Cells and Neuron Structure in Nervous System
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Questions and Answers

CSF is reabsorbed into the ______.

blood

The ______ Plexus is the source of CSF.

Choroid

Microglia are the resident tissue ______ of the CNS.

macrophages

Activated microglia can turn good astrocytes ______.

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

Oligodendrocytes and Schwann cells are responsible for making ______ in the CNS and PNS, respectively.

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

Astrocytes help maintain extracellular ______ homeostasis.

<p>K+</p> Signup and view all the answers

The blood-brain barrier is formed by astrocyte ______ to ensure nutrient and signal selectivity.

<p>end-feet</p> Signup and view all the answers

Ependymal cells line the CSF-filled ______ of the brain and spinal cord.

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

Astrocytes are broadly divided into protoplasmic and ______ forms.

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

CSF bathes the brain and spinal cord and is rich in ______ and helps clear waste products.

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

The ______ nervous system consists of the brain and spinal cord.

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

The ______ nervous system connects the body to the brain.

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

Specialised cells called ______ are the building blocks of the nervous system.

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

The large projection neurons are found in the ______.

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

Nissl substance is a type of endoplasmic reticulum that is darkly stained with a ______ histological stain.

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

Neurons have a high demand for ______ synthesis.

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

In the cerebellum, neurons can be identified where the pale cell nucleus and large, prominent ______ are present.

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

Myelin, found in white matter tracts, can be stained deep blue with ______ fast blue.

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

In the cytoplasm of the cell body, most of the dark, purple-staining densities represent rough ______.

<p>endoplasmic reticulum</p> Signup and view all the answers

Cerebellar disorders can cause ______, which is impaired muscle coordination.

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

Dendrites can be either spiny or ______, contributing significantly to the neuron’s surface area.

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

A purkinje cell of the cerebellum receives tens of thousands of contacts from ______ of other neurons.

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

The axon connects neuron to ______, helping to transmit signals.

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

The neuronal cytoskeleton is composed of microtubules, microfilaments, and ______.

<p>intermediate filaments</p> Signup and view all the answers

Proteins are not synthesized in the axon because there are no ______.

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

Interrupted or deficient axon transport can result in neurodegeneration and ______.

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

Anterograde transport moves material from the soma to the ______ terminal under the direction of kinesin proteins.

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

Retrograde transport moves material from the axon terminal to the ______ by the action of dynein proteins.

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

Defects in axonal transport happen very early in the course of ______'s disease.

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

In Alzheimer's disease, defects in the Microtubule Associated Protein ______ lead to destabilization of microtubules.

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

Myelination organizes the axon to enable the transmission of action potentials by ______ conduction.

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

Nodes of Ranvier are approximately ______ wide and expose the neuron membrane to the external environment.

<p>1 µm</p> Signup and view all the answers

Astrocytes are essential for the formation and maintenance of the ______.

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

Astrocytes control the chemical environment at the synaptic ______, the gap between pre- and post-synapse.

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

Astrocytes partake in ______ by releasing neuroactive molecules that signal back to synapses.

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

The ______ barrier helps maintain a stable environment for normal neuronal functioning.

<p>blood-brain</p> Signup and view all the answers

Ependymal cells line the ______-filled ventricles of the brain and spinal cord.

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

Astrocytes control extracellular K+ ______ to maintain proper neuronal activity.

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

Astrocytes are classified into ______ and fibrous forms, based on their morphology and function.

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

The nervous system is composed of specialised cells called ______.

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

The ______ connects the body to the brain and includes the enteric nervous system.

<p>peripheral nervous system</p> Signup and view all the answers

Neurons have a high demand for ______ synthesis due to their active role in signaling.

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

Defects in the Microtubule Associated Protein ______ lead to a decrease in the microtubule binding affinity.

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

Astrocytes play a vital role in ______ transmission between neurons.

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

Myelination ensures fast conduction by axons through ______ conduction.

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

Synapses transmit chemical ______ between neurons.

