The Autonomic Nervous System Overview

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Questions and Answers

What type of receptors are typically found in sweat glands?

Nicotinic receptors
Adrenergic receptors
M3 muscarinic receptors (correct)
Alpha adrenergic receptors

What is the primary function of nicotinic receptors at the neuromuscular junction?

Inhibit muscle contraction
Facilitate slow depolarization
Assemble lipid membranes
Facilitate rapid depolarization (correct)

Which adrenergic receptor subtype has a greater affinity for noradrenaline?

Beta-2
Beta-1
Alpha-2
Alpha-1 (correct)

Which signaling pathway is activated by M2 muscarinic receptors?

Inhibitory pathway via Gi (B) Signup and view all the answers

What is the role of chromaffin cells within the adrenal medulla in the sympathetic nervous system?

Promoting secretion of NA and A (D) Signup and view all the answers

Which of the following best describes G-protein coupled receptors?

Include both adrenergic and muscarinic receptor types (C) Signup and view all the answers

Which neurotransmitter is primarily associated with adrenergic receptors?

Noradrenaline (B) Signup and view all the answers

What characterizes the N2 or Nn subtype of nicotinic receptors?

Located in post-ganglionic neurons (B) Signup and view all the answers

Which neurotransmitter is primarily released by post-ganglionic sympathetic neurons to act on adrenergic receptors?

Noradrenaline (B) Signup and view all the answers

What type of receptors do pre-ganglionic neurons in both the sympathetic and parasympathetic systems activate on post-ganglionic neurons?

Nicotinic receptors (B) Signup and view all the answers

Which adrenergic receptor subtype is primarily responsible for causing vasoconstriction in the gastrointestinal tract?

α1 receptors (D) Signup and view all the answers

Which of the following is NOT a function of β2 adrenergic receptors?

Increased heart rate (C) Signup and view all the answers

What is the primary mechanism by which noradrenaline exerts a negative feedback effect in adrenergic transmission?

Binding to α2-receptors on the pre-synaptic membrane (B) Signup and view all the answers

What effect does ATP have when binding to P2X receptors on smooth muscle cells?

Depolarization of the membrane (C) Signup and view all the answers

What is one effect of co-transmission of noradrenaline and ATP in sympathetic post-ganglionic neurons?

Fast contraction followed by slower contraction (A) Signup and view all the answers

Which type of adrenergic receptor is associated with increased cardiac muscle contractility?

β1 receptors (A) Signup and view all the answers

What role does the calcium influx play during adrenergic signaling when noradrenaline binds to α1 receptors?

Smooth muscle contraction (D) Signup and view all the answers

Which of the following best describes the primary function of the sympathetic nervous system?

To increase alertness and activate the fight or flight response (A) Signup and view all the answers

What is a key structural difference between the parasympathetic and sympathetic nervous systems?

The pre-ganglionic axons are shorter in sympathetic neurons compared to parasympathetic neurons. (A) Signup and view all the answers

Which response accurately represents the effect of the parasympathetic nervous system on the heart?

Decreases cardiac output by lowering heart rate and force of contraction. (B) Signup and view all the answers

During the fight or flight response, which of the following physiological changes occurs?

Pupils dilate to increase the field of vision. (D) Signup and view all the answers

Which neurotransmitter is primarily associated with the sympathetic nervous system's response?

Norepinephrine (B) Signup and view all the answers

What is the general role of afferent neurons within the autonomic nervous system?

To detect and carry sensory information to the brain. (A) Signup and view all the answers

Which of the following statements about the autonomic nervous system is incorrect?

The sympathetic nervous system operates under voluntary control. (B) Signup and view all the answers

In terms of receptor types and functions, which statement is accurate regarding the effects of the sympathetic nervous system?

It primarily uses beta-adrenergic receptors to increase heart rate. (D) Signup and view all the answers

Which aspect of neurotransmitter co-transmission typically occurs in the autonomic nervous system?

Increased efficiency through the release of two or more neurotransmitters simultaneously. (B) Signup and view all the answers

Which statement correctly describes the neuroendocrine functions associated with the sympathetic nervous system?

