Physiology: Chapter 11 Part B Quiz

Questions and Answers

What is the primary neurotransmitter used in sympathetic pathways?

Dopamine

Norepinephrine (correct)

Epinephrine

Acetylcholine

Which nerve carries approximately 75% of all parasympathetic fibers?

Phrenic Nerve

Sciatic Nerve

Median Nerve

Vagus Nerve (correct)

Why do we see antagonistic control primarily at the SA node and not in other areas such as the ventricles or arterioles?

Only the SA node regulates blood flow.

The SA node requires independent control.

Ventricles are innervated exclusively by sympathetic pathways.

Antagonistic control is not needed in those areas. (correct)

Which of the following statements about parasympathetic pathways is correct?

They primarily utilize acetylcholine. Signup and view all the answers

What do sympathetic ganglia resemble in terms of structure?

Two ganglion chains Signup and view all the answers

What is the role of the vagus nerve in relation to internal organs?

It provides output from the brain to the organs. Signup and view all the answers

In comparison to parasympathetic pathways, which neurotransmitter is NOT used by sympathetic pathways?

Acetylcholine Signup and view all the answers

Which of the following best describes the overall function of antagonistic control in the autonomic system?

Balancing opposing forces for homeostasis Signup and view all the answers

What are the two components required for the synthesis of acetylcholine?

Choline and acetyl CoA Signup and view all the answers

Which enzyme is responsible for breaking down acetylcholine in the synaptic cleft?

Acetylcholinesterase Signup and view all the answers

How is choline transported back into the axon terminal?

Cotransport with sodium ions Signup and view all the answers

What role does recycled choline play after its transport back into the axon terminal?

It is used to synthesize more acetylcholine Signup and view all the answers

Where does the synthesis of acetylcholine primarily occur?

In the varicosities Signup and view all the answers

Which receptor is associated with the parasympathetic pathway?

Muscarinic receptor Signup and view all the answers

What neurotransmitter is primarily used in sympathetic pathways?

Norepinephrine Signup and view all the answers

Which pathway involves the adrenal medulla?

Sympathetic pathway Signup and view all the answers

What are the target tissues of the parasympathetic pathway?

Smooth and cardiac muscles, and glands Signup and view all the answers

Which of the following is a characteristic of the somatic motor pathway?

Uses ACh at target cells Signup and view all the answers

What is the major difference in the number of neurons between the somatic motor and autonomic pathways?

Somatic motor has one neuron while autonomic has two neurons Signup and view all the answers

Which receptor subtype is responsible for responding to epinephrine?

Beta-2 receptor Signup and view all the answers

What neurotransmitter is used by the adrenal sympathetic pathway?

Epinephrine Signup and view all the answers

Which receptor is primarily activated by acetylcholine in the sympathetic pathway?

Nicotinic receptor Signup and view all the answers

What triggers the exocytosis of synaptic vesicles at the varicosity?

Opening of voltage-gated Ca2+ channels Signup and view all the answers

Which type of receptors do all adrenergic receptors belong to?

G-protein coupled receptors Signup and view all the answers

What happens to norepinephrine (NE) after it binds to the receptor on the target cell?

Its activation ceases when it diffuses away from the synapse. Signup and view all the answers

What is the effect of increased neurotransmitter concentration in the synapse?

A longer or stronger response Signup and view all the answers

Which ion entry is responsible for the depolarization that triggers exocytosis?

Ca2+ Signup and view all the answers

What is the primary role of norepinephrine (NE) at a sympathetic neuroeffector junction?

Modulating autonomic control of targets Signup and view all the answers

How do adrenergic receptors influence the speed of the response?

They lead to slower responses. Signup and view all the answers

What initiates the release of norepinephrine (NE) at a sympathetic neuroeffector junction?

Depolarization causing the opening of voltage-gated Ca2+ channels Signup and view all the answers

What begins the action potential at the varicosity?

