Autonomic Nervous System MCQ Trivia: Quiz!

ACh, or acetylcholine, is indeed the primary neurotransmitter of the parasympathetic nervous system. It is responsible for transmitting signals between nerve cells and plays a crucial role in regulating various bodily functions, such as digestion, heart rate, and glandular secretion. ACh acts on specific receptors in target tissues, leading to the activation of parasympathetic responses. Therefore, the statement "ACh is the primary neurotransmitter of the parasympathetic nervous system" is true.

Uses both acetylcholine (ACh) and norepinephrine (NE) as neurotransmitters.

ACh, or acetylcholine, binds at both muscarinic and nicotinic receptors. Muscarinic receptors are found in various tissues and organs, including the heart, smooth muscles, and glands. Activation of muscarinic receptors by ACh leads to a variety of physiological responses, such as decreased heart rate and smooth muscle contraction. Nicotinic receptors are found in the neuromuscular junction and autonomic ganglia. Activation of nicotinic receptors by ACh results in muscle contraction and the transmission of signals between nerve cells. Therefore, ACh binds to both muscarinic and nicotinic receptors to mediate different physiological effects.

The autonomic nervous system includes neurons in both the central nervous system (CNS) and the periphery. The CNS consists of the brain and spinal cord, while the periphery refers to the nerves that extend from the CNS to the rest of the body. The autonomic nervous system controls involuntary bodily functions such as heart rate, digestion, and breathing. It consists of two divisions, the sympathetic and parasympathetic, which work together to maintain homeostasis in the body. Therefore, the correct answer is CNS and Periphery.

The given answer states that all the statements provided are true. The statements mentioned in the question are as follows:
1. AChE is a membrane-bound enzyme that converts ACh to choline and acetate.
2. AChE is located in the neuromuscular junction and in cholinergic synapses in the CNS.
3. One AChE molecule can degrade approximately 25,000 ACh molecules.

The explanation for the given answer is that all these statements are accurate. AChE is indeed a membrane-bound enzyme responsible for breaking down the neurotransmitter acetylcholine (ACh) into choline and acetate. It is found in both the neuromuscular junction and cholinergic synapses in the central nervous system. Additionally, one molecule of AChE has the ability to degrade around 25,000 molecules of ACh. Therefore, all the statements provided are true.

The cranial nervous system is not a component of the human nervous system. The human nervous system is composed of the central nervous system (including the brain and spinal cord), the somatic nervous system (responsible for voluntary movements), the enteric nervous system (controlling the digestive system), and the autonomic nervous system (regulating involuntary functions). The cranial nervous system refers specifically to the nerves that originate from the brain and pass through openings in the skull to reach their target organs or tissues. However, it is not considered a separate system within the human nervous system.

The termination of catecholamine signaling involves multiple mechanisms. Catecholamines can be taken back up into the nerve terminals and nearby glial cells through a process called reuptake. They can also diffuse out of the synaptic cleft. Additionally, catecholamines can undergo metabolic transformation by enzymes like monoamine oxidase and catechol-O-methyltransferase. Therefore, all of the given statements are true.

The autonomic nervous system is divided into two branches: the sympathetic and parasympathetic nervous systems. The sympathetic nervous system prepares the body for "fight or flight" responses, increasing heart rate, dilating pupils, and releasing adrenaline. On the other hand, the parasympathetic nervous system promotes "rest and digest" activities, such as slowing heart rate, constricting pupils, and stimulating digestion. Both branches work in tandem to maintain a balance in the body's physiological functions.

The sympathetic nervous system is responsible for the "fight or flight" response in the body. When activated, it causes the pupil to dilate, which allows more light to enter the eye and improves vision in low-light conditions. It also accelerates the heart rate, increasing blood flow and preparing the body for physical activity. The sympathetic nervous system dilates the bronchi, allowing more air to enter the lungs and improving breathing. It inhibits bladder contractions, preventing the need to urinate during times of stress. Additionally, it stimulates the secretion of adrenaline and noradrenaline, hormones that increase alertness and energy levels.

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Choline is recycled from degraded ACh in nerve terminals.

Choline acetyltransferase catalyzes the final step in acetylcholine (ACh) biosynthesis. ACh is a neurotransmitter that is involved in various physiological processes, including muscle contraction and cognitive function. Choline acetyltransferase transfers an acetyl group from acetyl-CoA to choline, resulting in the formation of ACh. This enzyme is primarily found in cholinergic neurons, where it plays a crucial role in maintaining proper levels of ACh for normal neurotransmission. Acetylcholine acetyltransferase, acetate acetyltransferase, and catecholine acetyltransferase are not involved in the final step of ACh biosynthesis, making choline acetyltransferase the correct answer.

In the sympathetic nervous system, the efferent and afferent fibers are found in the paravertebral chains and prevertebral ganglia. The paravertebral chains are a series of ganglia located on either side of the vertebral column, running parallel to it. These ganglia house the cell bodies of the sympathetic preganglionic neurons. The prevertebral ganglia are located anteriorly to the vertebral column and receive input from the preganglionic neurons. Together, these structures play a crucial role in transmitting signals and coordinating the sympathetic response throughout the body.

Acetylcholine is a neurotransmitter that is involved in the transmission of nerve impulses. It is synthesized in the body from acetyl coenzyme A (CoA) and choline. Acetyl CoA provides the acetyl group, while choline provides the other component necessary for the synthesis of acetylcholine. Acetylcholinesterase, on the other hand, is an enzyme that breaks down acetylcholine, rather than being involved in its synthesis. Therefore, the correct answer is acetyl coenzyme A (CoA) and choline.