It initiates the release of hormones that prepare the body for action during stress. (D) Signup and view all the answers

Match the following glands with their primary function:

Tear glands = Secretion of tears Sweat glands = Regulation of body temperature Mammary glands = Production of milk Liver = Metabolism and detoxification Signup and view all the answers

Match the following structures with their role in the autonomic nervous system:

Pre-ganglionic axons = Transmit signals from the CNS to autonomic ganglia Post-ganglionic axons = Send signals to effector organs Ganglia = Clusters of nerve cell bodies Boutons = Sites of synapse between axons and other cells Signup and view all the answers

Match the division of the nervous system with its primary characteristics:

Central Nervous System (CNS) = Includes brain and spinal cord Peripheral Nervous System (PNS) = Comprises nerves and ganglia outside CNS Somatic Nervous System = Controls voluntary movements Autonomic Nervous System (ANS) = Functions unconsciously and regulates intrinsic processes Signup and view all the answers

Match the following types of smooth muscle with their characteristics:

Single-unit smooth muscle = Coupled by gap junctions Multi-unit smooth muscle = Independently controlled cells Visceral effector cells = Respond to autonomic signals Cardiac muscle = Striated and involuntary Signup and view all the answers

Match the following terms with their definitions in the context of the ANS:

Divergence = Separation of pre-ganglionic information Convergence = Combining of pre-ganglionic signals Afferent neurons = Transmit sensory information to CNS Efferent neurons = Carry signals away from CNS to effectors Signup and view all the answers

Match the type of neuron with its function:

Afferent neurons = Carry sensory information to the brain Efferent neurons = Carry motor commands from the brain Pre-ganglionic neurons = Connect spinal cord to ganglia Post-ganglionic neurons = Innervate target organs Signup and view all the answers

Match the autonomic nervous system branch with its function:

Sympathetic nervous system = Activates fight or flight response Parasympathetic nervous system = Calms the body down Sympathetic ganglia location = Close to spinal cord Parasympathetic ganglia location = Close to the innervated organ Signup and view all the answers

Match the following components of autonomic ganglia with their function:

Pre-ganglionic fibers = Process signals in the ganglia Post-ganglionic fibers = Transmit signals to visceral effectors Visceral receptors = Activate upon mechanical strain Neuroeffector junction = Site of signal transmission to effector cells Signup and view all the answers

Match the following features with their corresponding types of axon terminals:

Synaptic boutons = Small swellings at axon terminals Varicosities = Strings of beads along post-ganglionic axons Axon terminals = End points of nerve fibers Neurotransmitter release sites = Sites where chemical signals are transmitted Signup and view all the answers

Match the physiological response with the appropriate nervous system branch:

Increased heart rate = Sympathetic nervous system Pupil constriction = Parasympathetic nervous system Increased alertness = Sympathetic nervous system Decreased force of contraction = Parasympathetic nervous system Signup and view all the answers

Match the following responses with their appropriate stimuli in the autonomic nervous system:

Mechanical strain = Activates visceral receptors Chemical changes = Stimulate sensory information transmission Sympathetic activation = Leads to fight or flight response Parasympathetic activation = Promotes rest and digest functions Signup and view all the answers

Match the anatomical feature with the autonomic nervous system:

Thoracic and lumbar motor neurons = Sympathetic nervous system Brainstem and sacral motor neurons = Parasympathetic nervous system Short pre-ganglionic axons = Sympathetic nervous system Long pre-ganglionic axons = Parasympathetic nervous system Signup and view all the answers

Match the following types of neurons with their functions:

Autonomic motor neurons = Efferent neurons of the ANS Sensory neurons = Afferent neurons in the ANS Interneurons = Connect sensory and motor neurons Post-ganglionic neurons = Signal effectors after ganglia Signup and view all the answers

Match the term with its correct description in the autonomic nervous system:

Pre-ganglionic axons = Connect to ganglia Post-ganglionic axons = Innervate target organs Afferent function = Sensory input to CNS Efferent function = Motor output from CNS Signup and view all the answers

Match the following phrases with their correct descriptions in neural signaling:

Amplification = Increasing the strength of signals Inhibition = Decreasing the strength of signals Divergence = Spreading signals to multiple targets Convergence = Bringing signals together to a single point Signup and view all the answers

Match the type of response with the respective organ activation:

