The Tripartite Synapse exam with complete verified solutions ( PASS GUARANTEED )

How many glial cells are there in the body compared to neurons?

10-50 times as many glial cells as neurons

What are the glial cells in the PNS?

What is their role?

- called schwann cells

- make myelin for peripheral axons

what are the glial cells of the CNS? What is their role?

- microglia

- oligodendrocytes

- astrocytes

- Regulate channel expression, specifically K+ channels (so they can maintain a resting membrane potential close to Ek)

What is the most common type of glial cell in the CNS?

Where is it found?

Astrocytes

- found in gray and white matter

The tripartite (3-part) synapse consists of:

- presynaptic neuron

- postsynaptic neuron

- astrocytes

How do astrocytic processes affect synaptic transmission?

- affect diffusion and uptake of neurotransmitter from the synaptic cleft

- shape/ proximity of astrocytes is not stable

- can change over the course of minutes

- changes across sleep/ wake cycle

What are the characteristics of astrocytic transporters for glutamate uptake?

- transporters use 1 K+ to transfer 1 Glu, 1H+, 3 Na+

- transporters are EAATs, so they are electrogenic and you should be able to record current changes

what other two transporters can be found on astrocytes?

GLYT-1 and GAT

- GABA and glycine

How can astrocytes be coupled together?

astrocytes are connected to other astrocytes via gap junctions

- groups of 50-100 electrically coupled astrocytes can be regulated together

- exclusive, forming microdomains of 200-300 um

How are astrocytes involved in "information processing"?

1) astrocytes respond to external signals from other elements of the nervous system, including neurons

2) responses to external signals can change cytosolic calcium levels inside astrocytes rapidly and high temporal precision

3) astrocytes release neurotransmitters in a calcium-dependent manner

- release of neurotransmitter by astrocytes can affect neuronal responses

What does THA do to glutamate transporters on astrocytes, and how does this effect the EPSC?

Blocks all of the glutamate transporters

- completely abolishes the EPSC

what does DHK do to glutamate transporters on astrocytes, and how does this effect the EPSC?

It blocks half of the glutamate transporters, decreasing the EPSC

What types of channels can be found on astrocytes?

Potassium channels

- voltage gated Na+, Cl-, Ca2+

- Intracellular

- mechanosensitive