1,T h e c h a r ac t er i s t ic s o f th e ne u r o n a l c e l l
W h a t w o u l d c o me t o y o u r m i nd a s a d e f in it i o n?
It i s a ce ll o f t he b r a i n, t ha t i s no t co r r e c t,i t i s m o r e w i de l y sp r e a d, CN S =
b ra in + s p in a l c o r d,S NP,e nt er i c sy s t e m,
It i s an e x c it ab l e ce ll,it is t r ue bu t t h i s p r o p e rt y is s ha r ed w it h o t h e r ce lls,
Mu s c l e s,s t ri a t ed m u s c l e,h e ar t,A n d o t he r ce lls t oo s u c h a s e n d o c ri ne ce ll s pr e s e n t an
e x c it ab il i t y t h a t i s t he p r o p e rt y t o g e n e r a t e a c ti on po t en ti a ls wh i ch p r o p a ga t es a ll o v e r th e
ce ll,Ex c i t a bi l ity a n d co nd u c t i o n a r e l i n k e d p ro p er ti e s,a n d i n t he CN S w e fi nd a
c a p a bi lit y of a v e r y f a s t c o n d u c ti o n,
Neuronal fast signalling
I t i s an in te g r a ti ve ce ll,E n d o c r i n e ce lls a ls o a r e ab l e t o i n t eg r a t e si g n a l s of
d if fe r en t or i g i n s, T h e s p e c i fi c it y o f t he n e u r o n e i s t ha t it is ab le t o g e n e r at e t h r o u g h s y n a p ti c
r e c e p t o r s a t t he l e v e l of s y n a p ti c c o n t ac ts a v e r y a m p li f i ed si g n a l,1 m ol e cu l e o f
n e u r o t r a ns m it ter h it t ing a r e c e p t or w ill a ll ow t he e n t ry of so m e 1 0 0 0 i on s du ri ng it s 1
m il l i s e c o n d o p e n i n g, Th is y i e l d s a f as t si g n a llin g, N e u r o t r a ns m it te r s wh i ch c a r r y t h is
p r o p e r t y a r e, Glu ta m a t e,G A B A,g l yc in e,a nd a ls o bu t l es s w i d e l y d i st r i b ut e d
a c e t y l c h o lin e,a n d se r o t o n i n
A n d d u r i ng d e v e l op m en t,it is t he on l y ce ll wh i ch m o v e s a n d e x t e n d s t ow a rd s
it s t a r g et ce ll,T h i s d e v e l op m en t a l p r o p e rt y l e a ds to t he c o n s tr uc ti on o f v e r y co mp l e x
n e t w o r k s,
R,Y,Cajal
Golji
Nerve Cell
What is the shape of a neuron?
? Axon
? Myelin sheath
? Dendrites
[Ca entry]
Dendrites Axon Synaptic endings
[Transmitter concentration] [Membrane potential]
Response
Synaptic
channels
Dose
Sodium
channels
Transmitter
release
Soma
Neuron and fast transmission
[Ca entry]
Dendrites Axon Synaptic endings
[Transmitter concentration] [Membrane potential]
Response
Synaptic
channels
Dose
Sodium
channels
Transmitter
release
Soma
Neuron and fast transmission
Synapse
A synaptic delay < 1 ms
The synpatic potential is local
Synaptobrevin
SNAP-25 Syntaxin
[Ca entry]
Response
Dose
Transmitter
release
Fast signalling
Kd= a few μM
Hormonal signalling
KD= a few nM
Gap junction
[Ca entry]
Dendrites Axon Synaptic endings
[Transmitter concentration] [Membrane potential]
Response
Synaptic
channels
Dose
Sodium
channels
Transmitter
release
Soma
Neuron and fast transmission
? muscle spindle
Proprioception,muscle spindle
Neuroglia
? Figure 1.4,Neuroglial cells,Tracings of an astrocyte
(A),an oligodendrocyte (B),and a microglial cell (C)
visualized by impregnation with silver salts,The images
are at approximately the same scale,(D) Astrocytes in the
brain labeled with an antibody against the astrocyte-
specific protein (glial fibrillary acidic protein),(E) A
scanning electron micrograph of a single oligodendroglial
cell imaged in tissue culture,(F) A peripheral axon
ensheated by the processes of Schwann cells (in green),
except for at a distinct region called the node of Ranvier
(labeled in red),(G) A microglial cell from the spinal
cord,labeled with a cell-type-specific antibody,(AC after
Jones and Cowan,1983; D courtesy of A.-S,LaMantia;
E,F courtesy of B,Popko; G courtesy of A,Light.)
We just spoke of fast signalling in the neuron
which is itself part of a complex network…,
In the neuron,
What is the role of the soma?
