Autonomic and Somatic Nervous Systems Overview

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Questions and Answers

What is the primary role of the parasympathetic division of the ANS?

To prepare the body for high-energy tasks

To increase blood flow to muscles during emergencies

To enhance heart rate and respiratory function

To keep body energy use low and facilitate rest and digestion (correct)

Which neurotransmitter is predominantly used by the parasympathetic division?

Norepinephrine

Acetylcholine (correct)

Serotonin

Dopamine

What is a physiological effect of sympathetic activation?

Pupil constriction

Inhibition of digestion (correct)

Decrease in heart rate

Increased gastrointestinal activity

How do the sympathetic and parasympathetic divisions interact?

They work antagonistically to maintain homeostasis. Signup and view all the answers

During sympathetic activation, what happens to blood flow?

Decreased to internal organs and increased to muscles Signup and view all the answers

What is the effect of parasympathetic activation on pupils?

They constrict to reduce light entry. Signup and view all the answers

Which scenario best illustrates the functions of the sympathetic division?

A person experiencing excitement during a sports event. Signup and view all the answers

Which of the following descriptions best characterizes the vagal nerve?

It stimulates digestive glands and decreases heart rate. Signup and view all the answers

What type of muscle does the autonomic nervous system primarily innervate?

Both B and C Signup and view all the answers

Which neurotransmitter is primarily released by preganglionic fibers in the autonomic nervous system?

Acetylcholine Signup and view all the answers

What is the main function of the autonomic nervous system?

To regulate visceral organ functions Signup and view all the answers

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

It uses a two-neuron chain to reach effector organs. Signup and view all the answers

How do the effects of neurotransmitters differ in the autonomic nervous system?

They are stimulatory or inhibitory depending on the receptor type. Signup and view all the answers

What distinguishes the efferent pathways of the somatic nervous system from those of the autonomic nervous system?

SNS uses a single neuron chain. Signup and view all the answers

Which of the following best describes the control exerted by the autonomic nervous system?

Subconscious and involuntary Signup and view all the answers

What happens to the body when the autonomic nervous system is activated?

Visceral organs receive enhanced signals to function. Signup and view all the answers

What neurotransmitter is primarily released by the adrenal gland during sympathetic activation?

Adrenaline Signup and view all the answers

Which receptor type mediates responses to adrenaline and noradrenaline?

Beta receptors Signup and view all the answers

Which function is associated with the alpha-1 adrenergic receptor?

Vasoconstriction Signup and view all the answers

What type of receptors mediate responses to acetylcholine in the peripheral nervous system?

Cholinergic receptors Signup and view all the answers

Which of the following statements about the sympathetic nervous system is correct?

It affects every part of the body. Signup and view all the answers

What is the role of the alpha-2 adrenergic receptor?

Inhibits the release of norepinephrine Signup and view all the answers

In which organ does the beta-1 adrenergic receptor primarily increase output?

Heart Signup and view all the answers

What physiological effect is associated with the activation of beta-2 adrenergic receptors?

Vasodilation of arterioles Signup and view all the answers

Which of the following neurotransmitters is NOT typically associated with the autonomic nervous system?

Serotonin Signup and view all the answers

How does the sympathetic nervous system primarily affect blood vessels during stress?

Promotes vasoconstriction Signup and view all the answers

What is the primary function of epinephrine (adrenaline) as described in the content?

It acts to stimulate both alpha and beta receptors. Signup and view all the answers

What process occurs after noradrenaline is released from the presynaptic neuron?

It binds selectively to a1 or b1 receptors on the postsynaptic cell. Signup and view all the answers

Which of the following conditions is NOT indicated for the use of propranolol?

Severe cardiac disease Signup and view all the answers

What side effect is common to both salbutamol and epinephrine?

Nervousness Signup and view all the answers

Which drug is a selective antagonist for beta-1 receptors?

Metoprolol Signup and view all the answers

In which scenario is salbutamol contraindicated?

Severe cardiac disease Signup and view all the answers

What should be considered regarding the reuptake of noradrenaline?

It is reused or converted by MAO. Signup and view all the answers

What is a common side effect of using beta-blockers like propranolol?

Hypoglycemia Signup and view all the answers

What is the primary role of the parasympathetic nervous system in autonomic tone?

To provide the basal tone in day-to-day functions Signup and view all the answers

Which receptor type is responsible for promoting ganglionic transmission at all ganglia?

Nicotinic receptors Signup and view all the answers

What is a common effect of muscarinic receptor activation?

Contraction of smooth muscle Signup and view all the answers

Which process correctly describes the synthesis of acetylcholine?

Synthesized in the presynaptic terminal from choline and Acetylcoenzyme A Signup and view all the answers

What is the primary function of atropine as a cholinergic antagonist?

Blocks vagal effects leading to increased heart rate Signup and view all the answers

Which of the following is an effect of cholinergic agonists?

