ANS Drugs Flashcards
What are the 2 main divisions of the nervous system?
CNS
PNS
What are the 2 divisions of the PNS?
Afferent, and Efferent
What do the afferent neurons do?
Carry sensory input to the CNS.
What do the efferent neurons do?
Carry motor signals from the CNS to peripheral areas in the body.
What does the autonomic nervous system do?
Major involuntary part of the NS.
Responsible for automatic, unconscious bodily functions like BP, HR, GIT and GUT function.
What does the parasympathetic nervous system do?
- Rest and digest
- Save energy
- Dialate blood vessels.
- Decrease HR
- Increase digestion
- Constrict smooth muscle of bronchi
- Increase sweat gland
- Contract smooth muscles of urinary bladder.
What does the sympathetic system do?
Dominates during activity, fight or flight.
- Direct sympathetic activation of the effector organs
- Simulation of the adrenal medulla, to release epinephrine
How are the ANS and Endocrine systems similar?
- High level integration in the brain
- Ability to influence distant regions in the body.
- Extensive use of negative feedback
- Use chemical transmission.
How are the ANS and Endocrine systems different?
- Rapid response/ Slower response
- Brief duration/Long duration
- Transmission of electrical impulses over nerve fibers/Sends signals to target tissue by varying the level of blood-borne hormone
How do cholinergic drugs affect the ANS?
They act on receptors activated by acetylcholine.
Acts on pre and post ganglionic in the parasympathetic system.
Acts on all pre ganglionic fibers in the sympathetic system.
Acts on very few post ganglionic fibers in the sympathetic system.
How do adrenergic drugs affect the ANS?
Acts on receptors via the simulation of norepinephrine.
What are the parasympathetic receptors?
-Cholinergic receptors
-Muscarinic (M1 to M5)
Nicotinic receptors
What are the sympathetic receptors?
- Adrenergic receptors
- Alpha 1, alpha 2
- Beta 1 to Beta 3
- Dopamine (D1 to D5)
Where are the musicarnic receptors located?
Heart, smooth muscle, brain, exocrine glands, salivary glands, bladder, GI smooth muscle, eyes
What do agonists that affect M1, M3 and M5 do?
Increases IP3 which leads to an increase in Ca+. Ca+ stimulates or inhibits enzymes which cause hyperpolarization, secretion and contraction.
MOSTLY EXITATORY
What do agonists that affect M2 do?
Decreases cAMP, decreases Ca+ channels, increases K+.
Where are nicotonic receptors located?
– CNS,
– adrenal medulla,
– autonomic ganglia,
– neuromuscular junction.
What are Nn receptors responsible for?
-CNS stimulation
-decreased fatigue
- increased alertness.
- Ligand-gated ion channel.
• Binding of two Ach molecules elicits a
conformational change that allows the entry of
Na+ ions, resulting in the depolarization of the
effector cells.
• Nicotine initially stimulates and then blocks the
receptors
What are the 3 types of nicotonic receptors and where are they located?
Nn- CNS, Adrenal Medulla
Ng- autonomic ganglia
Nm- Skeletal muscle
What are Ng receptors responsible for?
Ganglionic transmission, stimulate both sympathetic and parasympathetic receptors. Produces mixed effects.
What are Nm receptors responsible for?
Produce contraction!!! Depolarization causes contraction.
Alpha 1 Receptor
Location and Role
Location: Smooth musclesurrounding blood vessels in skin and intestinal tract
Role:Mydriasis, contraction of sphincters, and vasoconstriction leading to increased blood pressure
Alpha 2 Receptor
Location and Role
Location:At the end of adrenergic neurons located in the cardiovascular system, GI tract, and genitourinary system, and CNS.
Role:Inhibition of norepinephrine, acetylcholine, and insulin release
Beta 1 Receptor
Location and Role
Location:Heart, fat cells, kidney
Role:Increase heart rate and strength of contraction, increased release of renin, increased release of fat
Beta 2 Receptor
Location:Smooth muscle surrounding blood vessels of the heart, skeletal muscles, arterioles, and the terminal bronchioles
Role:Vasodilation and bronchodilation, increased release of glucagon
What do musicarnic agonists do?
Stimulate parasympathetic nerves.
What is an example of a musicarnic agonist?
Bethanecol
What do musicarnic antagonists do?
Block acetylcholine at musicarnic receptors.
What are some uses for musicarnic antagonists?
Antispasmodics Mydriatics Bronchodilators Bladder Relaxants Antiemetic
What is an example of a musicarnic antagonist?
Atropine
What are the uses of musicarnic agonists?
-bradycardia
-increased secretion from sweat, salivary, bronchial,
gastric glands;
-contraction of intestinal and bronchial smooth muscle; -contraction of the bladder detrusor and relaxation of the bladder trigone and sphincter; and,
-in the eye, miosis and accommodation for near vision.
What does atropine do?
blocks the actions of acetylcholine (and all other muscarinic agonists) at muscarinic cholinergic receptors, and thereby
(1) increases heart rate;
(2) reduces secretion from sweat, salivary, bronchial, and gastric glands;
(3) relaxes intestinal and bronchial smooth muscle;
(4) causes urinary retention (by relaxing the bladder detrusor and contracting the trigone and sphincter);
(5) acts in the eye to cause mydriasis and cycloplegia;
(6) acts in the CNS to produce excitation (at low doses) and delirium and hallucinations (at toxic doses).
What are adverse effects of anticholinergic drugs?
dry mouth, blurred vision, photophobia, tachycardia, urinary retention, constipation, anhidrosis (suppression of sweating).
What is musicarnic agonist poisoning characterized by?
profuse salivation, tearing, visual disturbances, bronchospasm, diarrhea, bradycardia, hypotension
What is musicarnic antagonist poisoning characterized by?
dry mouth, blurred vision, photophobia, hyperthermia, hallucinations, delirium, skin that is hot, dry, and flushed.
How do you reverse musicarnic agonist poising?
Atropine
How do you reverse musicarnic antagonist poising?
Phycsostigmine, a cholinesterase inhibitor.
What are adrenergic agonists?
Produce their effects by activating adrenergic receptors.
What are the 3 properties of catecholamines?
- They cannot be used orally
- They have a brief duration
- They cannot cross the blood-brain barrier (polar molecules)
What are the 3 properties of noncatecholamines?
- Slow metabolism = greater half life
- Can be given orally
- Can cross the blood brain barrier
What are alpha 1 stimulants given for?
To stop bleeding and nasal decongestion.
What do alpha 1 stimulants do?
Cause vasoconstriction.
What adverse effects do alpha 1 agonists cause?
Bradycardia, hypertension and necrosis at the IV site.
What do alpha 2 stimulants cause?
- Decrease BP
- Decrease pain
What do Beta 1 stimulants do?
- ↑HR, ↑contractility
- ↑conductivity
- ↑renin release
What do Beta 2 stimulants do?
- bronchodilation
- hyperglycemia
- uterine relaxation
- skeletal muscle stimulation