11/10 Synapses

Question 1

two main types of the huge diversity of neurotransmitter receptors on postsynaptic neurotransmitters

Answer 1

Ionotropic, Metabotropic

Question 2

Describe Channel-Linked (ionotropic) Receptors

Answer 2

ligand gated ion channels. Action is immediate and brief. Excitatory receptors are channels for small cations. Inhibitory receptors allow Cl- or K+ to hyperpolarize.

Question 3

Examples of Ionotropic receptros

Answer 3

AMPA (glutamtate), nicotinic Ach, GABAa

Question 4

Describe G Protein-linked (metabotropic) Receptors.

Answer 4

Transmembrane protein complex that binds the neurotransmitter, triggering intracellular cascade. Slow, indirect, complex, and prolonged and widespredead.

Question 5

examples of G protein-linked metabotropic receptors

Answer 5

muscarinic Ach, GABAb, dopamine (D2 receptors

Question 6

what is the second messenger for the G-protien receptors?

Answer 6

activated G-protien activates adenylate cyclase that makes cAMP that brings about the cell signal change by opening/closing ion channels and activating enzymes and activating genes.

Question 7

Atropine (metabotropic receptor drug)

Answer 7

muscarinic Ach antagonis (treatment for bradychardia) increases SA node fireing

Question 8

Propanolol (metabotropic receptor drug)

Answer 8

(beta blockers) beta-adrenergic antagonist –treatment for hypertension, tachycardia

Question 9

opiates (metabotropic receptor drug)

Answer 9

(morphine, oxycodone, etc.) target opioid receptors.

Question 10

What do most post synaptic receptors have for a class of recepotor molecule?

Answer 10

both the ionotropic and metabotropic receptors.

Question 11

what really decides what the action at a synapse will be?

Answer 11

the postsynaptic receptor does!! it interprets the signal and responds…

Question 12

what will decide the strength of a postsynaptic potential?

Answer 12

the amount of neurotransmitter released; the time the neruortrnamitter is in the adrea; the density and conductance of postsynaptic receptors.

Question 13

what type of post-synaptic transmitter would usually lead to an IPSP due to Cl-?

Answer 13

IPSP triggered by ionotropic receptors (GABA) due to Cl- conductance

Question 14

what type of post-synaptic transmitter would usually lead to an IPSP due to K+

Answer 14

usually metabotropic receptors like mGluRs

Question 15

compare the spacial oriention of EPSP neurons and IPSPs

Answer 15

typically the IPSPs will be on the cell body and the EPSPs will be on the dendrites of the cell

Question 16

why would the spacial orientation of EPSPs and IPSPs neurons be significant

Answer 16

spacial summation occurs at the start of the axon and the IPSPs don’t have as much magnitude, but by being closer they can still overcome the EPSPs

Question 17

what is a dendritic spine?

Answer 17

these are specialized sites for synaptic input, they are the post synaptic sites for axon synapse.

Question 18

what is a dendritic spine do

Answer 18

it amplifies the electrical signals and can act as a small indipendent biochemical compartment. theis can allow for independent modulation at individual synapses

Question 19

what is common with genetci defects of dendritic spines?

Answer 19

defects that result in lackk of porper spine formation typically lead to severe mental retardation, congitive deficits

Question 20

how does the use of a synapse chage its character

Answer 20

repeated use increases the efficiency of neurotransmission, and disuse can reduce efficiency!!! this can be seen as an increase in release of neurotransmitter and neurotransmitter receptors; this could be function of memory.

Question 21

What might be the bio-molecular mechanism of long-term potentiation (highly used synapses become more efficient)

Answer 21

It seems to be related to the NMDA glutamate receptor. This receptor is both ligand and voltage gated. Glutamate will be released to the synapse and bind both the normal AMPA receptor and NMDA receptor. the AMPA opens for Na+ and depolarize the cell. This will then open the NMDA receptor and allow Ca+ to come in that will change the cell to lead to more AMPA receptors. therefore we need both the glutamate release and a good depolarizatio of the post synaptic to lead to more receptors. It also leads to remodeling of the cytoskeleton of the synapse to make it larger!

Question 22

Repeated use increased the ——– of neurotransmission

Answer 22

efficiency

Question 23

what will brief, high frequency stimulation partially depolarizing the postsynaptic neuron do to the neuron?

Answer 23

chemically gated channesl (NMDA receptors) allow Ca2+ entry and this activates kinase enzymes that promote more effective responses to subsequent stimuli

Question 24

You wish to design a drug to erase particular memoris would you….1. NMDA receptor antagonist; 2. Kinase inhibitor; 3. Inhibitor of presynaptic glutamate release; 4. inhibitor of protein synthesis

Answer 24

target a Kinase inhibitor itself since this is what is driving and maintaining the post-synaptic signalling.

Question 25

what will Kinase activation do in a post-synaptic receptor region to alter memory or learning?

Answer 25

it can also lead to changes in receptor expression

Question 26

what is epilepsy like a fat kid on a teater-totter?

Answer 26

it is a loss in the balance of excitation and inhibition signals … excitation runaway is what would lead to a seizure, just like the fat kid would lead to an imbalance in the teater totter,

Question 27

how can alzhimers lead to loss of memory

Answer 27

by having the amyloid plaques that end up blocking the dendrites and the synapse even before they break down the cell in other ways.

Question 28

why type of receptor could I block in a neuron to simulate a tonic-clonic seizure?

Answer 28

block the GABAa receptros. since these are the IPSP signals, if they are absent then the cell will be over-excited and seizure!

Question 29

what type of drugs are used for seizure control?

Answer 29

use drugs that enhance GABA-ergic transmission and block Na+, and Ca+ channels. in essence blocking the channels for EPSPs and promoting the channels for IPSPs

Question 30

what is the major protein to point a finger at for alzhiemers?

Answer 30

amyloid

Question 31

newest evidence is not so implicative of the amyloid plaques…what then could lead to nerve signal problems?

Answer 31

excess Ab peptide even before it forms an amyloid plaque. this will cause internilaztion of AMPA, NMDA, Glu receptors, nAchR blockade, spine retraction and loss of synaptic plasticity.

Question 32

what is the result of the damage caused by Ab peptide even before it makes an amyloid plaque?

Answer 32

synaptic depression at glutamatergic synapses, loss of cholinergic neurons.

Question 33

what is the current route of alzhiemer treatment?

Answer 33

simply take general acetylcholinesterase inhibitors to try and promote function of the neurons as they degenerate.