Nervous System and Nervous Tissue - MCAT Biological and Biochemical Foundations of Living Systems
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The cells that form myelin sheaths around axons outside of the central nervous system are .
The cells that form myelin sheaths around axons outside of the central nervous system are .
It is important to read this question carefully, as it asks for the cells that form myelin sheaths around axons outside of the central nervous system. In essence, it is asking about the peripheral nervous system.
Schwann cells and oligodendrocytes both form myelin sheaths (a white, fatty substance) around axons, which act as electrical insulation and increase the speed of action potential conduction. Schwann cells perform this function for neurons in the peripheral nervous system (outside of the central nervous system), while oligodendrocytes myelinate neurons in the central nervous system.
It is important to read this question carefully, as it asks for the cells that form myelin sheaths around axons outside of the central nervous system. In essence, it is asking about the peripheral nervous system.
Schwann cells and oligodendrocytes both form myelin sheaths (a white, fatty substance) around axons, which act as electrical insulation and increase the speed of action potential conduction. Schwann cells perform this function for neurons in the peripheral nervous system (outside of the central nervous system), while oligodendrocytes myelinate neurons in the central nervous system.
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Prions are the suspected cause of a wide variety of neurodegenerative diseases in mammals. According to prevailing theory, prions are infectious particles made only of protein and found in high concentrations in the brains of infected animals. All mammals produce normal prion protein, PrPC, a transmembrane protein whose function remains unclear.
Infectious prions, PrPRes, induce conformational changes in the existing PrPC proteins according to the following reaction:
PrPC + PrPRes → PrPRes + PrPRes
The PrPRes is then suspected to accumulate in the nervous tissue of infected patients and cause disease. This model of transmission generates replicated proteins, but does so bypassing the standard model of the central dogma of molecular biology. Transcription and translation apparently do not play a role in this replication process.
This theory is a major departure from previously established biological dogma. A scientist decides to test the protein-only theory of prion propagation. He establishes his experiment as follows:
Homogenized brain matter of infected rabbits is injected into the brains of healthy rabbits, as per the following table:
Rabbit 1 and 2: injected with normal saline on days 1 and 2
The above trials serve as controls.
Rabbit 3 and 4: injected with homogenized brain matter on days 1 and 2
The above trials use unmodified brain matter.
Rabbit 5 and 6: injected with irradiated homogenized brain matter on days 1 and 2
The above trials use brain matter that has been irradiated to destroy nucleic acids in the homogenate.
Rabbit 7 and 8: injected with protein-free centrifuged homogenized brain matter on days 1 and 2
The above trials use brain matter that has been centrifuged to generate a protein-free homogenate and a protein-rich homogenate based on molecular weight.
Rabbit 9 and 10: injected with boiled homogenized brain matter on days 1 and 2
The above trials use brain matter that have been boiled to destroy any bacterial contaminants in the homogenate.
A scientist shows that PrPC in normal nervous cells helps speed nervous transmission. What other structures help speed nervous transmission?
Prions are the suspected cause of a wide variety of neurodegenerative diseases in mammals. According to prevailing theory, prions are infectious particles made only of protein and found in high concentrations in the brains of infected animals. All mammals produce normal prion protein, PrPC, a transmembrane protein whose function remains unclear.
Infectious prions, PrPRes, induce conformational changes in the existing PrPC proteins according to the following reaction:
PrPC + PrPRes → PrPRes + PrPRes
The PrPRes is then suspected to accumulate in the nervous tissue of infected patients and cause disease. This model of transmission generates replicated proteins, but does so bypassing the standard model of the central dogma of molecular biology. Transcription and translation apparently do not play a role in this replication process.
This theory is a major departure from previously established biological dogma. A scientist decides to test the protein-only theory of prion propagation. He establishes his experiment as follows:
Homogenized brain matter of infected rabbits is injected into the brains of healthy rabbits, as per the following table:
Rabbit 1 and 2: injected with normal saline on days 1 and 2
The above trials serve as controls.
