Autonomic Nervous System Overview
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Questions and Answers

What are the two main divisions of the Autonomic Nervous System?

Sympathetic nervous system and parasympathetic nervous system

What is a division of the peripheral nervous system that regulates involuntary bodily functions?

  • Spinal Nervous System
  • Autonomic Nervous System (correct)
  • Central Nervous System
  • Somatic Nervous System

    • The parasympathetic nervous system predominates during emergency situations.

    False

    Which neurotransmitter is released by cholinergic fibers?

    <p>Acetylcholine</p> Signup and view all the answers

    What are the two types of receptors acetylcholine binds to?

    <p>Nicotinic receptors and muscarinic receptors</p> Signup and view all the answers

    The sympathetic nervous system is also known as the ______ system.

    <p>adrenergic</p> Signup and view all the answers

    The parasympathetic nervous system is also known as the ______ system.

    <p>cholinergic</p> Signup and view all the answers

    Which neurotransmitters are the most common in the Autonomic Nervous System?

    <p>Acetylcholine and norepinephrine</p> Signup and view all the answers

    What happens to neurotransmitters in the synaptic cleft?

    <p>They are degraded, taken back into the neuron, or diffuse away.</p> Signup and view all the answers

    What is the effect of M1 and M3 receptor activation on intracellular calcium levels?

    <p>Activation of M1 and M3 receptors increases intracellular Ca2+ levels.</p> Signup and view all the answers

    Distinguish between the G proteins coupled to M2 receptors and M1/M3 receptors.

    <p>M2 receptors couple with Gi proteins, while M1 and M3 receptors couple with Gq proteins.</p> Signup and view all the answers

    What role does phospholipase C play in the signaling pathway of M1 and M3 receptors?

    <p>Phospholipase C activation leads to the generation of inositol trisphosphate (IP3) and diacylglycerol (DAG).</p> Signup and view all the answers

    How does nicotine affect nicotinic receptors at varying concentrations?

    <p>At low concentrations, nicotine stimulates nicotinic receptors, whereas at high concentrations, it blocks them.</p> Signup and view all the answers

    What is the primary physiological response associated with M2 receptor activation in cardiac muscle?

    <p>Activation of M2 receptors leads to decreased heart rate and contractility.</p> Signup and view all the answers

    Describe the primary function of nicotinic receptors in the nervous system.

    <p>Nicotinic receptors function as ligand-gated ion channels that mediate neurotransmission.</p> Signup and view all the answers

    What is the effect of IP3 in the signaling pathway of M1 and M3 receptor activation?

    <p>IP3 increases intracellular calcium, leading to various physiological effects.</p> Signup and view all the answers

    What happens to cyclic AMP levels when M2 receptors are activated?

    <p>Activation of M2 receptors causes a reduction in cyclic AMP (cAMP) levels.</p> Signup and view all the answers

    Explain the role of preganglionic neurons in the Autonomic Nervous System.

    <p>Preganglionic neurons have their cell bodies in the CNS and transmit signals to autonomic ganglia.</p> Signup and view all the answers

    Differentiate between cholinergic and adrenergic fibers in terms of neurotransmitter release.

    <p>Cholinergic fibers release acetylcholine, while adrenergic fibers release norepinephrine.</p> Signup and view all the answers

    What effect does the sympathetic nervous system have on the body during exercise?

    <p>The sympathetic nervous system prepares the body for strenuous physical activity by increasing heart rate and blood flow.</p> Signup and view all the answers

    Describe the primary function of the parasympathetic nervous system.

    <p>The parasympathetic nervous system conserves and stores energy while regulating bodily functions like digestion.</p> Signup and view all the answers

    Explain the process of acetylcholine synthesis and its significance in neurotransmission.

    <p>Acetylcholine is synthesized in the axon terminal and is crucial for transmitting signals across the synapse to effector organs.</p> Signup and view all the answers

    Differentiate between cholinergic and adrenergic fibers in the autonomic nervous system.

    <p>Cholinergic fibers release acetylcholine, while adrenergic fibers release norepinephrine or epinephrine.</p> Signup and view all the answers

    How are neurotransmitters terminated in the synaptic cleft in the Autonomic Nervous System?

    <p>Neurotransmitters are terminated through reuptake into the presynaptic neuron or enzymatic degradation.</p> Signup and view all the answers

    What are the two main types of cholinergic receptors and their respective roles?

