Neurobiology 1 Flashcards
(120 cards)
1
Q
folds
A
gyri
2
Q
valleys
A
sulci
3
Q
how many neurons do humans have
A
86 billion
4
Q
superior
inferior
A
cranial/cephalic — towards head
— towards toes
5
Q
distal
proximal
A
furthest and closest from attachment
6
Q
medial
lateral
A
closest and furthest from midline
7
Q
anterior
posterior
A
ventral — front side
dorsal — back side
8
Q
ipsilateral
contralateral
A
ipsi: same side
contra: different side
9
Q
sections:
midsagittal
horizontal
coronal
A
midsagittal: cutting between eyes
horizontal: decapitate
coronal: cut both ears
10
Q
what does CNS consist of
A
brain & spinal cord
11
Q
what is CNS surrounded by
A
bone, meninges, and cerebrospinal fluid (CSF)
12
Q
meninges
- Dura mater
- Arachnoid
- Pia mater
A
Dura mater: tough outer membrane
Arachnoid: where CSF flows (web)
Pia mater: thin membrane on brain surface
13
Q
CSF produced in…
A
choroid plexus in cerebral ventricles
- moves by cilia
14
Q
functions of CSF
A
shock absorber
volume adjuster
provides nutrients (glucose)
removes wastes back to blood
15
Q
3 major brain components
A
cerebrum
cerebellum
brain stem
16
Q
BRAIN white/gray matter set up
A
white: INSIDE - myelin sheath
gray: OUTSIDE - cell bodies, somata, dendrites, synapses; where neurons talk to each other
17
Q
lobes of cortex
A
frontal, parietal, temporal, occipital
18
Q
Brodmann’s areas
A
cytoarchitectonic subdivisions of cortex
- 52 areas
- histologically different
19
Q
CEREBELLUM
A
- mini bulging brain
- arbor vitae / tree of life
- 100 billion neurons (more than cortex)
- 7 cell types
- – purkinje = output cell
- – motor coordination
20
Q
BRAIN STEM
A
- “primitive brain”
- maintains life functions
21
Q
thalamus f’n
A
filters signals
22
Q
midbrain f’n
A
superior colliculus/ inferior colliculus
– eye movements and attention
23
Q
pons
A
motor switchboard
24
Q
medulla oblongata
A
homeostasis; sensory switchboard
25
what does PNS consist of
cranial nerves + spinal nerves
26
_ cranial nerves
12
27
how many spinal nerves leave vertebral column through intervertebral foramina
31
28
SPINAL CORD white/gray matter set up
| horns
white OUTSIDE
gray INSIDE
- dorsal horn
- intermediate zone
- ventral horn
29
afferent VS efferent neurons
...carry nerve impulses...
afferent [sensory neurons] sensory stimuli to CNS and brain
-- in DORSAL horn
efferent [motor neurons] CNS to muscles to cause movement
-- in VENTRAL horn
30
flowchart of efferent neurons
efferent
1. somatic
2. autonomic
a. sympathetic (thoracolumbar) "fight or flight"
b. parasympathetic (craniosacral) "rest and digest"
31
cutting the dorsal roots along the spinal cord would ...
stop sensory reflexes from the arms
32
basic parts of neuron
soma/cell body
dendrites ---
axon --- NEURITES
33
SOMA
contains nucleus and "cellular machinery"
34
AXON HILLOCK
spike initiation zone, trigger zone
35
cytoskeleton elements are essential for axonal transport:
microtubule
neurofilament
microfilament -- made up of ACTIN: deals w/ movement
36
retrograde VS anterograde
TOWARDS: retrograde (diamine)
AWAY: anterograde/orthograde (kinesin)
37
in between myelin sheath
nodes of ranvier
38
saltatory conduction
"jumping" from node to node
39
signals during synapses
```
electrical --> chemical --> electrical
--
PRESYNAPTIC AXON TERMINAL
* synapse *
POSTSYNAPTIC DENDRITE
```
40
what do neurotransmitters do
travel in synaptic vesicles across synaptic cleft until reaching receptor site, where they bind
41
Boutons/varicosities
bulges on presynaptic cells @ synapse site
42
dendritic spines
structures for synaptic inputs
-- polyribosomes at the base of a dendritic spine indicate local site for protein synthesis
-- storage site for synaptic strength and help transmit electrical signals to the neuron's cell body
43
types of neurons:
unipolar
bipolar
multipolar
unipolar: one structure extending from soma
bi: one axon and one dendrite extending from the soma
multi: many dendrites
44
interneurons
neurons in CNS
45
stellate interneurons
| pyramidal interneurons
stellate - local; small axons that only talk to neighbors
| pyramidal - project further
46
```
glial cells
astrocytes
microglia
oligodendrocytes
schwann
```
GLIAL: support CNS
ASTRO: makes connections
MICROGLIA: cleans up debris & dead neurons; macrophages
OLIGO: wraps myelin sheath; grabs many sheaths -- CNS
SHWANN: many schwann, one axon -- PNS
47
voltage of cell (pos/neg) should be...
negative inside
| positive outside
48
cell barrier: phospholipid bilayer
fatty later; ions can't get through - only through CHANNELS
- polar "head"
- nonpolar "tail"
49
how is electrical current carried against membrane
through ion-specific channels
- current flow
- positive attracts negative & vice versa
50
what makes ions move across the plasma membrane
- voltage
| - concentration gradient
51
what would make the sodium equilibrium potential more positive?
increasing external sodium concentration
52
The membrane is much more permeable to __
K+
53
resting potential mV:
-70 mV
54
if the membrane potential becomes more positive than it is at the resting potential, it is __
depolarized
55
if the membrane potential becomes more negative than it is at the resting potential, it is __
hyperpolarized
56
when potassium channels in the membrane open, what happens to K+?
