Questions and Answers
What is the difference between an oligodendrocyte and a Schwann cell?
Oligodendrocytes occur in the central nervous system and can insulate up to 50 axons, while Schwann cells occur in the peripheral nervous system and wrap around only 1 axon.
Microglia are a type of ___ cell that act in the ___ nervous system and provide ____ defenses, such as acting as _____ (white blood cells).
glial, central, immune, macrophages
How are glial cells differentiated from nerve cells?
Glial cells are not excitable, meaning they do not fire action potentials.
What do glial cells do?
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What is a macrophage?
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If glial cells have so many different functions, why are they associated with the nervous system?
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What is the difference between the central nervous system and the peripheral nervous system?
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What is the most important aspect of the nervous system?
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Another important function of the nervous system is cell communication for ____.
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What has the nervous system in the human race provided most recently in evolution?
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At a synapse, the presynaptic neuron _____ the message, and while the postsynaptic neuron ____ the message.
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What is the difference between ATP synthase and ATPase?
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All neurons are myelinated.
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How do action potentials jump between nodes of Ranvier?
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What is myelin?
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What is the most common type of glial cell?
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What are the functions of astrocytes?
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What is a nerve net?
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Clusters of neurons are called ____.
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What is the brain?
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What is the nervous system of a sea anemone?
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What is the nervous system of a sponge?
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The nervous system of an earthworm consists of a segmental nerve cord with pairs of _____ going down it.
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Why do squid have a more complex nervous system than earthworms?
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The PNS can be divided into _ divisions, which are what?
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Study Notes
Oligodendrocytes vs. Schwann Cells
- Oligodendrocytes are found in the central nervous system (CNS) and can insulate multiple axons (up to 50).
- Schwann cells reside in the peripheral nervous system (PNS) and wrap around a single axon.
Microglia
- Microglia are a type of glial cell in the central nervous system.
- They provide immune defense and function similarly to macrophages by engulfing pathogens.
Glial Cells
- Glial cells are non-excitable cells that do not fire action potentials.
- They support neurons physically and metabolically.
Functions of Glial Cells
- Glial cells insulate axons with myelin, offer protection, and help maintain the extracellular environment.
- They also participate in neurotransmitter release and clearance.
Macrophages
- Macrophages are large white blood cells responsible for engulfing pathogens, including bacteria.
Nervous System Cell Types
- The nervous system consists of two main cell categories: neurons and glial cells (glia).
Central vs. Peripheral Nervous System
- The central nervous system includes the brain and spinal cord.
- The peripheral nervous system comprises all other neural components.
Functions of the Nervous System
- The nervous system rapidly responds to environmental changes and facilitates cell communication for homeostasis.
Evolutionary Aspects of the Nervous System
- The human nervous system has evolved to enhance cognition and emotion.
Synaptic Transmission
- At a synapse, the presynaptic neuron sends the signal, while the postsynaptic neuron receives it.
ATP Synthase vs. ATPase
- ATP synthase is responsible for synthesizing ATP, whereas ATPase hydrolyzes ATP for energy use.
Myelination of Neurons
- Not all neurons are myelinated; for instance, multipolar interneurons lack myelin.
Action Potentials and Nodes of Ranvier
- Action potentials "jump" between nodes of Ranvier due to the electrical conductivity of the axon cytoplasm and the insulating properties of myelin, allowing faster transmission.
Myelin Structure
- Myelin is formed by glial cell outgrowths and serves as an electrically insulating layer around axons.
Common Glial Cells
- The most prevalent type of glial cell is the astrocyte.
Functions of Astrocytes
- Astrocytes play key roles in maintaining the blood-brain barrier, regulating blood flow, neurotransmitter dynamics, and interstitial fluid composition.
Simple Nervous Systems
- A nerve net is a basic network of neurons found in some organisms, facilitating direct communication from sensory cells to effectors.
Neuronal Clusters
- Groups of neurons are referred to as ganglia.
Brain Structure
- The brain is a massive collection of ganglia that coordinates higher processing.
Nervous System in Simple Organisms
- Sea anemones possess a nerve net, while sponges do not have a nervous system.
Earthworm Nervous System
- Earthworms have a segmental nerve cord equipped with pairs of ganglia.
Complexity in Nervous Systems
- Squids exhibit more complex nervous systems than earthworms due to specialized ganglia that process and integrate information.
Divisions of the Peripheral Nervous System
- The PNS is divided into two main parts:
- Afferent (sensory) division
- Efferent (motor) division.
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Description
Explore the differences between oligodendrocytes and Schwann cells, and the crucial roles of microglia and other glial cells in the nervous system. This quiz will test your understanding of how these cells support neurons and maintain homeostasis in the nervous system. Dive into the essential functions of both glial cells and macrophages in immune defense.