Rabbit 3 and 4: injected with homogenized brain matter on days 1 and 2
The above trials use unmodified brain matter.
Rabbit 5 and 6: injected with irradiated homogenized brain matter on days 1 and 2
The above trials use brain matter that has been irradiated to destroy nucleic acids in the homogenate.
Rabbit 7 and 8: injected with protein-free centrifuged homogenized brain matter on days 1 and 2
The above trials use brain matter that has been centrifuged to generate a protein-free homogenate and a protein-rich homogenate based on molecular weight.
Rabbit 9 and 10: injected with boiled homogenized brain matter on days 1 and 2
The above trials use brain matter that have been boiled to destroy any bacterial contaminants in the homogenate.
A scientist shows that PrPC in normal nervous cells helps speed nervous transmission. What other structures help speed nervous transmission?
Schwann cells act as insulators on nervous tissue to help propagate nervous transmission via saltatory conduction. This speeds transmission and makes axonal signal propagation much more rapid.
Schwann cells act as insulators on nervous tissue to help propagate nervous transmission via saltatory conduction. This speeds transmission and makes axonal signal propagation much more rapid.
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Which of the following structures creates a myelin sheath for axons in the central nervous system?
Which of the following structures creates a myelin sheath for axons in the central nervous system?
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.
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.
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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?
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?
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.
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.
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Diseases which destroy the myelin sheath of neurons cause .
Diseases which destroy the myelin sheath of neurons cause .
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.
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.
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Which of the following describes the difference between oligodendrocytes and Schwann cells?
Which of the following describes the difference between oligodendrocytes and Schwann cells?
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.
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.
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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?
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?
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.
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.
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Which of the following is a location in the human body where oligodendrocytes will not be found?
Which of the following is a location in the human body where oligodendrocytes will not be found?
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.
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.
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Where might one find Schwann cells?
Where might one find Schwann cells?
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.
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.
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Schwann cells are responsible for which of the following?
Schwann cells are responsible for which of the following?
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.
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.
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Which of the following glial cells produces cerebrospinal fluid?
Which of the following glial cells produces cerebrospinal fluid?
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.
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.
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What is the major difference between Schwann cells and oligodendrocytes?
What is the major difference between Schwann cells and oligodendrocytes?
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.
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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Under which division of the nervous system does the "fight or flight" impulse originate?
Under which division of the nervous system does the "fight or flight" impulse originate?
The nervous system is divided into the central nervous system (brain and spinal cord) and peripheral nervous system (all other nerves). The peripheral nervous system is then divided into the sensory and motor divisions. Then, the motor division is further divided into the somatic and autonomic divisions. The autonomic division is then divided into the parasympathetic ("rest and digest") and sympathetic ("fight or flight") divisions.
The nervous system is divided into the central nervous system (brain and spinal cord) and peripheral nervous system (all other nerves). The peripheral nervous system is then divided into the sensory and motor divisions. Then, the motor division is further divided into the somatic and autonomic divisions. The autonomic division is then divided into the parasympathetic ("rest and digest") and sympathetic ("fight or flight") divisions.
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The amygdala is located in which part of the brain?
The amygdala is located in which part of the brain?
The amygdala is responsible for emotional memory and is part of the limbic system, which is located in the temporal lobe.
The amygdala is responsible for emotional memory and is part of the limbic system, which is located in the temporal lobe.
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Efferent neurons carry information in what direction?
Efferent neurons carry information in what direction?
Efferent neurons carry information from the central nervous system (CNS) to the peripheral nervous system (PNS). Afferent neurons carry information from the peripheral nervous system to the central nervous system.
In general, afferet neurons will relay sensory information about the environment (both internal and external), carrying these signals from the periphery to the central nervous system for integration and interpretation in the brain. Efferent neurons, in contrast, will carry motor signals or other internal stimuli to respond to the sensory information provided.