K+ begins to move down its concentration gradient and out of cell
- cell's interior loses a positive charge
- inside of cell becomes negative relative to outside
57
Na+/K+ pump
3 Na in
| 2 K out
58
resting potential is a __
steady state
59
what happens if permeability of membrane to potassium increased?
membrane would hyperpolarize
| - pulls down harder
60
what would happen if you remove Na+ from outside?
smaller concetration gradient
| - equilibrium of Na lowers
61
Higher K+ in some parts of nervous system bc ...
of action potentials!
62
phases of action potential
1. resting potential
2. depolarization: RISING PHASE
3. overshoot
4. repolarization: FALLING PHASE
5. hyperpolarization
63
all or nothing:
once it passes threshold, it can't stop
64
non-decrementing
all same size, don't decrease
| don't deteriorate over time
65
what causes depolarization
- excitatory synaptic input
- sensory signal
- incoming spike
66
protein channels characteristics
```
very selective (Na and K selective)
open or close by voltage (K: 1, Na: 2)
```
67
K+ info:
- only opens with POSITIVE VOLTAGE
opens with depolarization
opens slowly and closes slowly
68
Na+ info:
```
has activation gate
- opens with depolarization
- opens quickly
and inactivation gate
- closes with depolarization
- closes slowly
```
69
channels during phases:
AT REST: Na+ and K+ channels closed
RISING: Na+ channels open, K+ still closed
FALLING: Na+ inactive, K+ opening
UNDERSHOOT: Na+ channels still inactivated, K+ still open (hyperpolarizing)
70
what causes sodium inactivation gate to close?
depolarization of neuron
71
what's responsible for relative refractory period?
sodium inactivation
open potassium channels
after hyperpolarization
72
refractory periods
ABSOLUTE: repolarization
RELATIVE: hyperpol and after
73
Chloride is pumped...
in
74
K+ kinetics vs Na+
Na+ much faster
75
what if K+ channel kinetics were as fast as Na+
spikes wouldn't happen - would cancel out
76
multiple sclerosis
demyelination disease
77
what would happen if voltage-sensitive K+ channels were blocked?
spike would last longer (still go back to resting potential)
78
What is gray matter and why is it gray?
Collection of cell bodies in CNS
| No myelin
79
Where does CSF originate and what makes it move?
Choroid plexus in cerebral ventricles
| - Moves by cilia
80
On what basis did Brodmann create his system of numbered areas in the cerebral cortex?
Based on cellular structure - CYTOARCHITECTURE
| Different layers in brain
81
List 4 major components of the mammalian CNS
brain stem, cerebrum, spinal cord, cerebellum
82
Compare the location of gray matter in cerebral hemispheres with its location in spinal cord. What are the major divisions of gray matter in the spinal cord called?
Gray matter is on the inside in spinal cord; outside in cerebral hemispheres
- Dorsal horn
- Intermediate zone
- Ventral horn
83
Describe a major function of cerebellum, thalamus, pons, superior colliculus
Cerebellum: motor coordination
Thalamus: filters sensory signals
Pons: motor activity
Superior colliculus: eye movements and attention
84
Where is the cell body of a motor neuron that projects to the biceps muscle of the arm? Where is the cell body of a sensory afferent from the fingertip?
```
Motor neuron (efferent): Ventral ganglia of gray matter
Sensory neuron (afferent): Dorsal ganglia of the spinal cord
```
85
Where do preganglionic axons of the sympathetic nervous system terminate? Where do preganglionic axons of the parasympathetic nervous system terminate?
Sympathetic: terminate in sympathetic chain
Parasymp: terminate in organs
86
What surgical operation could be performed to determine whether a motor act (such as walking) requires sensory feedback?
Cutting the dorsal roots along the spinal cord
87
Specifically, where do we find myelin? What is the function of myelin? What are 2 types of glia that produce myelin?
Myelination pushes current forward
- Oligodendrocytes produce myelin in the central nervous system
- Schwann cells produce it in the Peripheral nervous system
88
What is the significance of finding polyribosomes at the base of a dendritic spine?
they produce proteins - to move/grow
89
What’s the most important difference between a pyramidal cell and a stellate cell? Which of the two always use action potentials?
