Intro to Autonomic Nervous System (ANS) Flashcards
Divisions of Peripheral Nervous System (PNS)
Somatic Motor System:
_Voluntary Movement
(Skeletal muscle)
Autonomic Nervous System: _Homeostatic Involuntary, "Visceral Motor" (Smooth Muscle, Cardiac Muscle, Exocrine Glands)
–>
Parasympathetic: 1) *Craniosacral (Cranial Nerves: III, VII, IX, X; S2-4) 2) Long Preganglionic (Myelinated), Short Postganglionic (Non-myelinated). 3) Ganglia on or Near Effector Tissues 4) Activation of Effectors usually Localized. 5) *Cholinergic (ACh)
*(Usually Dominant in Resting State)
_“Rest and Digest”
_“Feed and Breed”
Sympathetic: 1) *Thoracolumbar (T1-12, L1-2) 2) Short Preganglionic (Myelinated), Long Postganglionic (Non-myelinated) 3) Ganglia in Paravertebral chain or Prevertebral ganglia. 4) Activation of Effectors usually Diffuse and Synchronized. 5) *Adrenergic (NE)
“Fight or Flight”
Note: if Parasympathetic is involved, then it usually dominates.
_Thus, Parasympathetic generally dominates body in resting state, EXCEPT for Blood Pressure, which is dominated by Sympathetic.
**Sympathetic Regulates Blood Pressure!!
However! There are Muscarinic Receptors @ the Blood vessels, even though Parasympathetic does not act there.
_Therefore, if given a Muscarinic drug, it will cause Vasodilation!
(The endothelium of most blood vessels releases “endothelium-derived relaxing factor” (nitric oxide), which causes marked vasodilation in response to muscarinic stimuli. However, unlike the receptors innervated by sympathetic cholinergic fibers in skeletal muscle blood vessels, these muscarinic receptors are not innervated and respond only to circulating muscarinic agonists.)
Peripheral Nervous System
Neurotransmitters and Receptors
1) The Preganglionic Fiber is ALWAYS ACh and ALWAYS acts on a Nicotinic Receptor.
2) The Postganglionic Parasympathetic releases ACh to Muscarinic receptor.
3) The Postganglionic Sympathetic releases NE to Alpha or Beta Adrenergic receptor.
4) Adrenal Medulla (analogous to a big sympathetic ganglion) releases Epinephrine into Circulation.
Acetylcholine (ACh) Receptors:
_Nn = Nicotinic (neuron)
_Nm = Nicotinic (muscle)
_M = Muscarinic
Adrenergic Receptors:
_A = Alpha Adrenergic
_B = Beta Adrenergic
Somatic Motor System:
_Releases ACh @ Nm receptor @ Skeletal Muscle
Parasympathetic:
1) Preganglionic: ACh @ Nn receptor (@ postganglionic neuron)
2) Postganglionic: ACh @ M receptor (@ Effector)
Sympathetic:
1) Preganglionic: ACh @ Nn receptor (@ postganglionic neuron or Adrenal Medulla)
2) Postganglionic: NE @ A or B adrenergic receptor (@ Effector)
3) Adrenal Medulla: Epi @ into Circulation
Adrenergic Receptors
Alpha 1:
_Postsynaptic (generally)
_Excitatory
_Smooth Muscle, Cardiac, Exocrine Glands
Alpha 2:
_Presynaptic (generally)
_Inhibitory (generally)
_Are the Autoreceptors
Beta 1:
_Postsynaptic (generally)
_Excitatory (generally)
_Heart
Beta 2:
_Postsynaptic (generally)
_Inhibitory (generally)
_Relaxation or Decreased Secretion
Adrenergic:
_Odd numbers: usually Excitatory
_Even numbers: usually Inhibitory
Cholinergic Receptors
Nicotinic (Nn):
_Ganglionic
_Excitatory (generally)
Nicotinic (Nm):
_NMJ
_Excitatory
Muscarinic (M1-M5):
_Postsynaptic (generally)
_Excitatory or Inhibitory
Steps in Neurotransmitter Function
1) Uptake of Precursor into cell
(Precursor is usually an amino acid)
2) Synthesis of NT
3) Storage of NT
(in Presynaptic nerve terminal vesicles)
4) Release of NT
(upon Action potential, mediated by Calcium)
5) Action of NT on Receptors
(@ postganglionic cell or on effector tissue)
6) Termination of NT Activity:
_Reuptake: major means of terminating NE activity
_Metabolism: breakdown of ACh
_Diffusion
_Autoreceptors: NT binds to Inhibitory Autoreceptors on the presynaptic cell to reduce rate of NT synthesis in that presynaptic cell.
