The document provides an overview of the autonomic nervous system (ANS), including its divisions (sympathetic and parasympathetic), neurons, neurotransmitters, receptors, and effects on target organs. It also discusses how drugs can influence ANS activity by stimulating or blocking its components. The sympathetic division activates the fight or flight response, while the parasympathetic division promotes rest and digestion. Both use two-neuron chains and acetylcholine as a neurotransmitter.
The endocrine system is composed of organs positioned throughout the body in widely separated locations. Endocrinology is the study of the structure and functioning of the endocrine system.
Thalamus-Anatomy,Physiology,Applied aspectsRanadhi Das
Thalamus is a very important relay station.
All general and special sensory impulses (except smell) & afferent impulses from RAS are integrated here.
Thalamus however is the center of pain and protopathic sensations.
It has other non sensory functions as well, like motor control, sleep, wakefulness.
It is the largest structure deriving from the embryonic diencephalon, the posterior part of the forebrain situated between the midbrain and the cerebrum.
The thalamus is part of a nuclear complex structured of 4 parts, the hypothalamus, epithalamus, prethalamus (formerly called ventral thalamus) and dorsal thalamus.
The endocrine system is composed of organs positioned throughout the body in widely separated locations. Endocrinology is the study of the structure and functioning of the endocrine system.
Thalamus-Anatomy,Physiology,Applied aspectsRanadhi Das
Thalamus is a very important relay station.
All general and special sensory impulses (except smell) & afferent impulses from RAS are integrated here.
Thalamus however is the center of pain and protopathic sensations.
It has other non sensory functions as well, like motor control, sleep, wakefulness.
It is the largest structure deriving from the embryonic diencephalon, the posterior part of the forebrain situated between the midbrain and the cerebrum.
The thalamus is part of a nuclear complex structured of 4 parts, the hypothalamus, epithalamus, prethalamus (formerly called ventral thalamus) and dorsal thalamus.
Individualized Webcam facilitated and e-Classroom USMLE Step 1 Tutorials with Dr. Cray. For questions or more information.. drcray@imhotepvirtualmedsch.com
The Autonomic nervous system divided into two parts i.e sympathetic nervous system and parasympathetic nervous system.
ANS also consists cranial nerve and spinal nerve.
introduction to Autonomic Nervous System consisting of Cholinergic, adrenergic and enteric Nervous system with focus on location of neurotransmitters and broad functions of parasympathetic and sympathetic nervous system.
Autonomic nervous system: divisions
General organization of ANS Neurons of ANS
Physiological anatomy of sympathetic nervous system& parasympathetic nervous System
Autonomic neurotransmitters and receptors
Functions of ANS: effects of autonomic nerve impulses on effector organs
Differences between sympathetic and parasympathetic systems
APPLIED ASPECTS- Autonomic drugs, Autonomic failure, Autonomic function tests
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
2. Objectives
• Describe the location of the cell bodies of
preganglionic sympathetic and parasympathetic
neurons.
• Describe the location of postganglionic sympathetic
and parasympathetic neurons.
• Name the neurotransmitters that are released by
preganglionic autonomic neurons, postganglionic
sympathetic neurons, postganglionic parasympathetic
neurons, and adrenal medullary cells.
• Outline the functions of the autonomic nervous
system.
• List the ways that drugs act to increase or decrease the
activity of the components of the autonomic nervous
system.
3. Introduction
• Autonomic nervous system (ANS):
–Innervates organs whose functions are not
usually under voluntary control.
–Effectors include cardiac and smooth
muscles and glands.
• Effectors are part of visceral organs and
blood vessels.
4. Comparison of Somatic and
Autonomic Nervous Systems
• SNS provides motor fibers
to skeletal muscle fibers.
• In SNS, a single motor
neuron forms the efferent
[pathway from the CNS to
effectors.
• Acetylcholine, the
neurotransmitter of somatic
neurons is stimulatory to
skeletal muscle fibers.