Stellate cells are local interneurons; star-shaped; short axons
Pyramidal cells are projection interneurons; longer axon- use action potentials
90
equilibrium potential
vs
steady state
EP: lowest energy state
SS: requires energy
*concentrations not changing in both*
91
equilibrium mV's of K+ and Na+
K+: -86 ~
| Na+: 58 ~
92
Driving force def'n
&
of Na+ and K+
how far ion is out of equilibrium (difference of Voltage -- Equilibrium)
K+: -20
Na+: 120 mV
93
List one function for each of the following glial cell types: astrocytes, microglia, oligodendrocytes.
Astrocytes: make connections
Microglia: clean up crew (debris and dead neurons)
Oligodendrocytes: wrap myelin sheath around axons in the central nervous system
94
What are two forces that can drive ions through a channel across the plasma membrane?
voltage
| Concentration gradient
95
What happens to the resting potential in the presence of ouabain (a Na/K pump blocker)? What 2 important conclusions can be drawn from the result of that experiment?
Ouabain blocks the pump, and brings it all close to 0
Important conclusions: Resting Potential depends on Na/K pump (no pump, no resting potential) & only Na and K are important
-PROOF ITS A STEADY STATE
96
What is the difference between a steady state and an equilibrium? Is the resting potential a steady state or an equilibrium potential? At rest, what is the ratio of sodium leakage to potassium leakage?
- A steady state is an unchanging condition that requires more energy to run the pump continuously
- An equilibrium is lowest energy state
- RP: steady state
- 3 Na+ in:2 K+ out
97
What would happen to the resting potential if sodium permeability were higher than potassium permeability? Please explain.
If Na's permeability were higher than K, resting potential would be less polar (DEPOLARIZES) (would win the tug-of-war) - WINNER: MORE PERMEABILITY
Because more sodium comes in -- more positive inside
98
At rest, which ion, Na+ or K+, has a greater driving force acting on it? What two changes in concentration could you make to decrease the driving force on Na+?
Na+ DV: 123 mV
- decrease the driving force:
- -- Increase K+ outside
99
What would the approximate resting potential be in the presence of a drug that blocked membrane permeability to every ion except sodium?
- Would be more positive (58 mV)
| - Only sodium can flow in → would flow in until it’s at its equilibrium
100
Why is important to stabilize external potassium concentration in the brain? What cells are known to perform that function in the brain?
- Important because: it affects the resting potential (dominated by potassium equilibrium)
- Astroglia cells stabilize
101
What does it mean to say that spikes are “all or none”? What does it mean to say that spikes are non-decrementing?
- Reaches threshold → WILL send the message forward, no matter what
- Non-decrementing: all the spikes are the same size; regardless of the amount of signals, will never decrease or deteriorate over time
102
Explain the basis for the overshoot during the spike,
and
undershoot at the end of the spike.
OVERSHOOT: Na+ channels are open, making the neuron positive
UNDERSHOOT: Then, these Na+ channels close while K+ channels are opening, causing the cell to be extremely negative and then return to its resting potential again
-Have opened extra K+ channels → K+ permeability is higher than normal - shoots over, then goes back
103
What are 2 different events that cause the voltage to stop rising and start falling at the peak of the spike?
Na+ channels slowly begin to close as K+ gates slowly begin to open at the top of the spike
104
What are the 3 sources of membrane depolarization that can lead to a spike?
- Excitatory synaptic input (input from another neuron)
- Sensory signal (input from environment)
- input from another spike from same axon
105
rostral
| caudal
nose
| tail
106
No inactivation gate for....
K+
107
neurotransmitter in preganglion for Autonomic NS releases:
ACh
108
neurotransmitter in preganglion for parasympathetic & symp NS:
parasymp: ACh
symp: Neuroepinephrine
109
Dorsal horn:
| Ventral horn:
back (posterior)
| front
110
Ball and chain
Hunk of protein waiting at edge of Activation gate - positive charge, plugs the opening
111
ohm's law
V = IR
```
V = voltage
I = current
R = resistance
```
112
distance formula
D=r*t
113
Nernst equation
Ek=58log (Ko/K1)
o=inside
1=outside
114
Why it's important to stabilizing K+ ions outside of cell:
Not much outside
Small amount of K+ leaving cell can make a change in concentration
Resting potential MOSTLY due to potassium
Easy to change it
SAME AS Na+ INSIDE
115
Explain why most of the positive current that enters during the rising phase of the spike travels backwards
- Travels both ways but more open potassium channels behind the spike
- Less resistance behind the cell
116
intracellular electrode
| extracellular
intra: inside cell, measuring membrane
extra: used for spikes
117
If the chloride equilibrium potential for a given neuron is -70mV and the resting membrane potential of the neuron is -65mV, does this neuron pump chloride ions in or out? Which direction would chloride ions leak across the membrane?
Wants to pump out
| Leaked in
118
How does myelin increase the spike conduction speed? (This should be answered in terms of electrical current flow.)
Current forced to go down the axon (can’t get out because of myelin covering) - pushed down to next node
Forces current down axon
Increase axon diameter
119
List 2 sodium channel blockers and 1 potassium channel blocker.
Na+ channel blocker: lidocaine & tetrodotoxin (TTX)
| K+ blocker: tetraethylammonium (TEA)
120
When would driving force be 0
when equilibrium is 0
