Peripheral Nervous System Receptors & NTs Flashcards
3 Major Cholinergic receptors:
1) NicotinicN
2) NicotinicM
3) Muscarinic
4* Major Adrenergic receptors:
1) Alpha1
2) Alpha2
3) Beta1
4) Beta2
* 5) Dopamine
Cholinergic receptors respond to ____ (NT/s).
receptors that mediate responses to acetylcholine (ACh).
Adrenergic receptors respond to ____ (NT/s).
receptors that mediate responses to acetylcholine, E, and NE (and dopamine).
3 Main functions of Sympathetic Nervous System (SNS)
↑ HR, ↑ BP, ↓ peristalsis
3 Main functions of Parasympathetic Nervous System (PsNS)
↓ HR, ↓ BP, ↑ peristalsis
SNS function on eyes:
Dilates pupils
PsNS function on eyes:
Constricts pupils
SNS function on lungs:
Facilitates breathing
↑ rate and depth of breathing, Dilates bronchioles
PsNS function on lungs:
Constricts breathing (constricts bronchioles)
SNS function on bladder:
Relaxes bladder (detrusor muscle); inhibits urination
PsNS function on bladder:
Contracts bladder (detrusor muscle); promotes urination
PsNS Receptors (2) & Neurotransmitters (NTs):
Receptors:
1) Muscarinic
2) Nicotinic* (*ignore)
NTs:
ACh (pre- and postganglionic)
SNS Receptors (4*) & Neurotransmitters (NTs):
Receptors:
1) Alpha1
2) Alpha2
3) Beta1
4) Beta2
* 5) Muscarinic on sweat glands ONLY
NTs:
1) ACh (preganglionic; postganglionic –> muscarinic receptors on sweat gland)
2) NE (postganglionic) –> Alpha or Beta receptors (effector organs)
- *primary NT
3) E (postganglionic) –> Alpha or Beta receptors (effector organs)
- released from adrenal medulla
Drug categories that work on the SNS:
Adrenergic/Antiadrenergic Drugs:
1) Sympathomimetic AKA Adrenergic Agonists
2) Antiadrenergic AKA Adrenergic Antagonists
Drug categories that work on the PsNS:
Cholinergic/Anticholinergic Drugs:
1) Parasympathomimetic AKA Muscarinic Agonists
2) Anticholinergic AKA Muscarinic Antagonists
(AKA Parasympatholytic–“lytic” = lysis/destruction)
How do drugs Affect the Autonomic Nervous System (ANS)
1) Synthesis
2) Storage
3) Release
4) Binding
5) Prevent the normal destruction and reuptake of NTs
⧫For Functions 1-4:
1. ↑ Function 1-4 → ↑ ANS Effect
(**NOT the speed at which it occurs)
2. ↓ Function 1-4 → ↓ ANS Effect
⧫For Function #5:
Prevent NT reuptake → ↑ NT at synaptic cleft → ↑ ANS Effect
Alpha1 receptor locations:
1) Eyes
2) Blood vessels
3) Bladder
4) Male sex organs
5) prostatic capsule
(NT: NE)
Alpha2 receptor locations:
Nerve terminals (NOT organs)
Beta1 receptor locations
1) Heart
2) Kidneys
Beta2 receptor locations:
1) Lungs**
2) Blood vessels
3) Uterus
4) Skeletal muscle and liver
Muscarinic receptor locations:
1) Eyes
2) Heart
3) Lungs
4) Blood vessels
5) GI Tract
6) Bladder
7) Sweat glands
8) Sex organs
NicotinicN receptor locations:
1) All ANS ganglia
2) Adrenal medulla*** (only mentioned this)
Alpha1 Agonist Actions:
1) Contraction of Eye muscles (mydriasis)
2) Vasoconstriction of arterioles & veins
- skin, mucous membranes, & viscera
3) Contraction of Smooth muscle
- bladder sphincters
4) Ejaculation
Alpha2 Agonist Actions:
Regulates NT release
(Inhibits NT release at presynaptic nerve terminals)
- *INSIGNIFICANT ADRs from activation of peripheral receptors
- *SIGNIFICANT ADRs from activation of CNS receptors (reduced SNS outflow to the heart & bld vessels)
Beta1 Agonist Actions:
1) Heart: ↑HR, ↑ contractility, ↑ electrical conduction
2) Kidneys: release of renin –> Vasoconstriction
(NT: NE)
Beta2 Agonist Actions:
1) Bronchodilation of Lungs**
2) Vasodilation of blood vessels (arterioles)
- Heart, lungs, skeletal muscles
3) Uterine Relaxation
4) ↑ Glycogenolysis in Liver & Skeletal muscle
Muscarinic Agonist Actions:
1) ↓ HR
2) ↑Glandular secretions
- pulmonary, GI/Intestinal, sweat
3) Smooth muscle contraction
- Bronchi, GI tract, detrusor muscle of bladder, & eyes
4) Relaxation of urinary bladder sphincters
NicotinicN Agonist Actions:
1) Release of E from the Adrenal medulla***
2) Stimulation of the PsNS and SNS postganglionic nerves
Dopamine Agonist Actions:
1) Dilates renal blood flow and increases renal perfusion
How are Adrenergic Agents further differentiated?
Catecholamine vs. Noncatecholamine
Catecholamine Examples:
1) Epinephrine
2) Norepinephrine
3) Dopamine
4) Dobutamine
5) isoproterenol
Noncatecholamine Examples:
1) Ephedrine
2) Phenylephedrine
3) Terbutaline
Catecholamine Differences from Noncatecholamines:
1) Can’t be used PO due to rapid degradation
2) Brief duration of action
3) Can’t cross BBB
Noncatecholamine Differences from Catecholamines:
1) Can be given PO
2) Longer duration of action (longer half-life, metabolized slower)
3) CAN cross BBB
Alpha1 Blockers/Antagonists
Relax vascular smooth muscle
Decreases BP
Beta1 Blockers/Antagonists
Decrease HR and Contraction
Beta2 Agonists
Bronchodilation
Cholinergic Blockers/Antagonists
Increases HR
Dry mouth
Constipation
Urinary retention
Muscarinic Agonists
Promotes digestion thru salivation and GI smooth muscle contraction