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Questions and Answers
What are the two main cell types found in nervous tissue?
What are the two main cell types found in nervous tissue?
Neurones and neuroglial cells
What is the functional unit of the nervous system?
What is the functional unit of the nervous system?
What are the supporting cells of the nervous system called?
What are the supporting cells of the nervous system called?
Neuroglial cells
What are the processes that extend from the cell body of a neuron called?
What are the processes that extend from the cell body of a neuron called?
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Neurones are capable of cell division and replacement in the event of cell death.
Neurones are capable of cell division and replacement in the event of cell death.
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Which type of neuron has one axon and one dendrite?
Which type of neuron has one axon and one dendrite?
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Which type of neuron is most abundant in the nervous system?
Which type of neuron is most abundant in the nervous system?
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What is the specific name given to the cone-shaped portion of a cell body where an axon originates?
What is the specific name given to the cone-shaped portion of a cell body where an axon originates?
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The diameter of an axon has no influence on the rate of impulse conduction.
The diameter of an axon has no influence on the rate of impulse conduction.
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What are the four main classifications of neurones based on?
What are the four main classifications of neurones based on?
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What are the three types of neurons based on the configuration of their neurites?
What are the three types of neurons based on the configuration of their neurites?
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What role do glial cells play in the nervous system?
What role do glial cells play in the nervous system?
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Which type of glial cell is responsible for myelination of axons in the Central Nervous System (CNS)?
Which type of glial cell is responsible for myelination of axons in the Central Nervous System (CNS)?
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Which type of glial cell is equivalent to the monocyte-macrophage system?
Which type of glial cell is equivalent to the monocyte-macrophage system?
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What is the name of the specialized epithelium that lines the ventricles of the brain and the central canal of the spinal cord?
What is the name of the specialized epithelium that lines the ventricles of the brain and the central canal of the spinal cord?
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Which type of glial cell is responsible for forming scar tissue in the CNS?
Which type of glial cell is responsible for forming scar tissue in the CNS?
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All nerves contain both myelinated and unmyelinated fibers.
All nerves contain both myelinated and unmyelinated fibers.
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What are the three layers of connective tissue that form the structure of a nerve?
What are the three layers of connective tissue that form the structure of a nerve?
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Where is the synapse formed?
Where is the synapse formed?
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What is released at the axon terminal to transmit information across the synapse?
What is released at the axon terminal to transmit information across the synapse?
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Sensory receptors can only transduce stimuli from external environments.
Sensory receptors can only transduce stimuli from external environments.
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What type of sensory receptor is involved in detecting touch, light pressure, pain, and temperature?
What type of sensory receptor is involved in detecting touch, light pressure, pain, and temperature?
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What type of sensory receptor provides information about body position, orientation, tension, and movement?
What type of sensory receptor provides information about body position, orientation, tension, and movement?
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Which of the following is NOT an example of an exteroceptor?
Which of the following is NOT an example of an exteroceptor?
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Gliomas are cancerous tumors that are usually easy to remove and do not interfere with neuronal function.
Gliomas are cancerous tumors that are usually easy to remove and do not interfere with neuronal function.
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Match the following sensory receptors with their function:
Match the following sensory receptors with their function:
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Study Notes
Histology of Nervous Tissues
- Nervous tissue receives stimuli from internal and external environments, processing and responding through various effector organs.
- Neurons are the functional units of the nervous system.
- Neuroglial cells support the nervous system.
Learning Outcomes
- Classify nerve tissue.
- Describe the general structure and different types of neurons.
- Detail the structure and types of supporting cells (glia).
- Detail the classification of receptors.
Introduction: Tissues of the Body
- Basic tissues types are shown in the image.
Neurons and Neuroglial Cells
- Neurons receive stimuli, analyzed, integrated, and coordinated responses.
- Neurons are the basic functional unit of the nervous system.
- Neurons are responsible for sending electrical impulses.
- Neuroglial cells support the nervous system.
Types of Neuroglia
- Central Nervous System (CNS): Ependymal cells, Oligodendrocytes, Astrocytes, Microglia
- Peripheral Nervous System (PNS): Satellite cells, Schwann cells
Neuron Characteristics
- Neurons possess many processes.
