Sympathomimetics are drugs that stimulate the sympathetic nervous system and mimic the effects of sympathetic neurotransmitters like norepinephrine and epinephrine. They act on adrenergic receptors in smooth muscles and produce effects like increased heart rate, blood pressure, and bronchodilation. Examples include epinephrine, albuterol, and isoproterenol. Sympatholytics block the effects of sympathetic neurotransmitters and include alpha- and beta-adrenergic blockers used to treat conditions like hypertension. Parasympathomimetics mimic acetylcholine in the parasympathetic nervous system to slow the heart and increase gland secretion. They include direct-acting cholinergics and indirect-acting inhibitors
2. Sympathomimetics
• Drugs that stimulate the sympathetic nervous
system and mimic the sympathetic
neurotransmitters
(norepinephrine, epinephrine).
• They act on one or more adrenergic receptors
sites located on the cells of smooth muscles
such as the heart, bronchiole
walls, gastrointestinal tract, urinary
bladder, and ciliary, muscle of the eye.
The Anatomy & Physiology
of the nervous system
4. Sympathomimetics
Epinephrine
• Administered SC, IV, topically, or by inhalation. It is
not to be given orally as it is metabolized quickly in
the GI tract resulting to inadequate serum levels.
• It is frequently used in emergencies to combat
anaphylaxis.
• It is a potent inotropic drug that causes the blood
vessels to constrict; thus blood pressure
increases, the heart rate increases, and the bronchial
tubules dilate.
The Anatomy & Physiology
of the nervous system
5. Sympathomimetics
Albuterol Sulfate (Proventil, Ventolin)
• Selective beta2 adrenergic receptor
agonist which response is bronchodilation.
• Used primarily in asthmatic patients
The Anatomy & Physiology
of the nervous system
6. Sympathomimetics
Isoproterenol HCl
• Activates both beta1 and beta2 receptors.
It is more specific than epinephrine
becauseit acts on two different adrenergic
receptors but is not completely selective.
• Used to control asthma
The Anatomy & Physiology
of the nervous system
7. Sympathomimetics
Clonidine (Catapres) and Methyldopa
(Aldomet)
• They are selective alpha2 adrenergic drugs
that are used primarily to treat
hypertension.
• They regulate the release of
norepinephrine by inhibiting its release.
• They cause cardiovascular depression by
stimulating alpha2 receptors in the CNS
leading to a decrease in blood pressure.
The Anatomy & Physiology
of the nervous system
8. Sympatholytics
• Drugs that block the effects of the
adrenergic neurotransmitters. They act as
antagonists to the adrenergic agonists.
• Inhibits the release of the
neurotransmitters norepinephrine and
epinephrine.
The Anatomy & Physiology
of the nervous system
9. Sympatholytics
Alpha-Adrenergic Blockers
• Drugs that block or inhibit a response at
the alpha-adrenergic receptor site.
• They are divided into 2 groups: selective
alpha-blockers (those that block alpha1)
and nonselective alpha-blockers (those
that block alpha1 and alpha2).
The Anatomy & Physiology
of the nervous system
10. Sympatholytics
Beta-adrenergic Blockers
• These drugs cause a decrease in heart rate
and a decrease in blood pressure.
• They are divided into 2 groups: selective
beta-blockers (those that block beta1) and
nonselective beta-blockers (those that
block beta1 and beta2).
The Anatomy & Physiology
of the nervous system
11. Sympatholytics
Adrenergic Neuron Blockers
• Drugs that block the release of
norepinephrine from the sympathetic
terminal neurons.
• Its clinical use is to decrease blood pressure.
They are potent antihypertensive agents.
• Examples of this drugs are guanethidine
monosulfate (Ismelin) and guanadrel sulfate
(Hylorel).
The Anatomy & Physiology
of the nervous system
12. Parasympathetic Nervous System
• The parasympathetic system dominates
control of many visceral effectors under
normal, everyday conditions.
• The ANS is responsible for regulation of
internal organs and glands, which occurs
unconsciously.
The Anatomy & Physiology
of the nervous system
13. Parasympathetic Nervous System
• The two types of receptors are
1. muscarinic receptors - stimulates the
smooth muscles and slow heart rate
2. nicotinic receptors - stimulates skeletal
muscles for contraction
The Anatomy & Physiology
of the nervous system
14. Parasympathetic Nervous System
STRUCTURE
• Parasympathetic
preganglionic neurons –
dendrites and cell bodies
are located in the gray
matter of the brainstem and
the sacral segments of the
spinal cord.
