Autonomic nervous system Flashcards
What are the sensory receptors of the ANS?
Viscera - not consciously perceived.
E.g. Baroreceptors for monitoring blood pressure.
Somatosensory - e.g. on skin - monitior external environment.
How are autonomic motor components different to somatic?
Effectors innervated are smooth and cardiac muscles and glands (rather than skeletal muscle).
No neurones between CNS and effector in somatic.
In neurotransmission release in ANS there are thousands of vesicle release sites - beads on a string, compared to 1 in somatic.
What are the subcategories of the ANS?
Divided into sympathetic and parasympathetic neurones (and enteric nervous system.
What are the neurones in the ANS?
Preganglionic neurone has cell body in CNS, and terminals in ganglion.
Postganglionic neurone has cell body in ganglion and terminals in effector.
1 preganglionic neurone can connect to multiple postganglionic neurones.
What is the importance of multiple postganglionic neurones connecting to one preganglionic neurone?
One single message can influence multiple areas of the effector - e.g. can activate all the different blood vessels.
One postganglionic neurone can then influence hundreds of effector cells - very diffuse release.
What are the neurotransmitters in the sympathetic ANS?
Synapse in ganglia uses ACh.
In postganglionic neurone terminals uses noradrenaline.
What are the neurotransmitters used in the parasympathetic ANS?
In ganglion - ACh, and in postsynaptic ganglion also ACh.
How are the sweat glands in the ANS different?
Sweat glands are innervated by sympathetic neurones.
ACh in ganglion, but in the sweat glands are also ACh (should be noradrenaline as sympathetic).
How is the adrenal medulla of the ANS different?
Neuroendocrine organ: Middle of the adrenal gland, produces adrenaline and noradrenaline.
Controlled by innervation by sympathetic NS producing ACh.
They are not neurones, as no axons, but if stimulated by SNS, release adrenaline.
What is the importance of the Adrenal Medulla?
Adrenaline has non-innervated receptors.
e.g. smooth muscle of bronchioles and blood vessels.
What do the SNS and PNS do?
Homeostasis, vision and reproduction.
SNS - alert and active.
PNS - rest and digest - energy conservation, digest and emptying waste.
Most organs have dual innervation and are antagonistic.
How does the digestive system work?
Dual innervation and antagonistic:
Activation of the PNS increases motility and activity for digestion.
Activation of the SNS decreases motility and less digestion.
How does the pupil use the PNS and SNS?
SNS causes contraction of Radial muscle, pupil dilation.
PNS causes contraction of Circular muscle, pupil constriction.
What components of the ANS do not work antagonistically?
Exocrine glands e.g. salivary
Activated SNS causes salivary glands to produce saliva.
Activated PNS also causes salivary glands to produce saliva.
But raw materials of saliva are delivered through blood vessels - SNS causes vasoconstriction of blood vessels, so less saliva is produced.
PNS has a greater effect than SNS.
What components of the ANS do not have dual innervation?
Sweat glands only use the SNS - single innervation.
Most blood vessels have single innervation - smooth muscle has SNS only.
How does the SNS causes vasoconstriction and vasodilation?
In most blood vessels:
Vasovessel motor tone degree of activity
Can have more SNS activity to get vasoconstriction, and less SNS activity to get vasodilation.
How are blood vessels of the head and reproductive organs different?
SNS causes vasoconstriction
PNS causes vasodilation
How can the SNS vasodilate and vasoconstrict at the same time?
Activate SNS causes body wise activation.
SNS activates release of both noradrenaline and adrenaline.
Noradrenaline binds to alpha receptors - vasoconstriction.
Adrenaline binds to beta receptors of blood vessels - vasodilation.
So SNS can cause vasoconstriction and vasodilation in different parts of the body.
How can the PNS and SNS work together?
Male sex organs:
PNS - erection
SNS - ejaculation
What is the interaction of the somatic and autonomic systems?
Focusing the eye:
ANS - pupil adjustments.
Somatic - eye movements.
Response to the cold:
ANS - vasoconstriction in the skin
Somatic - shivering
