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Flashcards in Module 2 Deck (234)
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181

Nature of activity: Dominates in emergency (“fight or flight”) situations
Energy utilization: Involves expenditure of energy (catabolic)
Response: appropriate to emergency and stress situations; synchronized and coordinated
Range of Effect: Affects widespread regions of the body (“mass discharge”)

Sympathetic Nervous System

182

Fiber Connections: Due to divergent connection (1:20)
Branching of preganglionic fibers: Preganglionic fibers branch extensively
Neurotransmitters: Catecholamines secreted by adrenal medulla are distributed to all regions of the body through circulation
Duration of Response: Sustained duration due to slow deactivation of norepinephrine (active reuptake)
- Norepinephrine lingers in the synaptic cleft for a longer time than acetylcholine
- Effects triggered by adrenergic neurons are longer lasting

Sympathetic Nervous System

183

Nature of activity: Dominates in quiet, relaxed situations
Energy utilization: Tends to conserve energy (anabolic) and restores the body’s resources
Response: favors digestion and absorption of food ( activity of intestinal muslces, intestinal secretion)
Range of Effect: Discrete, selective and limited
Localized to a single organ

Parasympathetic Nervous System

184

Fiber Connections: Manner of fiber connection is 1:1 or 1:2
Branching of preganglionic fibers: Limited branching of preganglionic fibers
Neurotransmitters: Usually no acetylcholine in circulation
Duration of Response: Short duration due to fast deactivation of acetylcholine (enzyme hydrolysis by acetylcholinesterase)

Parasympathetic Nervous System

185

- Exert opposite effects but operate reciprocally to produce coordinated responses
- The 2 divisions can also act in a synergistic or cooperative manner

Dual Innervation

186

SYMPATHETIC only

sweat glands
adrenal glands
most blood vessels
pilomotor muscle

187

PARASYMPATHETIC only

lacrimal muscle (tear glands)
ciliary muscle (accommodation for near vision)

188

Parasympathetic transmitter

Acetylcholine

189

Synpathetic transmitter

Norepinephrine

190

2 tissue enzyme that can cause destruction of norepinephrine

- Monoamine oxidase (found in the nerve endings)
- Catechol-O-methyl transferase (present diffusely in the tissues)

191

Binding of norepinephrine with its receptor increases the activity of the enzyme adenylyl cyclase which causes formation of ___

Cyclic adenosine monophosphate (cAMP)

192

Acetylcholine activates two types of receptors which are called

Muscarinic
Nicotinic receptors

193

-A receptor which uses G protein as their signaling mechanism
- found on all effector cells that are stimulated by the postganglionic cholinergic neurons

Muscarinic receptors

194

- are ligand-gated ion channels found in autonomic ganglia at the synapses between the preganglionic and postganglionic neurons of both PNS and SNS
- are also present at many nonautonomic nerve endings

Nicotinic receptors

195

Alpha receptor and function

Vasoconstriction
Iris dilation
Intestinal relaxation
Intestinal sphincter contraction
Pilomotorcontraction
Bladder sphincter contraction
Inhibits neurotransmitter release (alpha1)

196

Beta receptor and fuction

Vasodilation (b2)
Cardioacceleration (B1)
Increased myocardial strength (B1)
Intestinal and uterus relaxation (B2)
Bronchodilation (B2)
Calorigenesis (B2)
Glycogenolysis, bladder wall relaxation (B2)
Lipolysis (B1)
Thermogenesis (B3)

197

A synthetic hormone chemically similar to epinephine and norepinephrine that has extremely strong action on B receptors but no action on A receptors

Isopropyl norepinephrine

198

Parasympathetic exitation contracts ___ which releases the tension on the ligaments and allow the lens to become more convex causing eye to focus near at hand.

Ciliary muscle

199

The nasal, lacrimal, salivary and many gastrointestinal glads ares strongly stimulated by ___, usually resulting in copious quantities of watery secretions.

Parasympathetic nervous system

200

Gland of the small and large intestines are controlled principally by local factors in the intestinal tract itself and by ___

Intestinal enteric nervous system

201

Synthesis and Storage: Acetylcholine (Parasympathetic)

Acetyl Coa + Choline -> Acetylcholine (choline acetyltransferase)

- synthesized in the cytoplasm of axon terminal by acetylation
- stored as clear round vesicles
choline comes from the ECF and enters the axon terminal by active transport
- acetyl-CoA and ATP provided by mitochondria
- choline acetyltransferase synthesized in the soma and brought to axon by axoplasmic transport

202

Synthesis and Storage: Norepinephrine (Sympathetic)

- synthesized from the amino acids phenylalanine and tyrosine
Phenylalanine -> Tyrosine (phenylalanine hydroxylase)
Tyrosine -> DOPA or dyhydroxy phenylalanine (tyrosine hydroxylase)
DOPA -> Dopamine (DOPA decarboxylase)

203

In the adrenal medulla, ____ catalyzes the conversion of norepinephrine to epinephrine.

phenylethanolamine-N-methyltransferase (PEMT)

204

undergoes enzymatic destruction via acetylcholinesterase diffusion

Acetylcholine

205

undergoes active reuptake by the prejunctional junctional fiber diffusion into the extracellular spaces

Norepinephrine

206

enzymatic destruction of NE (Norepinephrine) while it is still in the synaptic cleft

catechol-ortho-methyltransferase (COMT)

207

enzymatic destruction of NE while it is still in the axoplasm of the preganglionic fiber

monoamine oxidase (MAO)

208

Location: cell bodies of postganglionic neurons
effector organs

Mechanism of Action
when a NT binds with receptor → causes a conformational change in the structure of the protein molecule → the cell may either be activated or inhibited

Autonomic Receptors

209

How do NTs work?

by causing a change in membrane permeability to various ions

210

- have affinity for nicotine (small amounts)
- excess nicotine acts as a blocking agent by persistent depolarization
- sites: MEP, all autonomic ganglia, chromaffin cells of AM
- types: N1 and N2

Nicotinic Receptor