Lecture 6:Nervous System Anatomy and Physiology

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Questions and Answers

What is the function of oligodendrocytes in the CNS?

To produce myelin and form the myelin sheath (correct)

To insulate one neuron from another

To supply nutrients and oxygen to neurons

To destroy and remove debris of dead neurons

What type of neurons have a single axon and dendrite arising from a common stem?

Pseudo-unipolar neurons (correct)

Multipolar neurons

Bipolar neurons

Unipolar neurons

What is the term for non-neuronal support cells in the nervous tissue?

Neuroglia (correct)

Glioma

Neuroplasm

Neurons

What is the term for the tumor of oligodendrocytes?

Oligodendroglioma Signup and view all the answers

How many axons can a single oligodendrocyte wrap around?

Up to 50 Signup and view all the answers

What is the function of astrocytes in the CNS?

To supply nutrients and oxygen to neurons Signup and view all the answers

What is the function of microglia in the CNS?

To destroy and remove the debris of dead neurons Signup and view all the answers

What is the term for the cells that myelinate nerve fibers in the PNS?

Schwann cells Signup and view all the answers

What is the function of axons in neurons?

To conduct action potentials to influence other neurons or effector organs Signup and view all the answers

What is the structure that contains the nucleus and cytoplasm in a neuron?

Perikaryon Signup and view all the answers

What is the main function of dendrites in neurons?

To receive stimuli from other neurons Signup and view all the answers

What type of neuron has numerous dendrites and a single axon?

Multipolar neuron Signup and view all the answers

What is the term for the small swellings at the end of an axon?

Terminal boutons Signup and view all the answers

What is the function of the axon hillock?

To generate action potentials Signup and view all the answers

What is the term for the highly branched, tapering processes attached to the body of the nerve cell?

Dendrites Signup and view all the answers

What type of neuron has a single dendrite and a single axon?

Bipolar neuron Signup and view all the answers

What is the primary function of the nervous system?

To receive, transmit, and integrate information to control the body's activities Signup and view all the answers

What are the two primary divisions of the nervous system?

Central and peripheral nervous systems Signup and view all the answers

What is the function of cerebro-spinal fluid (CSF)?

To bath the surface of the brain and spinal cord Signup and view all the answers

What is the role of glial cells in the nervous system?

To provide structural support to neurons Signup and view all the answers

What is the term for the study of the structure of the nervous system?

Histology Signup and view all the answers

What are the two types of cells that make up the nervous tissue?

Neurons and glial cells Signup and view all the answers

What is the term for the nervous system that supplies the body wall and limbs?

Somatic nervous system Signup and view all the answers

What is the function of the meninges?

To protect the brain and spinal cord Signup and view all the answers

What is the characteristic of the axon labeled A?

It lacks Nissl substance Signup and view all the answers

What is the function of the gray matter in the cerebrum?

It is composed of layers of neurons arranged close to the surface of the brain Signup and view all the answers

What are the three layers of the cerebellar cortex?

Outer molecular, middle Purkinje cell, and inner granular Signup and view all the answers

What is the term for the gray matter in the spinal cord?

Central core Signup and view all the answers

What are the three types of ganglia in the peripheral nervous system?

Primary sensory, spinal, and autonomic Signup and view all the answers

What is the function of the myelin sheath?

It protects the axon and increases the speed of nerve impulse transmission Signup and view all the answers

What is the term for the segment of nerve fiber between two schwann cells?

Node of Ranvier Signup and view all the answers

What is the term for the connective tissue covering the entire nerve?

Epineurium Signup and view all the answers

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

To provide mechanical support and mediate the exchange of metabolites Signup and view all the answers

What type of cell is responsible for myelinating a segment of a nerve fiber?

Schwann cell Signup and view all the answers

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

To phagocytose damaged tissue and foreign substances Signup and view all the answers

What is the term for the tumor that arises from ependymal cells?

Ependymoma Signup and view all the answers

Which stain is used to study neuron-specific proteins?

Immunohistochemistry Signup and view all the answers

What is the primary function of ependymal cells in the central nervous system?

To produce cerebrospinal fluid Signup and view all the answers

Which of the following is NOT a function of astrocytes?

