Neuroscience Chapter 4: Action Potentials
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Questions and Answers

What role does the sodium-potassium pump play in maintaining the resting membrane potential?

  • It increases the intracellular K+ concentration.
  • It decreases the intracellular Na+ concentration.
  • It maintains the negative resting membrane potential. (correct)
  • It channels Na+ ions into the extracellular space.

What happens when the positive charge reaches a threshold during an action potential?

  • Na+ channels become permanently active.
  • The resting membrane potential is enhanced further.
  • K+ ions begin to flood into the cell.
  • Na+ channels close and become temporarily inactive. (correct)

Which of these best describes the propagation of an action potential along a neuron?

  • It occurs through passive diffusion along the membrane.
  • It travels at varying speeds based on the ion concentration.
  • It requires continuous reinforcement from the sodium-potassium pump.
  • It spreads in a 'one-way' direction along the axon. (correct)

What is the charge inside the cell when the action potential reaches its peak?

<p>+30 mV (C)</p> Signup and view all the answers

Which process is necessary for the sodium-potassium pump to function?

<p>Active transport using ATP (A)</p> Signup and view all the answers

What type of neurons have their cell bodies in ganglia?

<p>Sensory afferent (A)</p> Signup and view all the answers

Which neurotransmitter is associated with cholinergic motor neurons?

<p>Acetylcholine (B)</p> Signup and view all the answers

Which type of current carries the charge in a solution?

<p>Ions (A)</p> Signup and view all the answers

What is the typical resting potential of a neuron?

<p>-70 mV (A)</p> Signup and view all the answers

Which ion is primarily diffusing out of the neuron during resting potential?

<p>Potassium (K+) (B)</p> Signup and view all the answers

Which mechanism generates the resting potential in neurons?

<p>Sodium-potassium pump (C)</p> Signup and view all the answers

What type of neuron primarily has stellate or pyramidal shapes?

<p>Inter-neurons (C)</p> Signup and view all the answers

During resting potential, the inside of the neuron is primarily high in which ion?

<p>Potassium (K+) (A)</p> Signup and view all the answers

Which of the following neuron types is primarily involved in transmitting signals to muscles?

<p>Motor neurons (D)</p> Signup and view all the answers

What is the charge distribution across a neuron's plasma membrane during resting potential?

<p>Negative inside, positive outside (D)</p> Signup and view all the answers

Which taste is associated with sweet sensation?

<p>Sweet (C)</p> Signup and view all the answers

Which reflex is associated with the biceps muscle?

<p>C5, C6 (A)</p> Signup and view all the answers

What effect does the parasympathetic division have on the pupil of the eye?

<p>Constricts the pupil (A)</p> Signup and view all the answers

During rest and digestion, which of the following actions is promoted by the parasympathetic division?

<p>Inhibits heart rate (A)</p> Signup and view all the answers

Which neurotransmitters are released by the adrenal gland in a sympathetic response?

<p>Epinephrine and norepinephrine (B)</p> Signup and view all the answers

What is the effect of the sympathetic division on the bronchi?

<p>Relaxes the bronchi (B)</p> Signup and view all the answers

Which organ's functions are inhibited by the sympathetic division?

<p>Salivary glands (C)</p> Signup and view all the answers

Which of these functions is NOT associated with the parasympathetic division?

<p>Accelerates heart rate (B)</p> Signup and view all the answers

During a sympathetic response, which of the following is promoted?

<p>Epinephrine release (C)</p> Signup and view all the answers

Which reflex is primarily responsible for the knee jerk reaction?

<p>Patellar reflex (B)</p> Signup and view all the answers

What is one function of the myelin sheath in the nervous system?

<p>To allow saltatory conduction (C)</p> Signup and view all the answers

Which of the following describes the role of the nodes of Ranvier?

<p>They allow action potentials to jump during conduction (D)</p> Signup and view all the answers

What occurs when an action potential reaches the end of an axon?

<p>It triggers the release of neurotransmitters (B)</p> Signup and view all the answers

Which neurotransmitter is known for its role in muscle contraction?

<p>Acetylcholine (C)</p> Signup and view all the answers

What type of transmission occurs at the synapse?

<p>Electrical to chemical (C)</p> Signup and view all the answers

Which of the following best describes the term 'refractory period'?

<p>The time when a neuron is less responsive to stimulation (B)</p> Signup and view all the answers

What is the primary effect of increased axon diameter on signal transmission?

<p>Lower resistance to signal flow (C)</p> Signup and view all the answers

What is spatial summation in neuronal signaling?

