Nervous Tissue Overview
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Questions and Answers

What is the structural unit of nervous tissue?

Neurons or Nerve Cells

What is the origin of nervous tissue?

Ectoderm

What are the two main divisions of the nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

Which of the following are components of nervous tissue? (Select all that apply)

<p>Neuroglial Cells</p> Signup and view all the answers

Neurons are capable of undergoing mitosis.

<p>False</p> Signup and view all the answers

What are the three types of neurons categorized by their function?

<p>Sensory (afferent), Motor (efferent), and Interneurons</p> Signup and view all the answers

What are the four main types of neuroglia found in the CNS?

<p>Astrocytes, Oligodendrocytes, Microglia, and Ependymal Cells</p> Signup and view all the answers

What are two key functions of astrocytes in the CNS?

<p>Maintaining the blood-brain barrier and providing structural support</p> Signup and view all the answers

What is the primary function of oligodendrocytes in the CNS?

<p>Forming myelin sheaths around axons</p> Signup and view all the answers

What is the main function of microglia in the CNS?

<p>Phagocytosis of pathogens and cellular debris</p> Signup and view all the answers

What is the primary function of ependymal cells in the CNS?

<p>Forming the lining of the ventricles and the central canal</p> Signup and view all the answers

What is the main function of Schwann cells in the PNS?

<p>Forming myelin sheaths around axons</p> Signup and view all the answers

What two things comprise a nerve fiber?

<p>Axon and its myelin sheath</p> Signup and view all the answers

Myelin is a non-lipid substance.

<p>False</p> Signup and view all the answers

What is the process of myelin formation called?

<p>Myelination</p> Signup and view all the answers

What are the gaps between myelin sheaths along an axon called?

<p>Nodes of Ranvier</p> Signup and view all the answers

Which of the following are components of gray matter in the CNS? (Select all that apply)

<p>Dendrites</p> Signup and view all the answers

The spinal cord has a central canal containing white matter.

<p>False</p> Signup and view all the answers

The cerebellum has an outer layer of grey matter and inner layer of white matter.

<p>True</p> Signup and view all the answers

What are the three meninges that cover the brain and spinal cord?

<p>Dura mater, arachnoid mater, and pia mater</p> Signup and view all the answers

What is the name of the tangled network of axons, dendrites, and neuroglial processes in the CNS?

<p>Neuropil</p> Signup and view all the answers

What is the role of sensory receptors in the peripheral nervous system?

<p>Detecting stimuli from the environment</p> Signup and view all the answers

Taste receptors are mechanoreceptors.

<p>False</p> Signup and view all the answers

Touch receptors only detect pressure.

<p>False</p> Signup and view all the answers

Which of the following is NOT one of the five senses?

<p>Balance</p> Signup and view all the answers

What are the specialized cells in the olfactory epithelium that detect smells?

<p>Olfactory cells</p> Signup and view all the answers

Study Notes

Nervous Tissue

  • Nervous tissue is a communication network in the body, responsible for controlling and integrating body functions within limits that maintain life.
  • It's composed of closely associated cells that perform related functions.
  • There are four main types of tissue: nervous, epithelial, muscle, connective.
  • Nervous tissue originates from ectoderm.

Learning Objectives

  • Understand the general characteristics of nervous tissue.
  • Identify the components of nervous tissue.
  • Identify central nervous system (CNS) organs.
  • Identify peripheral nervous system (PNS) organs.

Divisions of Nervous System

  • Nervous system is divided into central (CNS) and peripheral (PNS).
  • CNS includes the brain and spinal cord.
  • PNS includes cranial nerves, spinal nerves, and ganglia.
  • The PNS further splits into somatic and autonomic nervous systems. Somatic controls voluntary movement. Autonomic controls involuntary processes (e.g., heart rate). Autonomic further divides into sympathetic (activating) and parasympathetic (calming).

General Organization

  • CNS includes the brain and spinal cord.
  • PNS includes cranial, spinal nerves, and ganglia.
  • Histology of CNS: neurons, astrocytes, oligodendrocytes, microglial cells, ependymal cells. Histology of PNS: Neurons, satellite cells, Schwann cells.
  • CNS tissue contains neurons and neuroglial cells (supportive, non-transmitting). PNS contains neurons and supporting neuroglial cells, involved in protection, nutrition, and structure support.

