The Autonomic NS Flashcards
Functions of the ANS:
Homeostasis
Intrinsic activity of tissue
Regulates body temp, cardiovascular activity, respiratory functions, digestive functions
The ANS is organised into…
Ganglions, nerves, and plexuses
The hypothalamus controls:
Water balance
Food intake
The brainstem controls:
Respiration
The hypothalamus AND brain stem control the:
Body temperature
Vasomotor control of blood pressure
The ANS is dependant on signalling from the
Periphery (chemoreceptors, baroreceptors)
and;
Cortex-thalamus-hypothalamus
What functions to keep people alive in the vegetative state?
The medulla
Thalamus:
Relay station and processing centre for sensory information
Hypothalamus:
Controls emotions, hormone production, and autonomic functions
Medulla Oblongata:
Relay station for sensory information to thalamus and to other parts of the brainstem.
Autonomic centres for regulation or visceral functions (cardiovascular, respiratory, digestive activity)
Skeletal muscle is part of the somatic system, innervated by 1 motor neuron:
Releases Ach –> Nicotinic Ach receptors –> Normuscular emplate
Visceral organs are innervated by 2 motor neurons, 1 preganglionic neuron, and 2 postganglionic neuron:
Preganglionic neuron synapses with either a sympathetic or a parasympathetic ganglion –> releases Ach –> nicotinincACh receptor on postganglionic neuron
2nd post ganglionic neuron (dependant on what ANS function is being used)
Sympathetic –> noradrenaline
Parasympathetic –> ACh –> muscarinic receptors
The second motor neuron is auto-inhibitory. T/F
True
Muscle excitation is due to…
An influx of Na2+ and Ca2+ into the cells
Nicotine stimulates…
All ANS functions:
- Somatic efferent
- Sympathetic
- Parasympathetic
Nicotine and ACh are agonists at the…
Nicotinic receptor
ACh, muscarine, carbachol are agonists at the…
Muscarinic receptors
Nicotinic receptors are ligand gated. T/F
True
Muscarinic receptors are GPCRs. T/F
True
M1,3,5 are all stimulatory receptors –>
Will stimulate cell –> stimulate phospholipase C and adenyl-cyclase.
Mediated by G-protein
M2 and M4 are inhibitory;
act via Gi –> inhibit Phospholipase C and adenyl cyclase
α1 receptors are found at the:
Eyes: Pupil dilation and contraction
Arteries and Veins: Vasoconstriction in skin and viscera
α1 and 2 receptors are found at the:
Stomach and GI
β1 receptors are found at the:
Heart: Increase heart rate and force of breathing
- Positive chronotrophy and inotrophy
β2 receptors are found at the:
Arteries and Veins: Vasodilation in skeletal muscle
Muscarinic receptors are found at the:
Sweat glands: secretion
Piloreceptor
Parasympathetic Nerves:
Originate in cranial-sacral regions of spinal cord
Synapse in ganglia/plexuses close to end-organs
Pre-ganglionic neurons:
Release ACh onto nAChR on post-ganglionic neurons
Post-ganglionic neurons:
Release ACh onto muscarinic receptors at end organs
S L U D G E
Salvation Lacrimation Urination Defecation Gastro- Emisis
B B B
Bronchorrhea
Bronchospasm
Bradycardia
D U M B E L L S
Diarrhea/ diaphoresis (sweating) Urination Miosis Bronchorrhea Bronchospasm Bradycardia Emesis Lacrimation Salvation
Accomodation:
Blurred vision
Parasympathetic system initiate short vision. T/F
True
Myriasis:
Widening of pupil
The PSNS innervates blood vessels. T/F
False
What would you expect is muscarinic receptors are antagonised?
Administration of Atropine
SLUDGE
Reduction in lacrimation Reduction in salvation *Anticholinergic effects Reduction in urination --> urinary retention Reduction in defecation Reduction in mucous production Slight tachycardia (reflexes) Increased ability to breathe --> useful for asthma treatment
Originate in thoracic-lumbar regions of the spinal cord
Synapse….
in paravertebral ganglia, prevertebral ganglia or in adrenal medulla
Pre-ganglionic neurons release…
ACh onto nACHR on post-ganglionic neurons
Post-ganglionic neurons release….
noradrenaline onto adrenergic receptors on the end organs
Adrenaline and noradrenaline are derived from….
catecholamines (tyrosine-derived neurotransmitters)
Preganglionic fibers from the hypothalamus pass though the sympathetic ganglion…
Without synapsing into the adrenal medulla
Preganglionic fibers directly synapse onto modified neurons…
Chromaffin cells
You are stimulating the Sympathetic control centre in a mouse. What do you see?
Eyes: Mydriasis
Lungs: Bronchodilation
GI-tract: Constipation
Body weight: Decreases due to high metabolic activity
Heart: Tachycardia. High HR and high contractility.
Blood vessels:
- Skin and viscera: Vasoconstriction
- Skeletal muscles: Vasodilation
- Adrenal gland: Activation, releases adrenaline and noradrenaline
Resistance in arteries is dependent on the…
Vessel diameter
Baroreceptors are stimulated by stretch or high BP, and the activation of PSNS acts to…
Lower BP
If baroreceptors are stimulated by low BP, and the activation of SNS acts to…
Incr. in HR and contractility and vasoconstriction of the skin
- BP rises
–> Orthostatic reflex
Which drugs will cause problems with the orthostatic reflex?
