Autonomic Nervous System BMF Year 1

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What are the two primary divisions of the autonomic nervous system?

Central and peripheral

Sensory and motor

Sympathetic and parasympathetic (correct)

Cerebral and spinal

Which of the following describes the general function of the autonomic nervous system?

Maintains homeostatic conditions in the body (correct)

Regulates conscious thought

Controls voluntary muscle movement

Processes sensory information

Which organ is NOT directly controlled by the autonomic nervous system?

Bladder

Skeletal muscles (correct)

Lungs

Heart

Which neurotransmitter is primarily associated with the sympathetic nervous system?

Norepinephrine Signup and view all the answers

What type of activity does the autonomic nervous system exhibit under most circumstances?

Tonic activity Signup and view all the answers

Which brain structure plays a major role in controlling the autonomic nervous system?

Hypothalamus Signup and view all the answers

What happens to an effector organ if the autonomic nerve fibers are cut?

It continues to function without regulation Signup and view all the answers

Which of the following is NOT a function of the autonomic nervous system?

Conscious control of movements Signup and view all the answers

What type of receptors are muscarinic ACh receptors?

Metabotropic receptors Signup and view all the answers

Which muscarinic receptor type is associated with an inhibitory response in cardiac tissue?

M2 Signup and view all the answers

What is the primary effect of M3 muscarinic receptors in the digestive system?

Increase Ca2+ conductance Signup and view all the answers

What is the result of ACh binding to nicotinic receptors?

Rapid depolarization Signup and view all the answers

What is a primary function of the parasympathetic nervous system?

Promote digestion Signup and view all the answers

How many types of muscarinic ACh receptors are there?

5 Signup and view all the answers

Which of the following best describes the sympathetic nervous system?

Prepares the body for emergencies Signup and view all the answers

Which neurotransmitter is released from postganglionic parasympathetic nerves?

ACh Signup and view all the answers

Dual innervation of visceral organs primarily allows for what?

Rapid and precise control over organ functions Signup and view all the answers

Which statement best describes the effect of the M2 muscarinic receptor?

It decreases heart contraction. Signup and view all the answers

What happens to heart rate during sympathetic stimulation?

It increases Signup and view all the answers

What does the nicotinic ACh receptor primarily act as when ACh binds?

An ion channel Signup and view all the answers

Which of the following is NOT a characteristic of the sympathetic nervous system?

Promotes relaxation Signup and view all the answers

How do the sympathetic and parasympathetic nervous systems generally interact?

Increased activity in one leads to decreased activity in the other Signup and view all the answers

Which bodily functions are primarily associated with the parasympathetic nervous system?

Increased urination and defecation Signup and view all the answers

What is an exception to the general rule of dual reciprocal innervation?

Blood vessel control Signup and view all the answers

What effect does NA have on heart rate and the digestive tract?

Increases heart rate and decreases contraction of the digestive tract Signup and view all the answers

What types of receptors can neurotransmitters bind to?

Ionotropic and metabotropic receptors Signup and view all the answers

Which type of receptor is typically ligand-gated and allows ions to pass directly?

Ionotropic receptor Signup and view all the answers

What role do metabotropic receptors require to modulate ionic activity?

Second messengers and G proteins Signup and view all the answers

Where are nicotinic receptors found?

On postganglionic ANS cell bodies Signup and view all the answers

Which neurotransmitter activates nicotinic receptors?

Acetylcholine (ACh) Signup and view all the answers

What type of receptor is muscarinic?

Metabotropic Signup and view all the answers

Which substance activates nicotinic receptors apart from acetylcholine?

Nicotine Signup and view all the answers

What is the primary neurotransmitter released by sweat glands?

Acetylcholine Signup and view all the answers

Which fibers are typically long and myelinated in the parasympathetic division?

Preganglionic fibers Signup and view all the answers

The adrenal medulla is considered a modified sympathetic ganglion because it is innervated by which type of fibers?

Sympathetic preganglionic fibers Signup and view all the answers

From where do the preganglionic neurons of the parasympathetic division originate?

Cranial and sacral spinal nerves Signup and view all the answers

What type of fibers are found in the sympathetic division?

Short and myelinated preganglionic fibers Signup and view all the answers

Which neurotransmitter is primarily released by the adrenal medulla?

Epinephrine Signup and view all the answers

What is the arrangement of the two-neuron chain in the parasympathetic pathway?

Preganglionic nerve → Ganglion → Effector Signup and view all the answers

How does the adrenal medulla function in relation to the sympathetic nervous system?

It is innervated by sympathetic preganglionic fibers Signup and view all the answers

What is the primary role of acetylcholine in neurotransmission?

Degraded by acetylcholinesterase Signup and view all the answers

Which condition is an example of autonomic dysfunction?

Chronic stress disorders Signup and view all the answers

What effect does an adrenergic agonist like Salbutamol have?

Dilates bronchioles Signup and view all the answers

Which neurotransmitter is taken back by pre- and post-synaptic cells for recycling?

Noradrenaline Signup and view all the answers

Which of the following is a muscarinic antagonist?

Atropine Signup and view all the answers

What is NOT a potential target for pharmacological intervention in neurochemical transmission?

