Autonomic nervous system Flashcards
pre-ganglionic nerve cell bodies are located in the ____
CNS - Brainstem or spinal cord
Post-ganglionic nerve cell bodies are located in _____
Ganglia
Are Autonomic, post-ganglionic nerves myelinated or not?
Usually not
Compared to the sympathetic NS, the parasympathetic preganglion fibres are ____ and the postganglionic fibres are ___
Parasympathetic has Long preganglionic fibres and Short postganglionic fibres becuase the ganglia are located near the target organs.
How do the SNS and the PNS differ in the way they act at their various target organs?
The SNS usually acts as a functional unit - discharging at multiple effector organs and releasing epinephrine from the adrenal gland simultaneously. The PNS, in contrast, acts discretely at different sites at different times - it is not activated as a complete system
Are the SNS and the PNS required for life?
SNS - no. PNS - yes
What are the three integrating centres of the ANS?
The hypothalamus, the medulla and the spinal cord.
Which systems are innervated only by the SNS
Adrenal Medulla Kidneys Pilomotor muscles sweat glands Blood pressure control
The 3 types of chemical signalling between cells…
Local Mediators e.g histamine, prostaglandins
Hormones
Neurotransmitters
Preganglionic neurones use ___ as their neurotransmitter on postganglionic cells. The receptors on the postganglionic cells and in the adrenal medulla are ____
Acetylcholine, Nicotinic
Postganglionic neurones use ____ and ____ as their neurotransmitters and these act on ____ and _____ receptors.
SNS - noradrenaline, adrenergic, ANS - acetylcholine, muscarinic
3 mechanisms for receptor - effector coupling
- Receptors/ion channels/change in membrane potential or intracellular ion concentrations
- Receptor/Gs protein/adenylyl cyclase/protein phosphorylation
- Receptor/Gq/Phospholipase C/Diacylglycerol, Inositol Triphosphate/Protein phosphorylation and increased intracellular Ca2+
Acetylcholine is formed by the reaction of ______ with ______, and is catalysed by ______
Choline and Acetyl coA, catalysed by Choline acetyltransferase
botulinum toxin causes ——
Prevents release of ACh at synapses
Black widow spider venom causes —-
Complete empyting of all presynaptic ACh vesicles into the synapse.
ACh is degraded in the synapse by….
Acetylcholinesterase
The stimulus for release of neurotransmitter vesicles into the synapse is….
Rise in intracellular calcium from opening of voltage gated Ca2+ channels
Carbachol
Muscarinic and nicotinic agonist. High potency and long duration of action. Used locally in the eye - causes accommodation and miosis - useful in glaucoma to reduce IOP
Pilocarpine
Muscarinic activity. Used in opthalmology. Causes miosis and ciliary muscle contraction. Used for emergency lowering of IOP in glaucoma by allowing increased draining of the aqueous humor.
Physostigmine and Neostigmine.
anticholinesterase - binds to and inactivates the acetylcholinesterase that breaks down ACh in the synaptic cleft. Can be used in myaesthenia Gravis
Pyridostigmine, ambenomium, edrophonium
anticholinesterases - can be used in the treatment and diagnosis of myasthenia gravis.
Tarcine, donezepil, ricastigmine and gelantamine
aticholinesterases used to slow the progression of alzheimers. These patients have a deficiency of cholinergic neurons in the CNS.