Orthostatic hypertension
Adrenergic antagonists; block sympathetic activation
Beta-blockers; block incr. In HR
α1 receptors act via:
IP3/DAG Gq coupled
β1 receptors act via:
cAMP, Gs coupled
β2 receptors act via:
cAMP, Gs coupled
Administering adrenaline will cause…
- Vasodilation
- Decr. HR
- BP and contractile force
Administering nor-adreanaline will cause
NO vasodilation
- Incr. peripheral resistance
- Decr. HR
Sympathomimetic Drugs:
Agonists at α1, β1 and β2 receptors
Sympatholytic Drugs:
Antagonists at α1, β1 and β2 receptors
- α2 agonists
Indirect Sympathomimetic Drugs:
- NA uptake inhibitors
- MAO-inhibitors
- Amphetamine, ephedrine
Adrenaline as a Drug (Epipen or Anapen)
- Release of histamines causes system vasodilation
- -> Drop in BP and lung oedema
Adrenaline injected via i.m. Will lead to:
- -> vasodilation in muscle
- -> vasoconstriction in skin
- -> Rise in BP and bronchodilation
Why not inject Epipen near the fingertips?
Adrenaline goes into the arteries, causes arterial dilation, reduction in BP
Adrenaline as a Drug (As an addition to local anaesthetics)
- Local anaesthetics block Na+ channels; cannot feel pain or feel pressure
- Adrenaline is added to local anaesthetics (administered subcutaneously)
- -> limits diffusion of local anaesthetic by vasoconstriction
What happens if both Adrenaline and a local anesthetics is injected i.m. During nose and throat surgery?
- Vasodilation, –> adrenaline will move towards the heart, incr. HR
- Local anaesthetics will distribute through the system.
Decr. HR –> heart block
α1 agonists cause… and cannot be administered to…
α1 agonists cause an incr. in BP and cannot be administered to someone with high BP
α2 agonists are auto-inhibitory. T/F
True
α2 agonists act to…
Lowers arterial pressure by acting on heart and vasculature
Bradycardia, orthostatic hypotension, sedation, depression
α2 antagonists whilst being useful for treating depression, are often avioided as they cause…
Hypertension
β1 agonists cause…
Incr. in HR and contractility
β1 agonists are used to treat…
Asthma
β-blockers should NOT be administered to someone with ____
Asthma
Side effects of β-blockers incl.
Bradycardia, and inability for the heart to respond to exercise
Noradrenaline:
Alertness, wakefulness, anti-depressant
Dopamine:
Pleasure, mediates addiction, movement
5-HT Serotonin:
Feeling happy, relaxed, calm, motivated, anti-depressant
Mirtazapine is an α2 antagonist that…
Blocks α2, 5-HT2c, and 5-HT3 receptors and enhances:
NA and 5-HT release
Mono Amine Oxidase (MAO) Inhibitors initiate:
Less Na2+ degregation
–> Incr. Na2+ levels
Dopamine is also degraded by MAO. T/F
True
Short-term effects of Amphetamines:
- Exhilaration
- Hyperactivity
- Loss of appetite
- Insomnia
- Incr. in energy
- Incr. in talkitivness
Long-term effects of Amphetamines:
- Nervousness
- Irritibility
- Hallucinations
- Paranoia
- Depression
Cocaine’s functions via
NA re-uptake inhibitor (NAT)
Amphatamines functions via
Incr. NA release
NA re-uptake activity
Chonidine is an
alpha2-agonist
Prazosin is an
alpha1 antagonist
Propanolol is a
Non-selective beta-receptor antagonist
Neurotransmitter mechanism:
- An action potential is propagated to the terminal of a presynaptic neuron
- Ca2+ enters the presynaptic terminal
- Neurotransmitter is released via exocytosis
- Neurotransmitter binds to receptor on post-synaptic neuron
- Specific ion channels open in the sub-synaptic membrane
mydriasis is the…
Dilation of the pupil
Acetyl CoA and choline undergo…
Choline acetyltransferase to become Acetylcholine and CoA
All effects within the parasympathetic NS are innervated by the…
Muscarinic receptor
Muscarine can stimulate what nerve?
Muscarine can stimulate the vagus nerve
Atropine can inhibit muscarinic effects as it is an…
muscarinic antagonist
Atropine prevents vagual reflexes. T/F
True
The 2 main neurotransmitters in the ANS are:
Acetylcholine and noradrenaline
All postganglionic parasympathetic fibres release
acetylcholine, which acts on muscarinic receptors. T/F
True
Preganglionic neurons are…
cholinergic, and ganglionic
transmission occurs via nicotinic ACh receptors
Postganglionic parasympathetic neurons are…
cholinergic,
acting on muscarinic receptors in target organs
Proliferation of receptors.
The number of acetylcholine receptors increases
20-fold or more after denervation;
Loss of mechanisms for transmitter removal:
At noradrenergic synapses, the loss of neuronal uptake of noradrenaline
contributes substantially to denervation supersensitivity.
At cholinergic synapses…
there is a partial loss of cholinesterase occurs
Noradrenergic and cholinergic nerve terminals often lie
close together in the…
myenteric plexus
VMAT:
Nesicular monoamine transporter.
VMAT is responsible for…
Noradrenaline uptake into nerve terminals and used a transvesicular proton gradient as its driving force.
Reserpine blocks VMAT and causes…
Nerve terminals to become depleted of their vesicular nor-adrenaline storage units.
Adrenorecepors all belong to the….
GPCR family
Anaphaylaxis is treated with…
Adrenaline
Prazosin is an…
a1 antagonist, used to treat hypertension`
Heart attacks can be treated with…
beta-adrenoteceptor antagonists
Drugs that enhance cholinergic transmission act either by…
- Inhibiting cholinesterase
2. Increasing ACh release
Antagonist binds to…
Resting and non-resting state