• ANS provides motor fibers
to smooth and cardiac
muscles and glands.
• In ANS efferent pathway
consists of a two neuron
chain, the preganglionic
neuron in the CNS and
postganglionic in a ganglion.
• Neurotransmitters released
by ANS motor neurons-
acetylcholine and
norepinephrine -may cause
excitation or inhibition.
5. • Involuntary effectors are somewhat independent
of their innervation.
– Smooth muscles maintain resting tone in
absence of nerve stimulation.
• Denervation hypersensitivity:
–Damage to autonomic nerve makes its
target tissue more sensitive than normal
to stimulating agents.
For example Cardiac and many smooth muscles
can contract rhythmically in absence of nerve
stimulation.
Visceral Effector Organs
7. • Sensory input transmitted to brain centers that
integrate information can modify activity of
preganglionic autonomic neurons.
• Medulla:
– Most directly controls activity of autonomic
system.
– Location of centers for control of cardiovascular,
pulmonary, urinary, reproductive and digestive
systems.
• Hypothalamus:
– Regulates medulla.
• Cerebral cortex and limbic system:
– Responsible for visceral responses that are
characteristic of emotional states.
Control of the ANS by Higher Brain Centers
9. • Myelinated preganglionic fibers exit spinal cord
in ventral roots from T1 to L2 levels.
• Most sympathetic nerve fibers separate from
somatic motor fibers and synapse with
postganglionic neurons within paravertebral
ganglia.
–Ganglia within each row are interconnected,
forming a chain of ganglia that parallels spinal
cord to synapse with postganglionic neurons.
Sympathetic Division
10.
11. SEPARATION OF FUNCTION
• Sympathetic – Fight, flight, Fear.
• Parasympathetic – rest, digestion, calm
• Both involuntary
12. • Fight or flight response.
• Release of norepinephrine (NT) from
postganglionic fibers and epinephrine (NT)
from adrenal medulla.
• Mass activation prepares for intense
activity.
Sympathetic Effects
13. • Increased arterial pressure
• Increased blood flow to active muscles
concurrent with decreased blood flow to organs
such as the gastrointestinal tract and the kidneys
that are not needed for rapid motor activity
• Increased rates of cellular metabolism
throughout the body
• Increased blood glucose concentration
• Increased glycolysis in the liver and in muscle
• Increased muscle strength
• Increased mental activity
• Increased rate of blood coagulation
14. At other times, activation occurs in isolated
portions of the sympathetic nervous system.
Important examples are the following:
(1)During the process of heat regulation, the
sympathetics control sweating and blood flow in
the skin without affecting other organs
innervated by the sympathetics.
(2)Many "local reflexes" involving sensory afferent
fibers travel centrally in the peripheral nerves to
the sympathetic ganglia and spinal cord and
cause highly localized reflex responses. For
instance, heating a skin area causes local
vasodilation and enhanced local sweating,
whereas cooling causes opposite effects.
15.
16.
17.
18.
19.
20.
21. • Adrenal medulla secretes epinephrine (Epi) and
norepinephrine (NE) when stimulated by the
sympathetic nervous system.
• Modified sympathetic ganglion:
– Its cells are derived form the same embryonic
tissue that forms postganglionic sympathetic
neurons.
• Sympathoadrenal system:
– Stimulated by mass activation of the sympathetic
nervous system.
– Innervated by preganglionic sympathetic fibers.
Adrenal Glands
22. Parasympathetic Division
• Preganglionic fibers originate in midbrain, medulla,
pons; and in the 2-4 sacral levels of the spinal
column.(craniosacral)
• Preganglionic fibers synapse in terminal ganglia
located next to or within organs innervated.
• Most parasympathetic fibers do not travel within
spinal nerves.
– Do not innervate blood vessels, sweat glands, and
arrector pili muscles.
23. • Normally not activated as a whole.
– Stimulation of separate parasympathetic nerves.
