Autonomics Flashcards
Define homeostasis
maintenance of steady states in the body by coordinated physiological mechanisms
What are some examples of ANS in homeostasis?
Blood glucose regulation
BP control
Blood flow
Temperature regulation
Smooth muscle - GI tracts, ducts, bronchi, uterus
GI motility & secretions
Endocrine glands - many glands receive ANS input
Exocrine glands (salivary & sweat gland)
Bladder
Vomit reflex
Sexual function
What is only a sympathetic control?
sweat glands & blood vessels
What is the importance of ANS to dentistry?
Routine procedure stress/anesthetic injections
Emergency medicine (w/ stress)
Environmental & disease induced stress
Malocclusion stress
Abnormal blood flow causing TMJ disease & pain
Postganglionic neurotransmitters of sympathetic division. What do they stimulate?
Ach
- stimulates vasodilation & sweat glands
NE
- stimulates piloerector muscle & vasoconstriction
___ nervous system activities are influenced by ANS
Enteric
The efferent arm, in the ANS, has __ neurons & ___ synapses
2 & 2
Describe (myelinated or not, location, type, length) the sympathetic & parasympathetic division in the preganglionic neurons
Sympathetic
- myelinated, B type, located in cell bodies in intermediolateral column, short length
Parasympathetic
- myelinated, B type, located in cell bodies in brain or sacral spinal cord, long length
Length of the sympathetic & parasympathetic division in the postganglionic neurons
Sympathetic = long
Parasympathetic = short
Discrete or diffuse for sympathetic & parasympathetic
Sympathetic = diffuse
Parasympathetic = discrete
The afferent arm stimulates
preganglionic neuron
Somatic nervous system enters the spinal cord through the ___, stimulates neurons in the ___ & activates or repressors ___. ANS enters the spinal cord through the ___ & stimulates preganglionic nerurons in the ___
Dorsal horn
Intermediolateral column
motor neuron activity
dorsal horn
intermediolateral column
Afferent sensory system receptors
mechanoreceptors, chemoreceptors, nocioreceptors
ANS effectors are ___. Where do they go through in the spinal cord?
Smooth muscle, cardiac muscle, glands
Ventral horn to postganglionic fiber
Define varicosities
Where neurotransmitters are released
Skeletal muscles motor neurons release ___, which binds to ___
Ach
Nicotinic
What destroys Ach?
Acetylcholinesterase
In the pregnanglionic neuron for the ANS, parasympathetic & sympathetic division release ___ & stimulates ___ receptor
Ach
Nicotinic
In the postganglionic neuron for the ANS, the parasympathetic division release ___ & activates ___
Ach
Muscarinic
In the postganglionic neuron for the ANS, the sympathetic division release ___ & activates ___
NE
adrenergic alpha or beta receptor
___ & ___ are extracted from amanita mushroom to increase parasympathetic response
Muscarinic & nicotinic
Special case when sympathetic postganglionic neruon release Ach occurs in ___
skeletal muscles
Ach synthesis & enzymes involved
Choline + acetyl-CoA → acetylcholine → choline + acetate
Enzyme 1: choline acetyltransferase
Enzyme 2: acetylcholinesterase (breaks down Ach)
Nicotinic receptor subunits
Has 2 alpha subunits, 1 beta, 1 gamma, & 1 delta subunit
Muscarinic receptor is/is not a channel? What are the 5 types & describe each?
