Autonomic Nervous System Overview
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Questions and Answers

What is the primary function of the autonomic nervous system?

  • Controlling voluntary muscle movements
  • Facilitating conscious thought processes
  • Regulating sensory perception
  • Maintaining homeostatic conditions within the body (correct)

    • During which conditions does the sympathetic division of the autonomic nervous system demonstrate increased output?

  • Stress and anxiety (correct)
  • Relaxation and calmness
  • Sleep and rest
  • Digestion and metabolic rest

    • Which of the following is NOT a division of the autonomic nervous system?

  • Enteric division
  • Sympathetic division
  • Parasympathetic division
  • Cerebral division (correct)

    • Which organ system is primarily regulated by the autonomic nervous system?

    <p>Involuntary organs</p> Signup and view all the answers

    What response is commonly associated with the activation of the sympathetic division?

    <p>Fight or flight</p> Signup and view all the answers

    Which of the following scenarios would most likely trigger the autonomic nervous system?

    <p>Running from a dog while on a walk</p> Signup and view all the answers

    How does the autonomic nervous system assist in regulating reproduction?

    <p>By assisting endocrine functions</p> Signup and view all the answers

    Which of the following is a feature of the parasympathetic division?

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

    What is primarily stimulated by the parasympathetic division during rest and digestion?

    <p>Increased secretion of saliva</p> Signup and view all the answers

    What effect does the sympathetic nervous system have on the urinary bladder?

    <p>Constricts urinary sphincter</p> Signup and view all the answers

    In the eye, the sympathetic nervous system is responsible for which of the following?

    <p>Dilating the pupil</p> Signup and view all the answers

    Which of the following is stimulated by the parasympathetic nervous system?

    <p>Increased tear secretion</p> Signup and view all the answers

    During physical activity, which of the following occurs due to the sympathetic nervous system?

    <p>Increased strength of muscle contraction</p> Signup and view all the answers

    Which of the following effects is associated with the parasympathetic nervous system?

    <p>Constricted airways</p> Signup and view all the answers

    What happens to blood flow in the skin when the sympathetic nervous system is activated?

    <p>Altered blood flow</p> Signup and view all the answers

    What is the effect of the sympathetic nervous system on the stomach?

    <p>Inhibits digestion</p> Signup and view all the answers

    Which receptor is responsible for vasoconstriction in the skin and kidneys?

    <p>α1-adrenergic receptor</p> Signup and view all the answers

    What effect does adrenaline have on cardiac muscle during sympathetic stimulation?

    <p>Increased contraction</p> Signup and view all the answers

    Which of the following best describes the effect of β2-adrenergic receptors?

    <p>Relaxation of smooth muscle in blood vessels</p> Signup and view all the answers

    In which part of the heart is the SA node located?

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

    How does sympathetic stimulation generally affect smooth muscle (SM) contraction?

    <p>Induces contraction</p> Signup and view all the answers

    What is the primary role of α2-adrenergic receptors?

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

    Which type of adrenergic receptor is associated with relaxing smooth muscle in blood vessels?

    <p>β2-adrenergic receptor</p> Signup and view all the answers

    Which autonomic nervous system component is responsible for decreasing heart rate?

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

    What is the function of β1-adrenergic receptors?

    <p>Increase in heart rate and force of contraction</p> Signup and view all the answers

    Which of the following is true regarding the role of α-adrenergic receptors in sympathetic stimulation?

    <p>They induce contraction of smooth muscle in blood vessels.</p> Signup and view all the answers

    What is the primary role of the sino-atrial (SA) node in the heart?

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

    How does parasympathetic stimulation affect heart rate?

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

    Which of the following receptors is primarily associated with increasing heart muscle contraction?

    <p>Beta (β) 1 adrenergic receptor</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on heart rate?

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

    The adrenergic receptor associated with smooth muscle contraction is which type?

