ANS Flashcards
Does presynaptic have a high or low affinity and does it occur at a fast or slow rate?
High affinity and slow rate.
Alpha1 receptors are found where?
CVS
Lower urinary tract
Contraction of the ciliary muscles means what for the shape of the lense and for vision? Which ANS component is this related to?
Thicker, shorter lense. Better for up-close reading. Parasympathetic nervous system is responsible for this.
Is AChE capable of breaking down suxamethonium?
Is AChE capable of breaking down procaine?
No.
No.
It is only capable of hydrolysing acetylcholine.
Long preganglionic fibres are typical of which part of the ANS?
Parasympathetic.
Alpha1 receptors perform contraction or relaxation on what muscles?
Contraction in: smooth muscle in blood vessels, GIT sphincters, bladder sphincters, uterus, iris.
Anticholinesterase poisoning results in what four main symptoms?
- Bradycardia
- Hypermotility
- Muscle fasiculation (twitching)
- Decreased intraocular pressure (leads to diplopia [blurred vision])
D receptors are found where? And is it during sympathetic or parasympathetic stimulation?
Renal vascular smooth muscle. Sympathetic stimulation.
Note which fibres release which neurotransmitters:
(i) Preganglionic parasympathetic
(ii) Preganglionic sympathetic
(iii) Postganglionic parasympathetic
(iv) Postganglionic sympathetic
(i) ACh
(ii) ACh
(iii) ACh
(iv) NAd, also possibly ACh
Prazosin can block which adrenoreceptor?
Alpha1.
If the ganglia are close to the neuroeffector junction, this indicates that it is part of which component of the ANS?
Parasympathetic. The ParaNS is a more discrete system, a one-to-one correspondence from neuron to effector organ.
What is the drug used to treat anticholinesterase poisoning? How does it work?
Pralidoxime.
It causes cholinesterase reactivation, meaning that it activates the enzymes that clean up all the ACh.
Neostigmine and physostigmine are used to do what? What kind of drugs are they?
They are anticholinesterases.
Neostigmine is used to treat Myasthenia Gravis.
Physostigmine is used to treat glaucoma (recall that increased ACh causes a decrease in intraocular pressure).
Alpha2 receptors are found where?
Neurons.
The eye contains the radial muscle and the circular muscle. Which one controls pupil dilation and which controls pupil constriction?
Radial = dilation = sympathetic
Circular = constriction = parasympathetic
True or false, nicotinic receptors play no part in the sympathetic response.
False. They are the receptor at the adrenal medulla.
Nicotinic receptors (nAChR) are located where?
- All junctions between preganglionic neurons and ganglia.
- Sympathetic stimulation of adrenal medulla.
- Neuromuscular junction.
Release of noradrenaline onto alpha2 receptors causes?
- Vasoconstriction of veins
- Platelet aggregation
- Inhibition of insulin secretion
- Inhibition of leptin production
What are the two enzymes responsible for enzymatic degradation of adrenaline and noradrenaline?
Catechol-o-methyltransferase (COMT) Monoamine oxidase (MAO)
Briefly explain what an anticholinesterase does.
Stops the hydrolysis of acetylcholine, meaning there is a build up. This can lead to increased muscle contraction, or eventually paralysis. Depends on the amount of ACh that is building up.
The eye is more capable of seeing close objects during sympathetic or parasympathetic stimulation?
Parasympathetic. During sympathetic stimulation, the body is attempting to see into the distance to detect predators. The opposite occurs during parasympathetic stimulation.