To phagocytose damaged tissue Signup and view all the answers

What is the term for the substance stained by the Nissl Method?

Rough endoplasmic reticulum Signup and view all the answers

Study Notes

Definition and Classification of Nervous System

Nervous tissue receives, transmits, and integrates information from outside and inside the body to control the activities of the body
Classified into Central Nervous System (CNS) and Peripheral Nervous System (PNS)

Divisions of Nervous System

Central Nervous System (CNS):
- Brain and Spinal cord
- Protected and enclosed within skull and vertebral canal respectively
- Covered by meninges
- Cerebro-spinal fluid (CSF) baths surface of brain and spinal cord
- Composed of neurons and supporting cells (glial cells)
Peripheral Nervous System (PNS):
- Paired spinal and cranial nerves
- Ganglia

Functions of Nervous System

Somatic nervous system: supplies the body wall and limbs, involved with voluntary functions
Autonomic nervous system: supplies the viscera and glands, exerts control over many involuntary organs

Cells of Nervous Tissue

Neurons: excitable cells that transmit electrical signals
Glial cells/Neuroglia: supporting cells that include:
- Astrocytes
- Oligodendrocytes
- Ependymal cells
- Microglia
- Schwann cells

Structure of a Neuron

Consists of:
- Cell body containing the nucleus surrounded by cytoplasm (perikaryon)
- Nissl bodies (H+E)
- Neurofilaments and microtubules
- Processes of two types:
  - Dendrites (receive signals)
  - Axon (conducts action potentials)

Types of Neurons

Multipolar neurons: multiple dendrites and a single axon (e.g. motor neurons, interneurons)
Bipolar neurons: single dendrite and a single axon (e.g. sensory neurons of special sensory organs)
Pseudo-unipolar neurons: single axon and dendrite arise from a common stem of the cell (e.g. primary spinal sensory neuron)

Glial Cells

Functions:
- Supply nutrients and oxygen to neurons
- Insulate one neuron from another
- Surround neurons and hold them in place
- Destroy and remove the debris of dead neurons
Types:
- Oligodendrocytes
- Astrocytes
- Microglia
- Ependymal cells

Stains Used to Study Nervous Tissue

Hematoxylin and Eosin (H+E)
Heavy Metal Impregnation Technique: gold and silver are used to study neuron morphology
Immunohistochemistry: used to study neuron-specific proteins (e.g. neurofilament protein)
Nissl Method: stains RNA, identifying the rough endoplasmic reticulum (Nissl Substance)

Organization of Neurons in CNS

Cerebrum:
- Layers of neurons arranged close to the surface of the brain to form the gray matter or cerebral cortex
- Neurons grouped together deep in the brain form nuclei (thalamus, basal ganglia)
- Inner white matter conveys axons of the neurons (bundles of nerve fibers)
Cerebellum:
- Surface layer, grey matter, cortex arranged in folds called the folia
- Central core of nerve fibers, white matter
- Three layers of cerebellar cortex: molecular layer, Purkinje cell layer, granular cell layer
Spinal cord:
- Neurons form central core (gray matter) of the spinal cord with fibers outside (white matter)
- Gray matter, butterfly-shaped central mass of neurons that extends to form ventral, dorsal, and lateral horns
- White matter: nerve fibers forming ascending and descending tracts surrounding the gray matter

Peripheral Nervous System

Consists of:
- 31 pairs of spinal nerves
- 12 pairs of cranial nerves
- Ganglia: primary sensory spinal ganglia, ganglia associated with cranial nerves, and autonomic ganglia

Connective Tissue Layers of Nerve Fibers

Each nerve fiber with investing Schwann cell is surrounded by delicate layer of connective tissue, the endoneurium
Each nerve fascicle in a nerve is wrapped by a connective tissue covering, the perineurium
Each nerve is externally covered by connective tissue, the epineurium

Myelinated and Non-Myelinated Nerve Fibers

Non-myelinated nerve fibers: small axons (ANS, pain fibers) are only enveloped by cytoplasm of Schwann cells
Myelinated nerve fibers: large axons are wrapped by concentric layers of Schwann cell plasma membrane called myelin sheath

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Description

Learn about the anatomy and physiology of the nervous system, including its classification, cellular components, and staining techniques. Understand the basics of nervous system histology.