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Example Questions
Example Question #61 : Nervous System And Nervous Tissue
In humans, nerve impulses are transmitted with the coordinated action of sodium and potassium ion channels. These channels open in a specific sequence, to allow for membrane potential changes to take place in a directional manner along the length of an axon.
Figure 1 depicts a single phospholipid layer of a cell membrane, and three transmembrane channels important to action potential propagation.
Action potential propagation down a membrane, as depicted in the figure, is typically very slow. Which of the following cell types is responsible for speeding nerve propagation by insulating peripheral axons?
Astrocytes
Monocytes
Schwann cells
Oligodendrocytes
Ependymal cells
Schwann cells
Schwann cells insulate peripheral axons with myelin. Oligodendrocytes serve a similar purpose, but do so in the central nervous system, and not the peripheral system.
Example Question #3 : Glia
Where might one find Schwann cells?
Trigeminal nerve
Broca's area
White matter
Optic nerve
Grey matter
Trigeminal nerve
Schwann cells are used to myelinate single axons in the peripheral nervous system. Oligodendrocytes are the counterpart of Schwann cells that exist in the central nervous system, but are capable of myelinating multiple axons at once.
To answer this question, we must select an answer that is part of the peripheral nervous system. Grey matter and white matter only exist in the central nervous system (brain and spinal cord) and can be eliminated. Broca's area is located in the frontal lobe of the cerebrum and will contain oligodendrocytes instead of Schwann cells. The optic nerve and trigeminal nerve are two of the cranial nerves, C2 and CV respectively. The optic nerve is the only cranial nerve to be myelinated by oligodendrocytes. The trigeminal nerve will be myelinated by Schwann cells.
Example Question #61 : Nervous System And Nervous Tissue
Schwann cells are responsible for which of the following?
Myelination of the central nervous system axons
Myelination of the peripheral nervous system dendrites
Circulation of cerebrospinal fluid
Myelination of the peripheral nervous system axons
Myelination of the peripheral nervous system axons
Schwann cells are responsible for producing myelin in the peripheral nervous system. These cells surround the axons with myelin sheaths, which increases the rate of signal transmission on axons.
Oligodendrocytes are responsible for myelinating axons in the central nervous system. Dendrites are not myelinated.
Example Question #2 : Glia
Which of the following is a location in the human body where oligodendrocytes will not be found?
Meninges
Pons
Wernicke's area
Frontal lobe
Spinal cord
Meninges
Oligodendrocytes are cells that insulate axons in the central nervous system. They are capable of producing the myelin sheathes for several surrounding cells and are the counterparts of the Schwann cells, which are located in the peripheral nervous system. The central nervous system includes the brain and spinal cord. Oligodendrocytes are responsible for producing the white matter of the central nervous system. The frontal lobe is a region of the cerebrum and will contain myelin. The spinal cord contains distinct white matter and grey matter regions. Wernicke's area is located in the temporal lobe of the cerebrum, and will contain oligodendrocytes. The pons is located in the hindbrain, or brainstem, and will and will also contain oligodendrocytes.
The meninges are the layers of connective tissue that surround the central nervous system. They are made primarily of collagen and do not contain nerve fibers. Oligodendrocytes will not be found in the meninges.
Example Question #62 : Nervous System And Nervous Tissue
Which of the following describes the difference between oligodendrocytes and Schwann cells?
Oligodendrocytes myelinate the central nervous system, while Schwann cells myelinate the peripheral nervous system
Schwann cells can mylinate multiple axons, while oligodendrocytes can only myelinate one axon per cell
Oligodendrocytes myelinate the peripheral nervous system, while Schwann cells myelinate the central nervous system
Oligodendrocytes and Schwann cell myelinate different structures of the neuron
Both cell types insulate the axons of cells, but use different insulating materials
Oligodendrocytes myelinate the central nervous system, while Schwann cells myelinate the peripheral nervous system
Both oligodendrocytes and Schwann cells are responsible for myelinating axons in order to increase the transmission rate of signals between neurons. The primary difference is their location. Oligodendrocytes myelinate the central nervous system, while Schwann cells myelinate the peripheral nervous system. Oligodendrocytes are also capable of myelinating multiple axons, while Schwann cells can only myelinate one axon per cell.
Example Question #6 : Glia
Which of the following structures creates a myelin sheath for axons in the central nervous system?
Schwann cells
Oligodendrocytes
Nodes of Ranvier
Axon hillock
Oligodendrocytes
Oligodendrocytes and Schwann cells both create myelin sheaths for axons, however, oligodendrocytes function in the central nervous system and Schwann cells function in the peripheral nervous system.
Example Question #7 : Glia
Diseases which destroy the myelin sheath of neurons cause __________.
cancer
a decrease in the speed of nerve conduction
decreased pain perception
an increase in the speed of nerve conduction
no change
a decrease in the speed of nerve conduction
Myelin sheathes function in insulating the neuron, and allows for much faster propogation of the action potential due to saltatory conduction. Loss of the myelin sheath would slow conduction of signals down the neural axon.
Pain perception is conducted to free nerve endings known as nociceptors, which are not myelinated.
Example Question #63 : Nervous System And Nervous Tissue
Excessive stimulation of the ulnar nerve results in the sensation known as the "funny bone," and can cause discomfort in the elbow and forearm. What cells are responsible for the myelination of the ulnar nerve?
Oligodendrocytes
Astrocytes
Dendritic cells
Schwann cells
Schwann cells
There are two types of cells responsible for the myelination of axons throughout the nervous system. Oligodendrocytes myelinate the axons of neurons in the central nervous system. Schwann cells myelinate neurons in the peripheral nervous system. This question is referring to a nerve in the elbow, which would be in the peripheral nervous system.
Astrocytes are a type of glial cell primarily found in the blood-brain barrier. Dendritic cells play a role in the adaptive immune response, and are not considered part of the nervous system.
Example Question #63 : Nervous System And Nervous Tissue
Which of the following glial cells produces cerebrospinal fluid?
Astrocytes
Ependymal cells
Oligodendrocytes
Satellite cells
Microglia
Ependymal cells
Ependymal cells, which line cerebral cavities and the central canal, produce cerebrospinal fluid (CSF). CSF is a colorless liquid that protects the brain and spinal cord against injury.
Microglia protect the central nervous system from microbes and debris of injured cells. Astrocytes, located in the central nervous system, provide structural support for neurons in addition to many other tasks involving nutrient and ion regulation. Oligodrendrocytes produce the myelin sheath around the axons of the central nervous system. Satellite cells are not found in the central nervous system, and therefore cannot produce CSF.
Example Question #131 : Systems Biology And Tissue Types
What is the major difference between Schwann cells and oligodendrocytes?
Oligodendrocytes myelinate central nervous system axons, whereas Schwann cells myelinate peripheral nervous system axons
Oligodendrocytes myelinate axons and dendrites, whereas Schwann cells only myelinate axons
Schwann cells are the most common glial cell type
Schwann cells myelinate axons, while oligodendocytes myelinate dendrites
Action potentials propagate faster down axons myelinated by Schwann cells
Oligodendrocytes myelinate central nervous system axons, whereas Schwann cells myelinate peripheral nervous system axons
Both oligodendrocytes and Schwann cells produce and maintain myelin along axons. Oligodendrocytes are the most common glial cell type, and provide myelination for all neural axons in the central nervous system. Schwann cells provide myelination for neurons in the peripheral nervous system.
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