Neurons or Nerve Cells

  • Structural unit of nervous tissue.
  • Conducts impulses.
  • Characteristics: longevity, amitotic, high metabolic rate (requiring O2 and glucose).
  • Structure: cell body, perikaryon or soma, processes or neurites. The cell body is the metabolic center of the neuron.
  • Cell body contains, Golgi apparatus, Rough ER (Nissl bodies), smooth ER, mitochondria, and other cellular components (cytoplasmic inclusions).
  • Processes or neurites extend from the cell body include dendrites (receive stimuli) and axons (transmit impulses).

Cell Body

  • Plasma membrane: receives stimuli, integrates them, and generates nerve impulses, contains ion channels and the Na+-K+ pump.
  • Cytoplasm: contains Nissl bodies (rough endoplasmic reticulum), Golgi apparatus, mitochondria.

Processes or Neurites

  • Dendrites: short, branched extensions that receive stimuli from other nerve cells, many, branched, irregularly shaped.
  • Axon: single long extension that transmits impulses to other neurons or effector cells, uniform diameter, branched at their ends (forming synaptic knobs) with neurotransmitters, no Nissl's granules.

Classification of Neuron

  • Function: sensory (afferent), interneurons, motor (efferent).
  • Number of processes: unipolar, bipolar, pseudounipolar, multipolar.

Synapses

  • Functional connection between a nerve fiber and a target cell.
  • Types: chemical, electrical. Chemical synapses are unidirectional and utilize neurotransmitters to signal. Electrical synapses provide direct electrical coupling.

Neuroglial Cells

  • 10 times more numerous than neurons in the nervous system.
  • Support, nourish, and protect neurons.
  • Types in CNS: astrocytes, oligodendrocytes, microglia, ependymal cells.
  • Types in PNS: satellite cells, Schwann cells.

Astrocytes

  • Star-shaped, abundant cytoplasm with intermediate filaments (GFAP)
  • Processes contact blood vessels and neurons.
  • Functions: maintain blood-brain barrier, regulate tissue fluid composition, structural support and organization, stimulate scar tissue formation.

Oligodendrocytes

  • Smaller than astrocytes, fewer processes.
  • Form myelin sheaths in the CNS.

Microglia

  • Smallest glial cells, originate from monocytes.
  • Phagocytic functions in the CNS for defense and debris removal.

Ependymal Cells

  • Low columnar or cuboidal epithelial cells.
  • Line ventricles of the brain and central canal of the spinal cord.
  • Form cerebrospinal fluid, facilitate its movement.

Satellite Cells

  • Small, round, spindle-shaped cells, surround neuron cell bodies in ganglia of PNS.
  • Functions: protect cell bodies, regulate nutrient supply for cell bodies.

Schwann Cells

  • Flattened cells, encase axons of peripheral nerves with a membrane.
  • Myelinate PNS axons
  • Allow faster nerve impulse conduction.

Nerve Fibers

  • Myelinated: enclosed in a myelin sheath for faster conduction.
  • Unmyelinated: no myelin sheath.

Myelin Sheath

  • Composed of phospholipids, glycolipids and cholesterol
  • Function: insulates the axons, increases speed of nerve impulses.

Myelination

  • Invagination of a single nerve axon into a Schwann cell forms myelin sheath.

Organization of Nervous Tissue in CNS

  • Grey matter: soma, dendrites, unmyelinated fibers, glial cells.
  • White matter: axons, myelinated fibers, network of neural tissue.
  • Meninges (connective tissue): dura mater, arachnoid mater, pia mater.

Spinal Cord

  • Ventral horns: motor neurons.
  • Dorsal horns: sensory neurons.

Cerebellum

  • Grey matter comprises the cortex, white matter comprises the medulla.

Organization of Nervous Tissue in PNS

  • Consists of peripheral nerves, ganglia, and sensory receptors.

Peripheral Nerves

  • Nerve fibers bundled together into elongated fascicles.
  • Includes epineurium, perineurium, endoneurium.

Peripheral Nerve Regeneration

  • Stages: injury, chromatolysis, atrophy, scarring, successful/unsuccessful regeneration.

Ganglia

  • Associated with cranial nerves (pseudounipolar cell bodies).
  • Multipolar neurons.

Sensory Receptors

  • Receptors detect stimuli.
  • Types: mechanoreceptors (touch, hearing), thermoreceptors (temperature), nociceptors (pain), photoreceptors (light), chemoreceptors (smell, taste).
  • Classification based on stimulus source (exteroceptors, interoceptors, proprioceptors).
  • Senses: vision, hearing, smell, taste, touch.

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Nervous Tissue Topic 13 PDF

Description

This quiz provides an overview of nervous tissue, exploring its characteristics and components. Learn about the central and peripheral nervous systems, including their respective organs and functions. Test your understanding of how nervous tissue integrates and regulates body functions.

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