C Synapses, Neurotransmitters Exam 3

What is a synapse?

A specialized site where a neuron communicates with another cell.

What is the role of the presynaptic neuron?

It sends the message.

What is the role of the postsynaptic neuron?

It receives the message.

What are the two types of synapses?

Electrical synapses and chemical synapses.

How do electrical synapses function?

They involve direct physical contact between cells, allowing ions to pass through gap junctions.

Where are electrical synapses commonly found?

In some areas of the brain, such as the respiratory nuclei of the brainstem.

What is the primary characteristic of chemical synapses?

They transmit signals across a gap using neurotransmitters.

What components are involved in a chemical synapse?

Presynaptic element, neurotransmitter, synaptic cleft, receptor proteins, and postsynaptic element.

What neurotransmitter is released at the neuromuscular junction (NMJ)?

Acetylcholine.

What happens when an action potential reaches the axon terminals?

Voltage-gated Ca2+ channels open, increasing Ca2+ concentration inside the end bulb.

What is the process of neurotransmitter release called?

Exocytosis.

How does a neurotransmitter interact with the postsynaptic membrane?

It diffuses across the synaptic cleft and binds to specific receptors.

What happens to neurotransmitters after they bind to receptors?

They are cleared from the synapse by enzymatic degradation, neuronal reuptake, or glial reuptake.

What are the four major groups of neurotransmitter systems?

Cholinergic system, amino acids, biogenic amines, and neuropeptides.

Which neurotransmitter is associated with the cholinergic system?

Acetylcholine.

Name two amino acid neurotransmitters.

Glutamate and GABA.

What are biogenic amines?

A group of neurotransmitters including serotonin, dopamine, norepinephrine, and epinephrine.

What are neuropeptides?

A group of neurotransmitters that includes met-enkephalin, beta-endorphin, and substance P.

What is the function of acetylcholinesterase at the NMJ?

It breaks down acetylcholine in the synaptic cleft.

What is the significance of neurotransmitter specificity?

Each neurotransmitter binds specifically to its receptor, ensuring precise signaling.

What neurotransmitter is released by the cholinergic system?

Acetylcholine (ACh)

Where is acetylcholine released?

At all neuromuscular junctions involving skeletal muscle fibers, many synapses in the CNS, all neuron-to-neuron synapses in the PNS, and all neuromuscular and neuroglandular junctions in the parasympathetic division of the ANS.

What are the two major types of receptors in the cholinergic system?

Nicotinic receptors and muscarinic receptors.

whats starts syntheiss of acytlCoA

vitamin B5 (pep..

What is the function of nicotinic receptors?

They are found in the neuromuscular junction (NMJ) and other synapses.

What is the function of muscarinic receptors?

They are involved in various parasympathetic responses.

What drugs bind to nicotinic and muscarinic receptors?

Nicotine binds to nicotinic receptors, while muscarine binds to muscarinic receptors.

Can nicotine bind to muscarinic receptors?

No, nicotine will not bind to muscarinic receptors.

Can muscarine bind to nicotinic receptors?

No, muscarine will not bind to nicotinic receptors.

What is the role of acetylcholine in the body?

It regulates learning, memory, and sleep-wake cycling.

What is the source of choline in acetylcholine synthesis?

Choline is a vital nutrient, though not classified as essential.

What is the enzyme responsible for synthesizing acetylcholine?

Choline acetyltransferase.

What are the reactants in the synthesis of acetylcholine?

Acetyl-CoA and choline.

What are the products of the acetylcholine synthesis reaction?

Acetylcholine (ACh) and HS-CoA.

What is the chemical structure of Acetyl-CoA?

H3C-C(=O)-S-CoA

What is the chemical structure of choline?

HO-CH2-CH2-N+(CH3)3

What is the chemical structure of acetylcholine?

H3C-C(=O)-O-CH2-CH2-N+(CH3)3

What is the chemical structure of HS-CoA?

HS-CoA

What vitamin is essential for the synthesis of Coenzyme A?

Pantothenate.

How many ATP molecules are required for the synthesis of Coenzyme A?

Four molecules of ATP.

What is the role of NAD in the context of acetylcholine synthesis?

NAD is converted to NADH, which is involved in various metabolic processes.

What are the three amino acids mentioned that function as neurotransmitters?

Glutamate, GABA (gamma-aminobutyric acid), and glycine.

What chemical groups are present in the structure of amino acids?

An amino group and a carboxyl group.

Which amino acid is used to make proteins?

Glutamate.

What are the names of the systems associated with each amino acid neurotransmitter?

Glutamatergic, GABAergic, and glycinergic systems.

Do amino acid neurotransmitters interact with each other?

No, they each have their own receptors and do not interact.

How are amino acid neurotransmitters eliminated from the synapse?

Through reuptake.

What role does the pump in the presynaptic cell membrane play?

It clears the amino acid from the synaptic cleft for recycling and repackaging.

What are biogenic amines made from?

They are enzymatically made from amino acids.

What is serotonin made from?

Tryptophan.

What system is serotonin the basis of?

The serotonergic system.