Pupils dilate = Sympathetic response Salivation increases = Parasympathetic response Breathing rate decreases = Parasympathetic response Cardiac output increases = Sympathetic response Signup and view all the answers

Match the characteristic of the autonomic nervous system with its division:

Involuntary control = Autonomic Nervous System Voluntary control = Somatic Nervous System Faster response times = Sympathetic Nervous System Promotes digestion = Parasympathetic Nervous System Signup and view all the answers

Match the type of physiological change with its occurring scenario:

Increased blood flow to muscles = Fight or flight response Decreased heart rate = Rest and digest mode Enhanced cognitive function = Sympathetic activation Pupil constriction for better focus = Parasympathetic activation Signup and view all the answers

Match the types of smooth muscle to their characteristics:

Single-unit smooth muscle = Contains gap junctions for synchronized contraction Multi-unit smooth muscle = Requires individual innervation Found in airways = Multi-unit smooth muscle Found in gastrointestinal tract = Single-unit smooth muscle Signup and view all the answers

Match the neurotransmitter with its corresponding action in the autonomic nervous system:

ACh = Activation of nicotinic receptors on post-ganglionic neurons NAd = Binding to α1 receptors for muscle contraction ATP = Causing depolarization in smooth muscle cells Dopamine = Converted from tyrosine in adrenergic transmission Signup and view all the answers

Match the adrenergic receptor subtype with its primary effect:

α1 receptors = Vasoconstriction in the gastrointestinal tract α2 receptors = Auto-inhibition of neurotransmitter release β1 receptors = Increased cardiac muscle contractility β2 receptors = Bronchodilation Signup and view all the answers

Match the types of neurotransmitter receptors to their descriptions:

Muscarinic receptors = G-Protein coupled receptors Nicotinic receptors = Ion channels M2 receptors = Found in cardiac muscle M3 receptors = Found in gastrointestinal smooth muscle Signup and view all the answers

Match the component of adrenergic signaling with its description:

Calcium influx = Triggers neurotransmitter release Post-ganglionic fibers = Release noradrenaline primarily Pre-ganglionic fibers = Release acetylcholine onto ganglionic receptors Receptors on effector organs = Determine the physiological response to NAd Signup and view all the answers

Match the neurotransmitter types with their associated nervous system:

Acetylcholine = Parasympathetic nervous system Noradrenaline = Sympathetic nervous system Adrenaline = Sympathetic nervous system Choline = Recycled in cholinergic transmission Signup and view all the answers

Match the receptor type with its location:

Nicotinic receptors = Post-ganglionic neurons Muscarinic receptors = Target organs of parasympathetic activation P2X receptors = Smooth muscle cells Adrenergic receptors = Effector organs in sympathetic response Signup and view all the answers

Match the processes involved in cholinergic transmission:

Calcium influx = Triggers vesicle fusion Post-synaptic action = Activates ACh receptors on effector organs Choline recycling = Reused to synthesize ACh Acetylcholine breakdown = Involves choline and acetate Signup and view all the answers

Match the process with its corresponding neurotransmitter action:

Vesicle fusion = Release of NAd into the synaptic cleft Influx of calcium ions = Smooth muscle contraction Negative feedback = Inhibition of NAd release by α2 receptors Co-transmission = Release of NAd and ATP together Signup and view all the answers

Match the components of ganglion cell innervation:

Pre-ganglionic neuron = Releases acetylcholine Post-synaptic receptors = Nicotinic receptors Post-ganglionic fibres = Transmit signals to effector organs Varicosities = Contain neurotransmitter packets Signup and view all the answers

Match the effect with the relevant adrenergic receptors:

GIT vasoconstriction = α1 receptors Skeletal muscle vasodilation = β2 receptors Cardiac accelerative response = β1 receptors CNS auto-inhibition = α2 receptors Signup and view all the answers

Match the effects of ACh when released in the synaptic cleft:

Acting on post-synaptic receptors = Produces a response in effector organs Inhibiting further release = ACh acts on pre-synaptic membrane Broken down into acetate and choline = Prevent persistency action Stored in vesicles = Ready for subsequent release Signup and view all the answers

Match the types of adrenergic signalling to their neurotransmitters:

