Neuroscience Neuron Classification

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Questions and Answers

How are epithelial tissues primarily nourished despite being avascular?

By absorption from the external environment.

Via diffusion from underlying connective tissue. (correct)

Through active transport mechanisms.

Through direct blood supply from capillaries.

What characteristic allows epithelial tissues to have distinct functional regions?

They are completely vascular.

They cannot regenerate.

They exhibit polarity. (correct)

They lack a basement membrane.

Which of the following structures is NOT typically associated with the apical surface of epithelial cells?

Desmosomes (correct)

Stereocilia

Microvilli

Cilia

What do hemidesmosomes primarily attach epithelial cells to?

The basement membrane. Signup and view all the answers

What is the primary role of tight junctions in epithelial tissues?

To provide a selective barrier. Signup and view all the answers

Which type of modification might be found on the apical surface of epithelial cells to facilitate absorption?

Microvilli Signup and view all the answers

What is a primary characteristic of astrocytes within the CNS?

They can undergo mitosis and provide metabolic support. Signup and view all the answers

Which characteristic of epithelial tissues enables them to undergo rapid repair?

They possess regenerative capabilities. Signup and view all the answers

Which type of junction serves as an anchor between adjacent epithelial cells, providing structural integrity?

Adherens junctions Signup and view all the answers

Which part of a neuron is the primary site for receiving incoming signals?

Dendrites Signup and view all the answers

What role do oligodendrocytes play in the CNS?

They provide insulation and support to the axons of neurons. Signup and view all the answers

Which of the following accurately describes the structure of an axon?

Axons are typically longer than dendrites and carry information away from the neuron. Signup and view all the answers

In the context of axon transport mechanisms, what is the difference between anterograde and retrograde transport?

Anterograde transport moves materials away from the cell body; retrograde moves them towards it. Signup and view all the answers

What distinguishes the autonomic nervous system from the somatic nervous system?

The autonomic system typically involves two neurons to transmit impulses to effectors. Signup and view all the answers

What is the main function of interneurons in the CNS?

They serve as a communication network between motor and sensory neurons. Signup and view all the answers

How do Schwann cells contribute to the PNS?

They form myelin sheaths around peripheral axons. Signup and view all the answers

Which type of neuron is characterized by having one axon and one dendrite and is primarily associated with sensory functions?

Bipolar Neurons Signup and view all the answers

What is the primary function of oligodendrocytes in the central nervous system?

Produce myelin for axons Signup and view all the answers

Which structure is responsible for conducting information away from the neuron’s cell body?

Axon Signup and view all the answers

What is the role of astrocytes in the central nervous system?

Maintain the blood-brain barrier and support neurons Signup and view all the answers

What type of neuronal structure contains the nucleus and surrounding cytoplasm?

Cell body/Soma Signup and view all the answers

Which of the following structures helps to insulate axons in the peripheral nervous system?

Schwann cells Signup and view all the answers

The terminal branches of an axon are known as which of the following?

Telodendria Signup and view all the answers

Which glial cell type is primarily involved in immune defense within the CNS?

Microglia Signup and view all the answers

What is the function of axon collaterals in the neuron?

Facilitate communication with multiple target cells Signup and view all the answers

Which structure in neurons is primarily responsible for receiving signals from other neurons?

Dendrites Signup and view all the answers

Study Notes

Neurons Classification

Neurons are classified by the number of processes extending from the cell body.
Multipolar Neurons: One axon and two or more dendrites; commonly involved in motor and interneuron functions.
Bipolar Neurons: One axon and one dendrite; associated with sensory receptors for taste, hearing, sight, and equilibrium.
Unipolar Neurons: Single axon that splits near the cell body into two branches; one branch extends to the periphery and the other to the CNS, such as in the dorsal root ganglia.

Neuron Structure

Neuron: The fundamental structural and functional unit of the nervous system.
Cell Body (Soma): Contains the nucleus and cytoplasm.
Dendrites: Receive and conduct information toward the cell body.
Axon: Conducts information away from the cell body, featuring an axon hillock connecting with the soma, and side branches called axon collaterals.
Telodendria: Fine terminal branches of the axon.

Central Nervous System (CNS) Overview

Derived from the neural tube.
Neuron cell bodies are grouped in areas called nuclei.
Grey matter consists of neuronal cell bodies, while white matter consists of myelinated axons.
Synaptic activities are primarily located in grey matter, forming the neuropil.
Axons are organized into nerve fiber bundles called tracts.

Connective Tissue in the Nervous System

Nerve fibers outside the CNS are surrounded by connective tissue layers.
Epineurium: Outer layer surrounding nerve.
Perineurium: Surrounds bundles of nerve fibers.
Endoneurium: Encloses individual axons.

Glial Cells Overview

Glial cells provide support and protection for neurons but do not conduct electrical impulses.
Types in the CNS: Oligodendrocytes, astrocytes, microglia, and ependymal cells.
In the PNS, glial cells are primarily Schwann cells.

Astrocytes

The most numerous glial cells, providing structural and metabolic support to neurons.
Regulate the blood-brain barrier and react to CNS damage by forming scar tissue.
Scavenge ions and neurotransmitters from the extracellular space.

Oligodendrocytes

Responsible for myelin production in the CNS, insulating axons to increase conduction velocity.
One oligodendrocyte can wrap around multiple axons, contributing to the formation of white matter.

Schwann Cells

Myelinate axons in the PNS, providing both myelinated and unmyelinated coverings.

Microglia

Act as resident macrophages in the CNS, serving as the immune defense.
They are small with many fine branches and are in constant movement.

Functional Divisions of the Nervous System

Sensory (Afferent) Functions: Transmit impulses from sensory receptors to the CNS for processing.
Motor (Efferent) Functions: Originate in the CNS and transmit impulses to effector organs.

PNS Motor Component Divisions

Somatic Nervous System: Voluntary control over skeletal muscles using a single neuron pathway.
Autonomic Nervous System: Involves two neurons; the first transmits impulses to an autonomic ganglion, then the second neuron sends impulses to cardiac muscles, smooth muscles, and glands.
- Divided into sympathetic and parasympathetic systems.

Structural Aspects of Neurons

Composed of a cell body (soma), which contains the nucleus and extensive rough endoplasmic reticulum (Nissl bodies).
Axons are long, conducting signals away from the neuron; they vary in thickness, affecting conduction speeds.
Dendrites, typically shorter, receive stimuli and conduct signals to the cell body.

Types of Neurons Based on Function

Sensory Neurons (Afferent): Carry information from sensory receptors to the CNS.
Motor Neurons (Efferent): Transmit impulses from the CNS to effectors.
Interneurons: Form connections between sensory and motor neurons; mainly located in the CNS.

Epithelial Tissue Characteristics

Exhibit polarity with distinct apical, lateral, and basal domains.
The basal surface is anchored to a basement membrane, creating a selective barrier.

Cell Junctions Summary

Various types include tight junctions, adherens junctions, desmosomes, gap junctions, and hemidesmosomes.
Desmosomes provide strong cell-to-cell adhesion while hemidesmosomes anchor cells to the basement membrane.

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Description

This quiz explores the classification of neurons based on the number of processes extending from the cell body. It focuses on the three major categories: multipolar, bipolar, and unipolar neurons, along with their functions and roles in the nervous system. Test your understanding of these essential neural structures.