Autonomous Nervous System Overview
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Questions and Answers

What role does the Autonomous Nervous System (ANS) play in the body?

  • Promotes sensory perception and interpretation
  • Regulates the internal environment and homeostasis (correct)
  • Generates conscious thoughts and actions
  • Regulates voluntary muscle movements

What happens during the activation of the parasympathetic nervous system?

  • Increases alertness and metabolic rate
  • Prepares the body for emergency responses
  • Stimulates the release of stress hormones
  • Promotes digestion and reduces metabolic rate (correct)

Which of the following statements is true about the sympathetic nervous system?

  • Decreases heart rate and metabolic function
  • Increases digestive activity and promotes rest
  • Kicks in during resting conditions
  • Prepares the body for exertion or emergency (correct)

Which control mechanism does the ANS primarily operate under?

<p>Unconscious and autonomic control (C)</p> Signup and view all the answers

Which of the following systems is NOT a part of the ANS?

<p>Somatic nervous system (B)</p> Signup and view all the answers

How does the ANS contribute to maintaining homeostasis?

<p>By regulating activities based on physiological demands (A)</p> Signup and view all the answers

During times of stress, which nervous system is primarily activated?

<p>Sympathetic nervous system (D)</p> Signup and view all the answers

In which scenario is the sympathetic nervous system likely to be activated?

<p>Running from a perceived threat (A)</p> Signup and view all the answers

What occurs to some neurotransmitters after they are released into the synaptic cleft?

<p>They are degraded by enzymes or recycled (C)</p> Signup and view all the answers

What is the primary advantage of synapses in nerve impulse transmission?

<p>They allow for unidirectional transmission (B)</p> Signup and view all the answers

What type of synapse is associated with the fastest possible neural responses?

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

Which of the following correctly describes the role of synaptic vesicles?

<p>They release neurotransmitters into the synaptic cleft (A)</p> Signup and view all the answers

Why are protein receptors linked to Na+ ion channels significant in synaptic transmission?

<p>They ensure unidirectional impulse transmission at the synapse (A)</p> Signup and view all the answers

What is the main function of the sympathetic nervous system?

<p>Prepares the body for high-energy activities (D)</p> Signup and view all the answers

What is the approximate resting potential of an axon?

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

Which activity is associated with the parasympathetic nervous system?

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

What occurs at the axon's resting state?

<p>A potential difference is established across the membrane (A)</p> Signup and view all the answers

What is primarily responsible for maintaining the resting potential of an axon?

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

What happens to the sodium and potassium ions during the action potential process?

<p>Sodium ions flow in, and potassium ions flow out of the axon (A)</p> Signup and view all the answers

During which phase is an axon said to be polarized?

<p>During resting potential (B)</p> Signup and view all the answers

What characterizes the ion channels when an axon is at rest?

<p>They are closed and not conducting ions (D)</p> Signup and view all the answers

What initiates the depolarization of a nerve membrane?

<p>Entry of Na+ ions due to mechanical-gated Na+ channels opening (A)</p> Signup and view all the answers

What is the threshold membrane potential for eliciting the action potential?

<p>-55 mV (C)</p> Signup and view all the answers

What occurs during the repolarization phase of the action potential?

<p>K+ ions leave the cell, restoring the negative charge (B)</p> Signup and view all the answers

What characterizes the all-or-none phenomenon in action potentials?

<p>If the threshold is reached, an action potential occurs; otherwise, it does not. (C)</p> Signup and view all the answers

During the repolarization phase, which channels close after 0.5 msec?

<p>Voltage-gated Na+ channels (A)</p> Signup and view all the answers

What causes hyperpolarization of the neuron membrane?

<p>Excessive K+ ions leaving the cell (D)</p> Signup and view all the answers

What role do sodium/potassium pumps play after the action potential?

<p>They help return the cell to its resting membrane potential. (C)</p> Signup and view all the answers

Which statement is true regarding the ionic basis of an action potential?

<p>Na+ ions enter the cell during depolarization, causing the inside to become positive. (C)</p> Signup and view all the answers

What occurs if the strength of the stimulus is below the threshold?

<p>No action potential occurs (D)</p> Signup and view all the answers

What does the all-or-none phenomenon state?

<p>The response of an axon remains consistent regardless of stimulus intensity (C)</p> Signup and view all the answers

What frequency of impulses is generated by firm pressure compared to light touch?

<p>Higher frequency of impulses (B)</p> Signup and view all the answers

How can a stronger stimulus be differentiated from a weaker one?

