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Flashcards in Problem 3 Deck (28)
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1

Postsynaptic Potential

- brief changes in membrane potential of the postsynaptic cell caused by the release of neurotransmitters

Whether cell excites or inhibits is dependent on the neurotransmitter

2

Excitatory postsynaptic potential (EPSP)

- pushes the postsynaptic cell closer to threshold for AP

--> Depolarizing

3

Synaptic delay

- Delay between arrival of Ap at axon terminal + creation of a postsynaptic potential

- Reflects the time needed for neurotransmitters to diffuse into synaptic cleft

4

Inhibitory postsynaptic potential (IPSP)

- moves postsynaptic cell away from threshold for AP

--> Hyperpolarizing

- increase of resting membrane potential

5

Spatial summation

The simultaneous summation of potentials ( E / IPSP ) from different locations ( dif. postsyn. membr. ) across the cell body

6

Temporal summation

- not absolutely simultaneous

--> the closer they are in time - the greater the overlap

7

Role of distance in EPSPs

Simultaneous EPSPs from synapses closer to the axon hillock will produce a larger sum than those farther away

8

Ligand

- molecule of the perfect/correct shape for a receptor
--> Schlüssel-Schloss Prinzip

-can activate or block the receptor

9

Endogenous ligands

Neurotransmitters/Hormones made inside the body

10

Exogenous ligands

Drugs/Toxins that work as neurotransmitters from outside the body

11

Agonist

Molecule that acts like a neurotransmitter

--> high efficacy

12

Antagonist

Molecule that prevents the action of a transmitter

--> low efficacy

13

Ionotropic receptors

control ion channels directly
--> when bound, ion channels open immediately

14

Metabotropic receptors

activate G-Proteins, which in turn activate ion channels
--> indirect control of ion channel

15

G-protein

molecule,

1. either directly opens ion channel

2. or activates another chemical signal which then opens the ion channel

16

Degradation

Special enzyme breaks transmitter down into pieces

--> products are recycled to make more of the transmitter in the axon terminal

17

Reuptake

Special receptors of the transmitter are located in the presynaptic membrane and bring the transmitter back inside its the help of transporters

18

Convergence

Type of neural circuit

- many cells send signals to one

19

Divergence

Type of neural circuit

- one cell sends signals to many

20

Binding Affinity

the degree of chemical attraction between ligand and receptor

21

Efficacy

Propensity (Neigung) of a ligand to activate the receptor to which it is bound

22

Partial Agonist

A partial agonist is a drug that has a very
high affinity for a particular receptor but activates that
receptor less than the normal ligand does

23

Division of a Synapse

1. Presynaptic Membrane = usually axon terminal

2. Synaptic Cleft = gap between pre- and postsynaptic membrane

3. Postsynaptic Membrane = usually dendrite

24

Synaptic Transmission

1. AP arrives at axon terminal

2. Depolarization opens voltage-gated Ca2+ channels in the membrane of axon terminal
--> Ca2+ ions enter the terminal

3. Exotysis= Ca2+ causes vesicles to fuse with presynaptic membrane, rupture, release transmitter into synaptic cleft
--> mediated by V/T-Snare and Synaptotagmin

4. transmitter molecules cross the cleft to bind to special receptors in postsynaptic membrane

5. ion flow creates a local E/IPSP in the postsynaptic neuron

6. Synaptic transmitter is either inactivated (Degradation) or removed (Reuptake) from synaptic cleft by transporters

7. Synaptic transmitters may also activate presynaptic autoreceptors

25

V-Snare

attached to the vesicle

26

T-Snare

attached to presynaptic membrane

27

Action of V/T Snares

- Their Snares attach

--> Vesicle is now docked on the presynaptic membrane and ready to be released

28

Function of Synaptotagmin

Triggers final fusion of the vesicle with the presynaptic membrane