Nervous System Organization
43 Questions
0 Views

Nervous System Organization

Created by
@AlluringHarpy

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which division of the peripheral nervous system is responsible for transmitting signals from the body to the central nervous system?

  • Autonomic nervous system
  • Efferent nervous system
  • Afferent nervous system (correct)
  • Somatic nervous system

    • Which neurotransmitter is primarily associated with the cholinergic neurons?

  • Serotonin
  • Dopamine
  • Norepinephrine
  • Acetylcholine (correct)

    • What are the primary receptors that respond to adrenergic neurotransmitters?

  • Nicotinic receptors
  • Alpha and beta receptors (correct)
  • GABA receptors
  • Muscarinic receptors

    • Which of the following best differentiates the autonomic and somatic nervous systems?

    <p>Autonomic regulates involuntary functions; somatic controls voluntary functions.</p> Signup and view all the answers

    Which type of cholinergic receptor is primarily located at the neuromuscular junction?

    <p>Nicotinic receptor</p> Signup and view all the answers

    What is the primary effect of acetylcholine on the heart?

    <p>Decreases heart rate</p> Signup and view all the answers

    Which of the following describes the action of α2 receptors?

    <p>Inhibit further norepinephrine release</p> Signup and view all the answers

    What role does acetylcholinesterase play in the degradation of acetylcholine?

    <p>Breaks down acetylcholine into choline and acetate</p> Signup and view all the answers

    Which subtype of β-adrenoceptors is primarily associated with cardiac stimulation?

    <p>β1</p> Signup and view all the answers

    Which action is primarily mediated by β2 receptors?

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

    What is the primary effect of acetylcholine on the urinary system?

    <p>Increases detrusor muscle tone leading to urination</p> Signup and view all the answers

    What triggers the release of calcium from the endoplasmic reticulum in response to α1 receptor activation?

    <p>IP3</p> Signup and view all the answers

    What is the consequence of presynaptic α2 receptor activation on norepinephrine release?

    <p>Decreases norepinephrine release</p> Signup and view all the answers

    Which neurotransmitter is primarily released during sympathetic nervous system activation?

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

    Which mechanism primarily mediates the effects of α1 receptors?

    <p>G-protein activation of phospholipase C</p> Signup and view all the answers

    What do cholinergic nerve fibers primarily release?

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

    Which neurotransmitter is associated with adrenergic nerve fibers?

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

    What differentiates the parasympathetic nervous system’s action potential response from the sympathetic system?

    <p>It innervates specific organs independently.</p> Signup and view all the answers

    Which receptors do acetylcholine bind to in parasympathetic postganglionic neurons?

    <p>Muscarinic receptors</p> Signup and view all the answers

    Which neurotransmitter is classified as the main excitatory neurotransmitter in the central nervous system?

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

    Which neurotransmitter pair is correctly matched with its associated receptor?

    <p>Dopamine - D receptors</p> Signup and view all the answers

    What characterizes neurotransmitter release during an action potential?

    <p>It requires calcium to facilitate vesicle fusion.</p> Signup and view all the answers

    Which type of neurotransmitter interaction occurs when acetylcholine binds to nicotinic receptors?

    <p>Excitatory response</p> Signup and view all the answers

    What primary function do local mediators serve in cellular signaling?

    <p>To facilitate rapid communication in the immediate environment.</p> Signup and view all the answers

    Which neurotransmitter is known as the major inhibitory neurotransmitter in the central nervous system?

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

    What is the primary function of the afferent division of the peripheral nervous system?

    <p>To send sensory signals to the CNS</p> Signup and view all the answers

    Which component of the autonomic nervous system is primarily responsible for the 'fight or flight' response?

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

    In the anatomy of efferent neurons, where do the preganglionic neurons originate?

    <p>In the CNS</p> Signup and view all the answers

    Which neurotransmitter is primarily associated with cholinergic neurons?

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

    Which aspect correctly describes the somatic nervous system (SNS)?

    <p>Involves a direct connection from the CNS to skeletal muscles with no ganglia</p> Signup and view all the answers

    What is a key characteristic of the autonomic nervous system?

