Unit 1 Flashcards
(142 cards)
1
Q
ventricles
A
where cerebral spinal fluid moves through brain
2
Q
grey matter
A
cortex
neural cell bodies and dendrites
nonmyelinated
processing and cognition
3
Q
white matter
A
glial cells and myelinated axons
transmits signals
action potentials
4
Q
gyri
A
ridge in brain
hump surrounded by sulci
5
Q
sulci
A
divit in brain
6
Q
fissure
A
groove of natural division
7
Q
phrenology
A
ancient myth of bumps on skull indicating larger portion of brain- more specialized in that area
“map” on skull
8
Q
neurons
A
conduct signals
10% of brain cells
9
Q
glia cells
A
help neurons- hold things together
responsible for ion balances
90% of brain cells
10
Q
experimental ablation method
A
make lesion on brain then study behavior
11
Q
aphasia
A
inability to speak
12
Q
broca’s aphasia
A
can understand, but not fluent
hard to GENERATE words
effect of stroke- frontal lobe, left hemisphere
13
Q
Wernicke’s aphasia
A
fluent, but don’t make sense
cant CONTROL speech
effect of stroke- left temporal lobe
14
Q
object agnosia
A
cannot name an object
15
Q
distinguishing parts of brain
A
anatomy- architecture/connection
function- recordings/behavior
16
Q
fMRI
A
visualize what parts of brain active during certain tasks
17
Q
somatosensation
A
perception based on senses
mice whiskers- more touch brain
bats audiology- more audio brain
18
Q
why be kind when animal experimenting
A
stress changes brain chemistry
data inaccurate
19
Q
similarities between mammal brains
A
structure- hemispheres, cortex, cerebellum
20
Q
differences between mammal brains
A
size
gyrification
size of localized regions
-Ex: mice have larger portion devoted to touch (whiskers)
21
Q
cortex
A
outermost covering of brain
memory, perception, attention, awareness, thought, language, consciousness
22
Q
cerebellum
A
back of brain
motor control, coordination, precision, timing
23
Q
Ramon y Cajal
A
visual system pathway
retinal connections
shape and position of a neuron
origin and destinations in neural network
24
Q
photoreceptors
A
cells in retina responding to photons (light)
rods and cones
25
ganglion cells
provide entire input for vision
| influenced by many photoreceptors
26
visual pathway
photoreceptors -> bipolar cells -> ganglion cells
| ganglion axons make optic nerve
27
cell body (soma)
nucleus and other intracellular organelles
28
axon
connects cell body to target cells
| typically small and hard to see
29
dendrite
branches upon which incoming fibers make connection
| receiving stations for excitation or inhibition
30
resting potential
inside of cell is negative relative to outside
| -65 mV
31
depolarize
make inside cell less negative
32
hyperpolarize
make inside cell more negative
33
graded potential
generated by extrinsic physical stimuli
short spread b/c passive
**decrease in amplitude as travel toward cell body
34
action potential (nerve impulse)
graded potentials are large enough to reach threshold and depolarize the cell
propagate rapidly over long distances
all or nothing response
**fixed in amplitude and duration
35
extracellular recordings
put electrode near neurons
signals sent by neurons can be heard
detecting current as neuron delivers output
lots of spikes (represent AP)
36
intracellular recording
capillary into neuron membrane
clear waveforms
single spike for AP
37
whole cell patch recording
rupture membrane to record inside cell
| clearest technique
38
receptor field
region of sensory neuron where presence of stimuli will alter firing of that neuron
larger field = more area to detect, but less precision
39
all or nothing response
once initiate, AP amplitude and duration are fixed
40
refractory period
after AP is fired
| second impulse at same site cannot be competed until first is completed
41
Action potential path
resting potential -> stimulus causes cell to depolarize (reach threshold) -> AP initiated -> Na rush into cell (inside + now) and K out -> AP propagates along axon to terminal -> transmitter released -> refractory period to repolarize
42
frequency
indicates intensity of stimulus
limited by refractory period
more effective stimulus -> higher frequency
all AP are the same size, so frequency tells intensity
43
synapse
structure at which one cell hands its information to the next
44
synaptic cleft
between pre and post synaptic terminals
contains extracellular fluid
cannot be transversed simply by currents generated in sensory receptor
45
Synaptic cleft mechanism
1. ) photoreceptor terminal releases neurotransmitter from presynaptic vesicles
2. ) transmitter diffuses across cleft and interacts with chemical receptor (protein) embedded in membrane of post-synaptic cell
