Lecture Three; Cell Communication; Brain Anatomy

Question 1

Whats axodentritic?

Answer 1

Pertaining to the synaptic relationship of an axon with a dendrite of another neuron.

Question 2

what isaxosomatic?

Answer 2

referring to a synapse between the axon of one neuron and the cell body of another.

Question 3

axoaxonic

Answer 3

referring to a synapse between the axon of one neuron and the axon of another.

Question 4

Exocytosis

Answer 4

When an action potential arrives vesicles with neurotransmitter (synaptic
vesicles) release their content in the synaptic cleft

Question 5

What triggers exocytosis?

Answer 5

Calcium
Depolarisation of the pre-synaptic membrane leads to the opening of “voltagedependent”
Calcium channels Calcium will flow into the cell

Question 6

What are the three Fate of vesicles after NT release?

Answer 6

1. kiss and run
2. merge and recycle
3. bulk endocytis

Question 7

What is thebinding site?

Answer 7

the location on the surface of a cell or a molecule where other cell fragments or molecules attach to initiate a chemical or physiological action.

Question 8

What is Excitatory Post-Synaptic Potential

(EPSP)?

Answer 8

When the neurotransmitter opens Na+ (sodium)
channels a depolarisation of the postsynaptic
neuron will occur

Question 9

What is depolarisation?

Answer 9

Depolarization is the process or the act by which polarity is eliminated.
Depolarization in a nerve cell occurs when the cell undergoes an electrical change. Most cells are negatively charged relative to their surroundings. This negative internal charge of the cell shifts to a positive through the process of depolarization. Depolarization though occurs for only a brief period of time.
Depolarization is essential because it allows the transmission of electrical signals (impulses) within the cell, and in certain instances, from one cell to another. Depolarization therefore is one mechanism employed by cell to carry on certain physiological functions and also to communicate with another cell.

Question 10

Hyperpolarisation?

Answer 10

any increase in the amount of electrical charge separated by the cell membrane and hence in the strength of the membrane potential. In cardiology this is the process by which an electrical fiber, at the end of phase 3 repolarization, becomes more negative than usual.

Question 11

repolarisation

Answer 11

the reestablishment of polarity, especially the return of a cell’s membrane potential to resting potential after depolarization.

Question 12

Inhibitory Post-Synaptic Potential

IPSP

Answer 12

When the neurotransmitter opens Clchannels
a hyperpolarisation of the postsynaptic
neuron will occur:

Question 13

What are Metabotropic receptors?

Answer 13

Ion channel opened in an indirect way

by small protein in membrane (G protein) or second messenger

Question 14

Second messengers

Answer 14

binding neurotransmitter
2 : leads tot activation G protein
\: α subunit activates enzym
that produces a second
messenger
3
\: the second messenger
opens ion channels
4
\: ions flow in/out the cell
(EPSP of IPSP)
5
\: Second messenger can also
influence other components
of the post-synaptic cell.
6
also! they can change cell function; by turning on/off genes

Question 15

how is the the NT concentration regulated?

Answer 15

Neurotransmitter cleared from
synaptic cleft through diffusion,
re-uptake, or degradation

Question 16

What is Enzymatic

degradation and which neurotransmitter is associated with it?

Answer 16

Only known for the neurotransmitter acetylcholine
(ACh)
The enzyme Acetylcholine-esterase (AChE) in the post-synaptic membrane
splits ACh into Choline and Acetate
Acetylcholine is present, in particular, in synapses on muscle fibers
Myasthenia Gravis: muscle weakness resulting from a deficiency in ACh
receptors
-> Treatment with AChE inhibitors: more ACh to activate remaining receptors

Question 17

What are autorecptors doing?

Answer 17

Autoreceptors regulate the reuptake and release of neurotransmitter by
the neuron.
…they are metabotropic
- Reuptake NT: G proteinen/second messengers activate reuptake transporters
- Reduction NT release: G proteinen/second messengers close Ca2+ channels, reduced
Ca2+ inflow results decreased opening of neurotransmitter vesicles
q Autoreceptoren are generally inhibitory (they reduce the concentration
of neurotransmitter in the synaptic cleft)

Question 18

Define Agonist and Antagonist!

Answer 18

Agonist: A substance that acts like another substance and therefore stimulates an action. Agonist is the opposite of antagonist, a substance which interferes with or inhibits the physiological action of another.
“LSD is a serotonin antagonist”

Question 19

Functions of neuromodulaters:
Peptides (Hormones/endogenous opioids)
Lipids (Anandamids, THC: Cannabis)
Nucleosides (Adenosine) 
Gasses (Nitric Oxide)

Answer 19

peptides: agression and bonding + pain perception
lipids: mood/ pain perception
nucleosides: control of sleep
gasses: learning/ blood vessel dilation

Question 20

Neurotransmitters vs. Neuromodulators

Answer 20

Neurotransmitters are directly involved in contact between neurons, neuromodulators are present in large regions of the brain to sensitise or desensitise complete neural networks.

