Drive - receptors Flashcards
What is the role of receptors in the pharynx?
To stop respiratory activity during swallowing - protecting against aspiration of food or liquid
Where/in what are slowly adapting stretch receptor found?
Airway smooth muscle
What are slowly adapting stretch receptors activated by?
Lung distension
Where/in what are rapidly stretch receptors found?
Between airway epithelial cells
What are rapidly adapting stretch receptor activated by?
Lung distension and irritants
What are receptors in the pharynx activated by?
Swallowing
In slowly adapting stretch receptors how long are the action potentials initiated in afferent neutrons?
For the duration of the stimulus
In rapidly adapting stretch receptors how long are the action potentials initiated in afferent neutrons?
At the onset of the stimulus but very quickly cease responding
Where are C fibres J receptors found?
In either capillary walls and the interstitium
For slowly adapting stretch fibres, rapidly adapting stretch fibres and C fibres J receptors say which are myelinated and which are not.
Slowly adapting stretch fibres = myelinated
Rapidly adapting stretch fibres = myelinated
C fibres J receptors = non-myelinated
What are C fibres J receptors stimulated by?
An increase in lung interstitial pressure (caused by the collection of fluid in the interstitium)
What is ventilatory drive extremely sensitive to?
Arterial partial CO2 pressure (particularly of blood entering the brain as it triggers central chemoreceptors)
What is hypoxia?
A deficiency of oxygen at tissue level
What is hypercapnia?
Carbon dioxide retention and arterial partial CO2 pressure.
What categorises respiratory failure as type 1?
pO2 = low pCO2 = low or normal
Name a common cause of type 1 respiratory failure:
Pulmonary embolism
What categorises respiratory failure type 2?
pO2 = low pCO2 = high
Name a common cause of type 2 respiratory failure:
Hypoventilation
Describe the process that occurs when acetylcholine binds to the M3 receptor: (6)
1) acetyl choline binds to the M3 receptor
2) Receptor couples with Gq protein
3) Gq protein activates phospholipase C
4) Phospholipase C catalyses the breakdown of a plasma membrane phospholipid to DAG and IP3.
5) DAG acts as a second messenger and activates a family of proteins known as protein kinase C
6) IP3 binds to ligand-gated Ca2+ receptors located on the endoplasmic reticulum in bronchial. Which then open resulting in the release of Ca2+ which then stimulates bronchoconstriction
Describe the process that occurs when noradrenaline binds to the G couple protein receptor: (5)
1) noradrenaline binds to receptor
2) Receptor couples with Gs protein
3) Gs protein adrenyl cyclase
4) Adrenyl cyclase then catalyses the conversion of cytosolic ATP to cyclic AMP (cAMP)
5) cAMP then acts as a second messenger then diffuses in the resulting in a decrease in Ca2+ concentrations resulting in bronchodilation.
What does an agonist receptor ligand do?
Binds to a receptor and activates it (affinity and efficacy)
What does an antagonist receptor ligand do?
Binds to a receptor (competitively inhibiting the agonist) but does NOT activate it (affinity but zero efficacy)
What is measured by the term affinity?
The degree to which a particular messenger binds to its receptor
What is measured by the term efficacy?
How well a ligand activates a receptor (how large the conformational change in shape is)
