ICPP 8 Flashcards
What regions of the spinal cord do sympathetic axons emerge from?
Thoracic and lumbar
Where do sympathetic pre-ganglionic neurones synapse with post-ganglionic neurones?
Paravertebral column
What region do parasympathetic nerves emerge from?
Medullary and Sacral region
Where do parasympathetic pre-ganglion neurones synapse onto post -ganglion ?
Close to or within target tissue, short post-ganglionic fibres
What is the neurotransmitter for all pre-ganglionic fibres?
ACh
Give examples of NANC transmitters.
NO, ATP, 5-HT
What is unique about post-ganglionic neurons in the adrenal glands?
They differentiate to form neurosecretory chromaffin cells which release adrenaline into the blood stream.
What receptors do parasympathetic post-ganglionic fibres synapse to?
muscarinic ACh receptors in target tissue
What enzyme is involved in acetylcholine synthesis?
Choline acetyltransferase
What is acetylcholine made from?
Acetyl CoA and choline
What is ACh degraded into?
Choline and acetate
What is pilocarpine?
muscarinic ACh receptor agonist
What acronym describes side effects of excessive parasympathetic discharge.
SLUDGE
What is atropine?
Anti-cholinergic agent
Outline the steps of Noradrenaline synthesis.
Tyrosine -> Dopa -> Dopamine -> Noradrenaline
Adrenal medulla further enzyme which converts to adrenaline
What are the 2 uptake mechanisms for NA?
Uptake 1 = Na+ dependent transporter uptake into pre-synaptic terminal
Uptake 2 = lower affinity, non-neuronal mechanism
What 2 enzymes are involves in NA metabolism?
MAO - monoaminoxidase
COMPT - catechol-o-methyltransferase (COMT)
What is thyrotixicosis?
High levels of thyroid hormone in the bloodstream
What are the functions of the 2 thyroid hormones?
T3 - active hormone, increases basal metabolic rate
T4- relatively inactive, reduces levels of T3
What are symptoms of thyrotoxicosis?
weight loss Increased appetite increased bowel movement Rapid and irregular heart rate Goitre Tremor
How is thyrotoxicosis related to the autonomic nervous system?
Thyroid hormones up-regulate the number of adrenoceptors in the body.
More beta receptors in the heart results in tachycardia and may cause hypertension
What ANS drug would be used to treat thyrotoxicosis?
Non-selective B-adenoceptor antagonists
E.g propanolol
What other treatment is used for thyrotoxicosis?
Iodide - blocks release of thyroid hormones
Thiomides - inhibit hormone synthesis
What are the clinical abnormalities in asthma?
Chronic airway inflammation
Episodes of bronchoconstriction
Hypersecretion of mucus which narrows airways
What is the major autonomic innervation of the airways?
Parasympathetic
But also beta-2-adrenoceptors in airway smooth muscle
What asthma drugs are used as ‘relievers’?
Bronchodilators
Beta-2 agonists - salbutamol and salmeterol
What anti-asthma drugs are used as preventers?
Glucocorticosteroids
What 2 systems regulate blood pressure?
Sympathetic NS
RAAS
What is the clinical criteria for hypertension?
140/90 mmHg
What target sites for drug action can you define to control hypertension?
heart
smooth muscle - arteriole contraction
Kidney - renin release
CNS - determines bp set point
What are the main unwanted side effects of using alpha-adrenoceptor antagonists to treat hypertension?
Postural hypotension
Impotence
Diarrhoea (increased Gi motility)
What 3 ways do beta adrenoceptor antagonists appear to exert anti-hypertensive action?
- reduced inotropy
- reduced chronotropy
- reduced renin release
What are unwanted side effects of b-adrenoceptor antagonists?
- bronchoconstriction in asthmatics
- cardiac failure in patients with heart disease
- bradycardia
- fatigue
- hypoglycaemia
- impotence
What effect does parasympathetic ACh release have on the heart?
M2 receptors
Bradycardia
What effect does parasympathetic ACh release have on smooth muscle?
M3 -bronchial contraction
Increased GI motility
What effect does parasympathetic ACh release have on glands?
Increased saliva and sweat secretion via M1 / M3
What effect does sympathetic NS have on the heart?
Increased inotropy and chronotropy via B1 receptor.
What effect does sympathetic NS have on smooth muscle?
Alpha 1 causes arteriole constriction
Beta 2 cause bronchiole, uterine and intestinal relaxation
What effect does sympathetic NS have on the kidney?
Increased renin release