Cholinergic signalling = Involves acetylcholine Adrenergic signalling = Involves noradrenaline Sympathetic nerves = Releases adrenaline or noradrenaline Parasympathetic nerves = Releases acetylcholine Signup and view all the answers

Match the type of receptor with its mechanism of action:

P2X receptors = Form channels that open upon ATP binding Muscarinic (M2) receptors = Activated by ACh for parasympathetic effect Nicotinic (N2) receptors = Act on post-ganglionic neurons at ganglia Adrenergic receptors = G-protein coupled receptors influencing smooth muscle Signup and view all the answers

Match the physiological effects with the receptor subtype:

M1 receptors = Primarily in the CNS M2 receptors = Affect cardiac muscle N1 receptors = Present in skeletal muscle N2 receptors = Involve neuronal signaling Signup and view all the answers

Match the neurotransmitter with its storage site:

Noradrenaline = Stored in vesicles in post-ganglionic nerve endings Acetylcholine = Released by post-ganglionic parasympathetic neurons ATP = Co-stored with NAd in sympathetic post-ganglionic varicosities Dopamine = Converted within the adrenergic nerve terminal Signup and view all the answers

Match the type of autonomic fiber with its corresponding characteristic:

Pre-ganglionic fibers = Release ACh at ganglia Post-ganglionic sympathetic fibers = Release NAd and ATP Post-ganglionic parasympathetic fibers = Act on muscarinic receptors Pre-ganglionic sympathetic fibers = Exist between CNS and sympathetic ganglia Signup and view all the answers

Match the roles of neurotransmitters with their definitions:

ACh = Main neurotransmitter of parasympathetic nervous system NAd = Primary neurotransmitter for sympathetic transmission Ad = Hormone released by adrenal medulla Cholinergic = Referring to neurotransmitters that use acetylcholine Signup and view all the answers

Match the neurotransmitter with its effect on receptor types:

NAd on α1 = Increases internal calcium release for contraction ACh on nicotinic = Excites post-ganglionic neurons ATP on P2X = Opens ion channels for calcium influx NAd on α2 = Inhibits further neurotransmitter release Signup and view all the answers

Match the following types of receptors with their characteristics:

Nicotinic Receptors = Ligand-gated ion channels Muscarinic Receptors = G-protein coupled receptors Adrenergic Receptors = G-coupled protein receptors M2 Receptors = Inhibitory signaling pathways Signup and view all the answers

Match the following subtypes of nicotinic receptors with their locations:

N1 or Nm = Neuromuscular junction N2 or Nn = Post-ganglionic neuron M1 = Cortex and gastric glands M3 = Sweat glands Signup and view all the answers

Match the following adrenergic receptor types with their greater affinity:

α receptors = Noradrenaline β receptors = Adrenaline α1 receptors = Vasoconstriction β2 receptors = Bronchodilation Signup and view all the answers

Match the following muscarinic receptor subtypes with their signaling pathways:

M1 = Couples with Gq M2 = Couples with Gi M3 = Couples with Gq M4 = Couples with Gi Signup and view all the answers

Match the following physiological effects with the corresponding receptors:

M3 receptors = Stimulates glandular secretion Nicotinic receptors = Facilitates rapid depolarization M2 receptors = Inhibits heart rate Adrenergic receptors = Promotes systemic circulation Signup and view all the answers

Match the following neurotransmitters with their corresponding receptors:

Acetylcholine = Nicotinic and Muscarinic Receptors Noradrenaline = Adrenergic Receptors Adrenaline = β receptors ATP = P2X receptors Signup and view all the answers

Match the following components of the sympathetic nervous system with their functions:

Sympathetic pre-ganglionic fibers = Innervate chromaffin cells Chromaffin cells = Secrete NA and A Adrenal medulla = Promotes systemic effects Vasoconstriction = Reduces blood flow to non-essential organs Signup and view all the answers

Match the following receptor functions to their effects:

Muscarinic M2 = Decreases heart rate Nicotinic N1 = Muscle contraction Adrenergic α1 = Vasoconstriction Adrenergic β1 = Increases cardiac contractility Signup and view all the answers

Study Notes

The Autonomic Nervous System (ANS)

The autonomic nervous system (ANS) unconsciously controls intrinsic processes such as breathing and digestion.
The ANS is divided into two branches: the sympathetic nervous system and the parasympathetic nervous system.
The sympathetic nervous system is responsible for the "fight or flight" response, activating the body for stressful situations.
The parasympathetic nervous system is responsible for the "rest and digest" response, calming the body and regulating internal functions.
The sympathetic nervous system originates from the thoracic and lumbar regions of the spinal cord, whereas the parasympathetic nervous system originates from the brainstem and sacral region of the spinal cord.

