Respiratory 30 Flashcards
What may cause tidal volume or respiratory rate to change?
Respiratory networks being stimulated or inhibited
What do small variations in PCO2 and PO2 occur with?
Activities such as sleep, exercise, talking, and panting
What are the chemical changes that alter ventilation mediated by?
The presence of peripheral and central chemoreceptors that give us control of ventilation
Where do chemoreceptors send their excitatory drive to when they sense changes in PO2, PCO2 and pH?
The dorsal respiratory group and the ventral respiratory group
Where are the Peripherial Chemoreceptors?
Outside the brain
Where are the Central Chemoreceptors?
Inside the brain
What conditions cause an increase in ventilation?
- Hypoxia (Low PO2)
- Hypercapnia (High PCO2)
- Acidosis (Low pH in blood)
What are the two Peripheral Chemoreceptors?
The Carotid and Aortic Bodies
What are the two peripheral chemoreceptors different from?
The Aortic and Carotid Sinuses which are baroreceptors
What do the Peripheral chemoreceptors sense?
Primarily hypoxia (low PO2) but are also sensitive to pH
What is the size of Carotid bodies?
They are extremely small
Why are Carotid bodies very chemosensitive?
Because they are highly vascularized
What is the metabolic rate of carotid bodies?
They have a very high metabolic rate with high consumption of oxygen and high carbon dioxide production
What is the ratio of metabolic rate to perfusion in Carotid bodies?
The ratio favors perfusion meaning that the blood composition is virtually the same as in the arteries despite the high metabolism
What are the two cell populations in the Carotid bodies?
- Type I (Glomus cells) - The chemosensitive cells
* Type II (Sustentacular cells) - Support in the carotid bodies
Which cells in the Carotid body are neuron like cells?
The Type I Glomus cells
What are the neuron like characteristics of Glomus cells in the Carotid body?
- Voltage gated ion channels
- Depolarization triggers action potentials
- Intracellular vesicles contain neurotransmitters
- Stimulation causes the release of neurotransmitters
What do the neurotransmitters released by the Carotid bodies excite?
The Glossopharyngeal afferents which will drive input to the dorsal respiratory group
From the Dorsal Respiratory group, where do signals from the Carotid bodies go?
To the PreBotzinger complex and PFRG to increase respiratory drive to the muscles and increase ventilation
What is the Primary stimulus for the peripheral chemoreceptors?
A decrease in arterial PO2
When does the firing rate of Glomus cells increase?
With the lowering of PO2
Besides changes in PO2, what are glomus cells also sensitive to?
Changes in PCO2 and pH because
At what pressure of PO2 does ventilation change?
Below 60 mmHg
What do the Peripheral chemoreceptors activate?
The dorsal and ventral respiratory group in the neurons
What is the overall effect of Peripheral chemoreceptors in response to low arterial PO2?
- Increase in respiratory rate
* Increase in Tidal volume
How can changes in arterial PCO2 affect breathing?
Small changes in PCO2 can provide very large changes in minute ventilation
