Questions and Answers
The parasympathetic nervous system primarily stimulates the piloerector muscle.
False
The vagus nerve is responsible for stimulating bronchial dilation.
False
In dual innervation, the sympathetic division predominates only during rest.
False
The secretion of tears is primarily regulated by the sympathetic nervous system.
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Both sympathetic and parasympathetic systems release acetylcholine at their postganglionic synapses.
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The sympathetic nervous system primarily uses acetylcholine for postganglionic neurotransmission.
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Ejaculation of semen is a sympathetic response.
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The constrictor pupillae muscle is under the control of the sympathetic nervous system.
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Horner syndrome results in increased sweating in the affected area.
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Parasympathetic discharge is more potent during physical exertion compared to sympathetic discharge.
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Antagonistic interaction between the sympathetic and parasympathetic nervous systems is exemplified by their functions in the heart.
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The parasympathetic nervous system stimulates glycogenolysis in the liver.
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Bronchodilation is a response primarily mediated by the parasympathetic nervous system.
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The sympathetic nervous system is associated with 'rest and digest' functions.
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Postganglionic fibers of the parasympathetic nervous system are typically long in length.
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The Orbelli phenomenon refers to improved recovery of skeletal muscle after fatigue.
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The sympathetic nervous system is continuously active under basal conditions, providing a tonic discharge to blood vessels.
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In an emergency, the sympathetic nervous system promotes vasoconstriction in the skin and splenic areas while enhancing blood flow to the heart and skeletal muscles.
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The sympathetic nervous system decreases glycogenolysis in the liver during stress responses.
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The activation of the sympathetic nervous system leads to constriction of bronchioles.
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The parasympathetic nervous system works in opposition to the sympathetic nervous system, promoting relaxation and energy conservation.
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The interaction between the sympathetic and parasympathetic systems results in dual innervation, which balances body functions during varying stress levels.
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Study Notes
Parasympathetic Nervous System
- Craniosacral outflow facilitates several key functions.
- Induces pupillary constriction and accommodation via the oculomotor nerve.
- Facilitates tear secretion through the facial nerve.
- Promotes secretion of watery saliva via facial and glossopharyngeal nerves.
- Decreases heart activity predominantly through the vagus nerve.
- Causes constriction of bronchioles, also mediated by the vagus nerve.
- Stimulates gastrointestinal secretion and peristalsis with contributions from vagus and sacral nerves.
- Activates emptying mechanisms of rectum and urinary bladder for micturition and defecation, primarily through sacral nerves.
- Responsible for erectile function via sacral nerves.
Dual Innervation
- Most visceral organs receive inputs from both sympathetic and parasympathetic divisions.
- The dominant system at any moment is determined by the body’s demands.
- Parasympathetic tone is more influential at rest, while sympathetic tone maintains vascular tone.
Structures Exclusively Supplied by Sympathetic Nervous System
- Includes the skin and sweat glands (sympathetic cholinergic).
- Supplies blood vessels everywhere except the penis and constrictor pupillae muscle.
- Controls the adrenal medulla and capsule of the spleen.
Structures Exclusively Supplied by Parasympathetic Nervous System
- Constrictor pupillae muscle, ciliary muscle, lacrimal gland, and penile erectile tissue.
Interaction Between Sympathetic and Parasympathetic Systems
- Antagonistic actions present in the cardiac system.
- Synergistic cooperation seen in salivary secretion and during sexual activity.
Chemical Transmission in the Autonomic Nervous System (ANS)
- Parasympathetic: Utilizes acetylcholine (Ach) with nicotinic receptors at ganglia and muscarinic receptors at target organs.
- Sympathetic: Primarily uses norepinephrine (nor-adrenaline) with adrenal medulla releasing adrenaline during stress responses.
Functions of Sympathetic Nervous System
- Continuously active under basal conditions as sympathetic tone.
- Responds to stress (mass discharge) enabling the "fight or flight" response.
- Increases heart properties and dilates bronchioles under stress.
- Constricts skin blood vessels and redistributes blood flow to core organs and muscles.
- Enhances liver glycogenolysis and raises blood glucose/free fatty acid levels.
Sympathetic Nervous System Distribution
- Head and Neck: Controls pupil dilation, eyelid retraction, and lacrimal gland atrophy.
- Thorax: Increases excitation of the heart and promotes vasodilation of coronary arteries; bronchodilation in lungs.
- Abdomen: Vasoconstricts blood vessels and inhibits gastrointestinal peristalsis; stimulates liver glycogen breakdown.
- Lower Body: Retains feces and urine, manages blood vessel responses, and evokes ejaculation in male sex organs.
Horner Syndrome
- Results from sympathetic damage resulting in ptosis (drooping eyelid), miosis (constricted pupil), anhidrosis (lack of sweating), enophthalmosis (sunken eye), and facial flushing.
Orbelli Phenomenon
- Describes improved contraction, decreased fatigue, and quicker recovery times in skeletal muscles post-exercise.
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Description
Explore the key functions and craniosacral outflow of the parasympathetic nervous system. This quiz covers vital aspects such as heart rate regulation, bronchial constriction, and digestive mechanisms. Test your knowledge of how this system operates in maintaining the body's rest and digest functions.