Arrival of an action potential Signup and view all the answers

Which process describes the removal of norepinephrine from the synapse?

Diffusion away from the synapse Signup and view all the answers

Which process is responsible for removing norepinephrine (NE) from the synaptic cleft?

Diffusion away from the region Signup and view all the answers

What is the outcome of the activation of adrenergic receptors?

Sustained, prolonged action in the target Signup and view all the answers

What role do voltage-gated Ca2+ channels play in the sympathetic neuroeffector junction?

They allow Ca2+ influx, triggering NE release Signup and view all the answers

Which statement about norepinephrine (NE) is incorrect in the context of its release and removal?

NE is only removed by diffusion away from the target site. Signup and view all the answers

Where does the action potential initiate the process of norepinephrine (NE) release?

At the varicosity Signup and view all the answers

How is norepinephrine (NE) synthesized before it is released?

From tyrosine through a series of enzymatic reactions Signup and view all the answers

What effect does norepinephrine (NE) binding to adrenergic receptors generally have?

It modulates various physiological responses including increased heart rate Signup and view all the answers

What happens to norepinephrine (NE) after it is released into the synaptic cleft?

It can be removed by reuptake into synaptic vesicles or metabolized Signup and view all the answers

Which of the following is a characteristic of norepinephrine (NE) metabolism?

It can involve enzymes such as monoamine oxidase (MAO) Signup and view all the answers

Study Notes

Autonomic and Somatic Motor Control

Antagonistic control is primarily observed at the Sinoatrial (SA) node, not in ventricular tissues, veins, or arterioles.
Sympathetic ganglia are organized in two chains alongside the vertebral column.

Vagus Nerve

Comprises approximately 75% of all parasympathetic fibers.
Carries sensory information from internal organs to the brain and transmits signals from the brain to organs.

Autonomic Pathways

Parasympathetic Pathway:
- Use acetylcholine (ACh) neurotransmitter.
- Involves muscarinic receptors at target tissues, affecting smooth muscle, cardiac muscle, certain glands, and adipose tissue.
Sympathetic Pathway:
- Predominantly uses norepinephrine (NE) and also ACh.
- Target cells possess alpha (α) and beta (β) adrenergic receptors.

Neurotransmitter Mechanism

Norepinephrine release occurs at sympathetic neuroeffector junctions upon action potential arrival.
Depolarization leads to the opening of voltage-gated Ca²⁺ channels, facilitating exocytosis of vesicles containing NE.
NE binds to adrenergic receptors on target cells, initiating a signal that is prolonged as NE diffuses away.

Neurotransmitter Release and Removal

NE concentration modulation leads to varied responses; higher levels produce stronger or longer-lasting effects.
NE can be reabsorbed into synaptic vesicles or metabolized by monoamine oxidase (MAO) after exerting its effect.

Acetylcholine Mechanism

ACh is synthesized from choline and acetyl CoA in the axon terminals.
Rapid breakdown of ACh occurs in the synaptic cleft due to acetylcholinesterase (AChE).
Choline is recycled back into the axon terminal for the re-synthesis of ACh.

Comparison of Pathways

Somatic motor pathways consist of a single neuron connecting CNS to the target muscle.
Autonomic pathways typically involve two neurons, with the first neuron synapsing in a ganglion.

Receptors and Effects

Somatic motor pathways use nicotinic receptors at the neuromuscular junction.
Sympathetic pathways can activate both α and β adrenergic receptors, leading to diverse physiological responses.
Parasympathetic pathways typically activate muscarinic receptors.

Neuroeffector Junction Dynamics

Response time for adrenergic receptor binding is slower compared to ion channel receptors due to reliance on G-protein signaling cascades.

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Description

This quiz covers the key concepts of autonomic and somatic motor control as presented in Chapter 11 Part B of the physiology textbook. Evaluate your understanding of physiological mechanisms, particularly focusing on antagonistic control. Prepare to test your knowledge on the details discussed in the chapter.