Question 1

When a neurotransmitter like acetylcholine is acting in an excitatory manner which of the following is likely a result of the acetylcholine acting on the post synaptic cell?

Accepted Answer

When acetylcholine acts in an excitatory manner, it binds to chemically gated sodium channels on the postsynaptic cell, causing them to open and sodium ions to diffuse into the cell, resulting in depolarization and activation of the postsynaptic cell.

Question 2

If a post synaptic neuron is stimulated to threshold by spatial summation this implies that ________.

Accepted Answer

Spatial summation occurs when multiple presynaptic neurons release neurotransmitters simultaneously, therefore adding up their effects to reach threshold in the postsynaptic neuron. Therefore, if a post synaptic neuron is stimulated to threshold by spatial summation, it implies that the postsynaptic cell has many synapses with many presynaptic neurons.

Question 3

Bipolar neurons are commonly ________.

Accepted Answer

Bipolar neurons are typically found in the retina of the eye, where they play a critical role in transmitting visual information from photoreceptor cells to ganglion cells. They are characterized by having two processes (one dendrite and one axon) that extend from opposite ends of the cell body.

Question 4

When a neurotransmitter like GABA is acting in an inhibitory manner which of the following is likely a result of the GABA acting on the post synaptic cell?

Accepted Answer

When GABA acts on the postsynaptic cell in an inhibitory manner, it typically opens chloride ion channels, allowing negatively charged chloride ions to move into the cell. This makes the inside of the cell more negative, or hyperpolarized, making it less likely for the cell to fire an action potential.

Question 5

If a post synaptic cell is stimulated to threshold by temporal summation this implies that ________.

Accepted Answer

Temporal summation occurs when a single presynaptic neuron sends frequent EPSPs to a postsynaptic neuron, causing the postsynaptic neuron to become depolarized to threshold and fire an action potential. Therefore, the correct choice is C, "a presynaptic neuron is sending frequent EPSPs." The other choices are incorrect as they do not accurately describe temporal summation.

Question 6

These cells in the CNS have cilia that move in order to circulate cerebrospinal fluid ________.

Accepted Answer

Ependymal cells are the only cells in the CNS that have cilia, which move in order to circulate cerebrospinal fluid. Astrocytes help support and maintain the structure of the CNS, oligodendrocytes produce myelin for neuron insulation, and Schwann cells produce myelin for PNS neuron insulation.

Question 7

What does the central nervous system use to determine the strength of a stimulus?

Accepted Answer

The central nervous system determines the strength of a stimulus based on the frequency of action potentials sent by sensory neurons. A stronger stimulus will generate a higher frequency of action potentials, and a weaker stimulus will generate a lower frequency of action potentials. Therefore, choice D (frequency of action potentials) is the best answer.

Question 8

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________.

Accepted Answer

The absolute refractory period is the period after an initial stimulus when a neuron is completely insensitive to another stimulus. During this period, the neuron is in the process of repolarization and cannot respond to any additional stimuli. This period is important for ensuring that action potentials do not overlap and that nerve signals are transmitted accurately. Option A refers to the process of restoring the electrical charge of a neuron after depolarization, and option D refers to the process of the change in electrical charge from negative to positive that causes an action potential. Option B is vague and does not specifically describe the period of insensitivity after an initial stimulus.

Question 9

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle?

Accepted Answer

Acetylcholine is the neurotransmitter secreted by motor neurons innervating skeletal muscle, and it is an excitatory neurotransmitter. The other options listed (gamma aminobutyric acid, cholinesterase, and norepinephrine) are not excitatory neurotransmitters secreted by motor neurons innervating skeletal muscle.

Question 10

Bacteria in the blood can be prevented entry to the fluids surrounding the brain.Which cells are most responsible for preventing bacteria from entering the fluids of the brain?

Accepted Answer

Astrocytes are the most responsible cells for preventing bacteria from entering the fluids of the brain. They are a type of glial cell that forms a protective barrier called the blood-brain barrier. This barrier prevents harmful substances, including bacteria, from entering the brain and damaging its delicate tissues. Satellite cells are found in the peripheral nervous system and are involved in supporting and protecting neurons. Schwann cells and oligodendrocytes are also involved in supporting and protecting neurons, but they do not play a direct role in preventing bacteria from entering the fluids around the brain.

Question 11

Like all cells,the neurons' internal organization dictates its function.Neurons have relatively many mitochondria,an extensive network of rough endoplasmic reticulum and many clusters of ribosomes.These cellular features indicate all of the following EXCEPT ________.

Accepted Answer

The presence of many mitochondria and extensive network of rough endoplasmic reticulum in neurons indicate that they produce a lot of energy and proteins, respectively. Additionally, the high consumption of oxygen indicates the need for aerobic energy production. However, the stable and unchanging internal environment is not indicated by these cellular features. Neurons frequently undergo changes in response to various stimuli, indicating their ability to adapt to changing environments.

