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.
Beta1 receptors are found where?
The heart.
Cholinergic ≠ parasympathetic, why?
Because ACh is also used to innervate sweat glands (a sympathetic response) and to innervate somatic muscles at the NMJ.
Atropine is an agonist of which receptor?
Muscarinic.
What is edrophonium used to do?
Differentially diagnose myasthenia gravis. It is an anticholinesterase, which prevents the breakdown of ACh, allowing the patient to temporarily increase their levels of ACh to determine if that is what is causing their symptoms.
Beta1 stimulation produces what?
They’re only located in the heart, so when noradrenaline stimulates them it causes increased rate of contraction and increased force of contraction (inotropic).
They’re only located in the heart, so when noradrenaline stimulates them it causes increased rate of contraction and increased force of contraction (inotropic).
AChE - the neuroeffector/neuromuscular junction.
BuChE - Plasma, liver, GIT, smooth muscle, brain and kidney.
The Craniosacral nervous system to which part of the nervous system?
Parasympathetic.
Muscarinic receptors (mAChR) are located at?
Parasympathetic neuroeffector organs and sympathetic neuroeffector junction to sweat glands.
Beta2 receptors are found where?
- Blood vessels
- Bronchi
- Uterus
- GIT
- Bladder
- Ciliary muscles
Short preganglionic fibres are typical of which part of the ANS?
Sympathetic.
Inotropes are?
Agents that increase the strength of muscle contraction.
Uptake of adreanaline and noradrenaline is mainly presynaptic or extraneuronal?
Presynaptic is about 75% of the uptake that occurs.
What are the effects of beta2 receptors?
Muscle relaxation.
Tremor of skeletal muscle.
Hypokalaemia.
Glycogenolysis (decreased glycogen synthase, increased phosphorylase).
Inhibition of histamine release from mast cells.
The neuroeffector junction occurs at which part of the Autonomic NS?
Between the postganglionic neuron and the effector orgain.
Does extraneuronal have a high or low affinity and does it occur at a fast or slow rate?
Low affinity and fast rate.
What are the three types of anticholinesterase?
- Short acting
- Medium acting
- Irreversible
Beta2 receptors are agonised by which two drugs?
Salbutamol and tetrabutaline.
What are the two processes by which adrenaline and noradrenaline are terminated?
Uptake and enzymatic degradation.
Muscarinic receptors are sub-categorised based on location. Where are the following found?
M1: neural
M2: cardiac
M3: glandular and smooth muscle
If the ganglia are close to the spinal cord, it indicates that the transmission line is part of which part of the ANS?
Sympathetic, because it will then be able to more readily diffuse to more effectors.
Activation of beta3 receptors causes what?
Lipolysis.
Via the activation of lipase.
An enlarged pupil is associated with sympathetic or parasympathetic stimulation?
Sympathetic.
Remember it as the brain is trying to let in as much light as possible to provide information about predators.
What are four things regulated by the ANS?
- Smooth muscle
- Exocrine glands
- Cardiac muscles
- Intermediary metabolism (metabolism within cells)
Contraction of bladder muscles occurs in parasympathetic or sympathetic stimulation?
Parasympathetic. This causes urination during the ‘rest and digest’ phase of neurological stimulation.
In general, alpha receptors cause _________
In general, ß receptors cause _________
In general, alpha receptors cause contraction
In general, ß receptors cause relaxation
The Thoracolumbar Nervous System refers to which part of the nervous system?
Sympathetic.
The Autonomic Nervous System is a sub system of which of the following? (select one or more)
(a) Central Nervous System
(b) Peripheral Nervous System
(c) Afferent Nervous System
(d) Efferent Nervous System
(b) and (d)
Noradrenaline is released onto what kind of receptors?
Alpha and beta receptors.
How many nerves innervate a NMJ?
One
Relaxation of the ciliary muscles means what for the shape of the lense and for vision? Which ANS component is this related to?
Taller, thinner lense. Better viewing of objects further way. Sympathetic nervous system is responsible for this.
Adrenergic ≠ sympathetic, why?
Sweat glands are activated by ACh.
What is a group of irreversible anticholinesterases?
Organophosphates.