3. ) local graded potential spreads to terminals
46
more neurotransmitter released
higher concentration in cleft
larger # activated receptors
larger local potential
47
excitatory signal
if enough to cause depolarization AP is fired
48
inhibitory signal
suppresses release of neurotransmitter
49
electrical synapses
pre and post synaptic membranes are linked by channels that connect intracellular fluids of the two cells and allows electrical potentials to spread directly rom cell to cell w/o a chemical transmitter
50
integration
neurons take account of influences arriving from diverse inputs to create own new messages with new meaning
51
Hubel and Wiesel
showed that cortical neurons do not respond simply to light or dark on retina; rather, activation depends on pattern of retinal illuminations
52
retinal illuminations
specific and distinctive patterns are required and most effective stimuli for different types of cortical cells
Ex: one cell may only fire if detects horizontal light
53
generation of complex stimulus
progressive integration of information derived from lower order units results in higher order central neurons
54
transformation of visual information (increasing complexity)
1. ) photoreceptor indicates a change in light
2. ) signal in ganglion indicates presence of contrast
3. ) signal in cortical neuron indicates orientation
55
columnar arrangement
as you go through the cortical layers (6 of them) processing of a stimuli remains the same
56
axon hillock
connects cell body to axon
where impulse originates from
if reaches threshold fires AP down axon
57
charge location relative to membrane
charges congregate around membrane
- inside
+ outside
58
phospholipid layer and membrane potential
thin so negative charges line inside and positive line the outside
59
ion channel
protein molecules that span the membrane and form pores through which ions can pass
60
passive diffusion
ions (K, NA, Ca, Cl) driven through channels by concentration gradients and by electrical potential
61
transport molecules
- pumps and transporters
- move substances across membrane AGAINST electrochemical gradients
- return ions back to proper side of membrane
- carry glucose and amino acids across
62
ion channel gate
opens and closes to control ion movement through channel
63
what causes gate opening
- membrane potential
| - binding of ligand
64
concentration gradient
ions move in or out of the cell based on trying to achieve equal concentrations inside and outside of the cell
65
how is the resting membrane potential maintained
ion pumps- sodium potassium pump
66
cytosol of cell in resting membrane
sodium concentration low; potassium concentration high
67
Na+/K+ pump mechanism
1. ) 3 Na+ ions on cytosolic side bind to pump
2. ) ATP transfers phosphate group to pump (need energy to move Na+ against gradient)
3. ) phosphorylation causes change in pump conformation
4. ) Na+ ions released outside cell
5. ) pump facing outside cell exposes K+ binding sites
6. ) 2 K+ bind to pump
7. ) phosphate group released
8. ) pump return to original conformation
9. ) K+ released inside cell and cycle repeats
68
inhibition
- big role in generating rhythmic output
- GABA, glycine, and Cl- channel common
- Ex: rhythm of walking inhibiting one leg, while stepping with other
69
diffusion
- must have a channel and gradient
- each ION has OWN channel
- once reach equilibrium, no net diffusion
70
Protein channels
- highly specific
- composed of 4-5 subunits
- open or closed conformation
71
subunits
- strings of amino acids held together in specific structure
- determine what channel is capable of
- often change morphology w/ ligand binding
72
subunit amino acid residue in membrane
- must be nonpolar
| - don't want to react w/ water, so stuck in place
73
what causes channels to open
1. ) ligands
2. ) change in membrane voltage
3. ) physical deformation
74
transmitter gated ion channel
- respond to ligand binding
- ligands can bind inside or outside
- often cause change in subunit conformation
- ACh, serotonin, glutamate, etc
75
voltage gated channels
- change membrane voltage
| - Ex: sodium potassium pump
76
mechanoreceptors
- responsible for channel opening in response to physical deformation
- Ex: wriggling of hair cells in ears cause channel to open (sound and position of head)
77
current
movement of charge accomplished by neurons
78
conductance
- ability to migrate (high conductance -> low resistivity)
| - ability of channel to pass current
79
Ohm's law
I = gV
* I- current
* g- conductance
* V- potential
80
patch clamp technique
