Communication in the Brain

Question 1

A rule of nature is that?

Answer 1

if you separate/move things out of equilibrium, they will tend to re-equilibrate

Question 2

What is the resting electric potential of a neuron?

Answer 2

The resting potential is -70mv.

Question 3

Neurons have more _______ charged ions inside their membrane than outside.

Answer 3

Negatively. The neuron is polarized.

Question 4

How do neurons send signals?

Answer 4

They send signals through action potentials.

Question 5

Action potentials are…?

Answer 5

Short lived, spreading, localized change in membrane polarity. They are fast and direct.

Question 6

Where do action potentials start?

Answer 6

Action potentials start in the axon hillock

Question 7

What is outside the neuron cell?

Answer 7

Positively charged sodium (Na) ions and even more negatively charged chloride (Cl) ions

Question 8

What is inside the neuron cell?

Answer 8

Lesser amount of positively charged potassium (K) ions and an even greater quantity of negatively charged proton ions

Question 9

What does the membrane potential reach during an action potential?

Answer 9

it briefly reaches a potential of +30mv

Question 10

What is depolarization?

Answer 10

Any changes that reduces the cell’s resting potential of -70mv is a depolarization occurring. Neurons move toward being (+) charged

Question 11

What is the way information follows?

Answer 11

Dendrites->cell body->axon-> axon terminal

Question 12

How fast do action potential travel?

Answer 12

Action potentials travel at around 30-120m/s

Question 13

What is a cell membrane?

Answer 13

The cell membrane separates the inside and the outside of cells

Question 14

What are ion channels?

Answer 14

Ion channels act as gates that permit what goes in and out of cells

Question 15

How does an action potential happen?

Answer 15

The action potential occurs when when a neuron releases a neurotransmitter into the synapse, which leads to an ion channel opening and allowing the flow of positively charged Na ions into the cell. The area around the cell becomes positively charged (EPSP) and cancels out the negative charged. if enough positively charged ions flow into the cell and the membrane potential reaches the threshold of excitation at the axon hillock, this will trigger an action potential. Once the action potential has been triggered it will moves all the way from the axon hillock down to the terminal buttons and cannot be stopped as it fires in an “all or nothing” way.

Question 16

What is the synapses?

Answer 16

The synapses are the points of contact between 2 neurons and the site of inter-neuron information transfer

Question 17

What is the post synaptic neuron?

Answer 17

The cell on the receiving end of the synapse

Question 18

What is the pre-synaptic neuron?

Answer 18

The cell sending the signal

Question 19

What is the synaptic cleft?

Answer 19

The empty space between the 2 neurons, chemical messages are sent across this gap

Question 20

What are the 4 steps of synaptic transmission?

Answer 20

1. Neurotransmitters are synthesized and stored in the pre-synaptic axon terminals
2. Action potentials stimulate the release if neurotransmitters into the synaptic cleft
3. Neurotransmitters bind to receptor-specialized proteins embedded into the post-synaptic membrane
4. Receptors are often coupled in ion channels that open when bound a neurotransmitter. Influx of ion changes the membrane potential of post synaptic neuron, causing post synaptic potentials

Question 21

What is a Excitatory Post Synaptic Potential (EPSP)?

Answer 21

an EPSP occurs when receptors (glutamate) allow influx of cations, it depolarizes post synaptic membrane, increasing likelihood of AP

Question 22

What is an Inhibitory Post Synaptic Potential (IPSP)?

Answer 22

an IPSP occurs when receptors (GABA and glycine) allow an influx of anions, it hyperpolarizes the post synaptic membrane, which decreases likelihood of AP

Question 23

What do EPSPS do

Answer 23

They move the neurons closer to -50mv (threshold of excitation for AP)

Question 24

What are the major classes of Neurotransmitters?

Answer 24

Amino Acids: Glutamate, Glycine, GABA

Monoamines: Dopamine, Norepinephrine, Epinephrine, Serotonin

Peptides: Vasopressin, Oxytocin, Neuropeptide Y

Question 25

What is a Ligand?

Answer 25

Molecules that bind to and activate receptors

Question 26

How do you deactivate NTs

Answer 26

Diffusion: some of the NT diffuses away from the synaptic cleft

Degradation: specialized enzymes break NTs down into inactive molecules

Reuptake: specialized protein called reuptake transporters recycle neurotransmitters into the pre-synaptic terminal

Glial Cells: neighbouring glial cells may also take up stray NTs