The Anatomy & Physiology
of the nervous system
15. Parasympathetic Nervous System
STRUCTURE
• Parasympathetic
preganglionic neurons –
axons extend some
distance before
terminating in the
parasympathetic ganglia
located in the head and in
the thoracic and
abdominal cavities close
to the visceral effectors
that they control
The Anatomy & Physiology
of the nervous system
16. Parasympathetic Nervous System
STRUCTURE
• Parasympathetic
postganglionic neurons –
dendrites and cell bodies
lie in the outlying
parasympathetic
ganglia, and their short
axons extend into the
nearby structures.
The Anatomy & Physiology
of the nervous system
18. PNS Neurotransmitters
(Postganglionic Neurons-Effectors}
• Acetylcholine
• 2 Types of Receptors
a) Muscarinic – stimulates smooth muscles
(Cardiac Muscle)
b) Nicotinic – stimulates skeletal muscles
(neuromuscular)
The Anatomy & Physiology
of the nervous system
20. Parasympathomimetics
(Cholinergics)
• These are drugs that stimulate the
parasympathetic nervous system.
• They mimic the parasympathetic
neurotransmitter acetylcholine.
The Anatomy & Physiology
of the nervous system
22. Parasympathomimetics
Direct-Acting Cholinergics
Bethanicol Chloride, Metoclopramide
HCl, Carbachol
• They are primarily selective to the
muscarinic receptors and are nonspecific
because the muscarinic receptors are
located in the smooth muscles of the GI
and genitourinary tracts, glands, and the
heart.
The Anatomy & Physiology
of the nervous system
23. Parasympathomimetics
Direct-Acting Cholinergics
• Eye: pilocarpine
• These drugs constricts the pupils of the
eyes thus opening the canal of Schlemm to
promote drainage of aqeous humor. This is
used to treat glaucoma by relieving fluid
(intraocular) pressure in the eye.
The Anatomy & Physiology
of the nervous system
25. Parasympathomimetics
Indirect-Acting Cholinergics
• demecarium bromide, echothiophate
iodide, isoflurophate
• These group of drugs do not act on
receptors, instead they inhibit or inactivate the
enzyme cholinesterase, thus permitting
acetylcholine to accumulate at the receptor
sites. Thus they are called cholinesterase
inhibitors or anticholinesterases.
The Anatomy & Physiology
of the nervous system
26. 2 Types of Indirect-Acting
Cholinergics
Reversible Cholinesterase Inhibitors
• Ex. ambenonium chloride, edrophonium
chloride
• These drugs are used
1. to produce papillary constriction in the treatment
of glaucoma
2. to increase muscle strength in clients with
myasthenia gravis.
The Anatomy & Physiology
of the nervous system
27. 2 Types of Indirect-Acting
Cholinergics
Irreversible Cholinesterase Inhibitors
• Ex. neostigmine, neostigmine
methylsulfate, pyridostigmine bromide
• These are potent agents because their effect
are long lasting. With irreversible inhibitors the
bond between the irreversible cholinesterase
inhibitor and cholinesterase are permanent.
The Anatomy & Physiology
of the nervous system
28. Parasympatholytics
(Anticholinergics)
• Drugs that inhibit the actions of
acetylcholine by occupying the
acetylcholine receptors.
• The major responses to anticholinergics
are a decrease in GI motility, a decrease
salivation, dilation of pupils
(mydriasis), and an increase in pulse rate.
The Anatomy & Physiology
of the nervous system
31. Parasympatholytics
(Anticholinergics)
Atropine
Uses of Atropine
1. Pre-operative medication to decrease salivary
secretions
2. Antispasmodic drug to treat peptic ulcers
because it relaxes the smooth muscles of the GI
tract and decreases peristalsis
3. Agent to increase the heart rate when
bradycardia is present.
4. This can also be given as an antidote for
muscarinic agonist poisoning.
The Anatomy & Physiology
of the nervous system
32. Disorders of the Autonomic Nervous
System
1. Stress-Induced Disease
– Heart Disease
– Digestive Problems
– Reduced resistance to disease
2. Neuroblastoma
– is a malignant tumor of the sympathetic
nervous system.
