ANS Physiology Flashcards
What is the efferent path of the ANS?
A two-neuron link
Which transmitters are present in the ANS?
ACh, adrenaline/nor
Can you control the ANS?
No, it is involuntary.
Where are the preganglionic fibers of the parasympathetic division located?
Cranial and sacral segments.
Where are the preganglionic fibers of the sympathetic division located?
Thoracic and lumbar segments.
How do the ganglion locations differ between SNS and ANS?
Ganglion in the ANS are close to the target.
What is the lateral horn?
The origin of the pre-ganglionic fiber in the lateral ventral root.
Divergence
Fibers split to different locations.
Convergence
Fibers accumulate to one ganglion, one common destination.
White ramus communicans
Myelinated branch between sensory nerve and ganglion.
Gray ramus communicans
Non-myelinated branch between afferent nerve and target.
Sympathetoc chain
Consists of chains of ganglions that divide into either another series of ganglia or a pathway towards a target.
Collateral/Prevertebral ganglion
In front of vertebral column, does not terminate in chain-ganglion.
Varicosities
Storage site for vesicles containing NT in smooth muscle cells
Briefly describe the flow of transmission in the sympathy-adrenal system
Spinal cord, sympathetic ganglion, adrenal medulla.
Chromaffin cells
similar to Sympathetic post-ganglion, release NT that travel via blood.
What is release influenced by in the sympathy-adrenal system?
Pre-ganglionic fibers.
Which NT is released from the somatic nerve?
Acetylcholine
Which NT is released from the parasympathetic fiber?
Ganglion: Acetylcholine Target: Acetylcholine
Which NT is released from the sympathetic fiber?
Ganglion: Acetylcholine, Target: Noradrenaline
Specifically, which NT is released in the sympathoadrenal system?
Adrenal medulla: Acetylcholine, target: NA
Briefly describe the production of Ach
Acetyl CoA, choline carrier + Acetyl CoA = acetylcholine
Briefly describe NA synthesis
Tyrosine, DOPA, Dopamine, NA
What are the two cholinergic receptors? What is the category of their target cells?
Nicotinic (Skeletic muscle and nervous tissue)
Muscarinic (Smooth muscle)
What are the two adrenergic receptors? What do these receptors target?
Alpha and Beta, target smooth muscle (IN ANS)
What do alpha receptors specifically target?
Eye, blood vessels, GIT, presynaptic endings
What do beta receptors specifically target?
Heart, kidney, blood vessels, GIT
Muscanaric and adrenergic receptors are ______ receptors
Metabotropic
The nicotinic receptor is a _______ receptor
Ionotropic
What do ionotropic receptors look like?
Doughnuts
What do metabotropic receptors look like?
Snake
What is the product of activating a metabotropic receptor?
Secondary messenger phosphorylates a protein, causing a cellular response.
What are non-adrenaline/choline messengers?
Peptides
Amines
Amino acids
Gases
Most tissues have _______ innervation, what does this means? What usually occurs when these nerves are activated?
dual, this means that the two divisions of ANS typically produce opposite or similar/complimentary effects on the same tissue.
What is the simplified function of the parasympathetic nervous system?
Rest and Digest
What is an oversimplified function of the sympathetic nervous system?
Fight or flight.
What happens in the eye (both SNS and PNS)
SNS: relaxes for far vision
PNS: constricts for near vision
What happens in the heart (SNS and PNS)
PNS: descreases heart rate
SNS: increases heart rate
What happens in the exocrine glands? (SNS and PNS)
PNS: lots of watery saliva
SNS: thick saliva, increases temperature regulation
What happens in blood vessels (SNS only)
Constriction
What happens in the gut? (SNS and PNS)
PNS: increased motility
SNS: Decreased motility
What happens in the lungs? (SNS and PNS)
PNS: airway constriction
SNS: airway dilation
What happens in the urinary bladder? (PNS only)
Contraction
What happens in the genitalia? (SNS and PNS)
PNS: increased erection
SNS: Contracts smooth muscle (ejaculation)
What are the major integrating centres for autonomic reflexes?
Hypothalamus, brainstem, spinal cord.
Role of ANS in mictrurition reflex
Stretch receptors in bladder activate ANS and somatic nerve, relaxation of sphincter and contraction of bladder.
Decreased resistance in blood vessels means:
dilated blood vessels
What is BP equal to?
Resistance x heart rate x force
Temperature regulation (Too cold)
Increased metabolism (symp.adrenaline) Inhibition of sweating (decreased symp to sweat glands) Vasoconstriction (increased symp to vessels)
Temperature regulation (Too hot)
Decreased metabolism (decreased symp.adreno) Increased sweating (increased symp ACH) Vasodilation (decreased symp to blood vessels)
Drugs that mimic the action of ACh
cholinomimetics
Drugs that mimic NA
adrenomimetics
Drugs that block action of ACh
anticholinergics
Drugs that block action of NA
antiadrenergics
