Exam 1 Flashcards
autonomic nervous system
innervates organs with
involuntary functions
Ex. Cardiac muscle (myocardium), smooth muscle (blood vessel
walls, GIT), and secretory cells (glands).
somatic nervous system
innervates organs with
voluntary function
Ex. Skeletal muscle, voluntary sphincter tone, portions of the
respiratory system
—> This is under conscious control
Autonomic function
no direct control
The Autonomic Nervous System Originates in the CNS and has both Parasympathetic and Sympathetic pathways.
Parasympathetic Characteristics Are…
CNS ————————-> PNS ——>Effector organ
- Fiber lengths
—> Prostganglionic Short - Anatomic Origin
—> Crainosacral - Neurotransmitters
—> Preganglionic = Acetylcholine (Nicotinic)
—> Postganglionic = Acetlycholine (Muscarinic)
The Autonomic Nervous System Originates in the CNS and has both Parasympathetic and Sympathetic pathways.
Sympathetic Characteristics are….
CNS——->PNS——————————>Effector Organ
OR
CNS——->Adrenal Medulla __________>Effector Organ
(Blood Stream)
-Fiber lengths
—>Preganglionic Short
-Anatomic origin
—>Thoracolumbar
-Neurotransmitters
—>Preganglionic = Acetylcholine
—>Postganglionic = Norepinephrine
Neurotransmitters
Acetylcholine
Released from presynaptic neuron
- Preganglionic neurons (SNS, PSNS)
- Post-ganglionic terminal (PSNS)
- Somatic terminal (NMJ)
Broken down by cholinesterases
- Acetylcholinesterase (in synapse)
- Pseudocholinesterases (plasma/other tissues)
Neurotransmitters
Norepinephrine & Epinephrine
- Norepinephrine released from
synaptic nerve endings - Epinephrine released from adrenal
glands
PNS Receptor
Cholinergic
Nictinic
Muscarinic
PNS Receptors
Adrenergic
Alpha
Beta
Dopminergic
Other PNS Receptor
Vasopressin
Acetylcholine (Ach) —> Agonist
Nicotinic (ionotropic receptors)
- Several subtypes of nicotinic receptor have been cloned
—NsubM (Neuromuscular junction- NMJ)
—NsubN (CNS and autonomic ganglia)
Muscarinic (metabotropic receptors) - Parasympathomimetic effects —Five subtypes (M1 - M5) —-M1, M3, and M5 stimulatory —-M2 and M4 inhibitory
Muscarinic Receptors
M1
Most Common Locations
- GIT smooth m.
—- ↑ Gastric secretion
—- Smooth m. contraction
- Urinary bladder smooth m.
—Contraction of the detrusor m. - Myocardium
—- ↓ Heart Rate - Exocrine Glands
—- ↑ Exocrine secretions
Muscarinic Receptors
SLUDD Signs
S alavation L acraination U rination D igestion D efecation
Adrenergic Receptors
Catacholamines (Epi/Norepi/Dopamine)—>Agonists
Alpha and Beta Receptors
- Metabolized by g-coupled receptors
Alpha 1
Alpha 2
Beta 1
Beta 2
Alpha 1
- Most Common
- Vascular smooth m.
- Vasoconstriction
- ↑ Blood pressure (MAP)
- Mydriasis
- Sphincter contraction
—- Urinary bladder
—- GI tract - Glycogenolysis
Alpha 2
- Brain & spinal cord
- Vascular endothelium
- Endocrine organs
- ↓ Insulin
- ↓ Renin
- ↓ NE release
- ↓ Pancreatic secretion
Beta 1
- Myocardium
- Adipose tissue
- ↑ Heart rate
- ↑ Cardiac contractility
- Lipolysis
- Smooth m. relaxation
- ↑ Renin ↑ BP
Beta 2
- Airway smooth m.
- Vascular smooth m.
- Bronchodilation
- Vasodilation
- Smooth m. relaxation
- ↑ Blood to skeletal m.