Question 12

The effect of acetylcholine can be stimulating or inhibiting.Which of the following gives the best explanation for why this is so?

Accepted Answer

Different post synaptic cells will have different receptors, which can lead to different effects of acetylcholine depending on the cell and its specific receptors.

Question 13

An action potential is regarded as an example of a positive feedback.Which of the following examples below best illustrates the positive feedback aspect of an action potential?

Accepted Answer

Positive feedback is a process where a stimulus has a self-amplifying effect leading to an increase in the output. In an action potential, the opening of voltage-gated sodium ion channels by a threshold stimulus results in depolarization, which opens more voltage-gated sodium ion channels. This leads to a self-amplifying effect, resulting in the generation of a large and rapid action potential, which is an example of positive feedback. A, B, and C do not illustrate positive feedback. A describes a mechanism that operates continuously and regardless of changes in membrane potential; B describes a difference in ion permeability and not feedback; C describes the opening of voltage-gated potassium ion channels that repolarize the membrane potential, and hence, it does not lead to a self-amplifying effect.

Question 14

During the relative refractory period of an action potential,a larger than normal stimulus is needed to cause another action potential.This is due to the fact that ________.

Accepted Answer

During the relative refractory period, the voltage-gated potassium ion channels remain open, causing hyperpolarization of the axon membrane. This makes it more difficult for the membrane potential to reach the threshold needed to trigger another action potential, thus requiring a larger than normal stimulus.

Question 15

The concentration neurotransmitters in the fluid of the synaptic cleft must be tightly regulated for neurons to function properly.Which of the following cells is most responsible for aiding in this regulation?

Accepted Answer

Astrocytes are responsible for aiding in the regulation of the concentration of neurotransmitters in the synaptic cleft. They take up excess neurotransmitter molecules and release them back into the synapse when needed. Satellite cells are found in ganglia and provide support to neurons. Schwann cells and oligodendrocytes are responsible for myelination of axons in the peripheral nervous system and central nervous system, respectively, and do not have a direct role in the regulation of neurotransmitter concentration in the synaptic cleft.

Question 16

Meningitis can be caused by infection of the central nervous system by bacteria.Which cells would be most responsible for removing the infection?

Accepted Answer

Microglia are specialized immune cells found in the central nervous system that are responsible for detecting, engulfing, and ultimately eliminating pathogens and other harmful substances in the CNS. Therefore, they would be most responsible for removing a bacterial infection that causes meningitis. Schwann cells and satellite cells are found in the peripheral nervous system, while oligodendrocytes are responsible for producing myelin in the CNS and do not play a significant role in immune response.

Question 17

Which of the choices below describes the ANS?

Accepted Answer

The ANS (autonomic nervous system) is responsible for involuntary control of smooth muscle, cardiac muscle, and glands. It consists of motor fibers that conduct nerve impulses from the CNS (central nervous system) to these tissues. Choice A accurately describes the ANS.

Option B is incorrect because it describes the somatic nervous system, not the ANS. Option C is partially correct but does not fully describe the ANS. Option D describes the somatic sensory nervous system, not the ANS.

Question 18

The concentration of ions in the chemical environment surrounding the neurons must be tightly regulated for neurons to function properly.Which of the following cells is most responsible for this?

Accepted Answer

Astrocytes are known to play a crucial role in regulating the chemical environment surrounding neurons, including the concentration of ions such as sodium, potassium, and calcium. They provide structural, metabolic, and functional support to neurons and are in close contact with them, allowing them to exchange signals and maintain homeostasis. Satellite cells are associated with sensory neurons, Schwann cells are responsible for myelination in the peripheral nervous system, and oligodendrocytes perform a similar function in the central nervous system, but none of these cells are primarily responsible for regulating ion concentration.

Question 19

Which of the following describes the nervous system integrative function?

Accepted Answer

The nervous system's integrative function involves analyzing sensory information, storing information, and making decisions. This is responsible for processing and interpreting sensory input, carrying out complex brain functions, and coordinating various body responses.

Question 20

The depolarization phase of an action potential is punctuated by the closing of inactivation gates in the voltage gated sodium ion channels.All of the following are consequences of this inactivation except one.Choose the statement below that is not a consequence of the closing of inactivating gates.

Accepted Answer

The closing of inactivation gates in voltage-gated sodium ion channels directly leads to the cessation of sodium influx, contributing to the stopping of depolarization, limiting the frequency of action potentials, and ensuring one-way transmission of the action potential. However, the efflux of potassium ions, which is crucial for repolarization, is primarily facilitated by the opening of voltage-gated potassium channels, not directly by the closing of sodium channel inactivation gates.

Quiz 11: Fundamentals of the Nervous System and Nervous Tissue