Autonomic Nervous System by Dr. Haitham Sewilam
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Questions and Answers

What is the main function of the afferent nerve fibers?

  • Control involuntary actions
  • Control voluntary actions
  • Convey impulses from receptors to CNS (correct)
  • Conduct impulses from CNS to various organs

    • What is the origin of the sympathetic nervous system?

  • Lumbar and sacral segments
  • Cranial and sacral segments
  • Thoracic and upper 2 to 3 lumbar segments (correct)
  • Cranial and thoracic segments

    • What is the primary function of the parasympathetic nervous system?

  • Control the activity of viscera during rest and digestion (correct)
  • Conduct impulses from CNS to various organs
  • Control voluntary actions
  • Prepare the body for vigorous activity

    • What is the central nervous system composed of?

    <p>Brain and spinal cord</p> Signup and view all the answers

    How many pairs of cranial nerves are there in the peripheral nervous system?

    <p>12 pairs</p> Signup and view all the answers

    What is the function of the somatic nervous system?

    <p>Control voluntary actions</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on the air passages in the lungs?

    <p>Widening of the air passages</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on the gastrointestinal tract?

    <p>Relaxation of the wall and sphincters</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on the liver?

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

    What is the effect of sympathetic stimulation on the spleen?

    <p>Contraction of the smooth muscles in the splenic capsule</p> Signup and view all the answers

    What is the effect of parasympathetic stimulation on the pupil?

    <p>Narrowing of the pupil</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on the urinary bladder?

    <p>Relaxation of the wall of the urinary bladder and contraction of the internal ureteral sphincter</p> Signup and view all the answers

    What type of receptors are found at the adrenal gland?

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

    Where are the autonomic ganglia typically located in the parasympathetic nervous system?

    <p>At the wall of organs</p> Signup and view all the answers

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

    <p>Dilatation of the pupil</p> Signup and view all the answers

    What is the effect of the sympathetic nervous system on the salivary glands?

    <p>Salivary secretion that is little in volume, viscid, and rich in organic substances &amp; enzymes</p> Signup and view all the answers

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

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

    Which of the following is a function of the parasympathetic nervous system?

    <p>None of the above</p> Signup and view all the answers

    What is the effect of the vagus nerve on the heart rate?

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

    What is the effect of the vagus nerve on coronary blood vessels?

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

    What is the effect of the vagus nerve on the smooth muscles of the gastrointestinal tract?

    <p>Stimulation of smooth muscles</p> Signup and view all the answers

    What is the effect of the vagus nerve on the pancreatic juice?

    <p>Stimulation of pancreatic juice</p> Signup and view all the answers

    What is the effect of the sacral parasympathetic outflow on the urinary bladder?

    <p>Stimulation of the urinary bladder</p> Signup and view all the answers

    What is the effect of the sacral parasympathetic outflow on the internal anal sphincter?

    <p>Inhibition of the internal anal sphincter</p> Signup and view all the answers

    Study Notes

    Nervous System Overview

    • Divided into Central Nervous System (CNS) and Peripheral Nervous System (PNS).
    • CNS consists of the brain and spinal cord.
    • PNS includes 12 pairs of cranial nerves and 31 pairs of spinal nerves.

    PNS Functional Divisions

    • Afferent (sensory) nerve fibers carry impulses from receptors to CNS.
    • Efferent (motor) nerve fibers transmit impulses from CNS to effectors.

    Autonomic Nervous System (ANS)

    • Regulates involuntary actions.
    • Divided into Sympathetic Nervous System and Parasympathetic Nervous System.

    Sympathetic Nervous System

    • Prepares the body for vigorous activities (fight or flight).
    • Originates from thoracic and upper lumbar segments (thoraco-lumbar).

    Functions of the Sympathetic Nervous System

    • Gastrointestinal Tract: Walls relax; sphincters contract.
    • Liver: Stimulates glycogenolysis.
    • Spleen: Contraction of smooth muscle; increases blood circulation.
    • Adrenal Medulla: Secretes adrenaline (80%) and noradrenaline (20%).
    • Kidneys: Increases renin secretion; decreases urine output.
    • Bladder: Wall relaxation; internal urethral sphincter contraction for urine retention.
    • Rectum: Wall relaxation; internal anal sphincter contraction for fecal retention.
    • Skeletal Muscle: Vasodilation enhances blood flow.

    Parasympathetic Nervous System

    • Controls viscera activity during rest and digestion.
    • Originates from cranial (nerves III, VII, IX, X) and sacral (nerves S2, S3, S4) regions (cranio-sacral outflow).

    Functions of the Parasympathetic Nervous System

    • Oculomotor Nerve (III): Causes pupil constriction (miosis), facilitates near vision.
    • Facial Nerve (VII): Stimulates salivary glands for watery saliva secretion.
    • Glossopharyngeal Nerve (IX): Stimulates parotid gland for salivary secretion.

    Neurotransmitters

    • Acetylcholine (ACh) released from all preganglionic fibers and postganglionic parasympathetic fibers.
    • Noradrenaline released from sympathetic postganglionic fibers and adrenal medulla.

    Receptors

    • Parasympathetic Receptors:
      • Cholinergic: Muscarinic (at most organs), Nicotinic (at adrenal gland, ganglia).
    • Sympathetic Receptors:
      • Adrenergic: Alpha (α) receptors (stimulatory) and Beta (β) receptors (inhibitory).

    Autonomic Ganglia

    • Lateral: Sympathetic relay beside the spinal cord.
    • Collateral: Sympathetic relay midway between the spinal cord and organs.
    • Terminal: Parasympathetic relay at organ walls.

    Fibers Length Comparison

    • Sympathetic preganglionic fibers are shorter than postganglionic fibers.
    • Parasympathetic preganglionic fibers are longer than postganglionic fibers.

    Cardiac and Respiratory Functions

    • Sympathetic Stimulation of Heart: Increases heart rate, contraction, conduction velocity, excitability.
    • Parasympathetic (Vagus Nerve): Decreases heart rate, force of contraction, and excitability; causes bronchoconstriction and mucus secretion.

    Gastrointestinal Functions

    • Sympathetic: Inhibits gastrointestinal motility.
    • Parasympathetic: Stimulates motility, gastrointestinal secretions, and gall bladder contractions.

    Urinary and Defecation Functions

    • Parasympathetic Outflow: Stimulates bladder contraction and defecation while inhibiting sphincters.

    This concise structure captures the essential knowledge about the autonomic nervous system and its functions, aiding in effective revision and understanding.

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    Description

    Learn about the autonomic nervous system, its divisions, and functions. This quiz covers the central and peripheral nervous systems, including cranial and spinal nerves, and afferent and efferent nerve fibers.

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