    <p>It functions involuntarily and regulates internal organs</p> Signup and view all the answers

    Which of the following best describes postganglionic neurons in the autonomic nervous system?

    <p>Longer than preganglionic neurons and nonmyelinated</p> Signup and view all the answers

    Which functions are primarily associated with the parasympathetic nervous system?

    <p>Promotes rest and digestion</p> Signup and view all the answers

    Where do sympathetic preganglionic neurons typically originate from?

    <p>Thoracic and lumbar regions of the spinal cord</p> Signup and view all the answers

    What is the role of ganglia in the peripheral nervous system?

    <p>Serve as synaptic relay stations between neurons</p> Signup and view all the answers

    What is the effect of alpha-1 adrenergic receptor stimulation on urine retention?

    <p>Causes contraction of the urine sphincter</p> Signup and view all the answers

    Which action is a result of beta-2 adrenergic receptor stimulation?

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

    What is the primary action of sympatholytics?

    <p>Block adrenergic receptor activation</p> Signup and view all the answers

    How do indirect-acting agonists function in adrenergic drug actions?

    <p>They enhance release or prevent reuptake of NE.</p> Signup and view all the answers

    What effect does alpha-2 receptor stimulation have on norepinephrine release?

    <p>Decreases norepinephrine release</p> Signup and view all the answers

    Which of the following describes the action of direct-acting agonists?

    <p>They stimulate adrenergic receptors directly.</p> Signup and view all the answers

    What is the primary adrenergic effect of beta-1 receptor stimulation?

    <p>Increased renin release</p> Signup and view all the answers

    What mechanism do sympathomimetics utilize?

    <p>They activate adrenergic receptors.</p> Signup and view all the answers

    Study Notes

    Nervous System Organization and Divisions

    • The Nervous System is made up of the Central Nervous System (CNS), the Peripheral Nervous System (PNS)
    • The CNS consists of the brain and spinal cord.
    • The PNS has two divisions: Afferent and Efferent
      • Afferent - Sends sensory signals TO the CNS; includes visceral stimuli (from internal organs & mucosal surfaces) and sensory stimuli (from external sources)
      • Efferent - Sends signals FROM the CNS to the effector organs; includes somatic nervous system (SNS) and Autonomic Nervous System (ANS)

    Anatomy of Afferent Neurons

    • Afferent neurons include sensory receptors, fibers, and are important for reflexes and signaling the CNS about the need for an efferent response.

    Functional Division of Efferent PNS

    • Somatic Nervous System (SNS) - Conscious, voluntary, controlled function; uses cholinergic motor neurons to innervate skeletal muscle
    • Autonomic Nervous System (ANS) - Unconscious, involuntary, regulatory function; uses cholinergic & adrenergic neurons to innervate various organs

    Anatomy of Efferent Neurons (somatic and autonomic)

    • Preganglionic neurons: Originate in CNS, emerge from brainstem/spinal cord, form synapses in ganglia, and are myelinated (fast transmission).
    • Postganglionic neurons: Cell body begins in ganglia, ends on effector organ, and is nonmyelinated.
    • Ganglia: Neural clusters that act as relay stations for signals; can transmit, redirect, or diffuse signals.

    Somatic Nervous System (SNS)

    • Directly connects the CNS to skeletal muscle.
    • No ganglia.
    • Myelinated for fast transmission.

    Autonomic Nervous System (ANS)

    • Sympathetic (Fight or Flight): Increases energy; releases epinephrine from adrenal medulla (works as a unit, discharges as a complete system).
    • Parasympathetic (Rest and Digest): Maintains homeostasis & essential bodily functions; opposes sympathetic actions; innervates specific organs and activates targets separately.
    • Enteric: Controls digestive organs; covered in greater detail in GI lectures.

    Anatomy of Sympathetic and Parasympathetic Neurons

    • Sympathetic: Most originate from thoracic and lumbar regions of spinal cord; preganglionic neurons are shorter than postganglionic neurons; ganglia are closer to CNS.
    • Parasympathetic: Originate from cranial nerves III, VII, IX, X and sacral spinal cord (S2-S4); preganglionic neurons are longer than postganglionic neurons; ganglia are closer to effector organs.