<p>Combining signals from multiple neurons at different locations (A)</p> Signup and view all the answers

What is the role of inhibitory neurotransmitters?

<p>They decrease the likelihood of action potentials (A)</p> Signup and view all the answers

Which of the following neurotransmitters has an excitatory effect?

<p>Acetylcholine (C)</p> Signup and view all the answers

Which component is responsible for releasing neurotransmitters into the synaptic cleft?

<p>Synaptic knob (D)</p> Signup and view all the answers

What happens after a neurotransmitter binds to a receptor on a receiving neuron?

<p>Ion channels open or close (A)</p> Signup and view all the answers

Which neurotransmitter is specifically classified as inhibitory?

<p>GABA (B)</p> Signup and view all the answers

Which of the following neurotransmitters is primarily associated with dopamine pathways?

<p>Dopamine (C)</p> Signup and view all the answers

What role do action potentials play in neurotransmitter release?

<p>They stimulate synaptic vesicles to fuse with the membrane. (A)</p> Signup and view all the answers

Which of the following is not a neurotransmitter?

<p>Tomato ketchup (C)</p> Signup and view all the answers

What is the main function of neurotransmitters in the nervous system?

<p>To facilitate communication between neurons (A)</p> Signup and view all the answers

Which neurotransmitter is linked to mood regulation and is often targeted by SSRIs?

<p>Serotonin (A)</p> Signup and view all the answers

Which of the following is a function of the sympathetic division?

<p>Accelerates heart rate (D)</p> Signup and view all the answers

What is the primary role of the parasympathetic division in the digestive system?

<p>Stimulates stomach activity (B)</p> Signup and view all the answers

What happens to the bronchi under the influence of the sympathetic division?

<p>They dilate (A)</p> Signup and view all the answers

How does the sympathetic division affect the salivary glands?

<p>Inhibits saliva production (D)</p> Signup and view all the answers

Which response is associated with the stimulation of the adrenal glands?

<p>Release of epinephrine and norepinephrine (A)</p> Signup and view all the answers

What happens to urination under sympathetic division activation?

<p>It is inhibited (B)</p> Signup and view all the answers

What effect does the parasympathetic division have on the heart?

<p>Inhibits heart rate (D)</p> Signup and view all the answers

How does the parasympathetic division affect the genitalia?

<p>Promotes erection (B)</p> Signup and view all the answers

What is a primary function of the pancreatic response in the sympathetic division?

<p>Stimulates glucose release (A)</p> Signup and view all the answers

Flashcards

Neurons

Specialized cells in the nervous system that transmit signals throughout the body.

Resting Potential

The resting potential is the electrical charge difference across the cell membrane of a neuron when it is not transmitting a signal.

Microglia

Microglia are small, specialized cells that act as the immune system of the brain.

Neuron Classification

Neurons are classified by several factors, including their function (motor, sensory, interneurons), location, shape (stellate, pyramidal), and the type of neurotransmitter they use.

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Motor Neurons

Motor neurons control muscle movement.

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Sensory Neurons

Sensory neurons transmit information from the senses to the brain.

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Interneurons

Interneurons connect neurons within the central nervous system.

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Unipolar Neurons

Unipolar neurons have a single extension that branches into two axons.

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Bipolar Neurons

Bipolar neurons have two extensions: one axon and one dendrite.

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Multipolar Neurons

Multipolar neurons have one axon and many dendrites. This is the most common type of neuron.

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Sodium-Potassium Pump

The Sodium-Potassium Pump actively moves ions against their concentration gradient, requiring ATP. It pumps 2 K+ ions into the cell and 3 Na+ ions out, maintaining the negative resting membrane potential.

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Action Potential

An action potential is a rapid change in membrane potential that travels along the neuron, caused by the influx of sodium ions (Na+) followed by the efflux of potassium ions (K+).

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Threshold Potential

The threshold potential is the critical level of depolarization that must be reached to trigger an action potential. Once this threshold is crossed, the action potential will fire.

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All-or-None Principle

An action potential is an all-or-none event. Either it occurs fully with a constant magnitude or it doesn't occur at all. The strength of the stimulus does not affect the amplitude of the action potential.

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Action Potential Propagation

The action potential travels along the axon, the long extension of a neuron, allowing communication between neurons.

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Refractory Period

The period after an action potential where a neuron cannot be stimulated, due to inactivated sodium channels.

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Myelin Sheath

Myelin is a fatty substance that covers axons, speeding up nerve impulses.

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Nodes of Ranvier

Gaps in the myelin sheath where nerve impulses jump, increasing the speed of transmission.

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Saltatory Conduction

The process where nerve impulses jump between nodes of Ranvier, increasing transmission speed.

