Autonomic Regualtion Of The Airways Flashcards
What are some difference between asthma and COPD?
Asthma usually < 50
COPD > 35
COPD more closely linked to smoking
COPD - progressive with exacerbations - never normally spirometry reading - persistent symptoms
Asthma - stable with exacerbations
Asthma - resends well t therapy and treatments
COPD less responsive
How are the airways smooth muscle regulated?
It is regulated by the autonomic nervous system
Contractile signals cause increase in intracellular calcium in smooth muscle which activated actin-myosin contraction.
Asthma and COPD can lead to these airways being continuously constricted.
How does the autonomic system work?
Especially in response to breathing?
The peripheral autonomic nervous system is divided into the sympathetic and parasympathetic branches which typically have opposing effects.
The autonomic nervous system conveys all outputs from the CNS except for Shetland muscle control.
How do the parasympathetic ganglia and sympathetic ganglia vary?
Rest and digest vs fight and flight.
The parasympathetic ganglia are near their targets with short post ganglionic nerves.
The sympathetic ganglia are near the spinal chord with a longer post ganglionic nerve fibre.
It is the parasympathetic pathway that is responsible for the constriction of the bronchi.
How does the parasympathetic nervous system cause bronchoconstriction?
Vagus nerve neutrons terminate in the parasympathetic ganglia in the airway wall.
Their short post ganglionic nerve fibres reach the smooth muscle and release acetylcholine which acts on muscarinic receptors (M3)on the muscle cells.
This stimulates muscle contraction…
To decrease symptoms of asthma, COPD and bronchiectasis which are caused by narrowing airways what can be used?
These act upon the M3 receptors …
SAMAs - short acting muscarinic antagonists
- such as ipratropium bromide
LAMAs - long acting muscarinic antagonists
- have a long duration of many hours - tiotropium. They increase bronchodilation and hence relieve breathlessness, they also reduced the chance of an exacerbation and decrease mucus production.
How is the sympathetic nervous system involved in bronchodilation?
Nerve fibres release noradrenaline which activates adrenergic receptors of which there are alpha and beta.
Airways smooth muscle have adrenergic receptors. Activation of the beta2 receptors on this smooth muscle cause muscle relaxation.
SABs and LABAs?
Short acting beta2 antagonist - salbutamol which is the blue inhaler and is used during a exacerbation.
Long acting beta2 antagonist - taken everyday to reduce the chance of an exacerbation.
What is the mechanism of Beta2 antagonist?
Beta 2 receptor on airway smooth muscle Inhaled beta2 antagonist attaches to receptor Effects stimulators G protein Acts on adenylate cyclase (ATP — Camp) This then activates protein kinase Causing airway relaxation
Adverse effects of beta2 antagonists?
Raising cAMP - K+ driven into cells and out of the blood
Tachycardia
Hyperglycaemia
inhalers are used to medicalise the patient with the required SABA, LABA or LAMA…
What is the goals of treatment?
Aim to prove control of symptoms
Reduce exacerbations
Save lives - 1200 deaths per year from asthma attacks alone.
Immediate management of someone having an asthma attack?
Oxygen up to 60%
SABA - salbutamol
Anti-muscarinics vs beta agonists?
Anti-muscarinics - oppose the action of the parasympathetic nervous system stop broncho -constriction.
Beta antagonists - engage sympathetic pathways causing broncho-dilation.