• Release ACh as NT.
• Relaxing effects:
– Decreases HR.
– Dilates visceral blood vessels.
– Increases digestive activity.
Parasympathetic Effects
24. Comparisons
• SYMPATHETIC
• Short preganglionic fibers
• Neurotransmitter:
norepinephrine
• Turn OFF most gut activities.
• Constrict blood vessels to
splanchnopleure.
• PARASYMPATHETIC
• Long preganglionic fibers
• Neurotransmitter:
acetylcholine
• Turn ON most gut activities.
• Dilate blood vessels to
splanchnopleure.
25.
26.
27. The neurons that are cholinergic
1. all preganglionic neurons,
2. all parasympathetic postganglionic neurons
3. sympathetic postganglionic neurons that innervate
sweat glands and
4. sympathetic postganglionic neurons that end on
blood vessels in some skeletal muscles and produce
vasodilation when stimulated (sympathetic
vasodilator nerves).
Adrenergic
The remaining sympathetic postganglionic neurons
are noradrenergic (ie, release norepinephrine). The
adrenal medulla is essentially a sympathetic ganglion
in which the postganglionic cells have lost their axons
and secrete norepinephrine and epinephrine directly
into the bloodstream. The cholinergic preganglionic
neurons to these cells have consequently become the
secretomotor nerve supply of this gland.
28. Receptors on the Effector Organs
• (1) causing a change in cell membrane
permeability to one or more ions or
• (2) activating or inactivating an enzyme
attached to the other end of the receptor
protein, where it protrudes into the interior of
the cell.
29. Two Principal Types of Acetylcholine
Receptors
• Muscarinic and Nicotinic Receptors
• Acetylcholine activates both of them.
• Muscarinic receptors are found on all effector cells that
are stimulated by the postganglionic cholinergic
neurons of either the parasympathetic nervous system
or the sympathetic system.
• Nicotinic receptors are found in the autonomic ganglia
at the synapses between the preganglionic and
postganglionic neurons of both the sympathetic and
parasympathetic systems. (Nicotinic receptors are also
present at many nonautonomic nerve endings-for
instance, at the neuromuscular junctions in skeletal
muscle
30. Adrenergic Receptors-Alpha and Beta
Receptors
• beta receptors in turn are divided into beta1, beta2 and
beta3
• alpha receptors are divided into alpha1 and alpha2
receptors.
• Norepinephrine excites mainly alpha receptors but
excites the beta receptors to a lesser extent as well.
• epinephrine excites both types of receptors
approximately equally.
• Therefore, the relative effects of norepinephrine and
epinephrine on different effector organs are
determined by the types of receptors in the organs. If
they are all beta receptors, epinephrine will be the
more effective excitant.
31. Most visceral organs receive dual innervation (innervation by
both sympathetic and parasympathetic fibers).
Antagonistic effects:
◦ Sympathetic and parasympathetic fibers innervate the same
cells.
Actions counteract each other.
Heart rate.
Complementary:
◦ Sympathetic and parasympathetic stimulation produces
similar effects.
Salivary gland secretion.
Cooperative:
◦ Sympathetic and parasympathetic stimulation produce
different effects that work together to produce desired effect.
Micturition.
Organs With Dual Innervation
32. • Regulation achieved by increasing or decreasing
firing rate.
• Adrenal medulla, arrector pili muscle, sweat
glands, and most blood vessels receive only
sympathetic innervation.
Organs Without Dual Innervation
33. Denervation Supersensitivity
In response to loss of innervation by
postganglionic sympathetic or
parasympathetic axons – there is increased
responsiveness of visceral target organ to
neurotransmitter or agonist that stimulates
adrenergic / muscarnic receptors.
Leads to exagerrated pressor responses to
adrenergic agonists
34. Sympathomimetic Drugs
Epinephrine and methoxamine are
sympathomimetic drugs.
