Curs 2. Transmiterea sinaptica si fiziologia unor grupe mici de neuroni
Curs 2. Transmiterea sinaptica si fiziologia unor grupe mici de neuroni
Curs 2. Transmiterea sinaptica si fiziologia unor grupe mici de neuroni
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Fiziologie, 2010<br />
<strong>Curs</strong> <strong>2.</strong><br />
<strong>Transmiterea</strong> <strong><strong>si</strong>naptica</strong> <strong>si</strong> <strong>fiziologia</strong> <strong>unor</strong> <strong>grupe</strong><br />
<strong>mici</strong> <strong>de</strong> <strong>neuroni</strong>
Fiziologie, 2010<br />
<strong>Curs</strong> 2 - Cuprins<br />
1. Tipuri <strong>de</strong> <strong>si</strong>napse: electrice <strong>si</strong> chimice.<br />
<strong>2.</strong> Procese <strong>de</strong> modulare a transmiterii <strong>si</strong>naptice.<br />
3. Circuite <strong>mici</strong> <strong>de</strong> <strong>neuroni</strong>.
Sinapsele electrice sunt formate din jonctiuni comunicante sau<br />
jonctiuni gap<br />
Fiziologie, 2010<br />
Membrane<br />
celulare<br />
Canal<br />
(1,6-2nm)<br />
Citoplasma<br />
celulei 2<br />
Citoplasma<br />
celulei 1<br />
Molecule <strong>de</strong> conexin„<br />
din celula 1<br />
Molecule <strong>de</strong> conexin„<br />
din celula 2<br />
Lan˛ proteic<br />
(27 kD)<br />
Structura unei jonc˛iuni gap. ase molecule <strong>de</strong> conexin„ dintr-o celul„ se<br />
asambleaz„ i formeaz„ un semi-canal care se une te cu unul <strong>si</strong>milar din<br />
membrana celulei Ónvecinate. Rezult„ un canal cu un diametru <strong>de</strong> 1,6-2nm<br />
care face leg„tura Óntre citoplasmele celor dou„ celule (dup„ Despopoulos,<br />
Silbernagel, 1991).
Sinapsele chimice sunt formate dintr-o dintr componenta pre-<br />
<strong><strong>si</strong>naptica</strong> <strong>si</strong> una post-<strong><strong>si</strong>naptica</strong><br />
post <strong><strong>si</strong>naptica</strong> separate <strong>de</strong> un spatiu <strong>si</strong>naptic<br />
Fiziologie, 2010
Fiziologie, 2010<br />
<strong>Transmiterea</strong> <strong><strong>si</strong>naptica</strong> chimica este mediata <strong>de</strong><br />
neurotransmitatori
Fiziologie, 2010<br />
Jonctiunea neuromusculara-Interactive<br />
neuromusculara Interactive<br />
Phy<strong>si</strong>ology
Neurotransmitatorii sunt<br />
compu<strong>si</strong> cu molecula micaÖ.<br />
Fiziologie, 2010
Neurotransmitatorii sunt<br />
compu<strong>si</strong> cu molecula micaÖ.<br />
Fiziologie, 2010
Ö sau mare<br />
(neuropepti<strong>de</strong><br />
neuropepti<strong>de</strong><br />
active)<br />
Fiziologie, 2010
Neurotransmitatorii<br />
cu molecula mica<br />
sunt eliberati<br />
separat <strong>de</strong> <strong>neuroni</strong>. <strong>neuroni</strong><br />
Pepti<strong>de</strong>le sunt<br />
colocalizate cu<br />
neurotransmitatorii<br />
Fiziologie, 2010<br />
Table 12-1. EXAMPLES OF NEUROACTIVE PEPTIDES THAT COLOCALIZE WITH<br />
SMALL-MOLECULE NEUROTRANSMITTERS*<br />
SMALL MOLECULE PEPTIDE<br />
ACh Enkephalin<br />
VIP<br />
CGRP<br />
Substance P<br />
Somatostatin and enkephalin<br />
GnRH<br />
Neuroten<strong>si</strong>n<br />
Galanin<br />
Dopamine CCK<br />
Enkephalin<br />
Neuroten<strong>si</strong>n<br />
Enkephalin<br />
Neuropepti<strong>de</strong> Y<br />
Neuroten<strong>si</strong>n<br />
Substance P<br />
GABA CCK<br />
Enkephalin<br />
Somatostatin<br />
Neuropepti<strong>de</strong> Y<br />
Substance P<br />
VIP<br />
Glutamate Substance P<br />
Neuroten<strong>si</strong>n<br />
Norepinephrine Enkephalin<br />
Neuropepti<strong>de</strong> Y<br />
Neuroten<strong>si</strong>n<br />
Somatostatin<br />
Serotonin CCK<br />
Enkephalin<br />
Substance P and TRH<br />
TRH<br />
* Each row on the right gives a pepti<strong>de</strong> or combination of pepti<strong>de</strong>s that co-localize with<br />