Is not
- M4 & M5 are only in CNS
- M1 & M3 are associated w/ smooth muscle
- M2: Galpha i or o → adenylyl cyclase inhibition (decrease cAMP), opening K+ channels
NE pathway & enzymes involved
L-tyrosine → L-DOPA → Dopamine → L-Norepinephrine
Enzyme 1: tyrosine hydroxylase
Enzyme 2: aromatic L-amino acid decarboxylase
Enzyme 3: dopamine beta-hydroxylase
epinephrine pathway & enzymes involved
L-tyrosine → L-DOPA → Dopamine → L-Norepinephrine → L-epinephrine (adrenalin)
Enzyme 1: tyrosine hydroxylase
Enzyme 2: aromatic L-amino acid decarboxylase
Enzyme 3: dopamine beta-hydroxylase
Enzyme 4: phenylethanolamine N-methyl transferase
End product inhibition by ___ & ___ blocks tyrosine hydroxylase during the formation of NE
DA & NE
Describe MAO & COMT
MAO
- degrades NE in presynaptic neuron
- Found in mitochondria
COMT
- degrades NE in postsynaptic neuron
- found in liver & blood
Chain events of NE
- Action potential arrives
- Depolarization opens voltage gated Ca2+ channels
- Ca2+ entry causes exocytosis of synaptic vesicles & release of NE
- NE binds adrenergic receptor on target cells
- Receptor activation ceases when NE diffuses away or is metabolized by COMT
- NE transported back into axon
- NE goes back into vesicles or gets metabolized by MAO
For each of the following, is NE or Epi preferred. Alpha1, alpha2, beta1, beta2
Alpha1: (NE> Epi)
Alpha2: (NE> Epi)
Beta1: (Epi> NE)
Beta2: (Epi»> NE)
Define receptor affinity
concentration a compound elicits a response from a receptor
- High affinity receptors only need a small amount of substance to activate receptors
- Low affinity needs more
Norepinephrine can activate what in alpha & beta
Alpha1: smooth muscle & vasoconstriction
Alpha2: smooth muscle & relaxation
Beta1: heart muscle contraction & increases heart rate
Epinephrine (adrenaline) can activate what in alpha & beta
Alpha1: smooth muscle & vasoconstriction
IP3 production
Alpha2: veinoconstriction
Beta1: heart muscle contraction & increase rate
cAMP production
Beta2: skeletal muscle blood vessels dilation & smooth muscle relaxation
cAMP production
Mainly activates beta2
Examples of effects of the sympathetic nervous system
Increase heart & lung action (caused by increase of blood flow)
Inhibition of stomach & intestinal action
Constriction of blood vessels in many parts of body (like skin & GI)
Liberation of nutrients for muscular action
Dilation of blood vessels
Inhibition of lacrimal gland & salivation
Dilation of pupil (increases sight of vision)
Increased anxiety/awareness
Relaxation of bladder
Inhibition of erection
Is NE acting as a neurotransmitter & hormone?
Yes
- If circulating, it’s a hormone
- If released in nerve directly to target tissue, it’s a neurotransmitter
In the following reaction, is there a faster or slower EPSP response? Preganglionic neuron releases Ach → binds to muscarinic receptor → activates postganglionic neuron
Slower
In the following reaction, is there a faster or slower EPSP response? Preganglionic neuron releases Ach → binds to nicotinic receptor → activates postganglionic neuron
Faster
In the following reaction, is there a EPSP or IPSP response? Preganglionic neuron releases Ach → binds to muscarinic receptor in SIF cell → releases dopamine
IPSP
___ may produce long lasting EPSP or IPSPs
Sensory afferents
Influences on ANS come from:
Spinal cord & brain stem
Hypothalamus
ANS influenced by neocortex & other higher brain centers
Integration at every level to insure proper responses
Does the ANS have dual innervation?
Yes
Increase or decrease for the following examples in parasympathetic & sympathetic division: heart rate, stomach, pylorus, salivary flow, BV
- Heart rate: sympathetic increases & parasympathetic decreases
- Stomach: sympathetic decreases, parasympathetic increases
- Pylorus: sympathetic increases, parasympathetic decreases (induces relaxation)
- Salivary flow: both increase
- Blood vessels: only sympathetic
Catabolic or anabolic for the parasympathetic & sympathetic division
anabolic for parasympathetic
catabolic for sympathetic
What are the 4 types of stresses
Fright (sympathetic)
Fear and anxiety (both)
Acute fear
Chronic stress
What increases norepinephrine production?
Ephedrine, amphetamine, pseudoephedrine
What blocks norepinephrine production?
Resperine & methyldopa