Eye
Iris: 1) Radial Muscle: Sympathetic Contraction: Alpha 1 (A1) Dilation of Iris (Mydriasis)
2) Circular Muscle:
Parasympathetic Contraction:
Muscarinic (M3)
Narrowing of Iris (Myosis)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Ciliary Muscle: Accommodation: 1) Parasympathetic Contraction: Muscarinic (M3) (Near Vision)
2) Sympathetic Relaxation Beta 2 (B2):
(Far Vision)
Heart
Sinoatrial (SA) Node: 1) Sympathetic: Acceleration (Positive Chronotropic Effect) **Primarily Beta 1 (B1)
2) Parasympathetic:
Deceleration
(Negative Chronotropic Effect)
Muscarinic (M2)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Contractility: 1) Sympathetic: Increases Contractility (Positive Ionotropic Effect) **Primarily Beta 1 (B1)
2) Parasympathetic:
Decreases Contractility
(Negative Ionotropic Effect)
Muscarinic (M2)
Vascular Smooth Muscle
1) Skin, Splanchnic Vessels:
_Sympathetic
Contraction (Vasoconstriction)
Alpha 1 (A1)
2) Skeletal Muscle Vessels:
_Sympathetic
Relaxation (Vasodilation)
Beta 2 (B2)
**Sympathetic Regulates Blood Pressure!!
However! There are Muscarinic Receptors @ the Blood vessels, even though Parasympathetic does not act there.
_Therefore, if given a Muscarinic drug, it will cause Vasodilation!
(The endothelium of most blood vessels releases “endothelium-derived relaxing factor” (nitric oxide), which causes marked vasodilation in response to muscarinic stimuli. However, unlike the receptors innervated by sympathetic cholinergic fibers in skeletal muscle blood vessels, these muscarinic receptors are not innervated and respond only to circulating muscarinic agonists.)
Lung
Bronchiolar Smooth Muscle
1) Sympathetic:
Relaxation (Bronchodilation)
Beta 2 (B2)
2) Parasympathetic:
Contraction (Bronchoconstriction)
Muscarinic (M3)
Bronchial Secretions
1) Parasympathetic M3 Secretion
GI Tract
Smooth Muscle Walls:
1) Sympathetic:
Relaxation
Beta 2 (B2)
2) Parasymptathetic:
Contraction
Muscarinic (M3)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Smooth Muscle Sphincters: 1) Sympathetic: Contraction Alpha 1 (A1)
2) Parasympathetic:
Relaxation
Muscarinic (M3)
________________
GI Secretions:
_Parasympathetic Increases
Muscarinic (M3)
________________
GI Myenteric Plexus:
_Sympathetic Inhibits
Alpha 1 (A1)
Note: Areas that involve Secretion have little to no sympathetic activity.
Genitourinary Smooth Muscle
Bladder Wall:
1) Sympathetic:
Relaxation
Beta 2 (B2)
2) Parasympathetic:
Contraction
Muscarinic (M3)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Bladder Sphincter: 1) Sympathetic: Contraction Alpha 1 (A1)
2) Parasympathetic:
Relaxation
Muscarinic (M3)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Uterus, Pregnant: _Sympathetic: Relaxation Beta 2 (B2)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Penis, Seminal Vesicles 1) Sympathetic: Ejaculation Alpha 1 (A1)
2) Parasympathetic:
Erection
Muscarinic (M3)
Skin
Pilomotor Smooth Muscle (hair standing on end) _Sympathetic Contraction Alpha 1 (A1)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Thermoregulatory Sweat Glands: (@ Whole body) _Sympathetic Increases *Muscarinic
(Sympathetic b/c goes thru Paravertebral Chain Ganglia)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Apocrine (Stress) Sweat Glands: (@ Palms, Soles, Axilla) _Sympathetic Increases Alpha 1 (A1)
Metabolic Functions
Gluconeogenesis (Liver):
_Sympathetic
Beta 2 (B2)
Glycogenolysis (Liver)
(Sympathetic, Epinephrine)
________________
Lipolysis (Fat Cells):
_Sympathetic
Beta 3 (B3)
Kidney
Renin Release:
_Sympathetic
Beta 1 (B1)
(Maintains Blood Pressure during Fight or Flight response)
Glands
1) Salivary Glands:
_Parasympathetic M3
_Secretion
2) Lacrimal Glands:
_Parasympathetic M3
_Secretion
3) Nasopharyngeal Glands:
_Parasympathetic M3
_Secretion
