High School Biology : Understanding Properties of Nervous Tissue

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Understanding Properties Of Nervous Tissue

Which of the following occurs in synaptic transmission?

Possible Answers:

The action potential depolarizes the end of the pre-synaptic neuron

Neurotransmitter chemicals diffuse across the synaptic cleft

All of these events occur during synaptic transmission

The membranes of synaptic vesicles fuse with the cell membrane of the pre-synaptic neuron

Only a small potential is generated in the post-synaptic neuron

Correct answer:

All of these events occur during synaptic transmission

Explanation:

As the action potential depolarizes the pre-synaptic terminal button, calcium enters the region and causes the vesicles (full of neurotransmitter) to fuse their membranes with the membrane of the neuron, leading to rapid release of their chemical content outside of the cell. The neurotransmitters must diffuse across the synaptic cleft in order to cause a post-synaptic effect. Typically, many, many excitatory inputs must summate to cause depolarization of the post-synaptic neuron. Each individual stimulus is generally well below threshold, and the post-synaptic neuron will only generate an action potential with several stimuli at once.

Example Question #2 : Understanding Properties Of Nervous Tissue

When an action potential reaches the axon of a neuron, what is the first event to occur?

Possible Answers:

Calcium rushes into the cytoplasm

Intracellular potassium rushes out of the cytoplasm

Extracellular sodium rushes into the cytoplasm

Intracellular sodium rushes out of the cytoplasm

Extracellular potassium rushes into the cytoplasm

Correct answer:

Extracellular sodium rushes into the cytoplasm

Explanation:

At rest, the neuron will have large amounts of sodium outside the cell and large amounts of potassium inside the cell. When an action potential reaches the axon of the neuron, it opens voltage-gated sodium channels. Sodium immediately rushes through these channels to enter the cell, flowing from high sodium concentration to low sodium concentration. This event is known as depolarization.

Later in the action potential, potassium channels will open and potassium will rush out of the cell along its concentration gradient. This is part of the action potential leads to hyperpolarization.

Example Question #3 : Understanding Properties Of Nervous Tissue

What is the purpose of the nodes of Ranvier?

Possible Answers:

They allow a way from neurons to communicate with each other, via connecting nodes

They allow the transport of proteins along the axon

They allow neurons to recieve oxygen

They allow the action potential to skip over sections of the axon

They provide support and protection to the axon

Correct answer:

They allow the action potential to skip over sections of the axon

Explanation:

A fatty substance called myelin wraps arounds the axon of a neuron, forming an insulating layer called the myelin sheath. Gaps in the myelin coating create small openings, called the nodes of Ranvier, where the cell membrane is exposed. During an action potential, the electrical signal is able to jump from on node to the next, skipping portions of the axon. This speeds up the conduction of the action potential signal. Instead of travelling in a constant wave down the axon, the signal can jump or bounce past segments of it. This process is known as saltatory conduction.

Many neurological diseases and disorders arise from the degeneration of the myelin sheath, slowing the propagation of action potentials and hindering neural functionality.

Example Question #4 : Understanding Properties Of Nervous Tissue

What do function do glial cells facilitate?

Possible Answers:

They produce neural impulses

They send and receive nerve impulses

They detect malfunctioning nerve impulses

They increase the speed of nerve impulses

They amplify neural impulses

Correct answer:

They increase the speed of nerve impulses

Explanation:

Glial cells are cells that make up nervous tissue and provide support, protection, and nutrients for the neurons in the brain and nervous system. While neurons are the cells responsible for actually generating, sending, and receiving neural impulses, glial cells are capable of enhancing the speed at which these impulses can be transmitted. In particular, Schwann cells and oligodendrocytes provide myelin sheaths to neurons. Myelin acts as an insulator and helps the action potential travel more quickly down the neural axon.

Example Question #5 : Understanding Properties Of Nervous Tissue

Into what structure does a neuron release neurotransmitters?

Possible Answers:

Axon

Synaptic cleft

Nodes of Ranvier 

Soma

Dendrite

Correct answer:

Synaptic cleft

Explanation:

Neurotransmitters are released from the axon terminal into the synaptic cleft.

Neurons are essential for transmitting signals, but do so without actually touching one another. The space between neurons is known as the synaptic cleft, or synapse. When a signal reaches the end of one neuron at the axon terminal, it causes neurotransmitters to be released from vesicles. The neurotransmitter molecules travel to the dendrites of the next neuron, which receives the signal and passes it down the next axon.

The soma is the cell body of the neuron, which synthesizes proteins and integrates incoming signals. Nodes of Ranvier are regions along myelinated axons that allow for faster action potential conduction.

Example Question #6 : Understanding Properties Of Nervous Tissue

Influx of sodium ions is very crucial for cell activity. The influx of sodium ions in an action potential causes which of the following? 

Possible Answers:

Hyperpolarization

Depolarization

The fusion of vesicles to the presynaptic end plate

Repolarization

Correct answer:

Depolarization

Explanation:

Influx of sodium ions causes depolarization in a cell. Influx of sodium ions causes the membrane potential to become more positive and leads to activation of cell activity. Repolarization is done by the efflux of potassium ions. Hyperpolarization is a state in which a cell cannot conduct another action potential. It must reach its resting membrane potential before it can cause another action potential to occur. 

Example Question #7 : Understanding Properties Of Nervous Tissue

Which of the following cells proliferates in response to injury? 

Possible Answers:

Microglial cells

Oligodendrocytes

Astrocytes

Ependymal cells

Correct answer:

Astrocytes

Explanation:

Astrocytes are responsible for proliferating in regards to brain injury. They also help to make the blood brain barrier (BBB) and are a glycogen fuel reserve buffer. Microglial cells are phagocytes of the central nervous system. They respond to tissue damage by differentiation into large phagocytic cells. Myelin helps to wrap and and insulate axons. It increases space constant (length constant) and increases conduction velocity. Oligodendrocytes myelinate the axons of neurons in the central nervous system.

Example Question #8 : Understanding Properties Of Nervous Tissue

What is the standard resting potential in a neuron?

Possible Answers:

Correct answer:

Explanation:

The inside of a neuron always has a net negative charge at resting state and only becomes positive briefly when threshold is reached causing an action potential. This is due to the concentration and flow of positive sodium and potassium ions that exist at differing gradients when the neuron is at rest. 

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