–Occurs in the developing nervous systems of
young children and metastasizes rapidly to
other parts f the body.
The Anatomy & Physiology
of the nervous system
Editor's Notes
#4: Direct-acting sympathomimetics– drugs which directly stimulate the adrenergic receptor (epinephrine and norepinephrine)Indirect-acting sympathomimetics– drugs which stimulates the release of norepinephrine from the terminal nerve endings (amphetamine)Mixed-acting sympathomimetics(both direct and indirect)- drugs which stimulate the adrenergic receptor sites and stimulate the release of norepinephrine from the terminal nerve endings.
#5: EpinephrineAdministered SC, IV, topically, or by inhalation. It is not to be given orally as it is metabolized quickly in the GI tract resulting to inadequate serum levels.It is frequently used in emergencies to combat anaphylaxis. It is a potent inotropic drug that causes the blood vessels to constrict; thus blood pressure increases, the heart rate increases, and the bronchial tubules dilate. Albuterol Sulfate (Proventil, Ventolin)Selective beta2 adrenergic receptor agonist which response is bronchodilation.Used primarily in asthmatic patients IsoproterenolHClActivates both beta1 and beta2 receptors. It is more specific than epinephrine becauseit acts on two different adrenergic receptors but is not completely selective.Used to control asthma Clonidine (Catapres) and Methyldopa (Aldomet)They are selective alpha2 adrenergic drugs that are used primarily to treat hypertension.They regulate the release of norepinephrine by inhibiting its release.They cause cardiovascular depression by stimulating alpha2 receptors in the CNS leading to a decrease in blood pressure.SE: Side results when the drug dosage is increased or the drug is nonselective. Side effects associated with adrenergic drugs include hypertension, tachycardia, palpitations, nausea and vomiting
#6: EpinephrineAdministered SC, IV, topically, or by inhalation. It is not to be given orally as it is metabolized quickly in the GI tract resulting to inadequate serum levels.It is frequently used in emergencies to combat anaphylaxis. It is a potent inotropic drug that causes the blood vessels to constrict; thus blood pressure increases, the heart rate increases, and the bronchial tubules dilate. Albuterol Sulfate (Proventil, Ventolin)Selective beta2 adrenergic receptor agonist which response is bronchodilation.Used primarily in asthmatic patients IsoproterenolHClActivates both beta1 and beta2 receptors. It is more specific than epinephrine becauseit acts on two different adrenergic receptors but is not completely selective.Used to control asthma Clonidine (Catapres) and Methyldopa (Aldomet)They are selective alpha2 adrenergic drugs that are used primarily to treat hypertension.They regulate the release of norepinephrine by inhibiting its release.They cause cardiovascular depression by stimulating alpha2 receptors in the CNS leading to a decrease in blood pressure.SE: Side results when the drug dosage is increased or the drug is nonselective. Side effects associated with adrenergic drugs include hypertension, tachycardia, palpitations, nausea and vomiting
#7: EpinephrineAdministered SC, IV, topically, or by inhalation. It is not to be given orally as it is metabolized quickly in the GI tract resulting to inadequate serum levels.It is frequently used in emergencies to combat anaphylaxis. It is a potent inotropic drug that causes the blood vessels to constrict; thus blood pressure increases, the heart rate increases, and the bronchial tubules dilate. Albuterol Sulfate (Proventil, Ventolin)Selective beta2 adrenergic receptor agonist which response is bronchodilation.Used primarily in asthmatic patients IsoproterenolHClActivates both beta1 and beta2 receptors. It is more specific than epinephrine becauseit acts on two different adrenergic receptors but is not completely selective.Used to control asthma Clonidine (Catapres) and Methyldopa (Aldomet)They are selective alpha2 adrenergic drugs that are used primarily to treat hypertension.They regulate the release of norepinephrine by inhibiting its release.They cause cardiovascular depression by stimulating alpha2 receptors in the CNS leading to a decrease in blood pressure.SE: Side results when the drug dosage is increased or the drug is nonselective. Side effects associated with adrenergic drugs include hypertension, tachycardia, palpitations, nausea and vomiting
#8: EpinephrineAdministered SC, IV, topically, or by inhalation. It is not to be given orally as it is metabolized quickly in the GI tract resulting to inadequate serum levels.It is frequently used in emergencies to combat anaphylaxis. It is a potent inotropic drug that causes the blood vessels to constrict; thus blood pressure increases, the heart rate increases, and the bronchial tubules dilate. Albuterol Sulfate (Proventil, Ventolin)Selective beta2 adrenergic receptor agonist which response is bronchodilation.Used primarily in asthmatic patients IsoproterenolHClActivates both beta1 and beta2 receptors. It is more specific than epinephrine becauseit acts on two different adrenergic receptors but is not completely selective.Used to control asthma Clonidine (Catapres) and Methyldopa (Aldomet)They are selective alpha2 adrenergic drugs that are used primarily to treat hypertension.They regulate the release of norepinephrine by inhibiting its release.They cause cardiovascular depression by stimulating alpha2 receptors in the CNS leading to a decrease in blood pressure.SE: Side results when the drug dosage is increased or the drug is nonselective. Side effects associated with adrenergic drugs include hypertension, tachycardia, palpitations, nausea and vomiting
#9: They block the effects of the neurotransmitter either directly by occupying the alpha or the beta receptors or indirectly by inhibiting the release of the neurotransmitters norepinephrine and epinephrine.