The co-release of peptides and fast transmitters
The release of growth factors….,
W h a t w o u l d c o me t o y o u r m i nd a s a d e f in it i o n?
It i s a ce ll o f t he b r a i n, t ha t i s no t co r r e c t,i t i s m o r e w i de l y sp r e a d, CN S =
b ra in + s p in a l c o r d,S NP,e nt er i c sy s t e m,
It i s an e x c it ab l e ce ll,it is t r ue bu t t h i s p r o p e rt y is s ha r ed w it h o t h e r ce lls,
Mu s c l e s,s t ri a t ed m u s c l e,h e ar t,A n d o t he r ce lls t oo s u c h a s e n d o c ri ne ce ll s pr e s e n t an
e x c it ab il i t y t h a t i s t he p r o p e rt y t o g e n e r a t e a c ti on po t en ti a ls wh i ch p r o p a ga t es a ll o v e r th e
ce ll,Ex c i t a bi l ity a n d co nd u c t i o n a r e l i n k e d p ro p er ti e s,a n d i n t he CN S w e fi nd a
c a p a bi lit y of a v e r y f a s t c o n d u c ti o n,
Neuronal fast signalling
I t i s an in te g r a ti ve ce ll,E n d o c r i n e ce lls a ls o a r e ab l e t o i n t eg r a t e si g n a l s of
d if fe r en t or i g i n s, T h e s p e c i fi c it y o f t he n e u r o n e i s t ha t it is ab le t o g e n e r at e t h r o u g h s y n a p ti c
r e c e p t o r s a t t he l e v e l of s y n a p ti c c o n t ac ts a v e r y a m p li f i ed si g n a l,1 m ol e cu l e o f
n e u r o t r a ns m it ter h it t ing a r e c e p t or w ill a ll ow t he e n t ry of so m e 1 0 0 0 i on s du ri ng it s 1
m il l i s e c o n d o p e n i n g, Th is y i e l d s a f as t si g n a llin g, N e u r o t r a ns m it te r s wh i ch c a r r y t h is
p r o p e r t y a r e, Glu ta m a t e,G A B A,g l yc in e,a nd a ls o bu t l es s w i d e l y d i st r i b ut e d
a c e t y l c h o lin e,a n d se r o t o n i n
A n d d u r i ng d e v e l op m en t,it is t he on l y ce ll wh i ch m o v e s a n d e x t e n d s t ow a rd s
it s t a r g et ce ll,T h i s d e v e l op m en t a l p r o p e rt y l e a ds to t he c o n s tr uc ti on o f v e r y co mp l e x
n e t w o r k s,
R,Y,Cajal
Golji
Nerve Cell
What is the shape of a neuron?
? Axon
? Myelin sheath
? Dendrites
[Ca entry]
Dendrites Axon Synaptic endings
[Transmitter concentration] [Membrane potential]
Response
Synaptic
channels
Dose
Sodium
channels
Transmitter
release
Soma
Neuron and fast transmission
[Ca entry]
Dendrites Axon Synaptic endings
[Transmitter concentration] [Membrane potential]
Response
Synaptic
channels
Dose
Sodium
channels
Transmitter
release
Soma
Neuron and fast transmission
Synapse
A synaptic delay < 1 ms
The synpatic potential is local
Synaptobrevin
SNAP-25 Syntaxin
[Ca entry]
Response
Dose
Transmitter
release
Fast signalling
Kd= a few μM
Hormonal signalling
KD= a few nM
Gap junction
[Ca entry]
Dendrites Axon Synaptic endings
[Transmitter concentration] [Membrane potential]
Response
Synaptic
channels
Dose
Sodium
channels
Transmitter
release
Soma
Neuron and fast transmission
? muscle spindle
Proprioception,muscle spindle
Neuroglia
? Figure 1.4,Neuroglial cells,Tracings of an astrocyte
(A),an oligodendrocyte (B),and a microglial cell (C)
visualized by impregnation with silver salts,The images
are at approximately the same scale,(D) Astrocytes in the
brain labeled with an antibody against the astrocyte-
specific protein (glial fibrillary acidic protein),(E) A
scanning electron micrograph of a single oligodendroglial
cell imaged in tissue culture,(F) A peripheral axon
ensheated by the processes of Schwann cells (in green),
except for at a distinct region called the node of Ranvier
(labeled in red),(G) A microglial cell from the spinal
cord,labeled with a cell-type-specific antibody,(AC after
Jones and Cowan,1983; D courtesy of A.-S,LaMantia;
E,F courtesy of B,Popko; G courtesy of A,Light.)
We just spoke of fast signalling in the neuron
which is itself part of a complex network…,
In the neuron,
What is the role of the soma?
The co-release of peptides and fast transmitters
The release of growth factors….,
