Question 1

A disease in which antibodies destroy myelin produced by oligodendrocytes would most likely cause which of the following?

Accepted Answer

Destruction of myelin produced by oligodendrocytes would interfere with the ability of neurons in the brain and spinal cord to conduct action potentials quickly and efficiently. Myelin serves as an insulating layer around axons, allowing for rapid electrical signaling. Without myelin, the signals would travel more slowly, resulting in slower neural processing and potential symptoms such as muscle weakness, sensory deficits, and coordination problems.

Question 2

Which statement about microglia is true?

Accepted Answer

Microglia are immune cells of the central nervous system that are activated in response to damage, injury, or infection. They act as the main form of active immune defense in the CNS and play a crucial role in maintaining brain homeostasis. B, C, D, and E are incorrect statements about microglia.

Question 3

Astrocytes influence the connectivity between a pre- and postsynaptic neuron by

Accepted Answer

Astrocytes are known to take up and release neurotransmitters, which can modulate the activity of synapses between pre- and postsynaptic neurons. This is an important mechanism for astrocytes to influence network activity and plasticity in the brain. Choices A, B, C, and E are incorrect because they do not directly relate to the role of astrocytes in synaptic connectivity.

Question 4

Refer to the figure showing two types of neurons.  Compared with neuron B, neuron A would be more likely to

Accepted Answer

The answer of Refer to the figure showing two types...

Question 5

Which of the following represents the correct order of the parts of neurons that are involved in the flow of information, beginning with the presynaptic cell and ending where a synapse is made with a postsynaptic cell?

Accepted Answer

The correct order of information flow in a neuron begins with the presynaptic cell and ends where a synapse is made with a postsynaptic cell. The order is dendrites, cell body, axon hillock, axon, and axon terminals.

Question 6

In a thin section through brain tissue, you see a cell that is wrapped around the axon of a neuron, forming concentric layers of cell membrane.This cell most likely

Accepted Answer

The cell described in the question is a myelin-forming cell, also known as an oligodendrocyte or Schwann cell, which wraps around the axon of a neuron to form concentric layers of cell membrane. This wrapping provides insulation to the axon, allowing for rapid conduction of action potentials. Therefore, the best choice is D.

Question 7

The area where a neuron comes extremely close to a target cell and transmits information to the target cell is

Accepted Answer

The synapse is the area where a neuron comes extremely close to a target cell (such as another neuron, muscle cell, or gland cell) and transmits information to the target cell. At the synapse, the neuron releases neurotransmitters that bind to receptors on the target cell, triggering a response. The ganglion refers to a cluster of neuron cell bodies, the axon hillock is the region where the axon joins the neuron cell body, the node of Ranvier is a gap in the myelin sheath that surrounds some axons, and myelin is a fatty substance that insulates and speeds up neural impulses along axons.

Question 8

A disease that destroys astrocytes would cause all of the following except

Accepted Answer

Peripheral nerves are not composed of astrocytes, so a disease that destroys astrocytes would not directly affect the myelin sheath in peripheral nerves.

Question 9

Neurons have different shapes and sizes depending on their roles.A bipolar cell in the retina of the eye collects information from a few inputs and transmits it a short distance to one or more closely spaced neurons.What shape would you predict it to have?

Accepted Answer

A bipolar cell has only a few inputs and transmits information over a short distance, therefore it is likely to have a few dendrites and a short axon with one or more terminals. Option B and D describe neurons that have long axons, which is not indicative of a bipolar cell. Option C describes a neuron with numerous dendrites and a single axon which is also not specific to a bipolar cell. Option E describes a neuron with highly branched axons, which is not necessary for a cell that collects information from a few inputs.

Question 10

A challenge to modern medicine is to design drugs that target the brain.Existing knowledge about the ability of _______ to cross the blood‒brain barrier seems to be the best starting point in the design of new treatments.

Accepted Answer

Lipid-soluble substances are able to pass through the blood‒brain barrier and therefore are a good starting point for the design of drugs targeting the brain. This is because the barrier is made up of tightly packed cells that prevent most substances from entering the brain, but lipid-soluble substances are able to pass through because they are able to dissolve in the fatty cell membranes that make up the barrier.