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

Nodes of Ranvier expose the neuron membrane to the ______ environment.

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

The myelinating glia include ______ and Schwann cells.

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

Astrocytes control the chemical environment at the synaptic ______.

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

Continued proliferation and myelin re-modeling occurs in ______.

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

The cytoskeleton is a network of fibers extending throughout the ______.

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

Dendrites can account for ______% of the surface area of the neuron.

<p>90</p> Signup and view all the answers

A purkinje cell in the cerebellum sums inputs from tens of thousands of ______.

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

The axon is a long projection that connects neuron to neuron or to a ______.

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

There are three types of molecular structures in the cytoskeleton: microtubules, microfilaments, and ______.

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

Axon transport is energy dependent and can be classified as slow or ______.

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

In the absence of ______, proteins cannot be synthesized in the axon.

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

Neurodegeneration and dementia can result from interrupted or deficient axon ______.

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

Movement of ______ helps to circulate the CSF around the ventricles and over the brain.

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

Activated microglia can induce astrocytes with poor trophic and synaptic functions for ______ and thus become neurotoxic.

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

The ______ are responsible for producing cerebrospinal fluid in the brain.

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

Microglia account for approximately ______% of brain cells.

<p>15</p> Signup and view all the answers

The ______ is performed to collect cerebrospinal fluid for diagnostic purposes.

<p>lumbar puncture</p> Signup and view all the answers

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

<p>Acting as the primary defense against injury or infection</p> Signup and view all the answers

Which inflammatory mediators are produced by activated microglia that can affect astrocyte function?

<p>IL-1alpha, TNF, and complement protein C1q</p> Signup and view all the answers

What role do ependymal cells play in the central nervous system?

<p>They circulate cerebrospinal fluid around the ventricles.</p> Signup and view all the answers

Which statement about astrocytes is correct?

<p>They help create the correct environment for nerve cells.</p> Signup and view all the answers

How do activated microglia transform the function of astrocytes?

<p>By inducing neurotoxic effects through inflammatory pathways.</p> Signup and view all the answers

What is one of the key functions of astrocytes in the central nervous system?

<p>Provide metabolic support to neurons</p> Signup and view all the answers

How do astrocytes contribute to synaptic maintenance?

<p>By controlling K+ homeostasis and supplying glutamine</p> Signup and view all the answers

What is the composition of the blood-brain barrier?

<p>Endothelium, basal lamina, and astrocyte end-feet</p> Signup and view all the answers

What shapes do ependymal cells take, and what is their function?

<p>Squamous to columnar; they line brain ventricles and help circulate CSF</p> Signup and view all the answers

Which type of astrocyte predominates in grey matter?

<p>Protoplasmic astrocytes</p> Signup and view all the answers

What is the primary role of dendrites in a neuron?

<p>To convey information to the neuron</p> Signup and view all the answers

What consequence can arise from interrupted or deficient axon transport?

<p>Neurodegeneration and dementia</p> Signup and view all the answers

Which component of the neuronal cytoskeleton is primarily responsible for providing structural support?

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

What is a characteristic feature of the axon in neurons?

<p>It can vary significantly in length</p> Signup and view all the answers

What role do Purkinje cells play in the cerebellum?

<p>Coordinate and refine movement</p> Signup and view all the answers

Which type of neuron structure is primarily involved in information input?

<p>The dendrites</p> Signup and view all the answers

What distinguishes the cytoskeletal components in neurons?

<p>They consist of microtubules, neurofilaments, and microfilaments</p> Signup and view all the answers

What is the significance of the proximal and distal organization of receptors and ion channels on dendrites?

<p>They affect how synaptic input alters neuron activity</p> Signup and view all the answers

What structure connects the body to the brain in the nervous system?

<p>Peripheral nervous system</p> Signup and view all the answers

Which type of cell is primarily responsible for myelination in the peripheral nervous system?

<p>Schwann cell</p> Signup and view all the answers

What is the Nissl substance primarily composed of?