- They are excitable and conductive.
- They receive stimuli and conduct impulses.
- The electrical nerve impulse spreads through neurons.
- Neurons cannot divide (lack mitosis) after injury.
- Axons (when severed) can regenerate.
Neuron Structure
- Cell body/perikaryon (soma): Contains the nucleus, nucleolus, and organelles.
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Neurites/Processes:
- Dendrites: highly branched extensions that receive signals
- Axons: long extensions that transmit signals away from the cell body
- Terminal button: Small swellings at the end of the axon.
Neuron ~ Characteristics (continued)
- Dendrites are short extensions of the cell body, highly branched and tapering.
- Some dendrites end in special sensory receptors or attach to other cells.
- They get thinner further away from the cell body.
- They contain Nissl substances (RER).
- Axons are long, cone-shaped extensions arising from the axon hillock.
- No Nissl granules.
- Tubular and a uniform diameter.
- Conduction of impulses increases when the diameter is higher.
- Impulses travel away from the cell body.
Classifications of Neurons
-
A: Configuration of neurites (number of processes)
- Bipolar
- Pseudounipolar
- Multipolar
- B: Functional role
- C: Cell size
- D: Neurotransmitter released
Neuron Types
- Bipolar Neurons: One axon, one dendrite, sensory function (smell, sight, balance).
- Pseudounipolar Neurons: Single process branching into two, sensory function (dorsal root ganglia).
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Multipolar Neurons: More than two processes, motor function (spinal cord, cerebral cortex, cerebellar cortex).
- Pyramidal cells, Purkinje cells
Neurotransmitter Released
-
Types and description: Cholinergic, Adrenergic, GABAergic, Dopaminergic, Serotonergic, Glycinergic.
- Examples Most somatic motor neurons, most postganglionic sympathetic motor neurones, some neurons in the cerebellum, cerebral cortex etc.
Neuroglia / Glia Cells
- Glial cells support neurons. They are non-excitable. They are smaller than neurons, but more abundant by a factor of 10.
- Glial cells provide the microenvironment necessary for neuronal activity.
- Functions: structural and nutritional support; electrical insulation; enhancement of impulse conduction velocity.
- Varieties: Astrocytes, Oligodendrocytes, Microglia cells, Ependymal cells, Satellite cells, and Schwann cells.
Nerve Fibers
- Two types: Myelinated and Unmyelinated
- Myelinated fibers: large diameter, wrapped by Schwann cells for insulation.
- Unmyelinated fibers: small diameter, axon enveloped in Schwann cell cytoplasm.
- Oligodendrocytes myelinate axons in the CNS; Schwann cells in the PNS.
Nerve Bundles
- Epineurium surrounds the entire nerve.
- Perineurium surrounds nerve fiber fascicles.
- Endoneurium surrounds individual nerve fibers.
Synapse
- Forms from the interaction of the axon terminal and cell wall of the target cell.
- Neurone – neurone and neurone – effector cells (muscle and gland) contact site.
- Neurotransmitter release is at the axon terminal.
Sensory Receptor Endings
- Specialized nerve endings (or separate cells) for signal transduction.
- Transduce stimuli (internal or external) into nerve impulses.
- Stimuli are then passed to the CNS for sensory and motor responses.
- Classification of types of sensory endings: exteroceptors, interoceptors, and proprioceptors.
- Types: Free nerve endings, Pacinian corpuscles, Meissner corpuscles, Ruffini end-organs and Golgi tendon organs, Krause corpuscles, Muscle Spindles
Clinical Application
- Dead neurons are removed by macrophages.
- Hyperplasia and hypertrophy of astrocytes can occur, leading to gliosis.
- Axon regeneration may occur if the damage is far from the cell body.
- Gliomas are invasive and have incomplete removal, recurrence, and interference of function.
References
- A list of references are provided.
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Description
Explore the histology of nervous tissues, focusing on the structure and function of neurons and neuroglial cells. This quiz covers types of nerve tissues, their classification, and the roles of supporting cells. Deepen your understanding of how the nervous system processes stimuli and coordinates responses.