    <p>The two main types of cholinergic receptors are nicotinic and muscarinic, with nicotinic affecting skeletal muscles and muscarinic influencing cardiac and smooth muscle.</p> Signup and view all the answers

    What are the three mechanisms for terminating neurotransmitter activity at the neuroeffector junction?

    <p>The three mechanisms are enzymatic degradation, reuptake into the neuron, and diffusion away from the synapse.</p> Signup and view all the answers

    Discuss the role of signal transduction pathways in the functioning of adrenergic receptors.

    <p>Signal transduction pathways convert the binding of norepinephrine to adrenergic receptors into cellular responses, such as increased energy mobilization.</p> Signup and view all the answers

    List and briefly describe the types of cholinergic receptors.

    <p>The two types of cholinergic receptors are nicotinic receptors, which respond to nicotine and acetylcholine, and muscarinic receptors, which mainly respond to acetylcholine.</p> Signup and view all the answers

    What is the role of muscarinic receptors in the parasympathetic nervous system?

    <p>Muscarinic receptors mediate the effects of acetylcholine on various organs in the parasympathetic nervous system.</p> Signup and view all the answers

    Characterize the situation under which the parasympathetic nervous system predominates.

    <p>The parasympathetic nervous system predominates during restful conditions, promoting calm states and energy conservation.</p> Signup and view all the answers

    Describe the two subclasses of adrenergic receptors and their primary functions.

    <p>The two subclasses are alpha (α) and beta (β) adrenergic receptors, which mediate different physiological responses such as vasoconstriction and increased heart rate, respectively.</p> Signup and view all the answers

    How does acetylcholine degradation occur in the synaptic cleft?

    <p>Acetylcholine is rapidly broken down by the enzyme acetylcholinesterase in the synaptic cleft, terminating its action.</p> Signup and view all the answers

    What roles do the G protein-coupled muscarinic receptors play in signal transduction?

    <p>Muscarinic receptors initiate intracellular signaling cascades through G proteins after binding to acetylcholine.</p> Signup and view all the answers

    Study Notes

    Autonomic Nervous System (ANS)

    • The ANS is a division of the peripheral nervous system (PNS) that controls involuntary bodily functions. These functions include heart rate, blood pressure, digestion, respiratory rate, and glandular secretion.
    • The ANS has two main branches:
      • The sympathetic nervous system (SNS) - "fight or flight" response.
      • The parasympathetic nervous system (PNS) - "rest and digest" response.
    • The ANS relies on a two-neuron system:
      • Preganglionic neurons: originate from the CNS and synapse in autonomic ganglia.
      • Postganglionic neurons: originate in autonomic ganglia and innervate target organs.
      • The synapse between the two neurons is located in an autonomic ganglion.
    • The ANS is comprised of two main systems:
      • Sympathetic nervous system (Adrenergic system)
      • Parasympathetic nervous system (cholinergic system)
    • The sympathetic system is activated during times of stress, exercise, and emergencies, preparing the body for physical activity.
    • The parasympathetic system dominates during resting conditions to conserve energy and regulate basic bodily functions.

    Neurotransmission in the ANS

    • The two primary neurotransmitters in the ANS are:
      • acetylcholine (Ach)
      • norepinephrine (NE)
    • Neurotransmitters are synthesized in the axon and stored in vesicles for release.
    • Fibers that release acetylcholine are called cholinergic fibers.
    • Fibers that release norepinephrine are called adrenergic fibers.
    • To enable new signals to reach target tissues, neurotransmitters must be rapidly removed or inactivated from the synapse.
    • Termination of neurotransmitter activity can occur through three mechanisms:
      • Enzymatic degradation: Neurotransmitters are broken down by enzymes in the synapse.
      • Reuptake: neurotransmitters are reabsorbed back into the neuron that released them.
      • Diffusion: neurotransmitters move away from the synapse.

    Types of ANS Receptors

    • Acetylcholine binds to two types of cholinergic receptors:
      • Nicotinic receptors
      • Muscarinic receptors
    • Norepinephrine and epinephrine bind to adrenergic receptors:
      • Alpha (α) receptors
      • Beta (β) receptors.

    Parasympathetic Nervous System (PNS)

    • Also known as the cholinergic system.
    • Cholinergic fibers use acetylcholine as a neurotransmitter.
    • All preganglionic fibers of the ANS (sympathetic and parasympathetic) are cholinergic.
    • All postganglionic fibers of the parasympathetic system are cholinergic.
    • Some sympathetic postganglionic fibers like those innervating sweat glands are cholinergic.