<p>Rough endoplasmic reticulum</p> Signup and view all the answers

What is one of the significant functions of astrocytes in the nervous system?

<p>Providing structural support</p> Signup and view all the answers

Where can large projection neurons be found in the brain?

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

Which component of the neuronal cytoskeleton is involved in anterograde transport?

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

What is the role of nodes of Ranvier in axonal transmission?

<p>Enhancing signal transmission speed</p> Signup and view all the answers

Which staining technique would best identify rough endoplasmic reticulum in neurons?

<p>Nissl stain</p> Signup and view all the answers

What role do dynein proteins play in axonal transport?

<p>They transport materials from the axon terminal to the soma.</p> Signup and view all the answers

How does myelination contribute to action potential propagation?

<p>By facilitating faster electrical conduction through saltatory conduction.</p> Signup and view all the answers

What is the primary consequence of defects in the Microtubule Associated Protein Tau in Alzheimer’s disease?

<p>Destabilization of microtubules and disrupted axonal transport.</p> Signup and view all the answers

What anatomical feature allows action potentials to propagate rapidly along myelinated neurons?

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

What is the role of astrocytes in synaptic transmission?

<p>They maintain the synaptic cleft's chemical balance.</p> Signup and view all the answers

What is a key function of the Nodes of Ranvier?

<p>To expose the neuron membrane to the external environment.</p> Signup and view all the answers

During which developmental period does the majority of axon myelination occur?

<p>Perinatal period.</p> Signup and view all the answers

What distinguishes oligodendrocytes and Schwann cells in the nervous system?

<p>Oligodendrocytes myelinate multiple axons in the CNS, while Schwann cells myelinate only one axon in the PNS.</p> Signup and view all the answers

What role do activated microglia play in the central nervous system?

<p>Induce neurotoxic effects in astrocytes</p> Signup and view all the answers

Which type of cells is responsible for the circulation of cerebrospinal fluid (CSF) within the brain ventricles?

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

What percentage of brain cells do microglia account for in the normal adult brain?

<p>15%</p> Signup and view all the answers

Which cells are known as the primary defense mechanism of the central nervous system?

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

What happens to astrocytes when they are induced by activated microglia?

<p>They become neurotoxic</p> Signup and view all the answers

Which protein is responsible for anterograde transport in neurons?

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

What is the main impact of defects in the Microtubule Associated Protein Tau in relation to Alzheimer's disease?

<p>Destabilization of microtubules</p> Signup and view all the answers

Which type of conduction is primarily enabled by the myelination of axons?

<p>Saltatory conduction</p> Signup and view all the answers

Astrocytes are known to regulate which aspect of synaptic function?

<p>Chemical environment in the synaptic cleft</p> Signup and view all the answers

Where are the Nodes of Ranvier predominantly located in relation to myelinated axons?

<p>Between segments of myelination</p> Signup and view all the answers

Which type of glial cell is primarily responsible for the myelination of axons in the peripheral nervous system?

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

The continued proliferation and differentiation of myelinating glia mainly occurs during which period of life?

<p>Childhood through adulthood</p> Signup and view all the answers

What is the primary role of astrocytes in synaptic transmission?

<p>Controlling synaptic cleft chemistry</p> Signup and view all the answers

What is one of the primary roles of astrocytes in the central nervous system?

<p>Maintaining extracellular potassium homeostasis</p> Signup and view all the answers

Which statement describes the blood-brain barrier?

<p>It selectively allows certain nutrients and molecules to pass.</p> Signup and view all the answers

Ependymal cells have which of the following characteristics?

<p>They are ciliated and line the CSF-filled ventricles.</p> Signup and view all the answers

What distinguishes protoplasmic astrocytes from fibrous astrocytes?

<p>Protoplasmic astrocytes predominate in gray matter, while fibrous astrocytes are found in white matter.</p> Signup and view all the answers

Which of the following roles do astrocyte end-feet play in the central nervous system?

<p>They help form the blood-brain barrier.</p> Signup and view all the answers

What is a primary function of dendrites in neurons?

