from frog, channels open at more negative voltages and stay open too long
132
scorpion and sea anemone toxins affect...
channel inactivation
133
voltage-gated K+ channels
- falling phase of AP also due to opening of K+ channels, NOT just Na+ - delayed opening after depolarization - delayed rectifier channels
134
threshold of AP
voltage at which Na+ channels open, more permeable to Na
135
rising phase of AP
Na+ ions enter cell due to large driving force
136
overshoot of AP
voltage approaches equilibrium of Na+, greater than 0mV
137
falling phase
Na+ channels inactive, K+ channels open, large driving force for K+ to leave the cell
138
undershoot
voltage moves toward equilibrium of K+. hyperpolarizing the cell, little permeability to Na+
139
gradients maintained by...
Na-K pump
140
action potential conduction
- moves down axon in ONE direction - can be started at either end - 10 m/s, lasts 2 msec
141
orthodromic
AP starting from cell body
142
antidromic
backward AP
143
synapses (person)
sherrington 1897
144
electrical synapses
furshpan and potter 1959
145
chemical synapses
loewi and vagusstoff 1921
146
katz
motor neuron to muscle
147
eccles
central nervous system
148
bidirectional synapse
cells are electronically coupled, fast | - common in mammalian CNS, glia, cardiac muscle cells, smooth muscle, epithelial cells, liver cells
149
is the synaptic cleft empty?
NO but it contains extracellular matrix proteins
150
postsynaptic density
receptors and associated proteins
151
chemical synapses
presynaptic and possynaptic with a 20-50 nm cleft
152
CNS synapses
- various sizes and configurations | - axodendtritic, axosomatic, axoaxonic, dendrodentritic
153
gray's type 1
asymmetrical membrane thickness at synapse, usually excitatory
154
gray's type 2
symmetrical, usually inhibitory
155
neuromuscular junction (NMJ)
- between motor neurons and muscle - similar to CNS synapses - easier to study than CNS synapses - fast, large, reliable synapses
156
principles of synaptic transmission
- neurotransmitter synthesis - load NT into synaptic vesicles - vesicles fuse to presynaptic terminal - binds to postsynaptic receptors - biochemical/electrical response elicited in postsynaptic cell - removal of NT from synaptic cleft
157
neurotransmitter synthesis and storage
- various transmitters have distinct synthetic pathways - in all cells (amino acids) - specific enzymes in neurons which synthesize unique transmitter - some neurons make multiple NTs
158
neurotransmitter release
- opening of voltage gated Ca2+ channels, large influx of Ca2+ - exocytosis, occurs rapidly, fusion of synaptic vesicle with membrane of active zone - some vesicles may be already docked - vesicle membrane recycled by endocytosis, multiple ways for this - peptides not released at active zone, slower time course, generally respond to higher Ca
159
neurotransmitter receptors
- 100 different ones - gated or ligand-gated - g-protein coupled - nAChRs
160
transmitter-gated channels
- pore usually closed until ligand binds - 4-5 subunits, change conformation after ligand binds, channel opens within microseconds - not as selective as voltage-gated channels - ACh gates Na, K, Ca, excitatory, EPSPs - Cl gated, IPSP, glycine, GABA
161
G-protein coupled receptors
- slower acting - amino acids, amines, peptides - also called metabotropic receptors - autoreceptors are often linked to this
162
neurotransmitter reuptake and degradation
- NT must be destroyed or removed from synaptic cleft to terminate signaling - diffusion - desensitization
163
reuptake is done by..
specific transporters
164
degradation is done by..
enzymes, blockade can result in death
165
neuropharmacology
many chemicals, diseases, and drugs can affect each of these steps
166
curare, cobra venom are...
antagonists
167
nicotine is an....
agonist
168
botulinum toxin
blocks transmitter release
169
black window venom
increases ACh release
170
synaptic integration
process in which these multiple inputs combine within one neuron, output then determined
171
integration of EPSPs
- thousands of channels - number that opens depend of quantity of NT released - amplitude is multiple of mini-amplitude
172
quantum
number of transmitter molecules in a vesicle (several thousand)
173
quantal analysis of EPSPs
- compare miniature and evoked potentials to decide how much NT is released - at NMJ 200 vesicles, -40mV needs to work every time
174
dendritic cable properties
- electrically passive calls - currents will dissipate over a distance Vx=Vo /e^(x/), e=2.718 V=0.37 (Vo)
175
lamda
- length constant, where depolarization is 37% of original current - gives some idea how far away from axon hillock depolarization can occur and still get AP
176
what does lambda depend on?
internal resistance and membrane resistance
177
internal resistance depends on
diameter and electrical properties of cytoplasm (constant in mature neuron)
178
membrane resistance
depends on synaptic activity and how many ion channels open