Neuroanatomy of Sensory Ganglia

Questions and Answers

How do transcription factors influence cell fate during development?

They determine the overall size of the cells during growth.

They regulate the on/off status of genes, defining cellular identity. (correct)

They directly code for proteins that determine cell structure.

They are responsible for the transportation of nutrients to the cells.

What role do transcription factors play in gene expression?

They inhibit all gene expression in a cell.

They bind to the promoter region, allowing mRNA transcription. (correct)

They only assemble proteins at the ribosome.

They are dissolved in the cytoplasm and do not affect gene binding.

What happens to the developmental potential of regionally specified cells?

It is dependent on external factors like temperature and nutrients.

It becomes locked in, ensuring they follow a specific developmental pathway. (correct)

It increases, allowing them to adapt to any environment.

It continuously changes throughout the organism’s life.

What was observed in the development of transplanted metencephalon cells?

They retained their identity and developed into cerebellar neurons. Signup and view all the answers

What characterizes the role of transcription factors in the early brain?

They specify cellular identity and ensure correct brain structure formation. Signup and view all the answers

Which cranial nerve is responsible for conveying taste information from the anterior 2/3rds of the tongue?

Cranial nerve VII Signup and view all the answers

What type of neurons are found in the ganglia that innervate visceral organs?

Pseudo-unipolar sensory neurons Signup and view all the answers

Which ganglion conveys both special visceral taste information from the posterior 3rd of the tongue and general visceral information?

Petrosal ganglion Signup and view all the answers

Which cranial nerve primarily provides parasympathetic preganglionic nerves to the head and neck?

Cranial nerve VII Signup and view all the answers

Which of the following is NOT part of the cranial outflow of the visceral nervous system?

Cranial nerve XI Signup and view all the answers

Which ganglion provides general visceral sensory innervation to the rest of the body via the vagus nerve?

Nodose ganglion Signup and view all the answers

What type of information do chemoreceptors and mechanoreceptors convey through the petrosal ganglion?

Special visceral and general visceral information Signup and view all the answers

Which of the following accurately describes the spinal outflow of the visceral nervous system?

Both sympathetic and parasympathetic preganglionic nerves exit from the thoracic/lumbar and sacral regions respectively. Signup and view all the answers

What are rhombomeres primarily responsible for in embryonic development?

Producing functionally distinct pools of neurons for the pons and medulla Signup and view all the answers

What characteristic of transcription factors is highlighted in the context of rhombomeres?

They exhibit an alternating expression pattern across sequential rhombomeres. Signup and view all the answers

Which of the following statements regarding krox20 is correct?

It sharply delimits r3 and r5, forming a stripe pattern. Signup and view all the answers

What happens to the rhombomeres as development progresses?

They disappear and leave no trace of their boundaries. Signup and view all the answers

What is the significance of bold coloring under a rhombomere in the context provided?

Representation of gene expression presence. Signup and view all the answers

What does the alternating pattern of expression of transcription factors across rhombomeres suggest?

It shows a conservative mechanism in vertebrate brain development. Signup and view all the answers

Which segment is specifically mentioned in the context of transcription factor expression?

r3 and r5 Signup and view all the answers

What type of pattern do transcription factors exhibit across odd and even rhombomeres?

An alternating expression pattern Signup and view all the answers

Where are the parasympathetic preganglionic neurons that control pelvic organs located?

At the sacral end of the spinal cord Signup and view all the answers

What type of neurons are located in the thoracic and lumbar regions of the spinal cord?

Sympathetic preganglionic neurons Signup and view all the answers

Which cranial nerve is associated with the parasympathetic ganglia of the eye?

Cranial nerve III Signup and view all the answers

Which cranial nerves are involved in the medullary outflow of parasympathetic preganglionic nerves?

VII, IX, X Signup and view all the answers

What type of neurons innervate sympathetic ganglia?

Short preganglionic neurons Signup and view all the answers

Which type of efferent nerves are responsible for innervating the branchial muscles of the head and neck?

Special visceral efferents Signup and view all the answers

Which of the following accurately describes the location of sympathetic preganglionic neurons?