    Function of Sympathetic Nervous System (SANS)

    • Fight or Flight response activated by direct sympathetic stimulation and adrenal medulla stimulation.
    • Releases epinephrine.
    • Functions as a unit; discharges as a complete system.

    Function of Parasympathetic Nervous System (PANS)

    • Maintains homeostasis and essential bodily functions.
    • Opposes or balances actions of the sympathetic system.
    • Never discharges as a complete system.
    • Innervates specific organs; activates targets separately.

    Neurotransmitters and Signal Transduction

    • Signals are sent from CNS to effector organs via neurotransmitters released from nerve terminals.
    • Neurotransmitters are responsible for communication neuron-to-neuron and neuron-to-effector organ.
    • Other signal types:
      • Hormones: Released by endocrine cells into bloodstream.
      • Local mediators: Act locally on surrounding cells; rapidly degraded and removed (e.g., prostaglandins).

    Neurotransmitters (NTMs)

    • Action Potential (AP) leads to NTM release.
    • AP arrives at axon terminal, depolarization occurs, voltage-gated Ca2+ channels open, Ca2+ enters, signals vesicles to move to membrane.
    • Vesicles merge with membrane releasing NTM into synapse.
    • NTM diffuses, binds to postsynaptic neuron receptors.
    • Triggers a response, which may trigger another action potential.

    Common Neurotransmitters

    • Cholinergic: Acetylcholine (ACh)
    • Adrenergic (NE): Norepinephrine (NE)
    • Dopaminergic: Dopamine (DA)
    • Serotonergic: Serotonin (5-HT)
    • GABAergic: Gamma-aminobutyric acid (GABA)
    • Glutamatergic: Glutamate (Glu)
    • Opioid: Endorphins

    Major Neurotransmitters

    • Glutamate: Major excitatory NTM
    • GABA: Major inhibitory NTM
    • They balance each other; an imbalance can lead to disease.

    Some Neurotransmitter/Receptor Pairs

    • Epinephrine, Norepinephrine (NE): α & β adrenergic receptors
    • Dopamine (DA): D receptors
    • Serotonin (5-HT): 5-HT receptors
    • GABA: GABA receptor (NMDA, AMPA)
    • Acetylcholine (ACh): Nicotinic & muscarinic cholinergic receptors
    • Glutamate (Glu): NMDA, AMPA, mGluR receptors
    • Endorphins: Opioid receptors

    Neurotransmitter Synthesis

    • Notice the enzymes involved.
    • Enzymes are good drug targets.

    Cholinergic Nerve Fibers

    • Neurons that release Acetylcholine (ACh)
    • All somatic motor neurons release ACh, which binds to nicotinic receptors on skeletal muscle cells.
    • All preganglionic autonomic neurons (sympathetic & parasympathetic) release ACh, which binds to nicotinic receptors.
    • Parasympathetic postganglionic neurons release ACh, which binds to muscarinic receptors.
    • Direct release of ACh onto adrenal medulla, which binds to nicotinic receptors on adrenal medulla.

    Adrenergic Nerve Fibers

    • Release Norepinephrine (NE) from sympathetic postganglionic neurons to adrenergic receptors on effector organs.
    • The adrenal medulla releases epinephrine into the bloodstream.
    • Epinephrine acts as a chemical messenger in effector organs (sometimes acts as neurotransmitter, but mostly as a hormone).

    Cholinergic Receptors

    • Nicotinic Receptors: Located on presynaptic receptors of cholinergic neurons (negative feedback mechanism), and on other presynaptic receptors.

    Actions of Acetylcholine (Parasympathetic Actions)

    • Decreases heart rate, cardiac output, blood pressure.
    • Stimulates salivary secretion.
    • Increases gastric acid secretion.
    • Stimulates intestinal secretions and motility.
    • Increases bronchiolar secretions.
    • Causes bronchoconstriction.
    • Increases detrusor muscle tone (causes urination).
    • Stimulates ciliary muscle contraction for near vision.
    • Constricts pupillary sphincter muscle (miosis).

    Degradation of Acetylcholine (ACh)

    • Signal is rapidly terminated at the postjunctional effector site.
    • Acetylcholinesterase (AChE) breaks down ACh into choline and acetate in the synaptic cleft.