What neurotransmitter affects attention and emotional states?

Serotonin.

What is the active form of Vitamin B that is dependent on pyridoxal phosphate?

5-Hydroxytryptamine (5-HT), also known as serotonin.

What is the treatment for major depressive disorder mentioned in the notes?

Selective Serotonin Reuptake Inhibitors (SSRIs), such as fluoxetine.

What is the process called when serotonin is transported back into the presynaptic cell?

Reuptake.

What are the two main biogenic amines made from tyrosine?

Norepinephrine (noradrenaline) and epinephrine (adrenaline)

Where are norepinephrine and epinephrine released?

By adrenergic synapses

What receptors do norepinephrine and epinephrine bind to?

Alpha and beta receptors

What is dopamine's role in the central nervous system?

It acts as a neurotransmitter.

How is dopamine removed from the synapse?

By transport proteins in the presynaptic cell membrane.

What are the effects of dopamine?

It may be excitatory or inhibitory and is involved in Parkinson's disease and cocaine use.

What is the first step in the synthesis of dopamine?

L-Tyrosine is converted to L-DOPA by the enzyme tyrosine hydroxylase.

What cofactor is required for the enzyme tyrosine hydroxylase?

Iron (Fe)

What is the role of DOPA Decarboxylase in dopamine synthesis?

It converts L-DOPA to dopamine.

What cofactor is needed for DOPA Decarboxylase?

Pyridoxal phosphate (PLP)

What enzyme converts dopamine to norepinephrine?

Dopamine β-Hydroxylase (DBH)

What cofactors are required for Dopamine β-Hydroxylase?

Ascorbic acid (Vitamin C) and Copper (Cu)

What enzyme converts norepinephrine to epinephrine?

Phenylethanolamine N-methyltransferase (PNMT)

What is the methyl donor in the conversion of norepinephrine to epinephrine?

S-Adenosylmethionine (SAM)

What are neuropeptides?

Chains of amino acids connected by peptide bonds.

What is an example of a short neuropeptide?

Met-enkephalin, which is five amino acids long.

What is an example of a long neuropeptide?

Beta-endorphin, which is 31 amino acids long.

How do neuropeptides act in the body?

They are often released at synapses and can act as hormones.

What is the role of endorphins in the body?

They act as natural pain relievers and enhance positive emotions.

What triggers the release of endorphins?

Physical activity, excitement, and emotional stress.

What physiological functions do endorphins regulate?

They help modulate the body's overall stress response.

What are endocannabinoids?

Endocannabinoids are neuromodulators that bind to cannabinoid receptors.

Which psychoactive compound binds to the same receptors as endocannabinoids?

Delta9-THC (tetrahydrocannabinol)

What is neurotransmission?

Neurotransmission is the process by which neurotransmitters are released by the presynaptic neuron and bind to and react with postsynaptic neurons.

What factors regulate neurotransmission?

The availability and rate-of-synthesis of the neurotransmitter, release of the neurotransmitter, baseline activity of the postsynaptic neuron, and the number of available postsynaptic receptors.

What are the two classes of receptors neurotransmitters can bind to?

Ionotropic receptors and metabotropic receptors.

What is the function of ionotropic receptors?

Ionotropic receptors are ligand-gated ion channels that open when a neurotransmitter binds to them.

What is an example of an ionotropic receptor?

The nicotinic receptor for acetylcholine.

What is the role of metabotropic receptors?

Metabotropic receptors cause metabolic changes in the cell when the neurotransmitter binds to them.

What is the process that occurs after a neurotransmitter binds to a metabotropic receptor?

The G protein hydrolyzes ATP and activates an effector protein, which can generate a second messenger like cAMP.

What are the three types of effects neurotransmitters can have?

Direct effect on membrane potential, indirect effect through G proteins, and indirect effect via intracellular enzymes.

What is glutamate classified as?

An excitatory amino acid neurotransmitter.

What is the effect of glutamate on the postsynaptic cell?

It causes depolarization of the postsynaptic cell.

What are glycine and GABA classified as?

Inhibitory amino acids.

What effect do glycine and GABA have on the postsynaptic cell?

They cause hyperpolarization of the postsynaptic cell.

How do neurotransmitters affect ion channels?

They can open or close ion channels, leading to changes in membrane potential.

What is the significance of the receptor type for neurotransmitters?

The effect of neurotransmitters is entirely dependent on the receptor they bind to.

What is a second messenger in the context of neurotransmitter action?

A molecule like cAMP that mediates metabolic changes in the neuron after receptor activation.

What neurotransmitters are associated with direct effects on membrane potential?

Acetylcholine (ACh), glutamate, and aspartate.

What neurotransmitters are known for their indirect effects through G proteins?

Epinephrine (E), norepinephrine (NE), dopamine, serotonin, histamine, and GABA.

What role do lipid-soluble gases play in neurotransmission?

They can have indirect effects via intracellular enzymes.

Biogenic amines

Have mixed effects.

D1 receptors

Excitatory dopamine receptors.

D2-type receptors

Inhibitory dopamine receptors.

Biogenic amine receptors

Can have more complex effects.