RS: Blood Gases Flashcards
What are the 2 types of breathing?
- Voluntary
2. Involuntary
How is voluntary (rhythmic) breathing controlled?
Controlled by sensory feedback receptors that are sensitive to partial pressure of carbon dioxide and oxygen, as well as pH.
What is voluntary breathing?
The overriding of involuntary breathing mechanisms during certain situations.
How is the diaphragm innervated?
Innervated by the phrenic nerves
How is the intercostal muscles innervated?
By intercostal nerves
When are the diaphragm and intercostal muscles innervated?
In times of need to trigger the appropriate muscles to contract and trigger inspiration or expiration, for the process of ventilation.
Where is the inspiratory centre situated?
In the medulla oblongata
What are the 3 regions of the respiratory centre?
- Dorsal respiratory group
- Ventral respiratory group
- Pontine respiratory group
What is the function of the dorsal respiratory group?
Integrates input from the stretch receptors and the chemoreceptors in the periphery.
The dorsal respiratory group is involved in maintaining a constant breathing rhythm by stimulating the diaphragm and intercostal muscles to contract, resulting in inspiration.
What happens when activity in the dorsal respiratory group ceases?
When activity in the DRG ceases, it no longer stimulates the diaphragm and intercostals to contract, allowing them to relax, resulting in expiration.
What is the function of the ventral respiratory group?
Generates the breathing rhythm and integrates data coming into the medulla.
The ventral respiratory group is involved in forced breathing, as the neurons in the VRG stimulate the accessory muscles involved in forced breathing to contract, resulting in forced inspiration. It also stimulates the accessory muscles involved in forced expiration to contract.
What is the function of the pontine respiratory group?
Influences and modifies the medulla oblongata functions.
Describe the structure of the pontine respiratory group
The pontine respiratory group consists of the apneustic and pneumotaxic centers.
What is the apneustic region of the pontine respiratory group?
The apneustic center is a double cluster of neuronal cell bodies that stimulate neurons in the DRG, controlling the depth of inspiration, particularly for deep breathing.
What is the pneumotaxic region of the pontine respiratory group?
The pneumotaxic center is a network of neurons that inhibits the activity of neurons in the DRG, allowing relaxation after inspiration, and thus controlling the overall rate.
How does inspiration arise?
Inspiration arises as a result of the progressive increase in the number of activated inspiratory neurones that increases the strength of the respiratory muscles.
How does expiration arise?
Expiration occurs as a result of the activation of inhibitory neurons which cause the inhibition if inspiratory neurons and activation of expiratory neurons. Expiratory neurons receive input from pons, lung stretch receptors, and other sources to trigger the relaxation of respiratory muscles.
Describe the rhythmic breathing processes of inspiration
Respiratory centre triggered by respiratory neurons to send nerve signals. Diaphragm and external intercostal muscles contract. Inspiration.
How long does inspiration take?
Roughly 2 seconds
How long does expiration take?
Roughly 3 seconds
Describe the rhythmic breathing processes of expiration
Respiratory centre receives signal to inhibit inspiratory neurons and activate expiratory neurons. Stops nerve signals so diaphragm and external intercostal muscles relax, and internal costal muscles and abdominal muscles contract. Expiration.
What inputs does the respiratory centre receive to alter rhythmic breathing?
Inputs from central chemoreceptors in the medulla oblongata and peripheral chemoreceptors associated with the aorta and carotid bodies, that are both sensitive to carbon dioxide, oxygen and pH.
What are the central chemoreceptors found?
In the medulla oblongata. Ventrolateral surface of medulla oblongata has a chemosensitive area that is anatomically distinct from, but synaptically connected to, the respiratory control centre.
Where are the peripheral chemoreceptors found?
Associated with the aorta and carotid bodies