Peripheral Nervous System And Synaptic Pharmacology 8: Neurotransmitters

Phenylethanolamine N-methyl transferase is the correct answer because it is the enzyme responsible for catalyzing the conversion of noradrenaline to adrenaline. This enzyme adds a methyl group to the noradrenaline molecule, resulting in the formation of adrenaline. Tyrosine hydroxylase is involved in the synthesis of noradrenaline from tyrosine, while dopamine beta-hydroxylase converts dopamine to noradrenaline. DOPA decarboxylase is responsible for converting L-DOPA to dopamine.

Acetylcholine acts as a neurotransmitter in the post-ganglionic fibers of the parasympathetic nervous system. This means that acetylcholine is released from nerve endings in the parasympathetic nervous system and acts on target cells to transmit signals between neurons. Acetylcholine is involved in many functions of the parasympathetic nervous system, such as regulating heart rate, digestion, and relaxation responses. Therefore, the statement "Acetylcholine acts as a neurotransmitter in the post-ganglionic fibers of the parasympathetic nervous system" is true.

In the uptake 1 mechanism of noradrenaline breakdown, noradrenaline is recycled back into the synaptic terminal through the NET (noradrenaline transporter). This means that after release, noradrenaline is taken back up by the presynaptic neuron, allowing for reuptake and reuse of the neurotransmitter. This process helps regulate the levels of noradrenaline in the synaptic cleft and allows for efficient neurotransmission.

Acetylcholine is indeed a neurotransmitter of the somatic efferent system. The somatic efferent system is responsible for the voluntary control of skeletal muscles. Acetylcholine is released at the neuromuscular junction, where it binds to receptors on the muscle fibers, initiating muscle contraction. This neurotransmitter plays a crucial role in transmitting signals from the central nervous system to the skeletal muscles, allowing for voluntary movement. Hence, the statement is true.

DOPA decarboxylase is the enzyme responsible for the conversion of DOPA to dopamine. This enzyme catalyzes the decarboxylation reaction, which removes a carboxyl group from DOPA and forms dopamine. Tyrosine hydroxylase, on the other hand, is responsible for the conversion of tyrosine to DOPA. Phenylethanolamine N-methyl transferase is involved in the conversion of norepinephrine to epinephrine. Dopamine beta-hydroxylase converts dopamine to norepinephrine. Therefore, DOPA decarboxylase is the correct enzyme for the conversion of DOPA to dopamine.

GABA is the major inhibitory neurotransmitter of the CNS. It plays a crucial role in regulating neuronal activity by inhibiting the firing of neurons. This helps to maintain a balance between excitation and inhibition in the brain, preventing overstimulation and promoting relaxation. GABA is involved in various physiological processes such as reducing anxiety, promoting sleep, and regulating muscle tone. Dysfunction in GABAergic signaling has been implicated in several neurological disorders, including epilepsy, anxiety disorders, and insomnia.

5-HT is another name for serotonin, a biogenic amine.

Noradrenaline acts as a neurotransmitter at the post-ganglionic fibers of the sympathetic nervous system. This means that it is released by neurons in the sympathetic ganglia and transmits signals to target cells in various organs and tissues. Noradrenaline is involved in the fight-or-flight response, increasing heart rate, constricting blood vessels, and mobilizing energy resources. It helps to activate and regulate the sympathetic nervous system, which is responsible for the body's response to stress and emergencies.

Tyrosine hydroxylase is the correct answer because it is the enzyme responsible for catalyzing the conversion of tyrosine to DOPA. This enzyme adds a hydroxyl group to the tyrosine molecule, resulting in the formation of DOPA. This conversion is an important step in the synthesis of neurotransmitters such as dopamine, norepinephrine, and epinephrine.

Dopamine beta-hydroxylase is the correct answer because it is the enzyme responsible for catalyzing the conversion of dopamine to noradrenaline. Tyrosine hydroxylase is involved in the conversion of tyrosine to dopamine, not the conversion of dopamine to noradrenaline. Phenylethanolamine N-methyl transferase is involved in the conversion of noradrenaline to adrenaline, not the conversion of dopamine to noradrenaline. DOPA decarboxylase is involved in the conversion of L-DOPA to dopamine, not the conversion of dopamine to noradrenaline.