the small molecule in the row on the left.<br />
ACh, acetylcholine; CCK, cholecystokinin; CGRP, calcitonin-gene-related pepti<strong>de</strong>;<br />
GABA, gamma-aminobutyric acid; GnRH, gonadotropin-relea<strong>si</strong>ng hormone. TRH,<br />
thyrotropin-relea<strong>si</strong>ng hormone; VIP, vasoactive intestinal polypepti<strong>de</strong>.<br />
Data from Hall ZW: An Introduction to Molecular Neurobiology. Sun<strong>de</strong>rland, Mass,<br />
Sinauer, 199<strong>2.</strong>
Medierea sen<strong>si</strong>bilitatii nociceptive la nivelul maduvei<br />
spinarii implica mai multi mediatori chi<strong>mici</strong><br />
Fiziologie, 2010
Fiziologie, 2010<br />
NO, <strong>si</strong> po<strong>si</strong>bil CO,<br />
au functii <strong>de</strong><br />
neurotransmitator
Fiziologie, 2010<br />
Compu<strong>si</strong>i ce actioneaza ca neurotransmitatori au<br />
<strong>si</strong> alte roluri in organism<br />
ï Aminoacizii intra in structura proteinelor.<br />
ï NO relaxeaza musculatura neteda a vaselor <strong>de</strong> sange.<br />
ï Cele mai ridicate nivele <strong>de</strong> Ach sunt in cornee, <strong>de</strong><strong>si</strong> lipsesc receptori<br />
pentru Ach.<br />
ï Intervin in <strong>de</strong>zvoltarea creierului: regleaza proliferarea celulara,<br />
migrarea <strong>si</strong> diferentierea.
Fiziologie, 2010<br />
Sinapsele pot fi excitatoareÖ<br />
excitatoare
Fiziologie, 2010<br />
Neurotransmitatorii excitatori ca acetilcolina,<br />
acetilcolina,<br />
substanta P, glutamatul,<br />
glutamatul,<br />
<strong>de</strong>termina potentiale<br />
potentiale<br />
post--<strong>si</strong>naptice<br />
post <strong>si</strong>naptice excitatorii<br />
excitatorii<br />
PPSE<br />
PPSI<br />
A<br />
B<br />
Stimul slab Stimul puternic<br />
C<br />
PPSE<br />
PPSE<br />
PPSI<br />
PPSI
Fiziologie, 2010<br />
Sinapsele pot fi excitatoare,<br />
excitatoare,<br />
inhibitoareÖ<br />
inhibitoare
PPSE<br />
PPSI<br />
Fiziologie, 2010<br />
Neurotransmitatorii inhibitori ca GABA sau<br />
glicina <strong>de</strong>termina potentiale potentiale post<strong>si</strong>naptice<br />
inhibitorii<br />
inhibitorii<br />
A<br />
B<br />
Stimul slab Stimul puternic<br />
C<br />
PPSE<br />
PPSE<br />
PPSI<br />
PPSI
Fiziologie, 2010<br />
Sinapsele pot fi excitatoare,<br />
excitatoare,<br />
inhibitoare <strong>si</strong><br />
modulatoare
Fiziologie, 2010<br />
Nicotina este un agonist competitiv pentru acetilcolina<br />
O tigara contine 10 mg sau mai mult <strong>de</strong> nicotina. Prin<br />
fumul inhalat ñ 1-2mg nicotina /tigara.<br />
Nicotina creaza <strong>de</strong>pen<strong>de</strong>nta: ar trebui sa se reduca cu 95%<br />
concentratia <strong>de</strong> nicotina pentru a reduce efectul adictiv.<br />
Molecula <strong>de</strong> nicotina inhalata odata cu fumul <strong>de</strong> tigara<br />
ajunge in creier in 10 secun<strong>de</strong>. In creier, nicotina se<br />
cupleaza cu receptorul nicotinic <strong>de</strong> acetilcolina
In creier exista receptori nicotinici in mai multe zone, localizati<br />
pre<strong>si</strong>naptic la nivelul <strong>unor</strong> terminatii colinergice,<br />
colinergice,<br />
dopaminergice<br />
sau glutamatergice<br />
Fiziologie, 2010
Nicotina <strong>de</strong>termina eliberarea in creier <strong>de</strong> mai multi<br />
compu<strong>si</strong><br />
Fiziologie, 2010
Fiziologie, 2010<br />
Efecte <strong>si</strong>naptice -animatie animatie
Efectele neurotransmitatorilor pe componenta post<strong><strong>si</strong>naptica</strong><br />
au durate diferite<br />
Fiziologie, 2010
Fiziologie, 2010<br />
<strong>Curs</strong> 2 - Cuprins<br />
1. Tipuri <strong>de</strong> <strong>si</strong>napse: electrice <strong>si</strong> chimice.<br />
<strong>2.</strong> Procese <strong>de</strong> modulare a transmiterii <strong>si</strong>naptice.<br />
3. Circuite <strong>mici</strong> <strong>de</strong> <strong>neuroni</strong>.
Fiziologie, 2010<br />
<strong>Transmiterea</strong> <strong><strong>si</strong>naptica</strong> poate fi influentata prin<br />
procese <strong>de</strong> inhibitie inhibitie pre<strong><strong>si</strong>naptica</strong> sauÖ. sauÖ.<br />
NEINHIBAT<br />
PA<br />
INHIBAT<br />
Inhibi˛ie prin<br />
feed-back<br />
Colaterale ale<br />
neuronului <strong>de</strong><br />
inhibat<br />
C„tre agonist<br />
(<strong>de</strong> exemplu,<br />
mu chi flexor)<br />
A. Inhibi˛ie pre<strong>si</strong>naptic„ B. Inhibi˛ie post<strong>si</strong>naptic„<br />
Inhibi˛ie feedforward<br />
Interneuron<br />
inhibitor<br />
Celul„<br />
Renshaw<br />
C„tre antagonist<br />
(<strong>de</strong> exemplu,<br />
mu chi extensor)<br />
Cale direct„<br />
<strong>de</strong> activare
Fiziologie, 2010<br />
Inhibitia pre<strong><strong>si</strong>naptica</strong> se poate face prin<br />
intermediul proteinelor G
Fiziologie, 2010<br />
<strong>Transmiterea</strong> <strong><strong>si</strong>naptica</strong> poate fi influentata prin<br />
procese <strong>de</strong> inhibitie inhibitie pre<strong><strong>si</strong>naptica</strong> sau<br />
post<strong><strong>si</strong>naptica</strong><br />
NEINHIBAT<br />
PA<br />
INHIBAT<br />
Inhibi˛ie prin<br />
feed-back<br />
Colaterale ale<br />
neuronului <strong>de</strong><br />
inhibat<br />
C„tre agonist<br />
(<strong>de</strong> exemplu,<br />
mu chi flexor)<br />
A. Inhibi˛ie pre<strong>si</strong>naptic„ B. Inhibi˛ie post<strong>si</strong>naptic„<br />
Inhibi˛ie feedforward<br />
Interneuron<br />
inhibitor<br />
Celul„<br />
Renshaw<br />
C„tre antagonist<br />
(<strong>de</strong> exemplu,<br />
mu chi extensor)<br />
Cale direct„<br />
<strong>de</strong> activare
Fiziologie, 2010<br />
In timpul mersului se modifica mo<strong>de</strong>lul <strong>de</strong><br />
coordonare a membrelor<br />
Generarea comenzilor motorii pentru comportamente ritmice:<br />
mers, alergat, inot, respiratie, mestecare, clipit, tremurat <strong>si</strong><br />
uneori scarpinat.<br />
Trap= fuga cu pa<strong>si</strong> marunti<br />
La pas
Generarea ritmului poate continua<br />
fara feedback <strong>de</strong> la muschi<br />
Fiziologie, 2010<br />
Inhibitia prin <strong>neuroni</strong> Renshaw este<br />
importanta pentru coordonarea <strong>unor</strong><br />
comportamente ritmice<br />
Generarea comenzilor motorii pentru comportamente ritmice:<br />
mers, alergat, inot, respiratie, mestecare, clipit, tremurat <strong>si</strong><br />
uneori scarpinat.
Fiziologie, 2010<br />
Analgezia indusa <strong>de</strong> stress este un exemplu <strong>de</strong><br />
inhibitie feed-forward<br />
feed forward<br />
NEINHIBAT<br />
PA<br />
INHIBAT<br />
Inhibi˛ie prin<br />
feed-back<br />
Colaterale ale<br />
neuronului <strong>de</strong><br />
inhibat<br />
C„tre agonist<br />
(<strong>de</strong> exemplu,<br />
mu chi flexor)<br />
A. Inhibi˛ie pre<strong>si</strong>naptic„ B. Inhibi˛ie post<strong>si</strong>naptic„<br />
Inhibi˛ie feedforward<br />
Interneuron<br />
inhibitor<br />
Celul„<br />
Renshaw<br />
C„tre antagonist<br />
(<strong>de</strong> exemplu,<br />
mu chi extensor)<br />
Cale direct„<br />
<strong>de</strong> activare
Fiziologie, 2010<br />
La nivelul <strong>si</strong>napselor chimice au loc fenomene<br />
<strong>de</strong> integrare integrare <strong><strong>si</strong>naptica</strong><br />
<strong><strong>si</strong>naptica</strong>
Fiziologie, 2010<br />
<strong>Curs</strong> 2 - Cuprins<br />
1. Tipuri <strong>de</strong> <strong>si</strong>napse: electrice <strong>si</strong> chimice.<br />
<strong>2.</strong> Procese <strong>de</strong> modulare a transmiterii <strong>si</strong>naptice.<br />
3. Circuite <strong>mici</strong> <strong>de</strong> <strong>neuroni</strong>.
Sistemul nervos central realizeaza multiple functii<br />
senzitive, senzitive,<br />
motorii <strong>si</strong> cognitive care nece<strong>si</strong>ta retele<br />
neuronale strict localizate sau difuze<br />
Operatii rapi<strong>de</strong>, precise.<br />
ex: cantatul la pian, cititul<br />
Fiziologie, 2010<br />
Operatii lente, difuze, generalizate.<br />
ex: adormirea, trezirea, schimbarea<br />
starii emotionale, etc.
Fiziologie, 2010<br />
Circuitele sau retelele neuronale stau la baza capacitatii<br />
<strong>si</strong>stemului nervos central <strong>de</strong> a coordona diverse<br />
comportamente
Fiziologie, 2010<br />
Circuitele sau retelele neuronale sunt <strong>de</strong> mai<br />
multe tipuri<br />
Input<br />
A. Divergen˛„ pe aceea i cale<br />
Output<br />
1<br />
Input Input<br />
Output<br />
1<br />
B. Divergen˛„ spre c„i multiple<br />
Input<br />
Output<br />
Input<br />
Input 1<br />
Input 2 Input 3<br />
Output<br />
1<br />
C. Convergen˛„, surse<br />
multiple<br />
Output<br />
1<br />
D. Convergen˛„,<br />
surs„ unic„<br />
E. Circuit reverberant F. Circuit paralel post<strong>de</strong>sc„rcare<br />
Output<br />
1
Fiziologie, 2010<br />
Circuitele neuronale se gasesc in maduva spinarii<br />
sauÖ sauÖ
Fiziologie, 2010<br />
Ö in neocortex
Fiziologie, 2010<br />
Procesarea informatiilor in diverse circuite se<br />
poate face in in serie serie sau in in paralel<br />
paralel
Fiziologie, 2010<br />
Procesarea informatiilor in<br />
diverse circuite se poate face<br />
in in serie serie sau in in paralel<br />
paralel
Fiziologie, 2010<br />
Concluzii<br />
1. Sinapsele pot fi electrice sau chimice. chimice.<br />
<strong>2.</strong> Sinapsele chimice pot fi excitatoare,<br />
excitatoare,<br />
inhibitoare sau modulatoare.<br />
modulatoare.<br />
3. Modularea post<strong><strong>si</strong>naptica</strong>.<br />
post<strong><strong>si</strong>naptica</strong><br />
activitatii <strong>si</strong>naptice se poate face prin procese <strong>de</strong> inhibitie pre- pre sau<br />
4. Circuitele sau retelele neuronale stau la baza capacitatii <strong>si</strong>stemului nervos central <strong>de</strong> a<br />
coordona diverse comportamente.<br />
comportamente
Change language