suction and isolate membrane channel; then put in dish with ions and measure current w/ electrode (ideal for single-channel current detection)
81
How to only get recording for channel of interest during patch
-have to induce blockage of other channels with poison b/c patch often result in sucking multiple channels
82
tetrodotoxin (TTX)
- from puffer fish
- selectively blocks Na+ channels (occludes pore)
- would allow for recording of K+ channels only
83
kinetic behavior channel
duration of closed and open states
84
driving force
- difference between the membrane potential and the equilibrium potential
- higher driving force -> more push
85
two factors influencing conductance
1. ) membrane permeability
| 2. ) concentration of ions in the region of the channel
86
channel permeability
ease at which ions can pass through the open channel
87
open channel
permeability
88
permeability + ions
conductance
89
reverse potential for K+ currents
- if cell receives applied negative voltage, the potential outward movement K+ is reduced
- completely retarded if voltage more negative than -80 mV
90
K+ currents w/ positive applied voltage
if the cell receives applied positive voltage, the potential gradient accelerates the K+ out of the cell (increasing current amp)
91
equilibrium potential
- where concentration and electrical gradients are balanced (at equilibrium)
- electrical gradient balances tendency for concentration gradient to drive ions into or out of cell
- driving force is 0
- ions diffuse in or out of cell until reach
92
equilibrium potential K+
- 80 mV
* channel opening hyperpolarizes resting cell
* flow outward to make more negative
93
equilibrium potential Na+
62 mV
* channel opening depolarizes cell
* flow in to make more positive
94
equilibrium potential Cl-
- 67.5 mV
* channel opening hyperpolarizes cell (inhibits)
* flow inward to make more negative
95
equilibrium potential Ca2+
123 mV
* channel opening depolarizes cell
* flow inward to make more positive
96
Nernst Equation bottom line
1. ) Ions diffuse DOWN concentration gradient trying to reach equilibrium potential
2. ) passive process
3. ) applies to single ion species at a time
4. ) point of equilibrium between diffusion and electrical forces for ion
97
valence for ion species (Z)
- K+ = 1
| - Ca2+ = 2
98
Cl- channel opening
- resting membrane potential is -65 mV
- Cl- equilib potential is -67.5 mV
- Cl- diffuses into the cell to make it more negative (hyperpolarize)
- inhibits
99
nicotinic acetylcholine receptor (nAChR)
- ligand activated channel
- activated by ACh release from presynaptic nerve terminals
- when activated, open to form channels through which cations can enter or leave post-syntaptic cell
100
mutations in receptor protein
- some affected ligand binding -> channel inactivation
- some affected ion selectivity
- some affected channel conductance
101
Proof that M2 helices line open channel pore
- mutations affecting selectivity and conductance were located on M2 helices (line inside of pore)
- replacing serines with alanines reduced channel conductance and binding affinity
102
hydrophilic amino acids
- serines and threonines
| - exposed to aqueous pore
103
hydrophobic isoleucines
- alanines
| - nestled against membrane lipid
104
electron microscopy
reveals general shape and orientation of receptor in membrane
105
polar substituents within pore
higher channel conductance
106
increasing side chain volume in pore
decrease conductance
107
pore differences in charge selectivity (anions vs. cations)
- related to sign of charged residues along ion pathway
| - mutations can chance ion selectivity
108
voltage-activated channels
- activated by cell membrane depolarization or repolarization
- Na+, K+, and Ca2+ channels
109
selectivity filter
- four inner channel links combine to form restricted passe responsible for ion selectivity of voltage-activated channels
- filter formed at extracellular opening
110
selectivity for potassium
- achieved by size and molecular composition of selectivity filter
- pore diameter accomidates dehydrated potassium
- ions that are too small can't be dehydrated
- ions that are too large don't fit
111
why Na+ cannot pass through K+ channel
- in order for K+ to pass it must be dehydrated, which is achieved by exposed oxygen atoms
- Na+ is too small for its hydration shell to make contact with the 4 oxygen atoms simultaneously, so it cannot be dehydrated
112
how to increase pore conductance
-replace neutral amino acid residues with those that are opposite in charge of the desired ion to pass
113
voltage-activated gating
occurs when depolarization causes displacement of charges of the pore helices, resulting in conformation changes and opening of conducting pathway from channel pore to cytoplasm