They differ from one another in the degree to
which they stimulate different sympathetic
effector organs and in their duration of action.
Norepinephrine and epinephrine have actions as
short as 1 to 2 minutes, whereas the actions of
some other commonly used sympathomimetic
drugs last for 30 minutes to 2 hours.
Important drugs that stimulate specific
adrenergic receptors are phenylephrine (alpha
receptors), isoproterenol (beta receptors), and
albuterol (only beta2 receptors).
35. Drugs That Cause Release of
Norepinephrine from Nerve Endings
Ephedrine, tyramine, and amphetamine.
Their effect is to cause release of norepinephrine
from its storage vesicles in the sympathetic nerve
endings.
The released norepinephrine in turn causes the
sympathetic effects.
36. Drugs That Block Adrenergic Activity
• The synthesis and storage of norepinephrine in the
sympathetic nerve endings can be prevented. The best
known drug that causes this effect is reserpine.
• Release of norepinephrine from the sympathetic
endings can be blocked. This can be caused by
guanethidine.
• The sympathetic alpha receptors can be blocked. Two
drugs that cause this effect are phenoxybenzamine and
phentolamine.
• The sympathetic beta receptors can be blocked. A drug
that blocks beta1 and beta2 receptors is propranolol.
One that blocks mainly beta1 receptors is metoprolol.
• Sympathetic activity can be blocked by drugs that block
transmission of nerve impulses through the autonomic
ganglia an important drug for blockade of both
sympathetic and parasympathetic transmission
through the ganglia is hexamethonium.
37. Drugs That Act on Cholinergic Effector
Organs Parasympathomimetic Drugs
(Cholinergic Drugs)
• Two commonly used parasympathomimetic drugs
are pilocarpine and methacholine.
• They act directly on the muscarinic type of
cholinergic receptors.
• Neostigmine, pyridostigmine, and ambenonium.
These drugs inhibit acetylcholinesterase, thus
preventing rapid destruction of the acetylcholine
liberated at parasympathetic nerve endings. As a
consequence, the quantity of acetylcholine
increases with successive stimuli and the degree
of action also increases.
38. Drugs That Block Cholinergic Activity at
Effector Organs-
• Antimuscarinic Drugs Atropine and similar
drugs, such as homatropine and scopolamine,
block the action of acetylcholine on the
muscarinic type of cholinergic effector organs.
These drugs do not affect the nicotinic action
of acetylcholine on the postganglionic neurons
or on skeletal muscle.
39. Drugs That Stimulate Postganglionic
Neurons
• Accetylcholine
• Nicotine is another drug that can stimulate postganglionic
neurons in the same manner as acetylcholine because the
membranes of these neurons all contain the nicotinic type
of acetylcholine receptor. Therefore, drugs that cause
autonomic effects by stimulating postganglionic neurons
are called nicotinic drugs.
• Some other drugs, such as methacholine, have both
nicotinic and muscarinic actions, whereas pilocarpine has
only muscarinic actions. Nicotine excites both the
sympathetic and parasympathetic postganglionic neurons
at the same time, resulting in strong sympathetic
vasoconstriction in the abdominal organs and limbs but at
the same time resulting in parasympathetic effects such as
increased gastrointestinal activity and, sometimes, slowing
of the heart.
40. Ganglionic Blocking Drugs
• Many important drugs block impulse transmission
from the autonomic preganglionic neurons to the
postganglionic neurons, including tetraethyl
ammonium ion, hexamethonium ion, and pentolinium.
• These drugs block acetylcholine stimulation of the
postganglionic neurons in both the sympathetic and
the parasympathetic systems simultaneously.
• They are often used for blocking sympathetic activity
but seldom for blocking parasympathetic activity
because their effects of sympathetic blockade usually
far overshadow the effects of parasympathetic
blockade.
• The ganglionic blocking drugs especially can reduce the
arterial pressure in many patients with hypertension,
but these drugs are not useful clinically because their
effects are difficult to control.