The correct answer is CNS. The central nervous system (CNS) consists of the brain and spinal cord. It is responsible for processing and coordinating information from the sensory organs and sending signals to the muscles and glands in the body. The CNS plays a crucial role in controlling and regulating various bodily functions, including the autonomic nervous system, which consists of preganglionic fibers that originate in the CNS. These fibers transmit signals from the CNS to the ganglia, which are clusters of nerve cells located outside the CNS.

Most postganglionic sympathetic fibers use norepinephrine (NE) as a neurotransmitter.

Endothelin receptors (ETA, ETB1, ETB2) are GPCRs (G-protein coupled receptors) that are coupled to Gq proteins. Gq proteins are responsible for activating phospholipase C (PLC), which leads to the production of inositol trisphosphate (IP3) and diacylglycerol (DAG). These second messengers then trigger various intracellular signaling pathways, such as calcium release and protein kinase C (PKC) activation. Therefore, the correct answer is Gq.

The parasympathetic nervous system is responsible for the "rest and digest" response in the body. It promotes relaxation and conserves energy. Stimulating bile release helps in the digestion and absorption of fats. Constricting bronchi reduces airflow to the lungs, which is beneficial during rest. Slowing the heart rate helps to lower blood pressure and conserve energy. Contracting the bladder promotes urination and eliminates waste. Stimulating the flow of saliva aids in the digestion process by starting the breakdown of food.

Norepinephrine, dopamine, and epinephrine are synthesized from tyrosine. Tyrosine is an amino acid that serves as a precursor for the synthesis of these neurotransmitters and hormones. These compounds play important roles in the nervous system and are involved in various physiological processes such as mood regulation, stress response, and cardiovascular function. Acetylcholine, on the other hand, is not synthesized from tyrosine but from choline. Serotonin is derived from the amino acid tryptophan, not tyrosine.

The release of endothelins onto vascular smooth muscle causes vasoconstriction. Endothelins are potent vasoconstrictor peptides that lead to the contraction of vascular smooth muscle, thereby reducing the diameter of blood vessels and increasing blood pressure.

Binding of two ACh molecules causes the gating of a Na++ channel in Nicotinic receptors (nAChRs). This means that for the channel to open and allow the influx of Na+ ions, two molecules of acetylcholine need to bind to the receptor. This binding triggers a conformational change in the receptor, leading to the opening of the channel. This mechanism is essential for the transmission of signals in the nervous system, as it allows the flow of ions across the cell membrane, resulting in the generation of action potentials.

In the vas deferens, ATP acts on smooth muscle P2X receptors to cause a rapid twitch. This is because P2X receptors are ligand-gated cation channels that, when activated by ATP, allow the influx of cations into the smooth muscle cells, leading to muscle contraction. On the other hand, NE acts on alpha 1 receptors to cause sustained contraction. Alpha 1 receptors are G-protein coupled receptors that, when activated by NE, initiate a signaling cascade that ultimately leads to the sustained contraction of smooth muscle in the vas deferens.

Endothelins, also known as ET, are peptides that are stored in vascular endothelial cells. These peptides play a crucial role in regulating blood vessel constriction and dilation, as well as in the control of blood pressure. Endothelins are released by endothelial cells in response to various stimuli, such as inflammation or injury, and they act on nearby smooth muscle cells to cause vasoconstriction. This helps to regulate blood flow and maintain proper vascular tone. Overall, endothelins are important mediators of cardiovascular function and play a role in various physiological processes.

Nicotinic receptors (nAChRs) are ligand-gated ion channels found in multiple locations in the body. They are present in the skeletal neuromuscular junction, where they mediate muscle contraction. They are also found in the autonomic ganglia, where they play a role in the transmission of signals between the central nervous system and the autonomic nervous system. Additionally, nAChRs are present in the adrenal medulla, where they regulate the release of adrenaline. Lastly, they are found in the central nervous system, where they are involved in various functions such as learning, memory, and reward.

NE, or norepinephrine, is a neurotransmitter that is commonly secreted along with other substances known as co-transmitters in peripheral nerves. These co-transmitters include neuropeptide Y (NPY) and ATP. Co-transmitters work together with NE to modulate the activity of the sympathetic nervous system, which is responsible for the body's fight or flight response. By acting in concert, NE and co-transmitters can have a more potent effect on target cells and help regulate various physiological processes.

Purines such as adenosine are used as transmitters in the gastrointestinal (GI) system and blood vessels. They activate purine (P1) receptors and ATP receptors (P2X, etc). Additionally, there are four adenosine-specific receptors, namely A1, A2A, A2B, and A3. These receptors are present in the GI tract and blood vessels, where adenosine acts as a transmitter.

Both alpha 2 and beta 2 receptors are found in vascular smooth muscle and platelets. This is significant because these receptors are located in areas that are relatively distant from presynaptic terminals. This means that they can be activated by circulating catecholamines, which are hormones that are released into the bloodstream and can travel to these distant receptor sites. This allows for a more widespread and systemic effect of the catecholamines on vascular smooth muscle and platelets.

Nitric oxide (NO) is used as a transmitter in various tissues, including the brain. It was previously known as endothelium-derived relaxing factor (EDRF). Activation of specific GPCRs (G-protein coupled receptors) on endothelial cells leads to the production of NO. NO, in turn, stimulates the production of cyclic GMP (cyclic guanosine monophosphate).

Presynaptic noradrenergic receptors refer to the receptors located on the presynaptic neuron that bind to the neurotransmitter noradrenaline (norepinephrine). These receptors are categorized into two types: alpha and beta 2. The alpha receptors are further divided into alpha-1 and alpha-2 subtypes, while the beta 2 receptors are part of the beta adrenergic receptor family. Activation of these receptors can modulate the release of noradrenaline, thereby influencing various physiological processes in the body.