Question 11

Diseases that destroy myelin

Accepted Answer

Myelin is a specialized cell membrane that wraps around axons in the peripheral and central nervous systems to facilitate conduction of action potentials. Diseases that destroy myelin impair this conduction, leading to various symptoms. Examples of such diseases include multiple sclerosis, leukodystrophies, and neuromyelitis optica. These diseases are not restricted to the central nervous system, and they do not destroy astrocytes or tripartite synapses. While some treatments exist to manage the symptoms of these diseases, there is currently no cure for myelin destruction.

Question 12

In looking at a section through the brain, you see a neuron with a number of shrublike projections extending from one side of the cell body and a single long projection extending from the other side.The shrublike projections are most likely _______, and the single long projection is most likely _______.

Accepted Answer

The shrublike projections are most likely dendrites, which receive signals from other neurons, while the single long projection is most likely the axon, which transmits signals to other neurons. Purkinje fibers are specialized muscle fibers found in the heart and have nothing to do with the brain. Axon terminals are the ends of axons, and presynaptic processes are part of the synaptic transmission process, neither of which fit the descriptions given in the question.

Question 13

Antibodies produced by the human immune system are typically prevented from getting to the brain by the blood‒brain barrier.Does this mean that the brain has no immune defenses?

Accepted Answer

Microglia are specialized immune cells in the brain and spinal cord that provide immune defense and maintain homeostasis in the central nervous system.

Question 14

In an active synapse composed of a presynaptic and postsynaptic cell, which part of the presynaptic cell is the last to participate in the action potential?

Accepted Answer

The axon terminals, located at the end of the presynaptic cell's axon, are the last to participate in the action potential. This is where neurotransmitters are released into the synaptic cleft, allowing communication with the postsynaptic cell.

Question 15

If a chemical prevents asymmetrical divisions of neuronal stem cells in the neural tube of a fish embryo, then

Accepted Answer

Asymmetrical divisions of neuronal stem cells in the neural tube of a fish embryo are required to produce neuroblasts (cells that differentiate into neurons) and gliablasts (cells that differentiate into glial cells). Without these asymmetrical divisions, neither of these cell types would be produced.

Question 16

Anesthetics and alcohol can permeate the blood-brain barrier because

Accepted Answer

Anesthetics and alcohol are both lipid-soluble and can easily pass through the lipid bilayer of the blood-brain barrier, which is made up of tightly packed endothelial cells with lipid membranes. This allows them to quickly enter the brain and exert their effects on the central nervous system.

Question 17

Slowing of early divisions of neuronal stem cells in the neural tube of a vertebrate embryo would result in

Accepted Answer

Slowing of early divisions of neuronal stem cells would result in fewer neuronal stem cells, as these cells are crucial for the development of the nervous system. This could ultimately lead to developmental disorders or neuronal dysfunction later in life. The other options are unlikely to be affected by early divisions of neuronal stem cells.

Question 18

The concept of a tripartite synapse is the idea that a synapse consists not only of pre- and postsynaptic neurons but also of connections from _______.This concept takes into account the _______ at the synapse.

Accepted Answer

The concept of a tripartite synapse includes not only pre- and postsynaptic neurons, but also the connections from astrocytes. This is because astrocytes have contact with neuronal elements and play a role in regulating the activity and communication at the synapse.

Question 19

The blood-brain barrier protects the brain

Accepted Answer

The blood-brain barrier (BBB) is primarily maintained through the action of astrocytes. These cells contribute to the structure and function of the BBB by reducing the permeability of capillaries in the brain, thereby limiting the substances that can pass from the bloodstream into the brain tissue. This mechanism is crucial for protecting the brain from potentially harmful substances and pathogens circulating in the blood.

Question 20

Which of the following is not a type of glial cell?

Accepted Answer

Bipolar cells are actually a type of neuron found in the retina of the eye, not a type of glial cell. The other options are all types of glial cells - oligodendrocytes produce myelin in the central nervous system, Schwann cells produce myelin in the peripheral nervous system, astrocytes support neuronal function, and microglia are involved in immune defense in the brain.

Quiz 44: Neurons, Glia, and Nervous Systems