Geneeskunde H1 + H2

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Questions and Answers

What is the primary reason gray rami appear gray in color?

They consist mostly of unmyelinated axons. (correct)

They contain myelinated axons.

They originate from the spinal cord.

They are associated with sensory neurons.

Where are preganglionic sympathetic neurons primarily located?

In the cervical spinal segments.

In the cranial and sacral spinal segments.

In the thoracic and upper lumbar spinal segments. (correct)

Throughout the entire spinal cord.

How do postganglionic sympathetic axons primarily reach their target organs?

By synapsing in sympathetic terminal ganglia.

By traveling through cranial nerves only.

By direct connection to the target organs.

By following the pathways of blood vessels or within other nerves. (correct)

What is a characteristic feature of postganglionic sympathetic axons?

They have longer projections to distant target organs. Signup and view all the answers

What technique has helped clarify the central pathways for autonomic control?

Pseudorabies virus tracing. Signup and view all the answers

What is the spinal cord segment range from which sympathetic preganglionic neurons originate?

T1 to L3 Signup and view all the answers

Where are the cell bodies of preganglionic sympathetic motor neurons located?

Intermediolateral cell column Signup and view all the answers

Through which structure do the axons of preganglionic sympathetic neurons exit the spinal cord?

Ventral roots Signup and view all the answers

What is the primary reason the rami communicantes are referred to as 'white'?

They contain mostly myelinated sympathetic axons. Signup and view all the answers

Which type of ganglia are located adjacent to the vertebral column?

Paravertebral ganglia Signup and view all the answers

Which ganglion arises from the fusion of C1 to C4?

Superior cervical ganglion Signup and view all the answers

What characterizes the chain of sympathetic ganglia in relation to the spinal cord?

It extends from the coccyx to the upper neck. Signup and view all the answers

What type of neurons enter the sympathetic paravertebral ganglion from the spinal nerves?

Preganglionic sympathetic neurons Signup and view all the answers

Which of the following describes the position of sympathetic ganglia in relation to spinal roots?

One ganglion positioned at the level of each spinal root Signup and view all the answers

What type of axons do the white rami communicantes mainly contain?

Preganglionic sympathetic axons Signup and view all the answers

What forms the stellate ganglion?

Fusion of C7 with the first thoracic ganglion Signup and view all the answers

Which ganglia are primarily responsible for innervating the heart, lungs, and bronchi?

Middle cervical and upper thoracic ganglia Signup and view all the answers

Which of the following describes a fate of a preganglionic sympathetic axon after entering a paravertebral ganglion?

May travel up or down the sympathetic chain to synapse Signup and view all the answers

What is the role of the prevertebral plexus?

It lies in front of the aorta along major arterial branches Signup and view all the answers

How many postganglionic sympathetic neurons can a single preganglionic neuron typically synapse with?

Around 200 Signup and view all the answers

Where do postganglionic sympathetic neurons send their axons?

Through gray rami communicantes back to the spinal nerves Signup and view all the answers

Which ganglia are named according to the adjacent arteries?

Prevertebral ganglia Signup and view all the answers

What distinguishes the prevertebral ganglia from paravertebral ganglia?

They lie in front of the aorta and along major arteries Signup and view all the answers

What is the characteristic function of gray rami communicantes?

They reconnect postganglionic neurons with spinal nerves Signup and view all the answers

What defines the structure of the prevertebral plexus?

It consists of a network of sympathetic neuron cell bodies and fibers Signup and view all the answers

Which physiological change occurs during REM sleep to prevent physical actions while dreaming?

Complete paralysis of skeletal muscles Signup and view all the answers

What role does the autonomic nervous system (ANS) play during both wakefulness and sleep?

Regulates visceral functions regardless of consciousness Signup and view all the answers

Which of the following divisions is NOT part of the autonomic nervous system?

Somatic division Signup and view all the answers

In which way is the autonomic nervous system (ANS) regarded as a model system for studying neuronal function?

Peripheral neurons are reasonably easy to isolate and study Signup and view all the answers

What characterizes the control of visceral sensory input while awake?

Unconscious filtering of most sensory input Signup and view all the answers

How does the nervous system dissociate sensory input from motor output during sleep?