    Neurotransmission at Cholinergic Neurons

    • Neurotransmission in cholinergic neurons involves six steps:
      1. Synthesis of ACh.
      2. Storage of ACh in vesicles.
      3. Release of ACh into the synapse.
      4. Binding of ACh to the receptor.
      5. Degradation of ACh in the synaptic cleft.
      6. Recycling of choline.

    Cholinergic Receptors (Cholinoceptors)

    • Two families of cholinoceptors:
      • Muscarinic receptors: G protein-coupled receptors, bind to muscarine and acetylcholine.
      • Nicotinic receptors: ion channel receptors, found in skeletal muscle, autonomic ganglia, and the brain.

    Location of Muscarinic Receptors

    • Muscarinic receptors are found on organs such as the heart, smooth muscle, brain, and exocrine glands.

    Muscarinic Receptors

    • Part of the G protein-coupled receptor class
    • Bind to both muscarine and acetylcholine
    • Weak affinity for nicotine
    • Five subclasses, but only M1, M2, and M3 are well understood.
    • Location: autonomic effector organs (e.g., heart, smooth muscle, brain, exocrine glands)
    • All five subtypes are found on neurons.

    Nicotinic Receptors

    • Ligand-gated ion channels
    • Activated by acetylcholine (ACh) and nicotine
    • Crucial for neurotransmission in both central and peripheral nervous systems
    • Binding of ACh or nicotine causes a conformational change that opens the ion channel, allowing sodium ions influx and leading to cell depolarization.
    • Nicotine can stimulate or block receptors depending on concentration: low concentration stimulates, high concentration blocks.

    Neurotransmission

    • Acetylcholine (ACh) and norepinephrine (NE) are the two most common neurotransmitters released by neurons in the autonomic nervous system (ANS).
    • These neurotransmitters are synthesized in the axon and stored in vesicles for subsequent release.
    • Cholinergic fibers release acetylcholine.
    • Adrenergic fibers release norepinephrine.

    Termination of Neurotransmitter Activity

    • Three mechanisms for termination of neurotransmitter activity:
      • Enzymatic degradation
      • Reuptake into the neuron
      • Diffusion away from the synapse

    Types of ANS receptors

    • Acetylcholine binds to two types of cholinergic receptors:
      • Nicotinic receptors
      • Muscarinic receptors
    • Norepinephrine and epinephrine bind to adrenergic receptors:
      • Alpha (α)
      • Beta (β)

    Parasympathetic Nervous System (PNS)

    • Also called cholinergic
    • All preganglionic fibers of the ANS
    • All postganglionic fibers of the parasympathetic system
    • Some sympathetic postganglionic fibers like sweat glands

    Neurotransmission at Cholinergic Neurons

    • Six sequential steps:
      • Synthesis of ACh
      • Storage
      • Release
      • Binding of ACh to the receptor
      • Degradation of ACh in the synaptic cleft
      • Recycling of choline

    Autonomic Nervous System (ANS)

    • Regulates involuntary bodily functions
    • Controls functions like heart rate, blood pressure, digestion, respiratory rate, and glandular secretion.
    • Two main divisions:
      • Sympathetic nervous system (SNS) (fight or flight)
      • Parasympathetic nervous system (PNS) (rest and digest)

    The ANS Neuron

    • Contains two neurons:
      • Preganglionic neurons (cell body in the CNS)
      • Postganglionic neurons (cell body in the autonomic ganglion)

    Sympathetic vs. Parasympathetic Systems

    • Sympathetic (Adrenergic System):
      • Dominant during emergency, fight-or-flight reactions and exercise
      • Prepares the body for strenuous physical activity.
    • Parasympathetic (Cholinergic System):
      • Dominant during resting conditions, rest and digest
      • Conserves and stores energy, regulates basic body functions (digestion, urination).

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    Related Documents

    Autonomic Nervous System (ANS) Lecture PDF
    Autonomic Nervous System (ANS) Lecture Notes PDF

    Description

    Test your understanding of the autonomic nervous system (ANS) and its role in controlling involuntary bodily functions. This quiz covers key concepts including the sympathetic and parasympathetic nervous systems, their functions, and neuron systems. Perfect for students studying anatomy and physiology.

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