- Cycloplegia
- Glycogenolysis
- ↑ Insulin
- ↑ NE release
Vasopressin Receptors
Antidiuretic Hormone (ADH)
OR
Arginine Vasopressin (AVP)
ADH and AVP facts
—-> Lysine vasopressin (pigs)
- Synthesized in hypothalamus
—-> 9-amino-acid-glycopeptide with disulfide bond - Stored in posterior pituitary (neurohypophysis)
- Released from vesicles into circulation in response to extracellular fluid hypertonicity
Vasopressin Receptors
V1
V2
V3
Vasopressin Receptor Main Effects
- Increases the amount of solute-free water reabsorbed back into circulation by renal tubular cells -> main site of action is collecting ducts
- Arteriolar vasoconstriction -> increases peripheral vascular resistance (PVR) & mean arterial blood pressure (MAP)
V1
- Vascular smooth m.
—- Vasoconstriction
—- Preferentially shunts blood to CNS & heart - Platelets
—- Aggregation - Juxtoglomerular cells
—- Inhibits renin release
V2
- Renal collecting ducts
—- ↑ water permeability, aquaporins
—- ↑ urea ports - Endothelial cells
—- vWF release - Platelets
—- Aggregation - Vascular endothelium
—- Vasodilation
V3
- Pituitary gland
—- Negative feedback for ADH
-——↑ vasopressin will cause ↓ ADH release - Stimulates ACTH release
Autonomic Drugs are Classified as Either:
Mimetics: Drugs that simulate (mimic) autonomic input or effects.
—> Parasympathomimetics (parasympathetic signs)
—> Sympathomimetics (sympathetic signs)
Lytics: Drugs that block (lyse) autonomic input or effects
—> Parasympatholytic (sympathetic signs)
—> Sympatholytic (parasympathetic signs)
General Mechanisms of Action of Drugs
Autonomic Drugs
Direct-Acting
- Agonists and antagonists
- Act directly on the receptor
• Ex. cholinergic agonist, adrenergic antagonist -> both will result in net parasympathomimetic signs
General Mechanisms of Action of Drugs
Autonomic Drugs
Indirect-Acting
- Non-receptor interactions
• Ex. acetylcholinesterase inhibitors -> inhibits the enzyme responsible for the breakdown of Ach -> results in Ach buildup & net parasympathomimetic signs
The EYE
Sympathetic
Parasympathetic
Sympathetic:
- Relaxation of ciliary muscle (far vision)
- Contraction of the iris radial muscle (mydriasis)
- Decrease aqueous humor production
Parasympathetic:
- Contraction of ciliary muscle (lens accommodation for near vision)
- Contraction of the iris sphincter muscle (miosis)
The HEART
Sympathetic (β-1):
- Increased heart rate (tachycardia, positive chrontropy)
- Increased contractility (positive inotropy)
- Increased automaticity and conduction of AV node (positive dromotropy)
Parasympathetic (M1):
- Decreased heart rate (bradycardia, negative chronotropy)
- Decreased contractility (negative inotropy)
- Decreased AV node conduction (negative dromotropy)
The Vasculature
Sympathetic:
(α-1 & V1) - Vasoconstriction
(β-2 & V2) - Vasodilation
(α-2) - Various (vasoconstriction or vasodilation)
Parasympathetic:
- Indirect vasodilation through release of NO (nitric oxide)
The LUNG
Sympathetic: (β-2) - Bronchodilation - Increase in cilia synchronicity (β-1) - Increase pulmonary blood flow
Parasympathetic:
- Bronchoconstriction
- Increase respiratory secretions
The GI Tract
Sympathetic: (α-1, β-1, β-2) - Decrease motility - Closure of sphincters & increased tone - Inhibit secretion
Parasympathetic:
(M1)
- Increase motility - Relaxation of sphincters & decreased tone
- Stimulate secretion
The URINARY BLADDER
Sympathetic:
(β-2) - Relaxation of detrusor muscle
(α-1) - Contraction of internal urethral sphincter
Parasympathetic:
(M1)
- Contraction of detrusor muscle
- Relaxation of internal urethral sphincter
DRUGS
ParasympathoMIMETICS
Direct Acting
Choline Esters
—> Bethanechol
DRUGS
ParasympathoMIMETICS
Indirect Acting
Reversible Cholinesterase Inhibitors
—> Neostigmine
—> Edrophonium
—> Pyridostigmine
DRUGS
ParasympathoLYTICS
Direct Acting
Atropine
Glycopyrrolate
Oxybutynin
Propantheline
