Nervous system: ANS Flashcards
What is the cephalic reflex
Parasympathetic
salivate with anticipation of food
What are the two plexuses of the enteric nervous system?
Myenteric plexus
motility, churning food
- b/w circular and longitudinal muscle layer
Submucosal plexus
secretion and muscle function
mucosal (muscularis mucosae) layer
T/F: ENS receives extrinsic inputs from only parasympathetic vagal inputs
False
extrinsic efferent inputs:
1. parasympathetic vagal preganglionic
2. sympathetic postganglionic fibres
What is the higher up control of autonomic function
Reticular formation
Where are the reflexes centre for urination, defecation, erection and ejaculation found?
spinal cord
What are the functions of the parasympathetic system? Name its effect on 4 systems
3 ‘D’s
- Digestion
- Diuresis
- Defecation
Gut increase secretion from salivary glands increase GI motility and secretion Bladder contration sphincter relaxation
Heart
Decrease heart rate and contractility
Lungs
Bronchoconstriction and secretion
Eyes
contract pupils (miosis)
Thickens lens (short range vision)
Lacrimation (crying)
Genitals
Erection (vasodilation)
What are the functions of the sympathetic NS?
3 ‘E’s
- Exercise
- Excitement
- Emergency
Eyes
dilation of pupil (mydriasis)
flattening of lens (long range vision)
Lungs
Bronchodilation
Blood vessels
Vasodilation- blood flow to skeletal muscles
Vasoconstriction- decrease flow to gut
Heart
increase heart rate and contractility
Adrenal medulla
increase adrenaline and NA release
- bronchodilation
- glycogenolysis (skeletal muscle)
Gut
reduce motility and secretion
Genitals
Ejaculation
Kidneys
increase renin secretion
Sweat glands
increase secretion and piloerection
Which is the myelinated and unmyelinated neuron in the efferent neurons
Pre (myelinated)- slow conducting
Post (unmyelinated)1
Where are the cell bodies of
- sympathetic preganglionic
- parasympathetic preganglionic
symapathetic: visceral efferent (lateral gray) column of the spinal cord.
parasymapathetic: homologous motor nuclei of the cranial nerves.
Where are M4/5 receptors found? What NT do they use
CNS
ACh
Which muscarinic receptors are inhibitory, which are excitatory?
M1, M3, M5 - excitation (uses Gq- activate phospholipase C > DAG & IP3 > intracellular Ca2+ signalling)
M2, M4- inhibitory (uses Gi- increase K+ conductance, decrease Ca2+ conductance)
Where is M3 ACh receptors found? Fxn?
Lungs
Bronchoconstriction
Smooth muscle contraction
Where is M2 ACh receptors found? Fxn?
Heart
Reduce heart rate
Reduce atrial contractile forces
Reduce conduction velocity of AV node
Where is M1 ACh receptions found and what is their function?
Salivary glands and stomach
increase GI secretion
What are the two types of nicotinic AChR? + where are they found?
- Nm (Neuromuscular)
THINK: ‘m’ = muscles - Nn (autonomic)
sympathetic & parasympathetic ganglia
Adrenal medulla
THINK: ‘n’= neurons
What does AChE breakdown ACh into?
Acetate and Choline
What makes Acetylcholine from Acetyl CoA and Choline?
Choline Acetyltransferase (ChAT)
Name a parasympathomimetics that causes diarrhoea, muscle weakness, bronchorrhea (constrict bronchi), bradycardia?
Explain mechanism
Sarin Gas
irreversible reaction
inhibitor of acetylcholinesterase (AChE)
What is pilocarpine?
Receptors
Effects
Use
nAChR and mAChR agonist
Not broken down easily
Constriction of pupil
increase salivation
1/ Eyedrop: Treat close angle glaucoma (mAChR; open trabecular meshwork, drain aqueous humour)
2/ Ocular hypertension
3/ Dry mouth (eg. Sjogren’s syndrom/radiation therapy)
What does ACh do?
Decrease HR, force of cardiac contraction and BP
Increase gastric motility
What is Carbachol/Carbamylocholine ?
Receptors
Effects
Use
mAChR and nAChR agonist
1/ Pupil constriction (Miosis)
2/ increased aqueous humour outflow (cry?- THINK ‘Carbachol- Cry’)
1/ Eyedrops: decrease intraoccular pressure
open-angle glaucoma
What is a mAChR agonist that increases GI motility and bladder contraction?
Bethanechol
THINK ‘ Bethanechol’ = ‘Bladder contraction’
What is donepizil?
Reversible AChE inhibitor
Improve cognition and behaviour in AD
Side effects of diarrhoea, vomitting, muscle cramping, insomnia
What is neostigmine?
AChE inhibitor
Does not cross BBB (polar), but crosses placenta
Myasthenia gravis (too little AChR) Urinary retention w/o blockage