<p>By the number of neurons activated and the frequency of impulses (D)</p> Signup and view all the answers

At what threshold does an action potential begin to occur?

<p>At -55mV (D)</p> Signup and view all the answers

What happens with further increases in the intensity of the stimulus after the threshold is met?

<p>A full-sized action potential occurs (A)</p> Signup and view all the answers

What is a consequence of more sensory neurons being activated during a stronger stimulus?

<p>More impulse frequencies generated (B)</p> Signup and view all the answers

What is indicated by the refractory period?

<p>The threshold becomes higher than -60mV (C)</p> Signup and view all the answers

What prevents the action potential from spreading in both directions?

<p>The refractory period (D)</p> Signup and view all the answers

How does an increase in axon diameter affect nerve impulse transmission?

<p>It increases the rate of transmission (D)</p> Signup and view all the answers

Why does a larger axon improve nerve impulse transmission?

<p>It provides a wider area for ionic exchanges (D)</p> Signup and view all the answers

What is the result of the refractory period after an action potential?

<p>A separation between sequential action potentials (A)</p> Signup and view all the answers

What role does the myelin sheath play in nerve impulse transmission?

<p>It allows for faster signal propagation (C)</p> Signup and view all the answers

Flashcards

What is the Autonomous Nervous System (ANS)?

The ANS is the part of the nervous system that controls our body's internal functions automatically, like heart rate, digestion, and breathing.

What is the main function of the ANS?

The ANS helps keep our body's internal environment stable, even when we are stressed or relaxed.

What type of organs does the ANS affect?

The ANS influences internal organs, like the heart, lungs, and stomach, without us having to consciously think about it.

What does the sympathetic nervous system do?

The sympathetic division kicks in when we're facing stress, danger, or excitement. It prepares us for 'fight or flight'.

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What does the parasympathetic nervous system do?

The parasympathetic division takes over when we're relaxed and resting. It helps us 'rest and digest'.

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How does the sympathetic nervous system affect heart rate?

The sympathetic nervous system increases heart rate, allowing more blood to flow to muscles for action.

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How does the parasympathetic nervous system affect heart rate?

The parasympathetic nervous system slows down heart rate, bringing it back to a normal resting rhythm.

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How do the sympathetic and parasympathetic nervous systems work together in terms of heart rate?

The sympathetic and parasympathetic nervous systems are like opposing forces that work together to control heart rate, maintaining a balanced rhythm.

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Neurotransmitter Degradation

The breakdown of neurotransmitters in the synaptic cleft by enzymes.

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Neurotransmitter Recycling

The process of reabsorbing neurotransmitters released from presynaptic neurons back into their vesicles for reuse.

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Unidirectional Transmission

Synapses ensure that nerve impulses travel in only one direction, from the presynaptic neuron to the postsynaptic neuron.

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Electrical Synapse

A type of synapse where electrical signals directly pass from one neuron to another through gap junctions.

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All-or-None Phenomenon

The principle that a nerve impulse will either fire at full strength or not at all, there are no varying degrees of firing intensity.

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Depolarization

A change in the membrane potential of a neuron from negative to positive, resulting in a nerve impulse.

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Repolarization

The process of restoring the membrane potential of a neuron to its resting state after depolarization.

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Hyperpolarization

A state where the membrane potential of a neuron becomes even more negative than its resting potential.

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Threshold

The minimum level of stimulation required to trigger an action potential in a neuron.

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Voltage-gated ion channel

A type of ion channel that opens in response to a change in voltage across the cell membrane.

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Ligand-gated ion channel

A type of ion channel that opens in response to the binding of a neurotransmitter to a receptor.

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Mechanically-gated ion channel

A type of ion channel that opens in response to mechanical stimulation, such as stretching or pressure.

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Resting Potential

The state of a neuron when it is not actively transmitting a nerve impulse.

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What is the potential difference in a resting neuron?

A difference in electrical charge across the cell membrane of a neuron, typically around -70mV.

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Action Potential

The difference in electrical charge across the membrane of a neuron when it is actively transmitting a nerve impulse. It's a rapid change in voltage that travels along the axon.

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Ion Channels

Specialized proteins embedded in the cell membrane that allow ions to pass through, playing a crucial role in generating and transmitting nerve signals.

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Sodium-Potassium Pump

A type of ion channel that actively pumps sodium (Na+) ions out of the cell and potassium (K+) ions into the cell, maintaining the resting membrane potential.

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What is the role of the Sodium-Potassium Pump in the cell membrane?