<p>Receiving and conveying information to the neuron</p> Signup and view all the answers

Which structure in neurons is responsible for axon transport?

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

What characterizes a Purkinje cell in the cerebellum?

<p>It integrates a large number of inputs from other neurons.</p> Signup and view all the answers

What happens when there is interrupted or deficient axon transport?

<p>Neurodegeneration and dementia</p> Signup and view all the answers

Which type of neuronal cytoskeletal structure contributes to the organization of neuronal activities?

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

What is the primary role of myelination in neurons?

<p>To enhance the speed of action potential transmission</p> Signup and view all the answers

What feature distinguishes axons from dendrites?

<p>Axons are uniform in diameter and can be very long.</p> Signup and view all the answers

What describes the structure of the neuronal cytoskeleton?

<p>Dynamic network composed of three types of fibers</p> Signup and view all the answers

What specialized function do neurons primarily serve in the nervous system?

<p>Transmitting electrical impulses</p> Signup and view all the answers

Which of the following statements accurately describes the role of Nissl substance in neurons?

<p>It is indicative of the cell's ability to synthesize proteins</p> Signup and view all the answers

What distinguishes oligodendrocytes in the central nervous system from Schwann cells in the peripheral nervous system?

<p>Oligodendrocytes can myelinate multiple axons, Schwann cells can myelinate only one</p> Signup and view all the answers

In the context of neurons, what is the primary function of the cytoskeleton?

<p>To organize and transport proteins within the neuron</p> Signup and view all the answers

Which histological technique is primarily used to visualize Nissl-stained neurons?

<p>Nissl staining</p> Signup and view all the answers

How do astrocytes contribute to neurotransmission?

<p>By releasing neuroactive molecules that signal to neurons</p> Signup and view all the answers

What is the primary histological characteristic of neurons that allows them to be distinguished from other cell types?

<p>Large size and unique staining patterns</p> Signup and view all the answers

Which of the following accurately explains the role of the enteric nervous system?

<p>It regulates autonomic functions within the gastrointestinal tract</p> Signup and view all the answers

What is one of the primary functions of astrocytes in the brain?

<p>Formation of the blood-brain barrier</p> Signup and view all the answers

What are the two main morphological types of astrocytes?

<p>Protoplasmic and fibrous</p> Signup and view all the answers

Which structural feature is essential for the blood-brain barrier?

<p>Astrocyte end-feet</p> Signup and view all the answers

How do astrocytes maintain extracellular potassium homeostasis?

<p>By absorbing excess potassium ions</p> Signup and view all the answers

What is the primary function of glial cells in the nervous system?

<p>Providing structural support and insulation</p> Signup and view all the answers

What is the composition of the central nervous system?

<p>Brain and spinal cord</p> Signup and view all the answers

Which type of glial cell is responsible for myelination in the central nervous system?

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

Which type of ataxia is characterized by atrophy of the cerebellum and neurodegeneration?

<p>Spinocerebellar ataxia</p> Signup and view all the answers

What is the significance of Nissl substance in neurons?

<p>It indicates high levels of protein synthesis</p> Signup and view all the answers

What primarily composes the neuronal cytoskeleton?

<p>Microtubules, microfilaments, and intermediate filaments</p> Signup and view all the answers

What role do astrocytes play in the nervous system?

<p>Maintaining blood flow</p> Signup and view all the answers

How do neurons transport materials to distant points along their structure?

<p>By axonal transport along the cytoskeleton</p> Signup and view all the answers

Which statement about axons is true?

<p>They can be uniform in diameter</p> Signup and view all the answers

What distinguishes the structure of neurons from that of other cell types?

<p>Unique shape and specialized projections</p> Signup and view all the answers

What condition can result from interrupted or deficient axon transport?

<p>Neurodegeneration and dementia</p> Signup and view all the answers

How do Purkinje cells contribute to movement control?

<p>By summing inputs to produce a single output</p> Signup and view all the answers

What type of histological stain is used to visualize Nissl substance in neurons?