    <p>Alpha (α) 1 adrenergic receptor</p> Signup and view all the answers

    What neurotransmitter do postganglionic fibers from the sympathetic nervous system release to sweat glands?

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

    Which G-protein does the Beta (β) adrenergic receptor signal through?

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

    Which of the following is an exception to the general rule of sympathetic stimulation?

    <p>Sweat gland stimulation</p> Signup and view all the answers

    What is the role of stimulatory G proteins in cellular signaling?

    <p>They stimulate the production of cAMP.</p> Signup and view all the answers

    Which second messenger is produced by the action of phospholipase C?

    <p>Both B and C</p> Signup and view all the answers

    Which type of receptor generally produces faster effects?

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

    What is the primary neurotransmitter released in the sympathetic nervous system at the postganglionic level?

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

    Which adrenergic receptor type is primarily responsible for vasoconstriction in blood vessels?

    <p>Alpha-adrenergic receptors</p> Signup and view all the answers

    What unique characteristic does the adrenal medulla have in the sympathetic nervous system?

    <p>It releases adrenaline directly into the bloodstream.</p> Signup and view all the answers

    In which organs does adrenaline cause vasodilation?

    <p>Heart and skeletal muscle</p> Signup and view all the answers

    What type of receptor is the acetylcholine muscarinic receptor categorized as?

    <p>G-protein coupled receptor</p> Signup and view all the answers

    What is the synthesis ratio of adrenaline to noradrenaline in the adrenal medulla?

    <p>8:1</p> Signup and view all the answers

    What effect does stimulation of β-adrenergic receptors have on blood vessels?

    <p>It causes dilation.</p> Signup and view all the answers

    What type of neurons convey information from tissues and organs to the central nervous system (CNS)?

    <p>Afferent neurons</p> Signup and view all the answers

    What is the primary action of inhibitory G proteins?

    <p>Inhibit cAMP production.</p> Signup and view all the answers

    How is the action of adrenaline different depending on the organ?

    <p>It causes both vasodilation and vasoconstriction.</p> Signup and view all the answers

    What is the role of efferent neurons in the nervous system?

    <p>To transmit information from the CNS to tissues and organs</p> Signup and view all the answers

    What neurotransmitter is released at the neuromuscular junction in the somatic nervous system?

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

    What is the function of inositol trisphosphate (IP₃) as a second messenger?

    <p>It increases intracellular calcium levels.</p> Signup and view all the answers

    Which type of receptor is classified as ionotropic and opens ion channels upon activation?

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

    How many neurons are involved in the efferent pathway of the autonomic nervous system?

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

    What is the function of synapses in the nervous system?

    <p>To transmit signals between neurons</p> Signup and view all the answers

    Which type of receptors are found at the postganglionic effector cells in the parasympathetic nervous system?

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

    What effect does stimulation of the M2 muscarinic receptors in the heart have?

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

    Which division of the nervous system is responsible for voluntary movements?

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

    What is a key characteristic of metabotropic receptors?

    <p>They activate intracellular signaling through second messengers</p> Signup and view all the answers

    The connection between the first and second neurons in the autonomic nervous system occurs at which structure?

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

    What effect does acetylcholine have when binding to nicotinic receptors?

    <p>Rapid depolarization of postganglionic neuron</p> Signup and view all the answers

    Which type of receptor is NOT a subtype of muscarinic receptors?

    <p>M6</p> Signup and view all the answers

    Study Notes

    Autonomic Nervous System (ANS)

    • The ANS regulates involuntary functions, like sweating and heart rate, without conscious thought.
    • This is different to the somatic nervous system which controls voluntary actions like moving your arm.
    • It is divided into 3 divisions: sympathetic, parasympathetic, and enteric.

    Functions of the ANS

    • Maintaining homeostasis, keeping the body's internal conditions stable.
    • Coordinating responses to situations like exercise and stress.
    • Working with the endocrine system to regulate reproduction.
    • Regulating involuntary organs like the heart, blood vessels, exocrine glands, and visceral organs.