    Adrenergic Receptors

    • Two subtypes based on affinities for α agonists and antagonists:
      • α1 Receptors: Primarily on postsynaptic membranes of effector organs; mediate smooth muscle constriction.
      • α2 Receptors: Primarily on sympathetic presynaptic nerve endings; control release of NE.

    Alpha-1 Receptors

    • Found on postsynaptic membranes of effector organs.
    • Mediate many of the classic effects involving smooth muscle constriction.
    • Activate G-protein pathway, leading to:
      • Phospholipase C activation
      • Generation of second messengers DAG and IP3
      • IP3 triggers release of calcium from ER into cytosol.
      • DAG activates other proteins in the cell.

    Alpha-2 Receptors

    • Located on sympathetic presynaptic nerve endings.
    • Control NE release.
    • Most released NE activates the sympathetic adrenergic postsynaptic neuron, but some circles back to α2 receptors on the presynaptic membrane.
    • Presynaptic receptor stimulation leads to feedback inhibition and blocks further NE release.
    • This acts as local regulation for NE output during high sympathetic activity.

    Beta-Adrenoreceptors

    • Strong response to isoproterenol.
    • Three subgroups based on affinities for adrenergic agonists and antagonists:
      • β1: Heart
      • β2: Lungs
      • β3: Adipose tissue
    • β1 equal affinity for epinephrine and NE.
    • β2 higher affinity for epinephrine than NE.
    • Binding activates adenylyl cyclase and increases cAMP concentrations inside the effector cell.

    Locations of Alpha and Beta Receptors

    • α1: Vessels, smooth muscle, iris sphincter.
    • α2: Presynaptic nerve endings, platelets, pancreatic beta cells (some on postsynaptic organs).
    • β1: Heart, kidneys, adipose tissue.
    • β2: Lungs, skeletal muscle, blood vessels in skeletal muscle, liver, uterus, pancreatic beta cells.

    Characteristic Responses Mediated by Adrenoreceptors

    • α1 stimulation: Vasoconstriction and increased total peripheral resistance and blood pressure.
    • β1 stimulation: Cardiac stimulation.
    • β2 stimulation: Vasodilation and smooth muscle relaxation.

    Summary Table of Adrenoreceptors in ANS

    Adrenergic Receptor Location Effector Response
    α1 Vessels, smooth muscle, iris sphincter Vasoconstriction, contraction of smooth muscle
    α2 Presynaptic nerve endings, platelets, pancreatic β cells Inhibition of NE release, decreased sympathetic outflow
    β1 Heart, kidneys, adipose tissue Increased HR, contractility, renin secretion
    β2 Lungs, skeletal muscle, blood vessels in skeletal muscle Bronchodilation, vasodilation, relaxation of smooth muscle

    Adrenergic Drug Actions

    • Affect receptors stimulated by NE or epinephrine.
    • Sympathomimetics: Activate adrenergic receptors.
      • Direct acting agonists: Directly activate adrenergic receptors.
      • Indirect-acting agonists: Enhance release or stop reuptake of NE.
    • Sympatholytics: Block activation of adrenergic receptors.

    Summary Review Table - Adrenergic Receptors and Drug Actions

    Adrenergic Receptor Effect when Stimulated Actions of Receptor Agonist Actions of Receptor Antagonist
    α1 Vasoconstriction; contraction of urinary sphincter vasoconstriction vasodilation
    α2 Presynaptic: Decreases NE release; Postsynaptic: Decreases sympathetic outflow Decreases NE release, decreased sympathetic outflow Increases NE release
    β1 Increases HR, contractility, renin secretion Increases HR, contractility, renin secretion Decreases HR, contractility, renin secretion
    β2 Bronchodilation; arteriole dilation (except skin and brain) Bronchodilation, vasodilation Bronchoconstriction, vasoconstriction

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Neurotransmitters in Pharmacology PDF

    Description

    Explore the divisions of the Nervous System, including the Central and Peripheral Nervous Systems. This quiz will cover the roles of Afferent and Efferent neurons, as well as the functions of the Somatic and Autonomic Nervous Systems. Test your knowledge on the anatomy and functionality of the nervous system components.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser