Synapse and neurotransmitters

Question 1

Electric synapse

Answer 1

Fast response, bideriectional, synchronization among neurons, coordination intracellular signaling.

Question 2

Chemical synapse

Answer 2

Slower, but more controlled response or abundant, more precise and selective. Uses neurotransmitters or chemical signals.

Question 3

The steps in the chemical synapse (9 steps)

Answer 3

1. Transmitter synthezised and stored in synaptic vesicles
2. Action potential invading axon terminal
3. Depolarization of axon terminal and calcium channel opening
4. Fusion of synaptic vesicles with presynaptic membrane
5. release of neurotransmitters via exocytosis
6. transmitter binding to receptor molecules on postsynaptic membrane.
7. Opening or closing of postsynaptic channels.
8. Removal of neurotransmitters for synaptic cleft
9. Retrieval of vesicles for recycling.

Question 4

Condition of neurotransmitters

Answer 4

1. They must be present in the presynaptic terminals
2. The release of transmitters must be a response to presynaptic depolarization and the release must be calcium dependent.
3. The transmitters must act on specific reseptors on the postsynaptic neuron.

Question 5

Small Molecule neurotransmitters

Answer 5

A type of neurotransmitters

Monoamines: dopamine, Noreniphrine, epinephrine

Aminoacid neurotransmitters: glutamate, GABA

Achetocholine

Question 6

Different kinds of neurotransmitters

Answer 6

Small molecule neurotransmitters

Neuropeptides

Gaseous neurotransmitters

Question 7

Ionotropic receptors

Answer 7

A type of neurotransmitter receptor that directly control the opening of ion channels in response to the binding of a neurotransmitter.

Key features:
- fast signaling
- direct action (ligand-gated channels)
- ionic flow, dependent on the type of ion it can lead to excitation (ex. Na+ or Ca+2) or inhibition (Cl-).

Types of inotropic receptors:
- AMPA or NMDA receptors (manly for glutamate)
- GABA (manly for inhibition)

Question 8

Metabotropic receptors

Answer 8

A type of neurotransmitter receptor that do not directly control ion channels but instead initiate a cascade of intracellular signaling processes through the activation of G-proteins or other second messenger systems.

Key features:
- Indirect action
- Slower but more long lasting effects.
- signaling diversity

Question 9

Agonist drug

Answer 9

Substance that promotes activity of neurotransmitters.

You can have a direct (binds directly to the cites of neurotransmitters) and indirect antagonist (binds to other sites, but thereby stimulates the original action process).

Question 10

Antagonist

Answer 10

Substance that reduce the activety of neurotransmitters. An antagonist directly or indirectly blocks the binding sites of neurotransmitters.

Question 11

Glutamate

Answer 11

Formed by glutamine + glutaminase

Famous for its excitatory actions

Question 12

NMDA receptor

Answer 12

A ligland-gated and voltage-gated receptor.

Important in a lot of different functions, ex. learning and memory.

Question 13

GABA

Answer 13

Inhibitory neurotransmitter

GABA-A: ionotropic receptors, open to negative ions, leads to hyperpolarizng the membrane, which makes it less likely to fire, and are therefore inhibitory.

Has a sedative effect.

Question 14

Types of monoamines

Answer 14

Dopamine
Norepinephrine
Epinephrine
Serotonin
Melatonin

Question 15

Dopamine

Answer 15

synteziesed from L-dopa.

Areas in the brain
- Substantia gratia
- Ventral tagmental area (VTA)
- Hypothalamus, ofactory bulb and retina

Several dopamine pathways in the brain.

5 subtypes of dopamine receptors in the brain; D1 to D5. the distribution of these receptors determine what kind of effect dopamine has on behavior. some cause inhibition, others exitation.

involved in many areas like; movement, reward experience, memory, lactation, attention, motivation, arousal etc.

Question 16

The dopaminergic pathways in the brain

Answer 16

Nigrosstratal pathway: from substantia nigra to the striatum

Mesostriatal pathway: Ventral tagmental area (VTA) to the nucleus accumbens and other limbic structures (amygdala and hippocampus)

Mesocortical pathway: from VTA to cerebral cortical ereas.