Histology of Ganglia and Receptors

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Questions and Answers

What characteristic distinguishes autonomic ganglia from cranio-spinal ganglia?

Autonomic ganglia have large oval-shaped cells.

Autonomic ganglia contain thick myelinated nerve fibers.

Autonomic ganglia have a thick capsule and regular septa.

Autonomic ganglia are smaller and rounded in shape. (correct)

Which type of neurons are found in autonomic ganglia?

Unipolar sensory neurons

Bipolar neurons

Stellate multipolar neurons (correct)

Large pseudo-unipolar neurons

Which of the following correctly describes the morphology of cranio-spinal ganglia?

They are characterized by large oval-shaped cells. (correct)

They have thin irregularly arranged septa.

They consist of small rounded cells.

They contain small multipolar neurons.

What type of nerve fibers predominantly compose autonomic ganglia?

Thin mostly unmyelinated fibers Signup and view all the answers

What is the primary function of autonomic ganglia?

Visceral motor actions Signup and view all the answers

Which of the following statements is true regarding nerve endings?

Sensory nerve endings include both encapsulated and non-encapsulated receptors. Signup and view all the answers

What type of sensory nerve ending is characterized as a touch receptor?

Merkel's discs Signup and view all the answers

Which of the following nerve endings are classified as pain receptors?

Naked nerve fibers Signup and view all the answers

What is the role of satellite cells in relation to ganglion cells?

They protect and support ganglion cells. Signup and view all the answers

What characteristic distinguishes cranio-spinal ganglia from autonomic ganglia?

Cranio-spinal ganglia are larger and have a thick capsule. Signup and view all the answers

Which type of neurons are found in cranio-spinal ganglia?

Pseudounipolar neurons Signup and view all the answers

Where are cranio-spinal ganglia typically located?

In the dorsal root of spinal nerves Signup and view all the answers

What is the primary function of Meissner's corpuscles?

Detection of light touch Signup and view all the answers

Where are free nerve endings primarily located?

In the dermis and epidermis Signup and view all the answers

What forms the connective tissue structure surrounding ganglion cells in cranio-spinal ganglia?

Thick septa and capsule Signup and view all the answers

Which type of functions are primarily associated with cranio-spinal ganglia?

Sensory functions Signup and view all the answers

What type of receptors are characterized as being non-encapsulated?

Free nerve endings Signup and view all the answers

What type of nerve fibers are found within cranio-spinal ganglia?

Thick myelinated fibers Signup and view all the answers

Which receptors are specifically known to respond to hair movement?

Plexus of Bounet Signup and view all the answers

What distinguishes autonomic ganglia from cranio-spinal ganglia in terms of function?

Autonomic ganglia are mainly responsible for involuntary processes. Signup and view all the answers

What is a characteristic feature of the histological structure of Meissner's corpuscles?

They contain densely packed Schwann cells. Signup and view all the answers

What types of ganglia are included under autonomic ganglia?

Sympathetic and parasympathetic ganglia Signup and view all the answers

Which of the following is true regarding thermoreceptors?

They ramify in the papillary layer of the skin. Signup and view all the answers

Which of the following types of receptors is involved in the sensation of pressure?

Both A and C Signup and view all the answers

What type of sensory nerve fiber is associated with Meissner's corpuscles?

Myelinated and loses its neurilemma Signup and view all the answers

Where are Pacinian corpuscles primarily located?

Deep in the dermis and hypodermis Signup and view all the answers

What is the main function of Ruffini’s corpuscles?

Response to stretch and torque Signup and view all the answers

What is the primary function of the muscle spindle?

To monitor the degree of stretch in the muscle Signup and view all the answers

Which structure is characterized by having concentric layers of flattened Schwann cells?

Pacinian corpuscles Signup and view all the answers

How many primary afferent fibers are associated with the muscle spindle's nuclear region?

6-8 fibers Signup and view all the answers

What type of sensitivity do muscle spindles provide?

Stretch sensitivity Signup and view all the answers

What distinguishes the nuclear chain fibers from the nuclear bag fibers?

Nuclear chain fibers are shorter and narrower Signup and view all the answers

What structure surrounds Ruffini’s corpuscles?

Thin connective tissue capsule Signup and view all the answers

What type of nerve fibers are associated with the motor innervation of muscle spindles?

Gamma motor fibers Signup and view all the answers

What is the role of the Golgi tendon organ in muscle physiology?

To monitor the tension produced by muscle contractions Signup and view all the answers

Which type of muscle fiber is found within the cavity of muscle spindles?

