Lecture 4- Synaptic communication

Question 1

What are the two proteins that set up the resting membrane potential:

Answer 1

1) Sodium potassium transporter
2) Leak potassium channels

Question 2

What are the 3 voltage gated ion channel proteins involved in the action potential:

Answer 2

3) Voltage gated SODIUM channel
4) Voltage gated POTASSIUM channel
5) Voltage gated CALCIUM channel

Question 3

Why is it that an ion channel can be permeable to K+ but not Na+?

Answer 3

Because K+ is bigger (more protons, neutrons, electrons) and they have the same charge when dissolved in water

Question 4

How do potassium ion channels only let in the bigger element? (K+)

Question 5

In genetics, a promoter is a region of DNA that initiates transcription of a particular GENE, what does it indicate regarding cells?

Answer 5

They indicate what kind of cells should read the gene and when.

—-Promoter———–|gene for potassium ion channel

Question 6

How many distinct genes does the human genome contain for the voltage gated potassium channel?

Answer 6

40, each cell can express any combination to optimize cell function.

Question 7

What is a Neuroglia (or Glial cells)? where are they found?
Name the 3 types of glial cells:

Answer 7

Glial are found all over neurons. They help traffic nutrients and maintain molecular stability. Glials outnumber neurons in the brain.

There are astrocytes, microglia, oligodendrocytes.

Question 8

What is an Astrocyte?

Answer 8

It is a glial cell that provides physical support and cleans up debris in the brain through PHAGOCYTOSIS.
They control chemical composition of the surrounding environment and help nourish neurons.

Question 9

What is microglia?

Answer 9

It is the smallest of the glial cells. Thye provide an immune system for the brain and protect the brain from invading microorganisms

Question 10

What are oligodendrocytes?

Answer 10

Oligodendrocytes produce myelin sheath, which encapsulates axons. The sheath is not continuous, it is a series of segments, The Exposed axon is called the NODE of RANVIER.

Question 11

What is saltatory conduction?

Answer 11

The conduction of actions potentials by myelinated axons.
Action potential jumps from one node of Ranvier to next, the strength of the signal is regenerated with additional voltage gated Na+ channels.

Question 12

What is is synapse? How is synaptic communication achieved?

Answer 12

It is a junctions between axon terminals of the sending neuron and the cell membrane of the receiving neuron.

The communication is achieved by the release of a molecule from an axon terminal called a neurotransmitter, it can have excitatory or inhibitory effect.

Question 13

What are synaptic vesicles? What doe they do?

Answer 13

They contain molecules of neurotransmitters. They attach to the presynaptic membrane and release a neurotransmitter into the synaptic cleft.

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Question 14

What is a synaptic cleft?

Answer 14

It is the the space between the pre and post synaptic membranes.

Question 15

What is the PRE-synaptic membrane?

Answer 15

The membrane of the terminal button, this is where the neurotransmitter is released from.

Question 16

What is the POST-synaptic membrane?

Answer 16

It is the membrane of a receiving cell that is opposite the axon terminal.

Question 17

What is an electron microscopy?

Answer 17

This allows us to see small anatomical structures using a special electron microscope

Question 18

What are signalling molecules that bind to protein receptors called?

Answer 18

Ligands, neurotransmitters are ligands.

Question 19

What are the two categories of neurotransmitter receptors:

Answer 19

-Ionotropic, which are ion channels
-Metabotropic receptors, Which are g proteins coupled receptors that can open ion channels through an intercellular signaling cascade.

Question 20

Neurotransmitter receptors that can be found on the cell membrane or inside the cell are called: (2)

Answer 20

-POST-synaptic receptors: located on postsynaptic membrane
-PRE-synaptic receptors: located on presynaptic membrane

Question 21

What is a Binding site?

Answer 21

The location on a receptor protein to which a ligand binds.

Question 22

What is a ligand-gated ion channel?

Answer 22

A receptor that is an ion channel, also known as an ionotropic receptor, the ion channel opens when the ligands binds to it.

Question 23

What is Enzymatic deactivation?

Answer 23

The destruction of a neurotransmitter by enzyme after its release

Question 24

What is the action of reuptake?

Answer 24

Reentry of a neurotransmitter just liberated by a terminal button back through its membrane, thus terminating postsynaptic potential.

Question 25

What is postsynaptic potential?

Answer 25

Alterations in the membrane potential of a postsynaptic neuron, produced by neurotransmitter release into the synapse and receptor activation.

Question 26

Postsynaptic potentials can either be (2):

Answer 26

EXCITATORY: positive sodium ions depolarize the cell
or
INHIBITORY: negative chloride ions hyperpolarize the cell.

Question 27

What is hyperpolarization? Give an example:

Answer 27

When the membrane potential of a cell becomes more negative than it normally is at rest.
Ex. Acute influx of negative ions Cl- hyperpolarize a neuron from -60 to -70 mV.

Question 28

What is depolarization? Give an example:

Answer 28

When the membrane potential of a cell becomes less negative than it normally is at rest.

Ex, Acute influx of positive ions Na+ depolarize an ion channel from -60 to -50mV.

Question 29

What is excitatory postsynaptic potential (EPSP)? What will it be more permeable to?

Answer 29

Excitatory depolarization of postsynaptic membrane caused by neutransmitter binding to a postsynapstic receptor protein.

EPSP are mediated by receptor prtoeins that open ions channels permeable to sodium (+) = depolarize cell.

Question 30

What is Inhibitory postsynaptic potential (IPSP)?
What will it be more permeable to?

Answer 30

Inhibitory hyperpolarization of postsynaptic membrane caused by neurotransmitter binding to a postsynaptic receptor protein.

IPSP are mediated by receptor proteins that open ions channels permeable to chloride(-).
= hyperbolize the cell.

Question 31

The interaction of the excitatory and inhibitory synapses on a particular neuron is called :

Answer 31

Neural integration