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Synapse

The junction between two neurons or a neuron and an effector cell, where information is passed.

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Neurotransmitters

Chemical messengers released at the synapse that transmit information between neurons.

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Excitatory Neurotransmitters

Neurotransmitters that increase the likelihood of an action potential in the receiving neuron.

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Inhibitory Neurotransmitters

Neurotransmitters that decrease the likelihood of an action potential in the receiving neuron.

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Summation of Inputs

The combination of multiple signals from different neurons, either spatially (from different locations) or temporally (over time).

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Axon Diameter and Speed

When an axon is thicker, it has lower resistance, allowing nerve impulses to travel faster.

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Acetylcholine

A neurotransmitter that plays a vital role in muscle movement, memory and learning. Its malfunction is linked to conditions like Alzheimer's disease.

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Dopamine

A neurotransmitter associated with pleasure, motivation, and reward. Its dysfunction can lead to conditions like Parkinson's disease.

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What is the "fight-or-flight" response?

The release of epinephrine and norepinephrine from the adrenal glands, triggered by the sympathetic nervous system, prepares the body for "fight or flight" responses such as increased heart rate, dilation of pupils, and redirection of blood flow to muscles.

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What is the role of the parasympathetic nervous system?

The parasympathetic division of the autonomic nervous system is responsible for slowing down the heart rate, stimulating digestion, and promoting relaxation in the body.

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What is the role of the sympathetic nervous system?

The sympathetic nervous system prepares the body for action and stress by increasing heart rate, dilating pupils, and diverting blood flow from digestive organs to skeletal muscles.

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How does the nervous system promote digestion?

The process of digestion is stimulated by the parasympathetic nervous system, which slows down the heart rate and increases blood flow to the digestive organs, facilitating the breakdown and absorption of food.

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What are the primary hormones released during the fight-or-flight response?

The sympathetic nervous system, through the adrenal medulla, releases epinephrine (adrenaline) and norepinephrine (noradrenaline), which trigger the fight-or-flight response, preparing the body for immediate action.

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How does the parasympathetic nervous system promote digestion?

The parasympathetic division of the autonomic nervous system promotes digestion by slowing down the heart rate, stimulating the production of digestive enzymes, and increasing blood flow to the digestive organs.

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What is the autonomic nervous system?

The autonomic nervous system is a part of the peripheral nervous system that regulates involuntary body functions, such as heart rate, respiration, digestion, and blood pressure.

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What are the two main branches of the autonomic nervous system?

The autonomic nervous system is divided into two branches: the sympathetic nervous system, which activates the fight-or-flight response, and the parasympathetic nervous system, which promotes rest and digestion.

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What is the role of the adrenal medulla in the fight-or-flight response?

The adrenal medulla, a part of the adrenal glands, releases epinephrine (adrenaline) and norepinephrine (noradrenaline) into the bloodstream, triggering the fight-or-flight response.

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What are some of the effects of the parasympathetic nervous system?

The parasympathetic nervous system promotes relaxation and digestion by slowing down heart rate, stimulating digestive processes, and constricting pupils.

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Sensory Transduction in Taste Buds

The sensory transduction of taste occurs when chemicals in food dissolve in saliva and interact with receptor cells within taste buds. The interaction triggers a signal that is transmitted to the brain, allowing us to perceive flavor.

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Sweet Taste

Sweet taste is elicited by sugars, such as glucose and fructose, and artificial sweeteners.

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Umami Taste

Umami taste is triggered by glutamate, an amino acid found in protein-rich foods.

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Bitter Taste

Bitter taste is often associated with potentially toxic substances. It's a warning signal to avoid harmful food.

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Salty Taste

Salty taste is produced by the presence of sodium ions (Na+).

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Sour Taste

Sour taste is caused by the presence of Hydrogen ions (H+), which contribute to acidity.

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Patellar Reflex

The Patellar reflex is a simple reflex that involves the stretching of the patellar tendon, triggering a contraction of the quadriceps muscle. It's tested clinically to assess the integrity of the spinal nerves (primarily L4).

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Biceps Reflex

The Biceps reflex involves the contraction of the biceps muscle in response to tapping the biceps tendon, primarily testing the spinal nerves C5 and C6.

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Triceps Reflex

The Triceps reflex involves the contraction of the triceps muscle in response to tapping the triceps tendon, primarily testing the spinal nerve C7.

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Divisions of the Peripheral Nervous System

Composed of the somatic nervous system (controls voluntary muscle movement), and the autonomic nervous system (regulates involuntary functions like breathing, heart rate, and digestion).

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