Nicotonic receptors are ligand-gated ion channels, meaning they open in response to the binding of a specific ligand (in this case, nicotine) and allow the flow of ions across the cell membrane. This is characteristic of ionotropic receptors, which directly control ion flow. G-protein coupled receptors, on the other hand, do not directly control ion flow but instead activate intracellular signaling pathways through G-proteins. Therefore, the correct answer is that nicotonic receptors are ligand-gated ion channels (ionotropic receptors).

The synthesis of adrenaline from tyrosine involves a series of enzymatic reactions. First, tyrosine is converted into DOPA by the enzyme tyrosine hydroxylase. DOPA is then decarboxylated to form dopamine by the enzyme DOPA decarboxylase. Dopamine is further converted into noradrenaline by the enzyme dopamine beta-hydroxylase. Finally, noradrenaline is methylated to form adrenaline by the enzyme phenylethanolamine N-methyltransferase. Therefore, the correct pathway in the synthesis of adrenaline from tyrosine is Tyrosine -> DOPA -> Dopamine -> Noradrenaline -> Adrenaline.

False. Most neurotransmitters are actually located within the central nervous system (CNS), which includes the brain and spinal cord. The CNS is responsible for processing and transmitting information throughout the body. While some neurotransmitters are also found in the peripheral nervous system (PNS), which consists of the nerves outside of the CNS, the majority of them are concentrated in the CNS.

Exogenous application exerts the same effect as endogenous.

Acetylcholine acts as the neurotransmitter of all pre-ganglionic fibres of the autonomic nervous system.

Choline acetyltransferase is involved in the process of producing acetylcholine via the modification of choline with an acetyl c-enzyme. It transfers an acetyl group from acetyl-CoA to choline, resulting in the formation of acetylcholine.

Muscarinic receptors are G-protein coupled receptors, which means they are metabotropic receptors. G-protein coupled receptors are a type of receptor that are activated by a ligand, such as a neurotransmitter, and then activate intracellular signaling pathways through the interaction with G-proteins. This is in contrast to ionotropic receptors, which are ligand-gated ion channels that directly allow ions to flow into or out of the cell when activated by a ligand. Therefore, the correct answer is that muscarinic receptors are G-protein coupled receptors (metabotropic receptors).

Glutamate is the major excitatory neurotransmitter of the central nervous system (CNS). It is involved in promoting the transmission of nerve impulses and plays a crucial role in various cognitive processes such as learning and memory. Glutamate acts on specific receptors in the brain, causing an excitatory response and enhancing the communication between neurons. This excitatory effect is essential for normal brain function and is balanced by inhibitory neurotransmitters to maintain the overall neuronal activity within a healthy range.

Glycine is an inhibitory neurotransmitter of the CNS. This means that it functions to decrease or inhibit the activity of neurons in the central nervous system. It helps to regulate and balance the overall excitability of the brain and spinal cord. By binding to specific receptors, glycine can decrease the likelihood of an action potential being generated, leading to a decrease in neuronal activity. This inhibitory effect is crucial for maintaining the proper functioning of the CNS and preventing excessive neuronal firing.

Acetylcholine is not a biogenic amine because it is not derived from the amino acids tyrosine or tryptophan, which are the precursors for the other neurotransmitters listed. Acetylcholine is synthesized from the precursor molecule choline, which is obtained from the diet. Therefore, while noradrenaline, adrenaline, dopamine, serotonin, and histamine are all biogenic amines, acetylcholine is not.

Sildenafil interferes with the action of nitric oxide as a neuromodulator. Nitric oxide is a signaling molecule that plays a role in various physiological processes, including neurotransmission. It acts as a neuromodulator by regulating the release and activity of neurotransmitters in the brain. Sildenafil is a medication used to treat erectile dysfunction by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which leads to increased levels of nitric oxide in the body. However, this increased level of nitric oxide can interfere with its normal neuromodulatory functions, potentially causing side effects.

Choline is reuptaken into the pre-synaptic terminal through a specific Ch-Na+ symport cotransporter. This means that choline is transported into the cell along with sodium ions, using the same transporter protein. This symport mechanism allows for the simultaneous movement of both choline and sodium ions in the same direction, into the pre-synaptic terminal.

Acetylcholine is transferred into the synaptic vesicles through cotransport against its concentration gradient. This process involves the use of a proton pump to generate energy and an antiport coupled channel (ACh-H+) to facilitate the transfer of acetylcholine into the cell. The proton pump creates a gradient by pumping protons out of the vesicle, which in turn generates energy for the cotransport of acetylcholine. The antiport coupled channel allows for the simultaneous exchange of protons and acetylcholine, effectively transferring acetylcholine into the synaptic vesicles.