Lecture 17: Synaptic Transmission, Nueral Intergration and CNS

What is temporal Summation?

Same stimulus coming from the presynaptic neuron

What is Spatial Summation?

Different stimuli with multiple presynaptic neuron

What is a neuromuscular junction?

between neuron & muscle

What is a neuroglandular junction?

between neuron & gland

What is the first step of Chemical Synapse and NT release?

Action potential spreads down the axon

Second step of chemical synapse & NT release

@ axon terminal, open Ca Channels

third step of chemical synapse & NT release

Ca then influxes

fourth step of chemical synapse & NT release

Synaptic vesicles w/ NT bind + cell membrane

fifth step of chemical synapse & NT release

Exocytosis of NT

sixth step of chemical synapse & NT release

NT cross the synaptic cleft

seventh step of chemical synapse & NT release

NT bind to ligand-gated channels on post-synaptic cleft

eighth step of chemical synapse & NT release

ions move into/out post-synaptic cell

nineth step of chemical synapse & NT release

membrane potential of post synapse closer to ions equilibrium potential

tenth step of chemical synapse & NT release

Result in graded potential

How many steps are there to remove a NT?

three

First step to remove NT

Degrade with enzymes

second step to remove NT

Reuptake into pre-synaptic neuron

third step to remove NT

diffuse away from cleft

How many steps are in the mechanism of fast response to a NT?

4

first step in the mechanism of fast response to a NT

NT binds to receptor

second step in the mechanism of fast response to a NT

channel opens

third step in the mechanism of fast response to a NT

ions move

fourth step in the mechanism of fast response to a NT

membrane potential of the cell moves closer to the equilibrium

How many steps are there in a slow response: direct coupling to a NT

7

first step of slow response: direct coupling to a NT

NT binds to receptor

second step of slow response: direct coupling to a NT

Activate G-protein

third step of slow response: direct coupling to a NT

GDP falls off Alpha subunit

fourth step of slow response: direct coupling to a NT

GTP attaches to subunit

fifth step of slow response: direct coupling to a NT

Alpha GTP slides over

sixth step of slow response: direct coupling to a NT

Open/ close channel

seventh step of slow response: direct coupling to a NT

membrane potential of post-synaptic change

What are the names of the two slow responses to a NT?

Secondary messenger and Direct coupling

How many steps are in the slow response: Secondary messenger to a NT

4

First step of Slow response: Secondary messenger in response to a NT

NT binds to a receptor

second step of Slow response: Secondary messenger in response to a NT

Activate G-Protein mechanism

third step of Slow response: Secondary messenger in response to a NT

Activate amplifier enzyme

fourth step of Slow response: Secondary messenger in response to a NT

open/ close channel then changes membrane potential of cell

How many types of graded potentials are there?

4

Where are postsynaptic potentials located?

neurons

where are End-plate potentials locate ?

Skeletal muscle

where are slow-wave potentials located?

smooth muscle

Where are pacemaker’s potentials located?

Cardiac Muscles

In fast EPSP’s what does it open?

Na/K channels

In slow EPSP’s what does it close?

K channels

In EPSP’s are the Na/ K depolarizing or hyperpolarizing?

depolarizing

In IPSP’s what are the two things the fast channel open?

K & Cl- channels

Is the IPSP fast open channels hyperpolarizing or depolarizing?

Hyperpolarizing

What exception do the open Cl- channels do in IPSPs? Depol or stable at rest

stable at rest

How many steps are in fast response EPSP

5

first step of fast response EPSP mechanism

NT binds to receptor

second step of fast response EPSP mechanism

channel

third step of fast response EPSP mechanism

Na influx & K efflux through same channel

fourth step of fast response EPSP mechanism

Na ions will bring their positive into cell

fifth step of fast response EPSP mechanism

depolarization of post-synaptic cell

first step of slow response EPSP mechanism

NT binds to a receptor

second step of slow response EPSP mechanism

activate 2nd messenger

third step of slow response EPSP mechanism

cell response closes K channels

fourth step of slow response EPSP mechanism

Allows more K to stay inside cell, having outside membrane a more positive

fifth step of slow response EPSP mechanism

Cell depolarization

First step of Fast IPSP: K channels mechanism

NT binds to receptor

second step of Fast IPSP: K channels mechanism

open K channels

third step of Fast IPSP: K channels mechanism

Increases K efflux

fourth step of Fast IPSP: K channels mechanism

Membrane potential hyperpolarizes

What are the 2 initial conditions of the Fast IPSP: Cl- channels

Cl- pumps with primary active transport create Cl- gradient

Acetyl Coa + Choline =

Acetylcholine

first step of acetylcholine synapse

make acetylcholine

second step of acetylcholine synapse

Ca influx of voltage gated Ca+ channels

third step of acetylcholine synapse

exocytosis of Ach

fourth step of acetylcholine synapse

Ach in cleft will bind to cholinergic receptor on post-synaptic cell

Nictinic slow or fast?

fast

Muscarinic slow or fast?

slow

How do you degrade away Ach?

turn Ach → acetate & choline

Does acetate once broken down diffuse away or reuptaken by presynaptic neuron?

diffuse away

Does choline once broken down diffuse away or reuptaken by presynaptic neuron?

reuptaken by presynaptic neuron

Where is Monoamine oxidase found?

synaptic cleft

What is the function of Monoamine oxidase?

Breaksdown biogenic amines