Increased muscle contraction and miosis Signup and view all the answers

What is a common side effect of atropine usage?

Constipation Signup and view all the answers

What happens to choline after acetylcholine is broken down?

It is re-absorbed by the neuron to synthesize more ACh Signup and view all the answers

Study Notes

Autonomic Nervous System Overview

The autonomic nervous system (ANS) is involved in involuntary bodily functions.
The ANS controls visceral organs, smooth muscle, and glands.
It operates via subconscious control.
Key neurotransmitters are acetylcholine (ACh) and noradrenaline (norepinephrine).
The two main branches of the ANS are the sympathetic and parasympathetic divisions.

Somatic Nervous System

The somatic nervous system (SNS) controls voluntary movements.
SNS controls skeletal muscles.
The neurotransmitter for the SNS is acetylcholine (ACh).

SNS axons are heavily myelinated, extending directly from the central nervous system (CNS) to the effector organ.
ANS axons are a two-neuron chain:
- Preganglionic neurons (lightly myelinated)
- Ganglionic neuron (extends to the effector organ)
The two neurons synapse in a ganglion.

ANS Neurotransmitters

Preganglionic fibers release acetylcholine (ACh).
Postganglionic fibers release either norepinephrine or acetylcholine.

ANS Divisions (Sympathetic)

The sympathetic nervous system (SNS) is activated under stress, producing the "fight-or-flight" response.
It increases heart rate, breathing rate, and blood flow to muscles.
It inhibits digestion and elimination.
Neurotransmitters: Acetylcholine (preganglionic) and norepinephrine (postganglionic).
The sympathetic pathway has a short preganglionic axon and a long postganglionic axon.
Ganglion location is close to the spinal cord (thoracolumbar).
There are specialized connections to the adrenal medulla. This results in a systemic release of epinephrine and norepinephrine.

ANS Divisions (Parasympathetic)

The parasympathetic nervous system (PNS) is activated in relaxed states.
It conserves energy and promotes digestion.
It slows heart rate, breathing rate, and increases digestion and elimination
Neurotransmitters: Acetylcholine (preganglionic and postganglionic).
The parasympathetic pathway has a long preganglionic axon and a short postganglionic axon.
Ganglion location is close to the target organ (craniosacral).

Interaction of ANS Divisions

Most visceral organs receive input from both sympathetic and parasympathetic divisions, creating dynamic antagonism.
Sympathetic and parasympathetic divisions often have opposing effects on the same target organ. For instance, sympathetic fibers increase heart rate, while parasympathetic fibers decrease it.
Cooperative effects are observed in external genitalia control. Parasympathetic fibers cause vasodilation, leading to erection. Sympathetic fibers control ejaculation and peristalsis.

ANS Peripheral Receptors

Cholinergic receptors respond to acetylcholine (ACh).
Muscarinic receptors are one type of cholinergic receptor.
Adrenergic receptors respond to epinephrine and norepinephrine.
Alpha (α) and beta (β) receptors are two types of adrenergic receptors.

Sympathetic Neurotransmitters

Norepinephrine is released at the effector organ.
Synthesized in the presynaptic terminal.
Stored in vesicles.
Released during action potentials.
Binds to receptors. It binds to presynaptic receptors a2 (autoreceptors). It binds to postsynaptic α1 or β1 receptors.
Reuptake by the presynaptic neuron. Some is broken down by Monoamine Oxidase (MAO).

Sympathomimetics/Sympatholytic Agents

Some drugs mimic the effects of the sympathetic nervous system, called sympathomimetics.
Examples include: Salbutamol (β2 agonist) and Epinephrine (stimulates α & β).
Drugs that block these effects are called sympatholytics.
Examples include: Propranolol (non-selective β-antagonist) and Metoprolol (β1 selective antagonist).

Parasympathetic Nervous System

The parasympathetic nervous system (PNS) is responsible for maintaining homeostasis and restorative activities.
Parasympathetic activity is often referred to as the “Rest-and-Digest” system.
ACh is the primary neurotransmitter.
Cholinergic agonists mimic the actions of acetylcholine. Pilocarpine is an example used in glaucoma treatment.
Cholinergic antagonists block the effects of acetylcholine. Atropine is an example.

Summary

The autonomic nervous system regulates visceral functions, including heart rate, digestion, and blood pressure.
The peripheral nervous system (PNS) includes sensory and motor pathways. The sensory pathway transmits information to the CNS, while the motor pathways transmit signals out to effectors.
The central nervous system (CNS) processes information and makes decisions. The sensory nervous system and the motor nervous system are collectively referred to as the peripheral nervous system. The sympathetic and parasympathetic systems are part of the autonomic nervous system, which regulates visceral organs and systems.

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Description

Explore the key distinctions between the autonomic and somatic nervous systems in this quiz. Understand their functions, components, and the role of neurotransmitters like acetylcholine and noradrenaline. Test your knowledge on both the involuntary and voluntary control mechanisms of the body.