Human Anatomy and Physiology : Systems Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

Example Question #2 : General Neuron Physiology

Which of the following is responsible for opening sodium channels in the plasma membrane of the receiving neuron, leading to an action potential or more excitable neuron? 

Possible Answers:

Chloride 

Calcium 

Norepinephrine 

Glutamate 

GABA (gamma-aminobutyric acid)

Correct answer:

Glutamate 

Explanation:

Glutamate opens sodium channels in the plasma membrane of the receiving neuron, moving the action potential towards (depolarize) the sodium Nernst potential (81mV). GABA is an inhibitory neurotransmitter which opens chloride channels in the plasma membrane of the receiving neuron, making the neuron more difficult to excite (hyperpolarized). 

Example Question #8 : Neural Physiology

The resting membrane potential (RMP) is primarily determined by which ion?

Possible Answers:

Calcium

Chloride

Sodium

Magnesium

Potassium

Correct answer:

Potassium

Explanation:

The resting membrane potential is based on the difference in electrical charges of the ions that flow through the membrane. The membrane potential has a greater permeability to potassium when at rest which causes a shift in its potential. Thus, potassium has the strongest affect on the RMP and causes it to be closer to potassium's reversal potential. Side note: This potential is strongly held by the sodium potassium pump.

Example Question #171 : Systems Physiology

A stimulus applied to a neuronal membrane that causes its potential to become more positive is __________. A stimulus that moves the potential closer to 0 is __________.

Possible Answers:

depolarization . . . depolarization

hyperpolarization . . . depolarization

hyperpolarization . . . resting membrane potential

hyperpolarization . . . hyperpolarization

depolarization . . . hyperpolarization

Correct answer:

hyperpolarization . . . depolarization

Explanation:

If an already positive membrane potential becomes more positive, it is becoming hyperpolarized because the electrical difference between the inside and outside of the cell is getting larger. On the other hand, a stimulus that moves the potential difference closer to 0 is depolarizing because it is decreasing the difference in electrical potential between the inside and outside of the cell.

Example Question #933 : Human Anatomy And Physiology

The presence of __________ dramatically increases the speed at which an action potential moves along an axon.

Possible Answers:

plasma protein

a capsule

myelin

neurilemma

Correct answer:

myelin

Explanation:

Myelin helps to increase resistance along the axon, which helps to propagate the action potential along the axon.

Example Question #172 : Systems Physiology

The following are the main steps in the generation of an action potential:

1. inactivation of Na channels and activation of K channels

2. depolarization to threshold

3. return to normal permeability

4. activation of Na channels

What is the proper sequence of these events?

Possible Answers:

4,3,2,1

2,4,3,1

1,2,3,4

2,4,1,3

Correct answer:

2,4,1,3

Explanation:

In order to have an action potential, you must have a depolarization. Na channels must close before K channels open

Example Question #13 : Help With Action Potential Physiology

Which part of the neuron generates the action potential?

Possible Answers:

axon

axon hillock

nucleus

dendrites

cell body

Correct answer:

axon hillock

Explanation:

The action potential of a neuron is generate at the axon hillock and is propagated down the axon and to the terminal branches where it will synapse with the dendrites of the next neuron.

Example Question #173 : Systems Physiology

Which of the following describes the influx of  ions into the neuron?

Possible Answers:

repolarization

none of these

polarization

hyperpolarization

depolarization

Correct answer:

depolarization

Explanation:

The influx of positive sodium ions into the neuron is known as depolarization. This is the loss of negative charge that occurs when positive sodium passes through the neural membrane and enters the neuron.

Example Question #174 : Systems Physiology

When the neuron becomes depolarized, which of the following events takes place?

Possible Answers:

efflux of sodium ions

influx of sodium ions

efflux of potassium ions

None of these will occur.

influx of potassium ions

Correct answer:

influx of sodium ions

Explanation:

Depolarization is when the neuron becomes more positive by gaining positively charged ions, specifically sodium ions. During depolarization the sodium ion channels open and sodium ions enter the neuron, reducing the membrane potential to roughly +35 mV.

Example Question #175 : Systems Physiology

Which of the following statements is true of a bipolar neuron?

Possible Answers:

It has two axons branching off of the neuron body

It has two processes extending off of the neuron's cell body

It only communicates with two other neurons

It is the most common neuron type in the brain

Correct answer:

It has two processes extending off of the neuron's cell body

Explanation:

There are three possible neural cell structures: unipolar, bipolar, and multipolar. Bipolar neurons have only two extensions coming off of the cell body, typically the dendrite extension and the axon extension. Although there are only two extensions coming off of the neuron, it is still capable of interacting with many other neurons due to subsequent branching beyond the junction with the cell body.

Example Question #176 : Systems Physiology

Which of the following is NOT a property of neurons?

Possible Answers:

Compose the nervous system

Permanent cells

Cells do not divide during adulthood

Undergo reactive gliosis in response to injury

Correct answer:

Undergo reactive gliosis in response to injury

Explanation:

Neurons are the cells that make up the nervous system. Neurons are large, permanent cells that do not divide during adulthood and spend most of their lives in the G0 phase of the cell cycle. If part of a neuron is damaged, it undergoes Wallerian degeneration, meaning that the neuron degenerates distal to the injury, and does not undergo reactive gliosis in response to injury. Astrocytes, a type of glial cell, do this.

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