Anatomical Differences

In the sympathetic system, pre-ganglionic axons are short and post-ganglionic axons are long, while in the parasympathetic system, pre-ganglionic axons are long and post-ganglionic axons are short.
Sympathetic ganglia are located closer to the spinal cord while parasympathetic ganglia are located close to the innervated organ.

Organ Responses

Heart: The sympathetic nervous system increases heart rate and force of contraction, while the parasympathetic nervous system decreases both.
Pupils: The sympathetic nervous system dilates pupils, increasing the field of vision, while the parasympathetic nervous system constricts pupils, allowing for better focus.
Digestive System: The sympathetic nervous system decreases digestive activity, diverting energy to the muscles, while the parasympathetic nervous system increases digestive activity, preparing the body for nutrient absorption.
Blood Vessels: The sympathetic nervous system generally causes vasoconstriction, diverting blood to the muscles and heart, while the parasympathetic nervous system has a limited effect on blood vessels.
Sweat Glands: The sympathetic nervous system activates sweat glands, increasing perspiration to cool the body.
Salivary Glands: The sympathetic nervous system decreases saliva production, while the parasympathetic nervous system increases saliva production.

Neurotransmitters: Acetylcholine (ACh), Norepinephrine (NA), and Epinephrine (A)

Acetylcholine (ACh): The primary neurotransmitter used by the parasympathetic nervous system. It is also used by all preganglionic neurons in both sympathetic and parasympathetic systems.
Norepinephrine (NA): The primary neurotransmitter used by the sympathetic nervous system (postganglionic fibers). It is also released by the adrenal medulla into the bloodstream.
Epinephrine (A): Also known as adrenaline, is released by the adrenal medulla into the bloodstream.

Receptors:

Nicotinic receptors: Found at the neuromuscular junction and on postganglionic neurons. They are stimulated by acetylcholine and are ligand-gated ion channels.
Muscarinic receptors: Found on target organs, stimulated by acetylcholine. They are G-protein coupled receptors, and different subtypes produce different effects.
Alpha receptors (α1 and α2): Primarily activated by norepinephrine. They are found on smooth muscle, the heart, and other tissues.
Beta receptors (β1, β2, and β3 ): Primarily activated by epinephrine. They are found on various tissues and can affect heart rate, blood pressure, and metabolism.

Adrenergic Transmission

Synthesis: Tyrosine is converted into dopamine, which is then converted into norepinephrine.
Release: When an action potential arrives at the nerve ending, calcium ions enter the terminal, triggering the release of norepinephrine from vesicles.
Receptor Activation: Norepinephrine acts on α and β receptors on target organs.
Feedback Mechanism: Norepinephrine also binds to α2 receptors on the presynaptic neuron, inhibiting further release of norepinephrine (negative feedback).

Co-transmission

Sympathetic neurons also release ATP alongside norepinephrine. ATP acts on P2X and P2Y receptors on target organs.
ATP acts faster than norepinephrine, causing a rapid contraction of smooth muscles.
ATP also acts on presynaptic receptors to inhibit the release of both norepinephrine and ATP.

Exceptions

Some organs, notably blood vessels, sweat glands, and salivary glands, are mostly innervated by the sympathetic nervous system.

Key Points to Remember

The sympathetic nervous system is responsible for mobilizing the body in stressful situations, while the parasympathetic nervous system is responsible for calming the body and conserving energy.
The specific effects of the ANS depend on the target organ and the types of receptors present.
Both the sympathetic and parasympathetic nervous systems utilize neurotransmitter signaling to influence target organ function.

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Description

Explore the intricacies of the autonomic nervous system (ANS) and its two primary branches: the sympathetic and parasympathetic systems. Understand how these systems manage vital processes like digestion and stress responses through their unique anatomical structures and functions.