Efferent neurons carry information from the central nervous system (CNS) to the peripheral nervous system (PNS). Afferent neurons carry information from the peripheral nervous system to the central nervous system.
In general, afferet neurons will relay sensory information about the environment (both internal and external), carrying these signals from the periphery to the central nervous system for integration and interpretation in the brain. Efferent neurons, in contrast, will carry motor signals or other internal stimuli to respond to the sensory information provided.
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Which of the following is a correct description of the sympathetic and parasympathetic nervous systems?
Which of the following is a correct description of the sympathetic and parasympathetic nervous systems?
The sympathetic (fight or flight) and the parasympathetic (rest and digest) systems control bodily processes that are involuntary, or autonomic. Somatic refers to voluntary actions, which are not controlled by either the sympathetic or parasympathetic systems.
The sympathetic (fight or flight) and the parasympathetic (rest and digest) systems control bodily processes that are involuntary, or autonomic. Somatic refers to voluntary actions, which are not controlled by either the sympathetic or parasympathetic systems.
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The relaxation of bronchial smooth muscle is stimulated by what type of neuron?
The relaxation of bronchial smooth muscle is stimulated by what type of neuron?
Relaxation of bronchial smooth muscle is an involuntary process, which is accomplished by the autonomic system rather than the somatic. It is also a part of the "fight or flight" response, which relates to the sympathetic system. Postganglionic neurons directly stimulate target tissues, while preganglionic neurons stimulate postganglionic neurons.
Relaxation of bronchial smooth muscle is an involuntary process, which is accomplished by the autonomic system rather than the somatic. It is also a part of the "fight or flight" response, which relates to the sympathetic system. Postganglionic neurons directly stimulate target tissues, while preganglionic neurons stimulate postganglionic neurons.
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Sympathetic nervous system reactions are associated with which of the following?
Sympathetic nervous system reactions are associated with which of the following?
The sympathetic nervous system is associated with the "fight or flight" response. Some bodily responses include pupil dilation, increased heart rate, increased perspiration, increased blood flow to muscles, relaxation of the bladder, and decreased digestion.
The sympathetic nervous system is associated with the "fight or flight" response. Some bodily responses include pupil dilation, increased heart rate, increased perspiration, increased blood flow to muscles, relaxation of the bladder, and decreased digestion.
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Which of the following is a parasympathetic nervous system response?
Which of the following is a parasympathetic nervous system response?
The correct answer is an increase in digestive activity. The parasympathetic nervous system is involved in "rest and digest" functions. This includes a lowering of heart rate, lowering of blood flow to skeletal muscle, and an increase in digestive functions. The incorrect answers are all responses of the sympathetic nervous system.
The correct answer is an increase in digestive activity. The parasympathetic nervous system is involved in "rest and digest" functions. This includes a lowering of heart rate, lowering of blood flow to skeletal muscle, and an increase in digestive functions. The incorrect answers are all responses of the sympathetic nervous system.
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Which of the following pairs describing the sympathetic and parasympathetic nervous systems accurately portray their roles?
Which of the following pairs describing the sympathetic and parasympathetic nervous systems accurately portray their roles?
The sympathetic nervous system (fight or flight) releases epinephrine and norepinephrine which activates adrenergic receptors throughout the body, causing bronchodilation, vasodilation to skeletal muscles, and vasodilation to coronary arteries. The parasympathetic nervous system (rest and digest) acts in the opposite manner, slowing the heart rate via the vagus nerve.
The sympathetic nervous system (fight or flight) releases epinephrine and norepinephrine which activates adrenergic receptors throughout the body, causing bronchodilation, vasodilation to skeletal muscles, and vasodilation to coronary arteries. The parasympathetic nervous system (rest and digest) acts in the opposite manner, slowing the heart rate via the vagus nerve.
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