Neurotransmitter receptor type Signup and view all the answers

What effect do sympathetic postganglionic fibers typically have on blood vessels?

Increased contraction Signup and view all the answers

Study Notes

Autonomic Nervous System Biology

Class: DEM Year 1
Course: The Body: Movement and Function (BMF)
Lecturer: Dr. Ebrahim Rajab ([email protected])
Date: 10/11/2024

Learning Objectives

Recall the divisions of the nervous system
Contrast the anatomical features of the sympathetic and parasympathetic systems
Identify the functions of the sympathetic and parasympathetic nervous systems
Describe the neurotransmitters and receptors located in the ANS

Divisions of Nervous System

Nervous system
- Central nervous system (CNS): brain and spinal cord
- Peripheral nervous system (PNS):
  - Autonomic nervous system (ANS): controls internal organs
  - Somatic nervous system: controls skeletal muscles
    - Sensory (afferent): sensory input
    - Motor (efferent): motor output

Divisions of Peripheral Nervous System

Sensory (afferent) division
- Somatic sensory: touch, pain, pressure, temperature, proprioception (skin, body wall, limbs)
- Visceral sensory: stretch, pain, temperature, chemical changes, and irritation in viscera; nausea and hunger
Motor (efferent) division
- Somatic nervous system: motor innervation of all skeletal muscles
- Autonomic nervous system (ANS): motor innervation of smooth muscle, cardiac muscle, and glands

Divisions of Autonomic Nervous System (ANS)

Involuntary system maintaining homeostasis
Regulates heart, circulation, digestion, and respiratory functions
Two main divisions: sympathetic and parasympathetic
Most visceral organs receive dual innervation from both systems (dual innervation)
Two divisions often exert opposing effects

Sympathetic and Parasympathetic Functions

Sympathetic: "fight-or-flight" response
- Increases cardiac output, blood flow to muscles, blood glucose
- Decreases digestion
Parasympathetic: "rest-and-digest" response
- Conserves energy, slows heart rate, promotes digestion

Advantages of Dual Innervation

Precise control over organs and tissues allows rapid transitions from rest to 'fight-or-flight'
Sympathetic stimulation increases heart rate, parasympathetic stimulation decreases it

Exceptions to Reciprocal Control

The two branches of the ANS often control organs reciprocally
However, some exceptions exist, such as blood vessels and sweat glands

ANS Pathways

Each ANS pathway follows a 2-neuron chain from the CNS to organ/effector.
- Preganglionic neuron (myelinated): extends from CNS to ganglion.
- Postganglionic neuron (unmyelinated): extends from ganglion to effector organ.
Sympathetic pathway: short preganglionic, long postganglionic neuron (preganglionic fibers originate in thoracic and lumbar regions of the spinal cord)
Parasympathetic pathway: long preganglionic neuron, short postganglionic neuron (preganglionic fibers originate in cranial and sacral regions of the spinal cord).

Modified Sympathetic Nervous System - Adrenal Medulla

Two adrenal glands adjacent to kidneys.
Adrenal medulla, an endocrine gland, is a modified sympathetic ganglion
Preganglionic sympathetic fibers directly contact adrenal medulla cells, influencing hormone release (adrenaline = epinephrine, noradrenaline = norepinephrine)

Neurotransmitters and Receptors

Parasympathetic postganglionic neurons: mostly release acetylcholine (ACh)
Sympathetic postganglionic neurons: mostly release norepinephrine (NE)
Important: receptors for ACh and NE are of different subtypes, resulting in varied responses due to differing effects (eg. increased heart rate but decreased digestive function)
There are cholinergic (bind to ACh) and adrenergic receptors (bind to NE)

Termination of Neurotransmitter Effects

Acetylcholine (ACh): broken down by acetylcholinesterase at the synapse.
Norepinephrine (NE): re-absorbed and broken down by the synapse

Neurotransmitter Receptors

Ionotropic receptors: direct ion channel opening and relatively fast response (e.g., nicotinic receptors)
Metabotropic receptors: activate second messenger systems and can result in slower responses (e.g., muscarinic and adrenergic receptors)

ANS Drugs

Drugs targeting receptors can mimic (agonists) or inhibit (antagonists) ANS actions
- Examples mentioned include atropine (muscarinic antagonist), salbutamol (β2 adrenergic agonist), and atenolol (β1 adrenergic antagonist)

Autonomic Dysfunction

Various conditions impacting the ANS
- Examples mentioned include orthostatic hypotension (dropping blood pressure from a sitting to standing position), neurocardiogenic syncope (fainting), chronic stress disorders

Comparison of Autonomic and Somatic Nervous Systems

ANS involves two-neuron pathways using a variety of neurotransmitters (preganglionic and postganglionic neurons)
Somatic involves only one neuron pathway mostly using acetylcholine

Additional Resources

Books include Neuroscience: exploring the brain, Bear, Connors, Paradiso, 3rd edition (chapters), Boron, Boulpaep, Medical Physiology, and Rhoades, Medical Physiology

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the autonomic nervous system as part of The Body: Movement and Function course for Year 1 students. Test your knowledge on the divisions, functions, and key features of the sympathetic and parasympathetic systems. Additionally, explore the neurotransmitters and receptors associated with the autonomic nervous system.