By closing the eyes and blocking sensory impulses Signup and view all the answers

Which of the following best describes the nature of autonomic control compared to conscious brain function?

Autonomic control is continuous regardless of conscious focus Signup and view all the answers

What is the primary function of the autonomic nervous system?

To regulate involuntary bodily functions. Signup and view all the answers

Which neurons are specifically included in the definition of the autonomic nervous system?

Enteric neurons only. Signup and view all the answers

How do the sympathetic and parasympathetic divisions typically function in relation to each other?

They work synergistically and often in opposite ways. Signup and view all the answers

What initiates the output of the sympathetic division?

Stress, anxiety, and excitement. Signup and view all the answers

What defines the enteric division of the autonomic nervous system?

It forms plexuses that surround the GI tract. Signup and view all the answers

Where are the cell bodies of preganglionic neurons located?

Within the brainstem and spinal cord. Signup and view all the answers

What occurs when parasympathetic output increases?

Facilitation of digestion and relaxation. Signup and view all the answers

Which components are primarily part of the visceral control system?

Visceral afferents and CNS input. Signup and view all the answers

What type of neurotransmission occurs between the preganglionic and postganglionic neurons?

Chemical transmission exclusively. Signup and view all the answers

What is the term used for the two-synapse pathway of the autonomic system?

Polysynaptic pathway. Signup and view all the answers

Study Notes

Autonomic Nervous System (ANS)

The ANS is responsible for involuntary bodily functions
It's independent of conscious control
Includes visceral functions like metabolism, cardiopulmonary function, and other bodily processes
Continues to regulate functions even when awake, attentive, or asleep
Most input from the internal environment is unnoticed; distress might trigger awareness
Voluntary control of visceral organs is minimal
The ANS is crucial for life and complex brain processes

Mechanisms of Sensory Input Dissociation During Sleep

Closing the eyes
Blocking sensory input to cortex through the thalamus
Complete paralysis of skeletal muscles during REM sleep (prevents acting out dreams)

Nature of Cortical vs. Autonomic Control

Cortical function is conscious and intermittent
Autonomic functions are continuous
Autonomic control is essential for visceral processes

Autonomic Nervous System Divisions

Sympathetic
Parasympathetic
Enteric

Sympathetic vs. Parasympathetic

Two-synapse pathways for target tissues other than skeletal muscle
Preganglionic neurons in CNS; synapse with postganglionic neurons
Axons extend to targets; sympathetic and parasympathetic can work independently or in opposition to each other to regulate visceral functions

Enteric Division

Network of neurons (plexuses) surrounding the gastrointestinal tract
Functions largely independently from the CNS
Also controlled to some degree by the CNS via sympathetic and parasympathetic fibers.

Preganglionic Neurons

Cell bodies in thoracic and upper lumbar spinal cord (T1-L3)
Located in the intermediolateral cell column or lateral horn
Exits spinal cord through ventral roots
Enters the white rami communicantes
Mostly myelinated

Postganglionic Neurons

Cell bodies in paravertebral ganglia
Axons exit ganglia in gray rami communicantes to rejoin spinal nerves
The neurons are located in the paravertebral and prevertebral ganglia
Postganglionic axons extend to their target organs/tissues
Preganglionic sympathetic neurons have connections to 200 or more postganglionic neurons

Tracts and Ganglia

Paravertebral ganglia are adjacent to the spinal cord
Prevertebral ganglia are in front of the aorta and major arteries
Ganglia receive axons from preganglionic sympathetic neurons
Sympathetic postganglionic neurons have axons that travel to organs through other nerves or through blood vessels

Role of ANS in the Body

Various functions—visceral, cardiovascular, digestive systems, and more
Sympathetic actions involved in stressful or high-activity states
Parasympathetic actions involved in relaxed states or during digestion

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Description

This quiz covers the key concepts of the Autonomic Nervous System (ANS), including its functions, mechanisms of sensory input dissociation during sleep, and the differences between cortical and autonomic control. Dive into the essential roles of the sympathetic and parasympathetic divisions in regulating bodily functions and maintaining homeostasis.