<p>Nissl stain</p> Signup and view all the answers

The primary function of the gaps found at intervals along myelinated axons, known as nodes of Ranvier, is to:

<p>Facilitate ion exchange</p> Signup and view all the answers

What type of cells produce cerebrospinal fluid?

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

What is the main function of activated microglia in the central nervous system?

<p>Inducing neurotoxic effects on astrocytes</p> Signup and view all the answers

Which inflammatory mediators are produced by activated microglia?

<p>IL-1alpha, TNF, and C1q</p> Signup and view all the answers

Which type of glial cells are responsible for myelination in the peripheral nervous system?

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

What type of transport moves material from the axon terminal to the soma?

<p>Retrograde transport</p> Signup and view all the answers

Which proteins direct anterograde transport in neurons?

<p>Kinesin proteins</p> Signup and view all the answers

The breakdown of microtubules in Alzheimer's disease is linked to defects in which protein?

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

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

<p>Maintain the chemical environment at synapses</p> Signup and view all the answers

What feature of nodes of Ranvier allows for fast conduction of action potentials?

<p>Rich in Nav+ &amp; Kv+ channels</p> Signup and view all the answers

During which period are the majority of axons myelinated?

<p>Perinatal period</p> Signup and view all the answers

What type of conduction do myelinated axons primarily use to transmit action potentials?

<p>Saltatory conduction</p> Signup and view all the answers

Astrocytes are the most abundant type of which cells in the nervous system?

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

Study Notes

Cells of the Nervous System

  • The nervous system is composed of specialized cells
  • The central nervous system (CNS) includes the brain and spinal cord
  • The peripheral nervous system (PNS) connects the body to the CNS, and includes the enteric nervous system
  • Neurons are the fundamental units of the nervous system
  • Glial cells support and protect neurons
    • Astrocytes: Maintain the chemical environment
    • Oligodendrocytes: Create myelin in the CNS
    • Schwann cells: Create myelin in the PNS
    • Ependymal cells line the ventricles and produce cerebrospinal fluid
    • Microglia are the macrophages of the CNS

Neuron Structure and Function

  • Dendrites are the receptive regions of a neuron, receiving signals
  • The cell body (soma) integrates signals
  • The axon carries signals away from the cell body
  • The axon terminal releases neurotransmitters
  • The axon can be myelinated or unmyelinated
  • Axon transport moves materials between the cell body and axon terminals (fast and slow)

Synaptic Transmission

  • Synapses are the junctions between neurons
  • Neurotransmitters are released from the presynaptic terminal
  • Neurotransmitters bind to receptors on the postsynaptic membrane
  • This binding triggers a response in the postsynaptic neuron
  • The synaptic cleft separates pre- and post-synaptic sides

Myelination

  • Myelin sheaths insulate axons, increasing the speed of signal transmission
  • Nodes of Ranvier are gaps in the myelin sheath
  • Saltatory conduction: Action potentials jump between nodes of Ranvier

Glial Cells

  • Astrocytes: Play a vital role in synaptic transmission because they maintain the chemical environment at the synaptic cleft; highly abundant
    • Control extracellular K+ homeostasis, and supply glutamine
  • Oligodendrocytes: Make myelin in the CNS, important for quick signal transmission
  • Schwann cells: Make myelin in the PNS
  • Ependymal cells: Line the ventricles of the brain and produce cerebrospinal fluid
  • Microglia: Are the resident macrophages of the CNS and are the first responders to injury or infection

Cerebellar Disorders

  • Cerebellar disorders include ataxia, hypotonia, and dysarthria
  • Spinocerebellar ataxias involve atrophy of the cerebellum and neurodegeneration (including loss of Purkinje cells)

Other Key Concepts

  • The neuronal cytoskeleton. A network of fibers in the neuron. There are three categories
    • Microtubules
    • Microfilaments
    • Neurofilaments
  • Defects in axonal transport are linked to diseases, like Alzheimer's Disease. Symptoms can include impaired motor function.

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