Autonomic Nervous System Flashcards
(26 cards)
What are the sensory components of the autonomic nervous system?
Receptors –> Baroreceptors
Viscera - not consciously perceived
What are the properties of the motor components of the ANS?
Effectors innervated —> viscera, smooth muscle/cardiac muscle
Somatic NS innervates Skeletal muscle
What is the anatomical difference between the ANS and CNS?
ANS is made up of a pre and post ganglionic neurone.
SNS has 1 neurone from CNS to skeletal muscle
What are the divisions of the ANS?
Sympathetic nervous system
Parasympathetic nervous system
How many neurones innervate viscera in the efferent pathway?
2 neurones
1 sympathetic
1 parasympathetic
Where are the preganglionic neurone cell bodies found?
in the CNS
Where are the postganglionic neurone cell bodies found?
In a ganglion
What neurotransmitter is released at the synapse between the pre and post ganglionic neurone?
ACh
What neurotransmitter is released via the sympathetic post ganglionic neurone? what is the exception to this?
Noradrenaline
Exception is sweat glands which are stimulated by their post ganglionic sympathetic neurone releasing ACh.
What neurotransmitter is released via the parasympathetic post ganglionic neurone?
ACh
What is the different in relationships between the SNS and the ANS?
SNS - One neurone to one muscle fibre (discrete relationship)
ANS - One postganglionic neurone cell branches to innervate many different effector cells (diffuse relationship)
What is the adrenal medulla?
Neuroendocrine organ - releasing adrenaline and noradrenaline in circulation.
Acts as a post ganglionic sympathetic neurones after being innervated by pre ganglionic sympathetic neurones releasing ACh.
What is the functional implication of the diffuse relationship in the ANS?
allow for single activation via ganglion branching by the varicosity to allow widespread control of the effector
What is the importance of adrenaline/noradrenaline release by neuroendocrine cells?
Allows for some receptors located away from nerve endings (such as in blood vessels/bronchioles) to be activated by adrenaline/NA circulating in the blood.
What are the functions of the ANS?
Homeostasis
Vision
Reproduction
What are the functions of the Sympathetic NS?
Used for alert and active function
Also defence response - fright/fight/flight
What are the functions of the Parasympathetic NS?
Used for rest and digest
Energy conservations, digestion, emptying
How does the ANS work for most organs?
Duel innervations - both sympathetic and parasympathetic (antagonistic responses)
What examples are there for antagonistic responses of the ANS?
Heart - Increase HR (symp) Decrease HR (p.symp)
GIT - Decrease motility (symp) Increase motility (p.symp)
Pupil - Dilation (symp) Constriction (p.symp)
What effectors of the ANS are not stimulated in an antagonistic way?
Endocrine glands (eg. sweat) Still duel innervation but not antagonistic
What effectors of the ANS receive single innervation?
Sweat glands - Sympathetic only
Most blood vessels - Smooth muscle is sympathetic only
How does vasomotor tone work?
In most blood vessels
Increase Sympathetic activity - Vasoconstriction
Decrease Sympathetic activity - Vasodilation
Which blood vessels receive duel innervation?
Blood vessels of the head and reproductive organs
Sympathetic - Vasoconstriction
Parasympathetic - Vasodilation
How is blood vessel diameter regulated?
All vessels:
Increase sympathetic activity releases NA at postganglionic neurones to innervate alpha receptors and cause vasoconstriction
Specific vessels:
Increase sympathetic activity stimulates adrenal medulla to release NA into circulation which will activate non-innervated beta receptors and cause vasodilation
Balancing act between them both will determine blood vessel diameter.