114
inactivate
- many voltage-sensitive channels inactivate following activation
- cytoplasmic residues move to mouth of pore, blocking channel access
115
how can you change the AP of a living cell
-make the amp higher by adding Na+ to extracellular environment
116
why need electrolytes during exercise
-have to replenish Na+ levels, so AP can continue to be fired
117
Botox
- degrades SNARE protein, which prevents ACh release at neuromuscluar junction
- prevents presynaptic membrane vesicles from fusing with postsynaptic membrane
118
neuromuscular junction reliability
1. ) large synapse
2. ) located peripherally
3. ) lots of synaptic vesicles full of ACh
4. ) lots of surface area
119
organophosphates and sarin
nerve gases that disrupt AChE at neuromuscular junctions
120
neuropharmacology
-method of studying receptors by observing how ligand binding impacts receptor
121
antagonist
works against the receptor
122
agonist
natural ligand for the receptor
123
ionotropic receptor
- receptor with an ion channel attached
| * nicotinic and glutamate receptors
124
2 types of cholinergic (ACh) receptors
1. ) nicotinic
| 2. ) muscarinic
125
nicotinic receptor
- transmitter gated ion channel
- ionotropic receptor
- nicotine is agonist
- curare is antagonist
126
metabotropic receptor
- G protein coupled receptor
- binding of ligand releases G protein, which stimulates other proteins down the line (may or may not be channels)
* muscarinic receptor
127
muscarinic receptor
- muscarine- agonist
- altropine- antagonist
- does not contain a channel- metabotropic receptor
128
temporal summation
- neuron receives increased frequency of impulse from a single location (multiple inputs from same presynaptic cell)
- results in greater stimulation than single input
129
spatial summation
-neuron receives inputs from multiple presynaptic cells, resulting in greater AP
130
membrane resistance
- walls of a hose
- increase membrane resistance -> increase conductance b/c harder for charge to escape
- Achieved through myelination (reduces capacitance)
131
internal resistance
- resistance in the direction of flow
| - increase internal resistance -> decrease AP conductance
132
3 criteria for a cell to remain stable
1. ) intracellular and extracellular must be electrically neutral- charges balanced
2. ) cell must be osmotically balanced
3. ) no net movement of any ion into/out of cell
133
model cell
- impermeable to Na+ and internal anions
- permeable to K+ and Cl-
- Na+ and Cl- in highest [ ] outside
- K+ and anion highest [ ] inside
* membrane permeable to K+ and Cl-
134
membrane as a capacitor
- as K+ ions diffuse out of the cell, the anions line up along the inner edge of the membrane and are attracted to the K+ ions extracellularly
- the membrane acts as a capacitor between the mutual attraction, separating and storing charge
135
mechanism for ACh receptor channel
- when channel is closed (gated), pore is occluded by ring of M2 helices
- channel activation (2 ACh binding) -> M2 helices swing outward and open pore
136
Equilibrium potential elaborated
Potential at which there is no net flux of a particular ion into or out of the cell
RMP is closest to equilibrium potential of K+, so k+ conductance dominates
During AP, K+ overwhelmed by Na+, so Na+ dominates and membrane potential brought to Na+ equilibrium potential
137
maintaining neutrality of internal and external environments
- charges from Cl- cancel out charges from Na+ extracellularly
- Charges from anions cancel out charges from K+ intracellularly
- If K+ flows out, form as cations on outer edge, attracting the counteranions to membrane and keeping center of cell neutral
138
why doesn't messing w/ Cl- change RMP much
- when intracellular leaves, lose same amount of K+
| - since tons of K+ in cell, losing some doesn't do much to cell
139
Main points of resting membrane potential
1. ) large changes in membrane potential can be due to minuscule concentration changes in ions
2. ) RMP isn't changed much by manipulating Cl-
3. ) Differences in charge is at the membrane itself
4. ) membrane capacitance- takes time for charge to build up
140
Messing with extracellular Na+
-doesn't make changes like K+ would b/c membrane isn't permeable to Na+ like it is K+
141
Goldman-Hodgkin-Katz
* take natural log of permeability of concentration out over concentration in gives RMP
- tells RMP for a given CELL
142
saltatory conduction
- propagation of AP along myelinated axons from one node of Ranvier to the next
- increases velocity of AP w/o having to increase diameter
