DONE ANS Flashcards
What is the general function of the ANS?
Is it entirely efferent or afferent?
Controls all involuntary functions (HR, BP)
Efferent, conduct away to peripheral syst.
What are the 2 divisions of the ANS?
Sympathetic and parasympathetic
What is the general function of the sympathetic and parasympathetic systems?
Sympathetic = fight or flight response, (increased HR, BP, chonotropy)
Parasympathetic = rest + digest, basal activities (basal HR)
What is the general structure of the sympathetic efferent system?
Short, myelinated pre-ganglionic neurone
Ganglia in paravertebral chain near spinal cord
Long, unmyelinated post-ganglionic neurone
What is the general structure of the parasympathetic efferent system?
Long, myelinated preganglionic fibres
Ganglia within innervated tissue
Short, unmyelinated post-ganglionic fibres
Where do the parasympathetic nerves originate?
Lateral horn of medulla + sacral spinal cord
Where do the sympathetic nerves originate?
Lateral horn of lumbar and thoracic spinal cord
What do all pre-ganglionic neurones use as their neurotransmitter and what word describes this?
What post-ganglionic receptors does this activate?
ACh (acetylcholine)
Cholinergic
Nicotinic ACh receptors (ligand-gated ion channels)
What neurotransmitter is released by parasympathetic post-ganglionic neurones and what word describes this?
What receptors in the target tissue does this act on?
ACh
Cholinergic
Muscarinic ACh receptors (are GPCRs)
What neurotransmitter is released by sympathetic post-ganglionic neurones and what word describes this?
What receptors does this act on?
Noradrenaline (NA)
Noradrenergic
Adrenoceptors (alpha or beta GPCRs)
What is an exception for neurotransmitter release by sympathetic post-ganglionic neurones?
Some are cholinergic, not noradrenergic
(Innervate sweat glands , hair follicles)
What is another type of transmitter in the ANS?
Non adrenergic, non cholinergic (NANC) transmitters
Released with either NA or ACh
E.g. ATP, NO
What do sympathetic post-ganglionic neurones in the adrenal medulla differentiate into, and what do they release into the blood (don’t project into a target tissue as are producing a hormonal sympathetic response)?
Chromaffin cells
Adrenaline
What does parasympathetic release of ACh cause in the heart and smooth muscle of the lungs?
Decrease HR (via mACh = M2)
Bronchiolar contraction/narrow airways (M3)
What does sympathetic release of noradrenaline cause in the heart, lungs and smooth muscle of arteries?
Increase HR , cause positive inotropy = (adrenoceptors = beta 1)
Smooth muscle of bronchioles relaxes (= beta 2)
Arteriolar contraction (= alpha 1 and beta 2)