Intrafusal muscle fibers Signup and view all the answers

Where do the axons of sensory nerve fibers in the tendon spindle lose their myelin?

Upon entering the spindle Signup and view all the answers

What feature gives Pacinian corpuscles their distinctive appearance?

Concentric layers making them look like an onion Signup and view all the answers

Which of the following best describes the histological structure of tendon spindles in comparison to muscle spindles?

Tendon spindles contain wavy collagen fibers instead of intrafusal muscle fibers Signup and view all the answers

What is the composition of the peripheral contractile regions in the intrafusal fibers of muscle spindles?

Striated muscle fibers Signup and view all the answers

Which of the following describes the innervation of muscle spindles?

Nerve fiber enters from the side and branches within Signup and view all the answers

Study Notes

Ganglia Overview

Collections of nerve cell bodies located outside the Central Nervous System (CNS), encased in a connective tissue capsule.
Types include cranio-spinal ganglia (sensory) and autonomic ganglia (sympathetic and parasympathetic).

Cranio-spinal Ganglia

Location: Found in spinal nerves' dorsal roots (dorsal root ganglia) and sensory roots of certain cranial nerves (e.g., trigeminal nerve).
Morphology: Larger, oval shape; consists of a thick connective tissue capsule and thick septa aligned parallel to the capsule.
Ganglion Cells: Large pseudounipolar neurons with central nuclei, arranged in groups, each surrounded by satellite cells.
Nerve Fibers: Thick, myelinated fibers within connective tissue septa; function primarily involves sensory processing.

Autonomic Ganglia

Location: Found along the sympathetic chain and parasympathetic nerves.
Morphology: Smaller, rounded shape; features a thin capsule and irregularly running thin septa.
Ganglion Cells: Small stellate multipolar neurons with eccentric nuclei, numerous and scattered, surrounded by an incomplete satellite cell capsule.
Nerve Fibers: Thin, mostly unmyelinated fibers that connect pre- and post-ganglionic nerves; primarily involved in visceral motor function.

Comparison: Cranio-spinal vs Autonomic Ganglia

Cranio-spinal Ganglia: Larger, oval, thick capsules, pseudounipolar cells, thick myelinated fibers, sensory function.
Autonomic Ganglia: Smaller, rounded, thin capsules, multipolar cells, thin unmyelinated fibers, visceral motor function.

Sensory Nerve Endings

Types of Receptors: Non-encapsulated (free nerve endings) and encapsulated receptors (Meissner's, Pacinian, Ruffini’s corpuscles, muscle and tendon spindles).
Free Nerve Endings: Include pain receptors (nociceptors), thermoreceptors, and fine touch receptors (plexus of Bounet around hair follicles).

Encapsulated Receptors

Meissner's Corpuscles: Located in dermal papillae; encapsulated, sensitive to light touch; consist of flattened Schwann cells.
Pacinian Corpuscles: Deep in dermis and hypodermis; pressure and vibration receptors; characterized by concentric layers resembling an onion.
Ruffini’s Corpuscles: Found deep in the dermis; mechanoreceptors responding to stretch and torque; surrounded by collagen fibers.
Muscle Spindles: Located in skeletal muscles; detect muscle stretch; consist of intrafusal muscle fibers and capsules; contain sensory and motor innervation.
Tendon Spindles (Golgi tendon organ): Found in tendons; monitor muscle tension; lack motor nerve endings, consist of collagen fibers.

Functional Aspects

Ganglia Functions: Cranio-spinal ganglia serve sensory roles; autonomic ganglia facilitate visceral motor responses.
Receptor Functions:
- Free nerve endings: pain, temperature, and light touch
- Meissner's: light touch detection
- Pacinian: pressure and vibration sensing
- Ruffini’s: detect stretch and torque
- Muscle spindles: monitor muscle stretch
- Tendon spindles: monitor muscle tension.

Key Structures & Terms

Intrafusal muscle fibers: Muscle fibers inside spindles; responsible for detecting stretch.
Gamma motor neurons: Innervate intrafusal fibers, maintaining spindle sensitivity.
Nerve Fibers:
- Primary afferent fibers: thicker, encircle muscle spindle fibers.
- Secondary afferent fibers: smaller, terminate at the chain fibers' peripheral ends.

Consider these crucial structures and functions for a comprehensive understanding of the central nervous system and sensory mechanisms.

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Description

This quiz explores the histological structures of spinal and autonomic ganglia. Students will learn to differentiate between these ganglia and identify various types of receptors. Enhance your understanding of the central nervous system and special senses with this comprehensive assessment.