    Autonomic Nervous System Divisions

    • Sympathetic: Involved in "fight or flight" responses occurring during stress, anxiety, physical activity, fear, or excitement.
      • Increased output results in increased metabolic resource use.
    • Parasympathetic: Involved in "rest and digest" functions associated with sedentary activity, eating, and restoration of body reserves.
      • Increased output promotes restorative processes and conservation of energy.
    • Enteric: A network of neurons surrounding the GI tract. It can function independently but is often controlled by the sympathetic and parasympathetic systems.

    Neurons

    • Neurons are nerve cells that communicate via electrical signals.
    • Afferent neurons carry signals from tissues and organs to the central nervous system (sensory information).
    • Efferent neurons carry signals from the central nervous system to tissues and organs (motor information).
    • Interneurons connect neurons within the central nervous system.
    • Axons transmit signals over long distances.

    Neurotransmitters in the ANS

    • Acetylcholine (ACh) is a key neurotransmitter in the parasympathetic system.
    • Parasympathetic: ACh acts on nicotinic receptors at the ganglion, and then muscarinic receptors in the effector organ.
    • Sympathetic: ACh acts on nicotinic receptors at the ganglion and then noradrenaline (norepinephrine) acts on adrenergic receptors in the effector organ.
    • Adrenaline (epinephrine) is released by the adrenal medulla into the bloodstream to act on adrenergic receptors.

    Receptors

    • Ionotropic receptors: These receptors directly change the flow of ions through the cell membrane.
    • Nicotinic receptors are ionotropic. They are activated by ACh and are found at the sympathetic and parasympathetic ganglia. Muscle receptors are also nicotinic.
    • Metabotropic receptors: These receptors are linked to intracellular signaling pathways that involve second messengers.

    Adrenergic Receptors

    • Two main families: Alpha (α) and Beta (β).
    • Alpha receptors generally cause vasoconstriction,
    • Beta receptors generally cause vasodilation. (But not always depending on the subtype)
    • There are various subtypes of alpha and beta receptors that mediate different responses in different tissues. For instance, Beta-1 receptors increase heart rate.

    ANS Control of Specific Organs

    • Heart: Sympathetic stimulation increases heart rate and force whereas parasympathetic stimulation decreases them.
    • Lungs: Sympathetic stimulation relaxes bronchioles whereas parasympathetic stimulation constricts them.
    • Gastrointestinal tract: Sympathetic stimulation inhibits GI function whereas parasympathetic stimulation stimulates it.
    • Liver: Sympathetic stimulation increase hepatic glycogenolysis whereas parasympathetic activity generally has less effect.
    • Urinary bladder: Sympathetic stimulation relaxes the bladder and constricts the urinary sphincter (decreasing urination). Parasympathetic stimulation contracts the bladder and relaxes the urinary sphincter (increasing urination).

    Summary of ANS

    • Convergence: Many preganglionic neurons synapse with a single postganglionic neuron, enabling fine control over the effector organ (e.g. precise control over heart rate).
    • Divergence: A single preganglionic neuron can synapse with multiple postganglionic neurons, amplifying a signal and allowing widespread and rapid response (e.g. "fight or flight" response).
    • Higher Brain Control: The hypothalamus, pons, and medulla oblongata modulate autonomic activity.

    Autonomic Pathways

    • Somatic: A single neuron pathway from CNS to effector organ.
    • Autonomic: Two neuron pathway from CNS to effector organ. The first neuron is preganglionic and synapses with the second neuron in a ganglion, which is then postganglionic, connected to the effector organ.

    Exceptions to the Rule

    • For the sweat gland, postganglionic fibers use ACh to stimulate it, this is different to typical sympathetic pathways which use noradrenaline (norepinephrine).

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    Description

    Test your knowledge on the autonomic nervous system, including its primary functions, divisions, and regulatory mechanisms. This quiz covers key concepts such as sympathetic and parasympathetic responses and their impact on various organ systems.

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