Term
|
Definition
| places of tight cell-cell contact (junctions) between neurons or neurons and other cells that allow the transduction of a nerve impuls |
|
|
Term
| Which types of synapses exist? |
|
Definition
Electrical and chemical.
electrical: communication between neurons
chemical: communication between neurons or between
neurons and other cells
|
|
|
Term
| How electrical synapse transduct the signal? |
|
Definition
signal transduction occurs directly via ion channels that connect both cells across the gap junction
direct ion flow from one cell to another |
|
|
Term
| How chemical synapse transduct the signal? |
|
Definition
| signal transduction occurs by vesicle mediated neurotransmitter release into the synaptic cleft that activates post-synaptic membrane receptors |
|
|
Term
| What are two types of chemical synapses? |
|
Definition
direct: neurotransmitter opens ligand-gated ion channel
indirect: neurotransmitter activates signaling cascade that might open a ion channel |
|
|
Term
| Describe how Na/K channels working during nerve impuls conduction? |
|
Definition
|
|
Term
| What acts as a sensor of membrane posention in Na/K ATPase? |
|
Definition
|
|
Term
| Describe the propagation of neural impuls thought the neuron |
|
Definition
|
|
Term
| What rhodopsin consists from? |
|
Definition
|
|
Term
| What happens then retinal absorbs the light? |
|
Definition
| Absorption of light (energy of the photon) induces a cis-trans isomerization of the Retinal between C11-C12. |
|
|
Term
| Outline the molecular basis of vision |
|
Definition
Conformational change in retinal -> significant conformational change in rhodopsin (rotation) -> open binding pocket to transdusin -> heterodimeric G-protein
Transducin is now in G coupled form -> exchange of GDP to GTP -> complex ruined -> α-subunit of the complex binds to γ-subunit of PDE -> PDEαβ is active and doing 5 GMP out of cyclic GMP
Lack of cGMPs closes a cGMP-gated Na+/Ca2+ symporter in the plasma membrane of the outer segment. |
|
|
Term
| What happens in the rod cells in the absence of photons? |
|
Definition
| A lot of cGNP -> open Na/Ca symporter and Na/K ATPases working in the opposite directions -> total -45mV |
|
|
Term
| What happens in the rod cells in the presence of photons? |
|
Definition
Little cGMP - >Na+ / Ca2+ Symporter is inactivated and
Na+/K+ ATPase is still active => cell is hyperpolarised (-75 mV) |
|
|
