Download nervous5

8 October 2010
Lecturer Dr. Kim Nguyen
Today:
Two 1QQs
Chapter 6 Section C Synapses p. 160-171
Monday lecture
Chapter 6 D Structure of Nervous System
special emphasis on Fig 6-44 p. 181
Lab Next Week
Sensory Physiology: Data Collection for Abstracts
Visual System: Textbook p. 208-216
1QQ # 13 for 8:30 class
1. Compared to non-myelinated axons, myelinated axons
a)
Require more Na+ K+ ATPase
b) Conduct action potentials slower
c)
Have higher thresholds
d) Have fewer voltage-gated ion channels
e)
Release more neurotransmitters from their axon terminals
2. Nicotine
a)
Acts just like Ach on muscarinic AChRs
b) Acts just like Ach on nicotinic AChRs
c)
Blocks mAChRs.
d) Blocks nAChRs
e)
If tagged with a fluorescent label could be used to detect the presence
and locations of nicotinic AChRs.
1QQ # 14 for 8:30 class
1. The cell bodies of second order neurons in the pathway for
pain and temperature
a)
Are located in the dorsal root ganglia
b) Are located in the gray matter of the spinal cord
c)
Are located in the dorsal column nuclei
d) Have axons that decussate
e)
Have axons that form synapses onto neurons in the thalamus
2. What would be the predicted deficits of a person whose entire
thalamus on the right side of the brain was completely
destroyed?
a)
No sense of pain or temperature in the right foot
b) No sense of pain or temperature in the right hand
c)
No sense of pain or temperature in the left hand
d) No sense of touch in the left hand
1QQ # 13 for 9:30 class
1. Compared to non-myelinated axons, myelinated axons
a)
Require less Na+ K+ ATPase
b) Conduct action potentials faster
c)
Have lower thresholds
d) Have more voltage-gated ion channels
e)
Release less neurotransmitters from their axon terminals
2. Muscarine
a)
Acts just like ACh on muscarinic AChRs
b) Acts just like ACh on nicotinic AChRs
c)
Blocks mAChRs.
d) Blocks nAChRs
e)
If tagged with a fluorescent label could be used to detect the presence
and locations of inotropic and metabotropic AChRs.
1QQ # 14 for 9:30 class
1. The cell bodies of second order neurons in the pathway for
touch and proprioception
a)
Are located in the dorsal root ganglia
b) Are located in the gray matter of the spinal cord
c)
Are located in the dorsal column nuclei
d) Have axons that decussate
e)
Have axons that form synapses onto neurons in the thalamus
2. What would be the predicted deficits of a person whose entire
thalamus on the left side of the brain was completely
destroyed?
a)
No sense of pain or temperature in the right foot
b) No sense of pain or temperature in the right hand
c)
No sense of pain or temperature in the left hand
d) No sense of touch in the left hand
S1
Figure 6.27
Most neurotransmitters are synthesized
in the axon terminal.
Exceptions: Peptide NTs originate in cell
body, move in vesicles by fast orthograde
axonal transport to axon terminal.
Vesicle release proportional to
Ca++ influx (High f AP leads to
residual Ca++ in terminal)
Fates of neurotransmitters:
1) Diffusion away from synapse,
2) Enzymatic degradation (e.g.
AChE and MAO)
3) Uptake by astrocytes
3) Reuptake into presynaptic
terminal (e.g. SSR)
S2
Figure 6.28
EPSPs :which ion moving
in which direction?
Duration of PSP vs AP
Synaptic delay
Some ion Channels that allow flux of
Na+ and K+ simultaneously
e.g. nicotinic Acetylcholine Receptor
(nAChR)
S3
Figure 6.29
IPSPs :which ion moving
in which direction?
Some IPSPs result in no change in membrane
potential by opening Chloride channels that
stabilize membrane potential at resting value
(Nernst Potential for Cl- = -70mV) or in cells
that actively transport Cl- out.
EK+
S4
Figure 6.31
Summation and Synaptic Integration
Different times
Different locations
Each IPSP hyperpolarizes by 5 mV. Each EPSP depolarizes by 5 mV.
If 4 inhibitory synapses are active at the same time, how many excitatory
synapses must be active simultaneously to exceed threshold (-55 mV) if
the resting membrane potential is -70mV?
S5
Priority by proximity
To axon hillock!
Diagram on Board:
Degree of depolarization
above threshold is
proportional to frequency
of action potentials.
S6
Presynaptic Facilitation
Presynaptic Inhibition
Mechanism: vary Ca++
entry in presynaptic
terminal B.
Size of PSP is
Variable!
Figure 6.33
Who Cares?
S7
Figure 6.34
S8
Figure 6.27
Tetanus toxin & Botulinum toxin
disrupt SNARE function.
S9
S 10
AChE and MAOSSRIs:
Lexapro,
Prozac,
& SSRI
Paxil,
Zoloft
Figure 6.34