#10: They block the effects of the neurotransmitter either directly by occupying the alpha or the beta receptors or indirectly by inhibiting the release of the neurotransmitters norepinephrine and epinephrine.
#11: They block the effects of the neurotransmitter either directly by occupying the alpha or the beta receptors or indirectly by inhibiting the release of the neurotransmitters norepinephrine and epinephrine.
#12: They block the effects of the neurotransmitter either directly by occupying the alpha or the beta receptors or indirectly by inhibiting the release of the neurotransmitters norepinephrine and epinephrine.
#13: To be specific, the parasympathetic system is responsible for stimulation of "rest-and-digest" activities that occur when the body is at rest, including 1.sexual arousal2.Salivation3.lacrimation (tears) 4. urination, digestion, and defecation. Its action is described as being complementary to that of one of the other main branches of the ANS, the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response.
#14: To be specific, the parasympathetic system is responsible for stimulation of "rest-and-digest" activities that occur when the body is at rest, including 1.sexual arousal2.Salivation3.lacrimation (tears) 4. urination, digestion, and defecation. Its action is described as being complementary to that of one of the other main branches of the ANS, the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response.
#15: Also been referred to as the craniosacral system.
#16: Also been referred to as the craniosacral system.
#17: Therefore each parasympathetic preganglionic neuron synapes only with postganglionic neurons to a single effector.Therefore, parasympathetic stimulation frequently involves response by only one organ.Not true in the SNS.
#18: The image illustrates information regarding autonomic neurotransmitters, the chemical compounds released from the axon terminals of autonomic neurons.Notice that 3 axons on the image release acetylcholine therefore you call them as cholinergic fibers.Only one type of autonomic axon releases the neurotransmitter norepinephrine (noradrenaline) this is the postganglionic neuron. Classified as adrenergic fibers.
#19: Acetylcholine is a neurotransmitter located at the ganglions and the parasympathetic terminal nerve endings that innervates the receptors in organs, tissues, and glands. The two types of receptors are 1) muscarinic receptors, which stimulate the smooth muscles and slow heart rate; and 2) nicotinic receptors (neuromuscular), which affect the skeletal muscles.
#28: These bond can be broken only in the presence of the drug pralidoxime chloride.
#33: Considering the variety of and number of effectors innervated by the autonomic nervous system, it is no wonder that autonomic disorders have varied and far-reaching consequences. This is especially true of stress-induced diseases. Prolonged or excessive physiological response to stress, the fight-or-flight response, can disrupt normal functioning throughout the body. Stress has been cited as an indirect cause or an important risk factor in a number of conditions.Heart Disease – Chronic stress is known to increase the risk of certain heart disorders. Hypertension can weaken the heart and blood vesselsDigestive Problems – colitis and gastic ulcers – precipitated by the changes in digestive secretion and movement, along with increased susceptibility to infection, that occur during prolonged or repeated stress responses.Reduced resistance to stress – hormones (glucocorticoids) are released by the adrenal glands during prolonged or repeated stress episodes depress the activity of the immune system. Depressed immune function leads to increased risk of infection and cancer.Neuroblastoma – symptoms include exaggerated or inappropriate sympathetic effects, including increased heart rate, sweating, and high blood pressure.