drugs and ANS Flashcards
WHICH ONE IS THE AUTONOMIC NERVOUS SYSTEM
part of the peripheral nervous system that controls motor neurons through the sympathetic and parasympathetic components and part of the enteric nervous system
FUNCTIONS OF THE AND AND ITS COMPONENTS
regulates functions of the body’s organs and maintains homeostasis, derives from the CNS and outside voluntary control.
- parasympathetic regulates the body at rest and digestion, the main neurotransmitter acetylcholine ACh
- sympathetic prepares the body for exertion, main neurotransmitter adrenaline A and noradrenaline NA
TYPES OF SYNAPSIS IN THE ANS
- NERVE-NERVE, presynaptic neuron releases NT to pst-synaptic neuron, the release is caused by action potential (difference of electric charge across neuron membranes)
- NERVE-MUSCLE, nerve releases NT thought its axon to the muscle fiber
TYPES OF ANS RECEPTORS
- PARASYMPATHETIC NERVE can influence the muscarinic receptor on the skeletal muscle or be influenced by the same
- sympathetic nerve links with alfa or beta-adrenergic receptors and can be negatively regulated by the release of catecholamines from the adrenal medulla
EFFECT ON THE BODY OF PARASYMPATHETIC SYSTEM
mediated by M3 muscarinic receptors
- EYE, miosis, near vision
- LACRIMAL GLANDS, secretion
- SALIVARY GLANDS, secretion
- HEART, increase rate/force of contraction
- LUNGS, contraction of smooth muscle, secretion from glands
- GIT, increased mobility, relaxation of sphincters, secretion from glands, gastric acid secretion
- BLADDER, increased micturition
SYMPATHETIC ACTIONS
- EYES, mydriasis, far vision
- BLOOD VESSELS, vasoconstriction
- SKELETAL MUSCLE BLOOD VESSELS, vasodilatation
- HEART, increase rate, FOC
- GIT, reduced mobility, constriction of sphincters
- LIVER, glycogen breakdowns
- KIDNEY, renin release
- UTERUS, relaxation
- GENITALIA, male ejaculation
- LUNGS, relaxation of smooth muscle
- SWEAT GLANDS, sweating
HOMEOSTASIS IN THE ANS
SYMPATHETIC AND PARASYMPATETHIC systems have opposite effects to balance the state of organs and compensate for changes. they operate via negative feedback-loop signals.
DRUGS THAT IMPACT OF THE ANS
- cholinomimetics
- drugs that interfere with the parasympathetic system
- sympathomimetics
- drugs that interfere with the sympathetic system
POSSIBLE TARGETS OF ANS DRUGS
- interfere with NT synthesis
- interfere with release
- block receptors (antagonist)
- mimic action at receptors (agonist)
- prevent inactivation or re uptake of NT
TYPES AND MOA OF CHOLINOMIMETICS
- MUSCARINIC AGONISTS, mimic the action of ACh at M receptors ( carbachol/pilocarpine), use to reduce intraocular pressure, post-op stimulation of the GUT and bladder
- ANTICHOLINESTERASES, increase the concentration of ACh at the effector junction by inhibiting neurotransmitter breakdown (physostigmine, neostigmine). used to reverse skeletal muscle paralysis (myasthenia gravis), treatment of glaucoma, reverse pesticides effect
DRUGS THAT BLOCK ACh RECEPTORS
- MUSCARINIC RECEPTOR ANTAGONISTS, atropine, block ACh action at all M receptors. used to treat smooth muscle spasms, dilate pupils, Parkinson’s disease, addiction to anesthesia.
- NICOTINIC ANTAGONISTS, used in adjunction to anesthesia to relax skeletal muscles, used at neuromuscular junctions
SYMPATHOMIMETICS
- ALFA 1 RECEPTORS AGONISTS, phenylephrine, increase PR, in hypotension
- ALFA 2 AGONISTS, clonidine, inhibit the release of NA in hypertension
- BETA 1 AGONIST, isoprenaline, stimulates the heart in CCF and heart attack
- BETA 2 AGONIST, salbutamol, used in asthma to relax smooth muscle
- INDIRECTLY ACTING, ephedrine, release NA from storage vescicles
ADRENERGIC RECEPTORS BLOCKERS
- ALFA RECEPTORS ANTAGONISTS, phentolamine, reduces BP/nasal congestion/impotence
- BETA RECEPTOR ANTAGONISTS, propranolol/metoprolol, may be selective for beta 1 or non-selective