Located in thoracic and lumbar regions of the spinal cord Signup and view all the answers

Which of the following pairs correctly match the outflows with their respective functional divisions?

Parasympathetic outflow – Medullary and Sacral Signup and view all the answers

What are the two transcription factors involved in specifying boundaries between rhombomeres mentioned in the content?

Hoxb1 and Krox20 Signup and view all the answers

How do Hoxb1 and Krox20 control each other's expression?

By binding to each other's promoter regions Signup and view all the answers

What role does retinoic acid play in establishing Hoxb1 and Krox20 expression?

It creates a gradient that determines their spatial distribution. Signup and view all the answers

What is meant by the 'fuzzy' boundary observed between Hoxb1 and Krox20 expressing cells?

It refers to intermingled expression in an intermediate range of the morphogen gradient. Signup and view all the answers

What happens to cells that express Hoxb1 and Krox20 at the intermediate morphogen concentration?

They migrate to their specified rhombomere positions. Signup and view all the answers

What consequence does the binding of EphA4 and ephrinB3 have on the cells expressing Hoxb1 and Krox20?

It pushes cells that express Hoxb1 and Krox20 away from each other. Signup and view all the answers

The establishment of transcription factor expression in the rhombomeres is primarily initiated by which factor?

Gradients of retinoic acid Signup and view all the answers

What is the significance of the mutual repression between Hoxb1 and Krox20 transcription factors?

It creates a clear boundary between expressing areas. Signup and view all the answers

Study Notes

Neuronal Ganglia and Sensory Pathways

Pseudo-unipolar sensory neurons are present in ganglia and are responsible for innervating visceral organs.
These neurons convey interoceptive sensory information from the body to the brainstem.
The geniculate ganglion relays taste information from the anterior two-thirds of the tongue via the facial nerve (cranial nerve VII).
The petrosal ganglion transmits taste information from the posterior third of the tongue and general visceral information from carotid chemoreceptors through the glossopharyngeal nerve (cranial nerve IX).
The nodose ganglion travels via the vagus nerve (cranial nerve X) and provides general visceral sensory innervation for the remaining body.

Visceral Nervous System Overview

The visceral nervous system has both cranial and spinal efferents for autonomic control.
Mesencephalic outflow includes parasympathetic preganglionic nerves targeting the eye (cranial nerve III).
Medullary outflow involves parasympathetic preganglionic nerves for the head, neck, and body (cranial nerves VII, IX, X).
Branchiomotor nerves (special visceral) innervate the branchial muscles in the head and neck.

Spinal Efferents

Thoracic and lumbar outflow contains sympathetic preganglionic nerves that innervate pre- and para-vertebral ganglia.
Sacral outflow manages parasympathetic preganglionic nerves that target pelvic ganglia.

Transcription Factors in Nervous System Development

Transcription factors bind DNA, regulating gene expression crucial for neural identity, including growth factors and neurotransmitters.
Expression of transcription factors is critical for ensuring the correct formation of cell types in specified locations during development.

Rhombomere Position Specification

Transcription factors specify segmental identity in the hindbrain, known as rhombomeres.
Each rhombomere expresses a unique pattern of transcription factors, with notable alternating expression across segments.
Even if cells are relocated during development, they retain their original developmental identity, resulting in ectopic structures like the cerebellum forming inappropriately.

Maintenance of Rhombomere Boundaries

Expression patterns of transcription factors like Krox-20 and Hoxb-1 create distinct boundaries between rhombomeres (r4 and r5).
Initial expression is established by a retinoic acid gradient, leading to mutual repression between transcription factors, refining boundaries.
EphA4 and ephrinB3 surface signals further reinforce boundaries by providing repulsive signals to intermixed cells, ensuring their correct positioning.

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Description

Explore the structure and function of sensory ganglia, focusing on pseudo-unipolar sensory neurons that process interoceptive information. This quiz delves into the roles of the geniculate and petrosal ganglia, including their involvement in taste sensation. Test your understanding of this essential aspect of neuroanatomy.