Lecture 23 - Autonomic Nervous System Flashcards
What are generalizations about preganglionic and postganglionic neurons?
L23 S5
Preganglionic:
- cell bodies in CNS
- myelinated
- use ACh
Postganglionic:
- cell bodies in peripheral ganglia
- unpyelinated
- ACh (parasympathetic) and norepinephrine (sympathetic)
What affect does ANS stimulation have on glands?
L23 S6
Sympathetic:
-sweat gland stimulation
Parasympathetic:
- lacrimal, nasal, and salivary gland stimulation
- upper GI gland stimulation
Enteric:
-lower GI gland stimulation
What affect does ANS stimulation have on the heart?
L23 S7
Sympathetic:
-increases rate and strength of contraction
Parasympathetic:
-decreases rate and strength of contraction
What affect does ANS stimulation have on blood vessels?
L23 S7
Sympathetic:
-constricts most vessels
Parasympathetic:
-little effect
What affect does ANS stimulation have on blood pressure?
L23 S8
Sympathetic:
-acute increase which returns to normal
Parasympathetic:
-little effect
What affect does ANS stimulation have on endodermal structures (GI, respiratory, endocrine, auditory, and urinary)?
L23 S8
Sympathetic:
-inhibits endodermal structure
Parasympathetic:
-excites endodermal structure
What affect does ANS stimulation have on the eyes?
L23 S9
Sympathetic:
-pupil dilation
Parasympathetic:
- pupil constriction
- lens focusing
What affect does ANS stimulation have on the GI tract?
L23 S9
Sympathetic:
- inhibit peristalsis (only with strong stimulation)
- otherwise little effect
Parasympathetic:
- promotes peristalsis
- relaxes sphincters
Where specifically are preganglionic fiber cell bodies located?
L23 S11
Lateral horn of the spinal cord
How is norepinephrine produced in the neuron?
L23 S18
- tyrosine is converted to dopa (hydroxylation)
- dopamine is converted to dopamine (decarboxylation)
- dopamine is transported into vesicles
- dopamine is converted into norepinephrine (hydroxylation)
What happens to norepinephrine after it is released?
L23 S19
Broken down in cleft:
-metabolized by monoamine oxidase to dihydroxyphenylglycol
Recycled:
-reuptaken by NE transporter
Broken down in circulation:
-metabolized by catechol-O-methyl transferase (COMT) which is found in all tissues
What are the types of adrenergic receptor and what stimulates them?
Alpha receptors:
-simulated by epinephrine and norepinephrine
Beta receptors:
- stimulated mainly by epinephrine
- weakly stimulated by norepinephrine
What functions are alpha receptors associated with?
L23 S22
Can be excitatory or inhibitory
- vasoconstriction
- iris dilation
- intestinal relaxation
- intestinal sphincter contraction
- bladder sphincter contraction
- pilomotor contraction
- inhibition of neurotransmitter release
What functions are associated with each of the different beta receptors?
L23 S23
Beta 1:
- cardioacceleration
- increased myocardial strength
- lipolysis
Beta 2:
- vasodilation
- intestinal relaxation
- uterus reaction
- bronchodilation
- calorigensis
- glycogenolyisis
- bladder wall relaxation
Beta 3:
-thermogenesis
What is the function of reserpine?
L23 S25
Blocks synthesis and storage of norepinephrine
What is the function of propranolol?
L23 S25
Blocks sympathetic beta 1 and beta 2 receptors
What is the function of metoprolol?
L23 S25
Blocks mostly sympathetic beta 1 receptors
What is difference is there between epinephrine/norepinephrine used as a neurotransmitter vs. released from the adrenal medulla?
L23 S29-31
Lasts 5-10 times longer due to lack of local reuptake/destruction
Circulating norepinephrine:
- constricts blood vessels
- increases heart activity
- inhibits GI
- dilates pupils
Circulating epinephrine:
- increases cardiac output
- increases metabolism
What nerves carry parasympathetic fibers and what is the function of each?
L23 S34
Oculomotor/CN III:
- constricts pupillae of iris
- constricts ciliary muscles
Facial/CN VII:
- stimulates submandibular and sublingual glands
- stimulates nasal mucosa
Glossopharyngeal/CN IX:
-stimulates parotid gland
CN X (75% of fibers): -affects heart, GI, kidneys, and reproduction
Sacral nerves
What enzymes are responsible for making and degrading acetylcholine?
L23 S45
Synthesis:
-choline acetyl-transferase
Degradation:
-acetylcholineesterase
What are the types of acetylcholine receptors?
L23 S46-47
Muscarinic:
- works through G proteins
- found on postganglionic effectors
Nicotine:
- ion channel
- found at synapse between preganglionic and postganglionic
- found on skeletal muscles
