Neurobiology- Neurophysiology

Question 1

What is chemical signaling in neurons and where is it utilized?

Answer 1

Is signaling between cells (neuron to neuron or neuron to myocyte)

Occurs at synapse

Question 2

What is electrical signaling in neurons and where is it utilized?

Answer 2

Is signaling within neurons themselves

Occurs in neurons

Question 3

What is the resting membrane potential?

Answer 3

concentration of ions creates a charge differential across the membrane

More negative inside the cell and more positive on the outside of the cell

Question 4

How is the resting membrane potential maintained?

Answer 4

Maintained by a Na/K pump and K+ leak channels

Question 5

What factors contribute to the ion gradients across the cell membrane?

Answer 5

The charge of the ion

The size of the ion

the concentration of the ion across the membrane

Question 6

What factors contribute to the opening of sodium, chloride and potassium channels?

Answer 6

the binding of signaling molecules such as neurotransmitters (ligand-gated ion channels), or on the voltage across the membrane (voltage-gated ion channels).

Question 7

What is an action potential?

Answer 7

Depends on the charge differential across the membrane

Question 8

Where are Action potentials formed?

Answer 8

At the synapse between 2 neurons or a neuron and a myocyte

Question 9

What is an Post-synaptic potential?

Answer 9

• Open when they bind to a ligand (neurotransmitter)

Question 10

Where each are Post-synaptic potentials formed?

Answer 10

at the axon terminal where neurotransmitters is stored and released

Question 11

Describe the role of voltage gated ion channels in action potential transmission along an axon.

Answer 11

Resting membrane potential depolarization that activates the Na+ channel allowing Na+ into the cell that causes further depolarization down the axon.
- This brings the membrane potential to be more positive on the inside and negative on the outside

Na+ channels close

K+ channels will open (slower than Na+ channels) allowing K+ into the cell.
- This brings the membrane potential back to more negative inside the cell and positive outside the cells.

Resting membrane potential is reached

Question 12

How does axon diameter affect the speed of action potential propagation.

Answer 12

The speed of action potential increases as the axon diameter increases

Question 13

How does myelination affect the speed of action potential propagation.

Answer 13

It increases the speed of the action potentials by decreasing leakage of ions. Electrical signals jump across the myelinated parts of the axon and only the voltage gated channels in the gaps between myelination (Nodes of Ranvier) have to open.

Question 14

What is myelin?

Answer 14

an insulating sheath

Question 15

How does excitatory postsynaptic potentials determine whether or not a neuron will fire an action potential.

Answer 15

Release of excitatory neurotransmitters binds and opens Na+ channels allowing Na+ to flow into the cell making the inside of the cell more positive and the outside of the cell more negative

Question 16

How does inhibitory postsynaptic potentials determine whether or not a neuron will fire an action potential.

Answer 16

Release of inhibitory neurotransmitters binds and opens Cl- channels allowing Cl- to flow into the cell making the inside of the cell more negative and the outside of the cell more positive

Question 17

What does Excitatory postsynaptic potentials do to the membrane & why?

Answer 17

Depolarizes the membrane

Usually due to sodium channel opening

Question 18

What does inhibitory postsynaptic potentials do to the membrane & why?

Answer 18

Hyperpolarizes membrane

Usually due to calcium channel opening

Question 19

What occurs at the axon hillock that determines whether or not a neuron will fire an action potential?

Answer 19

all of the changes are going to be added up either resulting in a big depolarization or big hyperpolarization, resulting in either the firing of an action potential or not.

Question 20

What are ionotropic neurotransmitter receptor characteristics?

Answer 20

Produce and electrical signal
Binding of a transmitter directly opens or closes ion channel
Usually made of protein subunits forming a pore
Fast
Short-lived effect
Local effect

Question 21

What are metabotropic neurotransmitter receptor characteristics?

Answer 21

Produce s a chemical signal with a potential secondary electrical signal
Binding of transmitter activates second messengers
Protein with 7 transmembrane regions
May indirectly open or close ion channels
Slower
Longer lasting
Can have effects throughout the cell

Question 22

Where is Acetylcholine made & how?
What is its function?
Where is its site of action?
What type of receptors does it have?

Answer 22

in nerve terminals from acetyl coenzyme A (acetyl CoA, which is synthesized from glucose) and choline, in a reaction catalyzed by choline acetyltransferase

Excitatory & inhibitory

CNS and PNS in the neuromuscular junctions

Ionotropic & Metabotropic

Question 23

Where is Glutamate made & how?
What is its function?
Where is its site of action?
What type of receptors does it have?

Answer 23

is recycled and made by glial cells in your brain. Glial cells convert “used” glutamate to glutamine, which is converted back again into glutamate when delivered back to the terminal area of nerve cells

Excitatory, responsible for excitatory postsynaptic potentials

acts on postsynaptic glutamate receptors

Ionotropic & Metabotropic

Question 24

Where is GABA made & how?
What is its function?
Where is its site of action?
What type of receptors does it have?

Answer 24

synthesized in the cytoplasm of the presynaptic neuron from the precursor glutamate by the enzyme glutamate decarboxylase

Inhibit postsynaptic potentials

brain

Ionotropic & Metabotropic

Question 25

Where is Catecholaminesmade & how?
What is its function?
Where is its site of action?
What type of receptors does it have?

Answer 25

produced by both neurons and by the cells of the adrenal medulla

Speed up HR, RR, blood pressure etc

CNS and sympathetic nervous system

Metabotropic

Question 26

Where is Serotonin & how?
What is its function?
Where is its site of action?
What type of receptors does it have?

Answer 26

produced in neurons

regulation of behavior

At rest, serotonin is stored within the vesicles of presynaptic neurons. When stimulated by nerve impulses, serotonin is released as a neurotransmitter into the synapse

Ionotropic & Metabotropic

Question 27

Where is Endogenous opioids& how?
What is its function?
Where is its site of action?
What type of receptors does it have?

Answer 27

produced in the pituitary gland

block pain signals

opioid receptors (mu, delta, nociception, zeta)

Metabotropic

Question 28

What is the role of astrocytes in synthesis and recycling of neurotransmitters?

Answer 28

Astrocytes can recycle glutamate & GABA in the CNS

Question 29

What happens in step one: neurotransmitter synthesis?

Answer 29

neuropeptide neurotransmitters synthesized in the bell body & transported to the axon terminal

Question 30

What happens in step two: neurotransmitter packaging?

Answer 30

Peptide is packaged in vesicle and then transported down the axon (Endogenous opioids)

Synaptic vesicle is formed in the golgi apparatus and transported down the axon (most neurotransmitters

Transmitters are packaged into vesicles by specific transporters

Process requires calcium

Question 31

What happens in step three: neurotransmitter release?

Answer 31

Mediated by voltage gated calcium channels

Vesicles move to the synapse

Vesicular membrane fuses with plasma membrane

Neurotransmitter is released into synaptic cleft

Question 32

What happens in step four: neurotransmitter binds to receptor?

Answer 32

Effects depend on type of receptor

Can also bind to presynaptic receptors which usually terminate release of transmitter

Question 33

What happens in step five: neurotransmitter is degraded or recycled?

Answer 33

The synaptic vesicle membrane that fused with the cell membrane can phagocytose & recycle neurotransmitters