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Questions and Answers
What are the two divisions of the Autonomic Nervous System (ANS)?
What are the two divisions of the Autonomic Nervous System (ANS)?
Parasympathetic nervous system and Sympathetic nervous system
Which neurotransmitter is usually found at the ganglia in the Sympathetic nervous system?
Which neurotransmitter is usually found at the ganglia in the Sympathetic nervous system?
The Parasympathetic nervous system is associated with 'rest and digest' functions.
The Parasympathetic nervous system is associated with 'rest and digest' functions.
True
The ____________ is the receptor activated by acetylcholine (ACh) in the effector organs of the Parasympathetic nervous system.
The ____________ is the receptor activated by acetylcholine (ACh) in the effector organs of the Parasympathetic nervous system.
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Which receptor is responsible for increasing insulin release from the pancreas?
Which receptor is responsible for increasing insulin release from the pancreas?
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What is the initial effect on potassium levels due to the release of K+ from the liver?
What is the initial effect on potassium levels due to the release of K+ from the liver?
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Most organs receive both sympathetic and parasympathetic innervation.
Most organs receive both sympathetic and parasympathetic innervation.
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Which of the following organs only receive sympathetic innervation?
Which of the following organs only receive sympathetic innervation?
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Which muscle is responsible for pupil constriction in the eye?
Which muscle is responsible for pupil constriction in the eye?
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The sympathetic nervous system causes bronchodilation.
The sympathetic nervous system causes bronchodilation.
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What effect does the parasympathetic nervous system have on heart rate and force?
What effect does the parasympathetic nervous system have on heart rate and force?
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Parasympathetic nervous system causes _____ in the urinary bladder's detrusor muscle.
Parasympathetic nervous system causes _____ in the urinary bladder's detrusor muscle.
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Match the following muscle actions with their corresponding nervous system activation: (A) Contraction of pilomotor smooth muscle, (B) Ejaculation in male sex organs, (C) Relaxation of urinary bladder wall
Match the following muscle actions with their corresponding nervous system activation: (A) Contraction of pilomotor smooth muscle, (B) Ejaculation in male sex organs, (C) Relaxation of urinary bladder wall
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Study Notes
Autonomic Nervous System (ANS) and NeuroMuscular Junction (NMJ)
- The autonomic nervous system (ANS) is a subdivision of the peripheral nervous system (PNS)
- The ANS is further divided into two branches:
- Parasympathetic nervous system (PNS)
- Sympathetic nervous system (SNS)
- The SNS is also known as the "efferent fibres"
- The ANS controls organs that are not under our control, such as the viscera (e.g. heart, lungs, digestive system)
Neurochemical Transmission of the ANS
- Cholinergic neurotransmission:
- Synthesis: acetylcholine (ACh) is produced from acetyl-CoA and choline
- Storage: ACh is stored in vesicles in the terminal buttons of cholinergic neurons
- Release: ACh is released from the vesicles into the synapse
- Binding: ACh binds to nicotinic receptors (NR) and muscarinic receptors (MR)
- Terminal action: ACh activates NR and MR, leading to muscle contraction or relaxation
- Adrenergic neurotransmission:
- Synthesis: norepinephrine (NE) is produced from tyrosine
- Storage: NE is stored in vesicles in the terminal buttons of adrenergic neurons
- Release: NE is released from the vesicles into the synapse
- Binding: NE binds to α and β receptors on the postsynaptic effector cells
- Terminal action: NE activates α and β receptors, leading to muscle contraction or relaxation
Parasympathetic Nervous System (PNS)
- Origin: midbrain, medulla oblongata, and sacral cord
- Nerve fibres: long preganglionic nerve fibres, short postganglionic nerve fibres
- Neurotransmitters:
- ACh: released at the ganglia (NR) and effector organs (MR)
- Functions:
- Digestion
- Conservation of energy
- Maintenance of organ function
Sympathetic Nervous System (SNS)
- Origin: thoracic and upper lumbar regions of the spinal cord
- Nerve fibres: short preganglionic nerve fibres, long postganglionic nerve fibres
- Neurotransmitters:
- ACh: released at the ganglia (NR)
- NE: released at the effector organs (α and β receptors)
- Functions:
- Mobilizing the body's resources to respond to fear and anxiety (3Fs: fear, fight, flight response)
Comparison between Voluntary “Somatic NS” and Involuntary “ANS”
- Somatic nervous system:
- Originates from the central nervous system (CNS)
- Controls skeletal muscles
- Neurotransmitter: ACh (nicotinic receptors)
- Autonomic nervous system:
- Originates from the peripheral nervous system (PNS)
- Controls involuntary muscles (smooth muscle, cardiac muscle)
- Neurotransmitters: ACh (muscarinic receptors), NE (α and β receptors)
Neurotransmitters of the ANS
- Cholinergic pathways:
- Synthesis, storage, and release of ACh
- Inactivation by acetylcholinesterase (AChE) and pseudocholinesterase
- Adrenergic pathways:
- Synthesis, storage, and release of NE
- Inactivation by reuptake, monoamine oxidase (MAO), and catechol-O-methyltransferase (COMT)
Effect of ANS on Various Organs
- Eye:
- Pupil dilation (sympathetic)
- Pupil constriction (parasympathetic)
- Accommodation for near vision (parasympathetic)
- Heart:
- Increased heart rate and force (sympathetic)
- Decreased heart rate and force (parasympathetic)
- Blood vessels:
- Constriction (sympathetic)
- Dilatation (parasympathetic)
- Lung:
- Bronchodilation (sympathetic)
- Bronchoconstriction (parasympathetic)
- Gastrointestinal tract (GIT):
- Relaxation (sympathetic)
- Contraction (parasympathetic)
- Urinary tract:
- Urinary retention (sympathetic)
- Urine flow and voiding (parasympathetic)
Note: The study notes are organized by topic, with bullet points and subtopics to help illustrate the key concepts and relationships between them.### Sympathetic and Parasympathetic Nervous System
Skin
- Pilomotor smooth muscle contraction (erects hair) is stimulated by α1 receptors
- Sweat glands are stimulated by α1 receptors, causing sweating, especially on the forehead and palms
- Parasympathetic system stimulates cholinergic sweating, which is thermoregulatory
Skeletal Muscle
- β2 receptors enhance neuromuscular transmission and cause tremors
- β2 receptors inhibit histamine release from mast cells
Metabolic Function
- α2 receptors in the pancreas decrease insulin release, leading to gluconeogenesis
- β2 receptors in the pancreas increase insulin release
- β2 receptors in the liver stimulate glycogenolysis, leading to increased glucose release
- β1,3 receptors in fat cells stimulate lipolysis, leading to increased FFA
- β2 receptors in skeletal muscle stimulate glycogenolysis, leading to increased lactic acid and contractility
Blood
- α2 receptors in the liver stimulate the release of K+, leading to initial hyperkalemia
- β2 receptors in skeletal muscle stimulate the uptake of K+, leading to subsequent hypokalemia
Nerve Terminals
- α2 receptors decrease noradrenaline release
- β2 receptors increase noradrenaline release
General ANS
- Most organs receive dual sympathetic and parasympathetic innervation
- Some organs, including the suprarenal gland, sweat glands, most blood vessels, spleen, and piloerector muscles, only receive sympathetic innervation
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Description
Learn about the autonomic nervous system, its two branches, and its role in controlling organs and neurochemical transmission. Discover the functions of the parasympathetic and sympathetic nervous systems.
