ANS Flashcards
Where does the parasympathetic nervous system originate from?
Craniosacral region
Which division has a longer pre-ganglionic neurone and shorter post-ganglionic neurone?
Parasympathetic
Where does the sympathetic originate from?
Thoracolumbar region
T1-L2/3
What do preganglionic neurones of both divisions release?
Acetylcholine
What receptors are found on the post-ganglionic neurones?
Nicotinic Ach receptors
What neurotransmitter is normally found in postganglionic sympathetic neurones?
Noradrenaline
What transmitter is used in postganglionic parasympathetic neurones?
Ach
What is the exception to noradrenergic sympathetic neurones?
Sweat glands - which are muscarinic
What receptors are found on parasympathetic effector cells?
Muscarinic
What nerve supplies the parasympathetic input to the heart?
Vagus (10th cranial nerve)
What receptors does Ach in the parasympathetic act on in the heart?
M2
Term for decreased heart rate?
Negative chronotropic effect
What effect does the parasympathetic have on the heart?
Negative chronotropic effect
Decreased AV node conduction velocity
Decreases sloe of pacemaker potential by decreasing cAMP
Which receptors does the sympathetic act on in the heart?
β1 adrenoreceptors
What effect does the sympathetic have on the heart?
Positive chronotropic effect
Increased inotropic effect
Increases cAMP to speed up pacemaker potential
How does NA increase inotropy?
Acts on β1 receptors to increase cAMP
Causes phosphorylation of L-type calcium channels so increased Ca entry during action potential
Increased Ca uptake in SR
Increased sensitivity of contractile machinery to Ca
Increased force of contraction
Which vessels do not receive sympathetic innervation?
Erectile
What type of innervation do most vessels receive?
Sympathetic
What receptors are in most arteries and veins?
α1 adrenoreceptors
What receptors are found on coronary, liver and skeletal muscle vessels?
α1 and β2
What is the effect of decreased sympathetic output on vessels?
Vasodilation
What receptor (out of the two on blood vessels) does adrenaline have the highest affinity for?
β2
What is the effect of activating β2?
Increases cAMP
Opens potassium channels
Relaxation of smooth muscle
Vasodilation
What is the effect of activating α1?
Increased calcium in cells
Contraction of smooth muscle
Vasoconstriction
What is the effect of a low circulating conc of adrenaline?
Vasodilation because it has a higher affinity for β2
What is the effect of a high conc of adrenaline?
Vasoconstriction
What is the effect of metabolites?
Vasodilation
Name some metabolites
Adenosine, K+, H+, carbon dioxide
What type of receptors give information about high pressure and low pressure?
High pressure - baroreceptors
Low pressure - atrial receptors
Where are baroreceptors found?
Carotid sinus and aortic arch
Synpathetic receptor in airways and effect?
Beta 2
Relax
Parasympathetic receptor in airways? Effect?
M3
Contract
Sympathetic receptor in pupil and effect?
Dilation
Alpha 1
Para receptor in pupil? Effect?
M3
Contraction
Sympathetic receptors in sweat glands? Effect?
α1 - localised secretion
M3 - generalised secretion
Effect of β adrenoreceptors?
Stimulate adenylyl cyclase causing glycogenolysis and lipolysis
Effect of M3-muscarinic receptors?
Stimulate phospholipase C
Smooth muscle contraction
Effect of M2 muscarinic receptors?
Inhibit adenylyl cyclase and stimulate potassium channels
Slows cardiac pacemaker
Effect of rhodopsin?
Stimulates cGMP and phosphodiesterase
Visual excitation
Where are α adrenoreceptors found and effects?
Arterioles- vasoconstriction Sweat glands - localised secretion Pancreas - increased secretion Salivary glands - viscous secretion Adipose tissue - increased lipolysis
Where are β adrenoreceptors found and their effects?
SA node - increases heart rate
Atria and ventricles - increases contractility
AV and Purkinje - increases conduction velocity
Arterioles of coronary and skeletal muscle - vasodilatation
Bronchial muscles - dilation
Adipose tissue - lipolysis