Active transport of sodium ions (Na+) and potassium ions (K+) across the cell membrane against their concentration gradients, requiring energy. This process is crucial for maintaining the resting membrane potential.

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Refractory Period Role in Action Potential Direction

The refractory period ensures that action potentials only travel in one direction along a nerve fiber. This prevents the signal from spreading backward and ensures efficient signal transmission.

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How Axon Diameter Affects Nerve Impulse Speed

The thicker the axon, the faster the nerve impulse travels. This is because a larger diameter reduces resistance to ionic flow and provides more surface area for exchange.

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Myelin Sheath's Role in Nerve Impulse Speed

The myelin sheath acts as an insulator around the axon, allowing nerve impulses to jump between gaps called nodes of Ranvier. This speeds up transmission significantly.

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Speed Difference: Myelinated vs. Unmyelinated Axons

Myelinated axons conduct impulses much faster than unmyelinated axons because the signal can jump between nodes of Ranvier.

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Myelin Sheath's Impact on Speed

The presence of a myelin sheath significantly increases the speed of nerve impulse transmission.

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All-or-None Principle

The principle stating that a neuron either fires a full-strength action potential or it doesn't fire at all, regardless of the stimulus intensity.

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Frequency of Impulses

The frequency of action potentials generated by a neuron is directly proportional to the intensity of the stimulus.

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Number of Sensory Neurons Activated

The number of sensory neurons activated by a stimulus is directly related to the stimulus intensity.

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Refractory Period

The period after an action potential where a neuron is less likely to fire another action potential.

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Refractory Period Threshold

The threshold during the refractory period becomes higher than the normal resting potential.

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Importance of Refractory Period

The refractory period helps to regulate the frequency of neuron firing and prevents the overstimulation of neurons.

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Study Notes

Autonomous Nervous System

  • The ANS regulates the body's internal environment, responding to changing demands.
  • It's a motor system innervating internal organs, under involuntary control.
  • It consists of two antagonistic systems: sympathetic and parasympathetic.

Parasympathetic Division

  • Active during resting conditions ("Rest and Digest").
  • Reduces metabolic rate and promotes digestion.
  • Acts to "kick in" during relaxing time.

Sympathetic Division

  • Active during exertion, stress, or emergency ("Fight or Flight").
  • Increases alertness, metabolic rate, and muscular abilities.
  • Acts to "kick in" during times of stress or emergency.

Nerve Impulse Transmission

  • Nerve impulses are electrical messages (action potentials).
  • They travel along neurons from dendrites to axons at high speed.
  • Neurons have three types of ion channels (Voltage-gated, ligand-gated, stress-activated) that are closed when the neuron is at rest.
  • Resting potential is maintained at -70mV through the sodium-potassium pump actively pumping Na+ ions out and K+ ions in, along with the presence of negatively-charged proteins inside the cytoplasm.
  • Action potential occurs when the membrane depolarizes and reverses the membrane potential. Increased Na+ entry causes rapid depolarization and then a negative charge.
  • These voltage gated K+ channels open and K+ ions flow out, repolarizing the membrane.

Conduction of Nerve Impulses

  • Action potential in neurons causes depolarization of the membrane, causing it to become more positive, creating an action potential.
  • For a neuron to depolarize, the stimulus must reach a threshold voltage.
  • During the refractory period, the membrane cannot respond to another stimulus.
  • Action potentials move in one direction, as the membrane moves away from the excitatory zone.

Importance of the Refractory Period (Inexcitability)

  • The refractory period ensures action potentials move in one direction only.
  • This prevents the backward movement of action potentials, and makes it possible for the neuron to prepare for another stimulus.

Transmission Speed

  • Axon diameter and presence of myelin sheath impact transmission speed.
  • Larger axons and myelinated axons transmit impulses faster; this is because they have lower resistance, enabling faster transmission.

Synaptic Transmission

  • Neurotransmitters are released by presynaptic neurons to communicate with postsynaptic neurons.
  • Neurotransmitter fate: Some degrade in the cleft, while others are recycled.
  • Different types of synapses exist (neuroglandular).

All-or-None Phenomenon

  • The strength of a stimulus does not affect the size of an action potential.
  • The frequency of action potentials differentiates intensities of stimuli, with stronger stimuli generating more frequent action potentials.

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Description

Test your understanding of the Autonomous Nervous System (ANS) and its critical functions in the human body. This quiz covers the roles of the sympathetic and parasympathetic systems, their contribution to homeostasis, and the mechanisms of synaptic transmission. Dive into the complexities of nerve impulse transmission and neurotransmitter activities.

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