Pharmacology Flashcards
Where are cell bodies of the parasympathetic preganglionic fibres located?
brainstem
Where are cell bodies of parasympathetic postganglionic fibres located?
Walls of the bronchi and bronchioles
What nerves carries preganglionic fibres to the bronchial and bronchi walls?
Vagus nerve (CN X)
Stimulation of postganglionic cholinergic fibres cause what?
Bronchial smooth muscle contraction (ASM airway smooth muscle cells)
Mucus secretion from goblet cells
Which neurotransmitter is used in stimulation of postganglionic cholinergic fibres?
ACh (acetylocholine)
What are the receptors which the ACh binds to on the smooth muscle cells and goblet cells?
M3 muscarinic ACh receptors
what does Stimulation of postganglionic noncholinergic fibres cause?
Relaxation of smooth muscle cells (ASM)
What neurotransmitters are involved in the noncholinergic pathway?
Nitric oxide (NO)
Vasoactive intestinal peptide (VIP)
There is sympathetic innervation of bronchial smooth muscle in humans true or false?
false
How does the sympathetic system act on bronchial smooth muscle cells?
Nicotinic acetylcholine receptor (nAChR) which are located on the adrenal grand, chromaffin cells when stimulated release adrenaline into circulation which act on smooth muscles
Which receptors does the adrenaline act on in both goblet and smooth muscle cells?
beta2 adrenoceptors
What does sympathetic stimulation cause on the airways?
- ASM cells relaxation
- decreased mucus secretion on goblet cells
- increased mucociliary clearance on epithelial cells
- vascular smooth muscle contraction- alpha 1 adrenoceptors
How does the release of Ca2+ cause contraction of smooth muscles?
- Ca2+ activates calmodulin to Ca2+ calmodulin
- Inactive MLCK is activated by Ca2+ calmodulin to form active MLCK
- Active MLCK and phosphate group (formed from hydrolysis of ATP) Cause inactive myosin cross bridge to phopshyrlated cross bridge (binds to actin)
What enzyme is responsible for phosphorylation of Myosin light chain (MLC) (contraction)?
Myosin light chain kinase (MLCK)
What enzyme is responsible for dephosphorylation of myosin Light chain (relaxation)?
Myosin phosphatase
What is asthma?
recurrent and episodic condition of the obstruction to the airways in response to substances or stimuli
What are the main causes of asthma?
- Allergens
- Exercise (cold,dry air)
- Resouratiry infections
- smoke, dust and environmental pollutants
What effects does chronic asthma have on the airways?
- increased mass of smooth muscle (hyperplasia + hypertrophy)
- accumulation of intestitial fluid (oedema)
- increased secretion of mucus
- epithelial damage (exposes sensory nerve endings)
- Sub-epithelial fibrosis
What is acute severe asthma called?
status asthmaticus
What effect does air narrowing have on airway resistance?
ii. what does this cause
Increases it
ii. FEV1 and PEFR values decrease
Epithelial damage from chronic asthma exposes what type of sensory nerve endings?
C fibres- irritant receptors
What does epithelial damage lead to in the airways?
Hypersensitivity (X axis)
Hyper-reactivity (Y axis)
What is inhaled with provocation tests which real hyper-responsiveness?
Broncho constrictors (spasmogens)
e.g. histamine (activates ASM H1 receptors)
Methacholine (activates ASM M3 receptors)
What does an asthma attack consist of ?
- immediate phase- Bronchospasm Type 1 hypersensitivity reaction
- Delayed phase ( inflammatory reaction) Type IV hypersensitivity reaction