Name the two cell types found in nervous tissue.
- Neurons
- Neuroglial Cells
Which cells are responsible for sending the electrical messages called action potentials?
Neurons
What is another name for action potentials?
Nerve impulses
The 3 Structural Areas of a Neuron
- Cell Body
- Axon
- Dendrites
Which structure contains the nucleus?
Cell Body
Which structure receives messages from other neurons?
Dendrites
Which structure produces and transmits the action potential?
Axon
What do nuclei and ganglia have in common? How are they different?
- Nuclei- clusters of cell bodies in Central Nervous System (CNS)
- Ganglia- clusters of cell bodies in Peripheral Nervous System (PNS)
What is the axolemma?
An axon’s plasma membrane
Where does a neuron store its synaptic vesicles containing neurotransmitters?
Axon Terminal
When an action potential travels “down” (along) an axon and arrives at the axon terminals, they release the neurotransmitters by exocytosis. What is the prupose of neurotransmitter release?
Sends to another target across the synaptic cleft, which can be another neuron.
Describe the function of dendrites.
Receive messages from other neurons. They transmit these messages to the neuron’s cell body, but they are not capable of generating action potentials.
Can dendrites produce action potentials?
No
3 Structural Classifications of Neurons
- Bipolar
- Unipolar
- Multipolar
Which type of neurons has more than two processes (extensions) from its cell body? Is its axon the longer process or its dendrites?
Multipolar
Axon is longer
Which type of neurons has only one process- a very short one- extending directly from its cell body? And what structure branches in both directions (T’s) from this single process?
Unipolar
Axon
Which type of neurons has two processes branching from its cell body? And name these two processes.
Bipolar
Axon and Dendrite
Which are the most common type of neuron?
Multipolar
Which types of neurons are less common and associated with sendory functions?
Bipolar and Unipolar
What is the function of the synapse?
Neurons communicate with one another and with their target cells at this junction.
Presynaptic Neuron
The neuron that sends the message. It contains neurotransmitters packaged in synaptic vesicles in its axon terminals.
Synaptic Cleft
The two neurons in a neuronal synapse are separated by this small space. This space is filled with extracellular fluid through which the neurotransmitters diffuse when they are released from the synaptic vesicles.
Postsynaptic Neuron
The neuron that receives the message. Its plasma membrane contains receptors for neurotransmitters. When the neurotranmitters bind to these receptors, the membrane potential of the postsynaptic neuron chenges.
Which cell type is smallest?
Neuroglial Cells
Which cell type is most abundant?
Neuroglial Cells
Neuroglia Located in the PNS
- Schwann Cells
- Satellite Cells
Which neuroglia of the PNS surround neuronal cell bodies in the PNS? What is thought to be thier function?
Satellite Cells
Believed to enclose and support the cell bodies, althogh their precise function is unknown.
Which neuroglia of the PNS form the myelin sheath along the axon in the PNS?
Schwann Cells
How do Schwann Cells form the myelin sheath?
Wrapping clockwise around the axon.
Does a myelinated axon have one or many Schwann Cells wrapping its axon?
Many Schwann Cells
What is the general function of myelination?
The myelin sheath protects and insulates the axons and speeds up conduction of action potential.
Name the spaces between the Schwann Cells where the axon is exposed.
Nodes of Ranvier
Neuroglia Located in the CNS
- Astrocytes
- Oligodendrocytes
- Microglial Cells
- Ependymal Cells
Astrocytes
The most numerous neuroglial cell type in the CNS. These star-shaped cells have many functions, including anchoring neurons and blood vessels in place with processes called perivasculaer feet and regulating the environment of the brain. In addition, they faciliate the formation of the blood-brain barrier, created by tight junctions in the brain cappilaries that prevent many substances in the blood from entering the brain tissue.
Oligodendrocytes
Have long extensions that wrap around the axons of certain neurons in the CNS to form the myelin sheath. Note that one oligodendrocyte can myelinate several axons.
Microglial Cells
The small microglial cells are very active phagocytes that clean up debris surrounding the neurons. Microglia also degrade and ingest damaged or dead neurons.
Ependymal Cells
The ciliated ependymal cells line the hollow spaces of the brain and spinal cord. They assist in forming the fluid that bathes the brain and spinal cord, cerebrospinal fluid, adn circulate it with their cilia.
Which neuroglia of the CNS performing a “cleaning” activity similar ro specific white blood cells? What is this activity called?
Microglial Cells
Phagocytosis
Which neuroglia of the CNS process and circulate cerebrospinal fluid (CSF)? What cellular structures do these neuroglia use to move the CSF?
Ependymal
Cilia
Which neuroglia of the CNS help position neurons in relation to blood vessels?
Astrocytes
Which neuroglia of the CNS form the myelin sheath along CNS axons? Does each of these neuroglia wrap one or many axons? How does this compare to Schwann Cells of the PNS?
Oligodendrocytes
Several Axons
Schwann Cells can only wrap one axon.
