Lecture 11 - Cough and Cold Flashcards
coughing is a ____ to clear the breathing passage of irritants, microbes, fluids, and mucus
reflex
a common symptom of upper respiratory tract infections
coughing
how is the coughing reflex initiated?
by stimulation of sensory nerves innervating the throat and lungs
sensory neurons in the through and lungs detect irritants and send this information to the _____ in the _____
nucleus tractus solitarus (nTS), brainstem medulla oblongata
efferent neurons via _____ and ______ stimulate the diaphragm, intercostal muscles, and lung to initiate a cough
parasympathetic, motor nerves
how do antitussives work?
they inhibit neurons in the nucelus tractus solitarus (nTS)
codeine
a mu opioid receptor agonist, acts as an antitussive
where are mu opioid receptors located?
the nucleus tractus solitarus (nTS), peripheral nerves innervating the respiratory tract, and the brainstem regions that mediate the breathing reflecx
what type of receptors are opioid receptors?
inhibitory Gi coupled GPCRs
what are the direct effects of activating mu opioid receptors?
- inhibit Ca++ channels
- activate K+ channels
- inhibit adenylate cyclase
- neuronal inactivation
- reduced transmitter release
what is a negative effect of using high doses of opioids?
inhibit breathing reflex and can lead to death
dextromethorphan
a centrally active NMDA receptor antagonist which inhibits neurons in the nucleus tractus solitarus, acts as an antitussive
what are NMDA receptors?
a ligand gated ion channel gated by glutamate (excitatory)
diphenhydramine
an antihistamine (H1 inverse agonist), inhibits histamine action at the H1 receptors, crosses the blood brain barrier to suppress neurons in the nucleus tractus solitarus (nTS)
what are H1 receptors?
Gq coupled CPCRs, located on respiratory smooth muscle, stimulates sensory nerves producing coughing