Neuromodulators bind to receptors of neurons to influence the number of opened ion channels in these neurons. Due to this, many neurons in a network can be either slightly depolarised or slightly hyperpolarised, making the network either more sensitive (in case of depolarisation) or less sensitive (in case of hyperpolarisation) to input.
if many neurons in a network are slightly depolarised, their membrane potential is closer to the threshold of excitation, and therefore it is easier to exit them (you might say that alertness of the network increases).
Conversely, if many neurons in a network are slightly hyperpolarised, their membrane potential is further from the threshold of excitation, and therefore it is more difficult to exit them (you might say that alertness of the network decreases).

Question 21

tryptophan is

Answer 21

a precursor processed to serotonine

Question 22

which are the most famous monoamines, how are they called

Answer 22

catecholamine: serotonin, dopamin, epinephrine norepinephrine
idolamine

Question 23

Fate of vesicles after NT release

Answer 23

1. Kiss and Run
2. merge and recycle
3. bulk endocytosis

Question 24

enzygmatic degradation

Answer 24

Only known for the neurotransmitter acetylcholine (ACh)

Question 25

Myasthenia Gravis

Answer 25

muscle weakness resulting from a deficiency in ACh receptors
The enzyme Acetylcholine-esterase (AChE) in the post-synaptic membrane splits ACh into Choline and Acetate
Acetylcholine is present, in particular, in synapses on muscle fibers
Treatment with AChE inhibitors: more ACh to activate remaining receptors

Question 26

autoreceptors

Answer 26

Autoreceptors regulate the production and release of neurotransmitter by the neuron
they are metabotropic: Reuptake NT: G proteins/second messengers activate reuptake transporters
- Reduction NT release: G proteinen/second messengers close Ca2+ channels, reduced Ca2+ inflow results decreased opening of neurotransmitter vesicles

Autoreceptors are generally inhibitory (they reduce the concentration of neurotransmitter in the synaptic cleft)

Question 27

Effect postsynaptic potentials on postsynaptic neuron

Answer 27

spatial integration

EPSPs spread across the neuron through passive conduction
New action potential if sum of all EPSPs results in depolarisation above a threshold
Action potential starts at axon hillock (little hill: highest concentration of Na+ channels

Question 28

In case of EPSP andIPSPs, new action potential only if:

Answer 28

EPSP-IPSP=Depolarisation

Question 29

Acetylcholine

Answer 29

(learning, memory, dreaming)

Question 30

Monoamines

Answer 30

Catecholamines

Indolamines

Question 31

Catecholamines

Answer 31

Dopamine (reinforcement, motor)
Norepinephrine (alertness, fight-flight sympathetic nervous system)
Epinephrine (fight-flight sympathic nervous system)

Question 32

indolamine

Answer 32

serotonin: mood

melatonin, which regulates the sleep-wake cycle (circadian rhythm

Question 33

Amino acids:

Answer 33

Glutamate (excitatory, motor, learning)
Glycine (inhibition [spine], motor)
GABA (inhibitory, motor)

Question 34

What are neuromodulators doing?

Answer 34

wander through the brain and sensitize/desensitize complete neural networks (through subthreshold depolarisations or hyperpolarisations)

Question 35

Neuromodulators, Peptides

Answer 35

Hormones (excreted by glands: kidneys, pituitary, thyroid, etc -> Vasopressine (agression), Oxytocine (bonding)

Endogenous opioids
β-endorphin, enkephalin en dynorphin (analgesics: pain reduction) –> Morphin from poppy seeds mimics the action of opioids

Question 36

Neuromodulators, Lipids (fats: easily cross the BBB)

Answer 36

Anandamide (pain, depression, memory)

TetraHydroCannabinol (THC) = marihuana mimics Anandamide

Question 37

Neuromodulators, Nucleosides

Answer 37

part of a DNA base pair bound to sugar
Adenosine (opens K+ channels and inhibits CNS to facilitate sleep)
Adenosine accumulates during the day
Caffeine blocks adenosine receptors

Question 38

Gasses

Answer 38

produced by enzymes in certain neurons

Nitric Oxide produced from the amino acid arginine, in different cell regions, and diffuses through the cell membrane
NO diffuses to other cells and activates a second messenger (cyclic GMP)
NO is involved in dilation of blood vessels and learning
Viagra suppresses the destruction of cyclic GMP

Question 39

drug functions as precursor

Answer 39

AGO e.g.L-dopa, by enzymes in theneuron it is transformed easily to dopamine

Question 40

differnce of neuromodulators to eurotransmitters:

Answer 40

A neuromodulator can be conceptualized as a neurotransmitter that is not reabsorbed by the pre-synaptic neuron or broken down into a metabolite. Such neuromodulators end up spending a significant amount of time in the cerebrospinal fluid (CSF), influencing (or “modulating”) the activity of several other neurons in the brain. For this reason, some neurotransmitters are also considered to be neuromodulators, such as serotonin and acetylcholine.